Investigation the heavy metal contents in surface water and sediment collected

Phetdalaphone BOUTTAVONG 2009-2011

1

VIETNAM NATIONAL UNIVERSITY, HANOI

VNU UNIVERSITY OF SCIENCE

PHETDALAPHONE BOUTTAVONG

INVESTIGATION THE HEAVY

METAL CONTENTS IN SURFACE WATER AND

SEDIMENT COLLECTED IN THADLUANG

MARSH (LAO PDR)

MASTER THESIS

HANOI, 2011


2

VIETNAM NATIONAL UNIVERSITY, HANOI

VNU UNIVERSITY OF SCIENCE

PHETDALAPHONE BOUTTAVONG

INVESTIGATION THE HEAVY METAL

CONTENTS IN SURFACE WATER AND SEDIMENT

COLLECTED IN THADLUANG

MARSH (LAO PDR)

MASTER THESIS

Supervisor: Assoc. Prof. PhD. Ta Thi Thao

HANOI, 2011


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Abstract

In Vientiane, water and sanitation management in the urban area is experiencing

stagnant pollution. Unsanitary conditions and threat of seasonal pollution in selected

spots is likely to occur and increase with the growing urban population. The

sanitation system entails an on-site disposal of human waste without introduction of

full water-borne sewerage with treatment facility and safe disposal arrangement. The

majorities of households relies on water flush latrines and are connected to a pit or

chamber for containment of excreta. However, due to the low permeability of the soil

and the high groundwater table around Vientiane, many soak-a-ways fail to operate

effectively resulting in discharge of sewage from tanks into drainage channels or low

lying areas. This pollution leads to effluent overflows, environmental degradation

and health hazards.

For the sake of assessment in what extent is water polluted, an analytical method

with high sensitivity and the capability and providing a good accuracy and precision

should be used. Atomic absorption spectroscopy (AAS) is a spectroanalytical

procedure for the qualitative and quantitative determination of chemical elements

employing the absorption of optical radiation (light) by free atoms in the gaseous

state. In analytical chemistry the technique is used for determining the concentration

of a particular element (the analyte) in a sample to be analyzed. The technique makes

use of absorption spectrometry to assess the concentration of an analyte in a sample.

My study focuses on heavy metals content in surface water and sediment collected in

ThadLuang Marsh in Vientiane Capital City. Providing an overview about

alarmingly polluted situation, this research based on determination of Copper, Lead,

Cadmium and Zinc by Flame – Atomic absorption spectroscopy.


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Acknowledgements

I would like to thank, DAAD, Deutscher Akademischer Austauschdienst (German

Academic Exchange Service) and Technich University Dresden for providing the

scholarship of the Master’s program. My sincere thanks also due to the Dean of

faculty Environmental of sciences in National University of Lao P.D.R for the kind

permission offered me to study.

Thank Assoc. Prof. Dr. Ta Thi Thao - my supervisors for encouragement,

constructive guidance's

I would like to express the profound gratitude and the great appreciation to my

advisor Prof. Bernd Bilitewski for his excellent guidance, excellent encouragement

and valuable suggestions throughout this study. Special appreciation is extended to

Prof. Dr. Nguyen Thi Diem Trang and Prof. Dr. Do Quang Trung committee

members for their valuable recommendation and dedicated the valuable time to

evaluate my work and my study during being in Vietnam.

During studying in Hanoi University of Science, I felt very lucky, it give me the

opportunity to have lots of good friends, good memories, so I would like to say

thanks and pleasure to meet all of you. Even though we came from different

countries, we can make friend together. I hope and wish that I would work together

and meet each other again in some conferment.

Finally I would like to express deep appreciation to my lovely family and relatives

for their love, kind support, and encouragement for the success of this study. This

thesis is dedicated for you.


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Contents List of Figures .............................................................................................................. 7

List of Tables ................................................................................................................ 8

List of Abbreviations .................................................................................................... 9

INTRODUCTION ...................................................................................................... 10

CHAPTER 1: OVERVIEW OF WATER AND SEDIMENT POLLUTION IN

THADLUANG MARSH............................................................................................10

1.1. Topography of ThadLuang marsh ................................................................... 13

1.2. Present status of water and sediment pollution in ThadLuang marsh ............. 14

1.3. Toxicity of Cadmium Cd, Copper Cu, Lead Pb, Zinc Zn ................................ 16

1.3.1. Cadmium Cd .............................................................................................. 16

1.3.2. Copper Cu .................................................................................................. 17

1.3.3. Lead Pb ...................................................................................................... 18

1.3.4. Zinc Zn ...................................................................................................... 20

1.4. Analytical methods for determination of heavy metals in water and sediment

samples .................................................................................................................... 22

1.4.1. Electrochemical methods ........................................................................... 22

1.4.2. Spectrophotometric methods ..................................................................... 24

CHAPTER 2: EXPERIMENTS ................................................................................. 28

2.1. Research Objects and research contents .......................................................... 28

2.1.1. Research objects ........................................................................................ 28

2.1.2. Research contents ...................................................................................... 28

2.2. Chemicals and Apparatus ................................................................................ 29

2.2.1. Chemicals .................................................................................................. 29


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2.2.2. Apparatus ................................................................................................... 29

2.2.3. Equipments ................................................................................................ 30

2.3 Sampling and Sample Preparation .................................................................... 30

2.3.1. Study Area ................................................................................................. 30

2.3.2. Sampling and sample preparation ............................................................. 35

2.3.3. Sediment samples ...................................................................................... 35

2.4. Analytical methods for determination of Cu, Pb, Cd, Zn ................................ 36

2.4.1. Flame atomic absorption spectroscopy method (F-AAS): determination of

heavy metal content in sediment samples ........................................................... 36

2.4.2. Inductive couple plasma – mass spectrophotometry (ICP-Ms) for the

determination of heavy metal contents in surface water samples ....................... 40

2.4.3. Quality control of analytical methods ....................................................... 43

CHAPTER 3: RESULTS AND DISCUSSION ......................................................... 45

3.1. Optimizations of some chemical factors influencing to absorbance in F- AAS

method ..................................................................................................................... 45

3.1.1. Study the effects of sample matrix and matrix modifier to F-AAS .......... 45

3.1.2. Calibration curves of Pb, Cd, Zn and Cu measurements. .......................... 49

3.1.3. Limit of detection (LOD) and Limit of quantitation (LOQ) ..................... 53

3.1.4. Effect of interferences to the determination of Pb, Cd and Cu, Zn by

FAAS. .................................................................................................................. 54

3.2. Determination of Pb, Cu, Zn, Cd in surface water samples using ICP-MS .... 57

3.2.1. Calibration curves for the determination of Cu, Zn, Pb and Cd in water

samples. ............................................................................................................... 57

3.2.2. Method validation ...................................................................................... 59

3.3. Total concentrations of Cu, Pb, Cd, Zn in surface water and sediment of

ThadLuang marsh ................................................................................................... 60

3.3.1. Water sample: ............................................................................................ 60

3.3.2. Sediment sample ........................................................................................ 60

3.4. Application of GIS to find out spartial distribution of heavy metals .............. 64


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CHAPTER 4: CONCLUSION .............................................................................. ….66

REFERENCE..............................................................................................................65

List of figures

Figure 1.1: Target Villages around ThadLuang Marsh

Figure 2.1: Spectrometer atomic absorption novAA 6800, Shimazhu

Figure 2.2: The map of Thatluang marsh showing water sampling sites.

Figure 2.3: The map of Thadluang marsh showing sediment sampling sites.

Figure 2.4: Operation principle of an atomic absorption spectrometer

Figure 2.5: Block diagram of atomic absorption spectrometer

Figure 2.6: Instrumentation for low-resolution ICP-MS.

Figure 3.1: The investigation of linear ranges for the determination of Pb, Cd, Zn and

Cu using F-AAS

Figure 3.2: The calibration curves for the determinations of Pb, Cd, Zn and Cu in

standard solutions

Figure 3.3: Calibration curves for the determination of Cu, Cd, Pb and Zn using ICP-

MS.

Figure 3.4: The Map of water quality of Thadluang Marsh.

Figure 3.5: The Map of sediment quality of Thadluang Marsh.


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List of tables

Table 1.1: Some data published on pollution in ThadLuang marsh

Table 2.1: Characteristics of the sampling points in Thadluang marsh

Table 2.2: Characteristics of the sediment points in Thadluang marsh

Table 2.3: The optimal conditions of F-AAS for measuring Pb, Cd, Zn, Cu

Table 2.4: The experimental conditions for determination of Cu, Pb, Cd and Zn using

ICP- MS techniques

Table 3.1: Investigation of HNO3 and NH4CH3COO effects on analysis of Pb, Cd, Cu

and Zn

Table 3.2: Two - way ANOVA table for evaluating effects of HNO3 and

NH4CH3COO

Table 3.3: Influence of types of acid media HCl, HNO3 and H2SO4 effects on Cu2+

and Pb2+

analysis

Table 3.4: The absorbance of each metal atom (after subtracting the absorbance of

the blank solution) vs. their concentrations

Table 3.5: The absorbance of each heavy metal standard solutions in the linear range

of concentrations

Table 3.6: LOD and LOQ of the determination of Pb, Cd, Zn and Cu using F-AAS

method

Table 3.7: Result of errors and repeatability of the measurements

Table 3.8: Accuracy and recovery of CRM using FAAS and ICP-MS

Table 3.9: The concentration of Pb, Cd, Zn, Cu in surface water samples of

ThadLuang Marsh (g/L)

Table 3.10: Heavy metal content (mg/kg) in sediment collected in Thadluang marsh.

Table 3.11: Proposed Surface Water Quality standard


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List of abbreviations

Lao PDR The Lao People’s Democratic Republic

EDTA Ethylene-diamine-tetracetic acid

DME Dropping mercury electrode

SMDE Static mercury drop electrode

AES Atomic emission spectroscopy

F-AAS Flame Atomic absorption spectroscopy

ICP-Ms Inductive couple plasma – mass spectrophotometry

ANOVA The analysis of variance

LOL The limit of linearity

LOD Limit of detection

LOQ Limit of quantitation

http://en.wikipedia.org/wiki/EDTA

http://en.wikipedia.org/wiki/Dropping_mercury_electrode


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INTRODUCTION

The Lao People’s Democratic Republic (Lao PDR) is a small landlocked and

sparsely populated country in the South East Asia. Laos is characterized by two main

geographical zones: the central plains along the Mekong River and the mountainous

regions to the north, east and south. Lao PDR has a land area of 236,800 square

kilometers (sq. km.). It is long and slender, the length from north to south is nearly

1,000 kilometers and the width has only 150 kilometers to 400 kilometers. [STEA,

2004] The total population is approximately 5,621,982 people, in which women

accounted for 51%, according to the 2005 population and housing census. The

population density of the country is around 24 people per hectare which is the lowest

population densities in Asia. 39% of Lao population is classified as poor and 36% are

under poverty line. [MRC, 2006] Their living condition depends on nature, hunting

wildlife, foraging for forest products and practicing slash and burn cultivation for

their crops with a low profit in order to survive.

Lao PDR has rich water resources, mainly good quality fresh water. The amount of

average water flow in the Mekong and its tributaries amount to about 8,500 m3/s.

Currently most of the water occurs in the agricultural sector, for instance, irrigation,

fisheries, plantations and livestock watering. 60 percent of urban population and 51

percent of rural population has access to clean water. [Draft Agreement, March 2009]

The total of annual water flow in Lao PDR is estimated at 270 billion cubic meters,

equivalent to 35% of the average annual flow of the whole Mekong Basin. The

monthly distribution of the flow of the rivers in Lao PDR closely follows the pattern

of rainfall: about 80% during the rainy season (May-October) and 20% in the dry

season, from November to April. For some rivers in the central and southern parts of

the country (particularly Se Bang Fai, Se Bang Hieng and Se Done) the flow in the

dry season is less: around 10 to 15% of the annual flow. [Agricultural Statistics


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[April 2005]. The rivers outside the Mekong Basin flow through Viet Nam into the

South China Sea. These rivers are Nam Ma, Nam Sam, and Nam Neune. The limited

information on these rivers restricts assessment of their potential.

Most of the water use occurs in the agricultural sector such as irrigation, fisheries,

plantations and livestock watering. In addition the water is used for hydro-power; the

country has the potential to produce 23,000 megawatts of electricity. Currently 5% of

that capacity has been exploited. [Would Back, 2007] The plenteous supply of water

in Lao PDR, especially in the rainy season, provides good condition for water

transport, industrial development and water supply. Sixty percent of urban

population and 51 % of rural population has access to clean water.

Currently there are some problems related to waste and polluted water in major urban

areas from varied community use (residential density, hotels, hospitals and

entertainments centers). In addition there is water pollution from agricultural and

industrial sectors, including mineral exploitation. This is not a major problem now,

but the problem could escalate. The degradation of natural water and water

catchments from sedimentation, land erosion and drying out continues.

However, as continued development takes place in all of these areas, increasing

scarcity and competition for water can be expected. Increasing impacts of

development on water quality and on human health and the natural environment will

also take place. Finally, floods and drought can have serious negative impacts and

may, in fact, increase as climate change takes place.

Vientiane Capital is located on an alluvial plain along the left bank of Mekong River

east to west. The area of Vientiane is about 3,920 km2 and the elevation of the ground

ranges from 160 m to 170 m above the sea level. The city comprises 9 districts;

Chanthabuly, Hadxayfong, Meungparkngum, Naxaithong Sangthong, Sikhottabong,

Sisattanak, Saysettha and Xaythany. The population is around 672,912 people. The

area designated for urbanization extends along the left bank of Mekong River and

occupies an area of 210 km2. [JICA, 2009] For Thadluang wetland, its water quality

is a part of the water quality-monitoring project of Mekong Secretariat, in the vicinity

of Vientiane Capital City. Main problems found are wastewater and sewage (from

the city area) discharged into the marsh.

Especially, no sooner do many factories appear and develop increasing fast than

water is polluted by heavy metals is over allowable limit. Owing to not taking part in


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biochemical process, heavy metals such as Cd, Pb, Zn, Cu … are accumulated in

human body, which leads to harmfulness for organism. The fact that water is polluted

by heavy metal is often seen in rivers near industrial area, big cities and minerals

exploiting area. The main reason leading to heavy metals pollution is pouring into

water environment a large amount of industrial and untreated wastewater. Pollution

by heavy metals accumulated through foods directly into organism has negative

effects on life environment. In order to reduce consequence of this problem, it is

necessary to cultivate measures of water treatment.


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CHAPTER 1: OVERVIEW OF WATER AND SEDIMENT

POLLUTION IN THADLUANG MARSH

1.1. Topography of Thad Luang marsh

The ThadLuang Marshland is the largest remaining wetland in Vientiane

Municipality, located on the eastern edge of the capital city of Lao PDR. The marsh

itself is approximately 20 km2 and is a part of the ThadLuang Basin drained from

Vientiane City and surrounding areas. A large portion of the wetland has been

converted to rice cultivation although changes in water regimes have resulted in

annual floods and cultivation has been limited to between 700 - 1000 ha

(approximately half of the wetland area) in recent years. The remaining area is

covered with permanent and seasonal aquaculture ponds, shrub and grassland, and

peat land. [NUOL, March, 2002] Water draining into the ThadLuang Marshland

comes primarily from irrigation canal at the Donnokkoom rice field, Hong Ke and

Hong Xeng stream, which collects its water from drainage canals running throughout

Vientiane. Water running out of the marsh follows Houay Mak Hiao River dumping

into the Mekong 64 km south east of Vientiane.

Based on a recent government survey in the That Lung area, about 90 percent

of households around ThadLuang Marsh are classified as poor and only 10 percent of

households as relatively better off category. Because of the structure of rural

employment, the livelihoods of households around ThadLuang Marsh are highly

depended upon the ThadLuang marsh, and the water resources availability at the

marsh. This is because agriculture and sale of agriculture produce are the primary

income generating activity for over 70 % of households living around the ThadLuang

marsh. About 7 percent of the total households there are without a primary form of

income from agriculture (farming), and it is likely that they rely heavily on collecting

fish and aquatic produce from the marsh area. [STO, 2009] Therefore, being one of

main reasons leading to poverty, water and sediment pollution in ThadLuang marsh

affect significantly on life of people here.


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Figure 1.1.Villages around ThadLuang Marsh

1.2. Present status of water and sediment pollution in ThadLuang marsh

ThadLuang Marsh receives domestic sewage discharge from a large

proportion of Vientiane city by way of several canals. While Vientiane has a

sewerage system, there is currently no functioning waste treatment facility near the

urban area. Sewage is either hauled to a waste treatment plant 17 km outside of the

city limits or, more commonly, discharged into natural water bodies, either as raw

wastes or as seepage from septic tanks. Sewerage and sanitation systems rely on the

infiltration of wastewater into the ground. However due to the low soil permeability

and the high groundwater table in Vientiane, many soak ways fail to operate

efficiently meaning that sewage is discharged from tanks and drains directly into

urban wetlands. As a result of considerable quantity of household waste and sewage

is discharged into Nong Chang, and then flows into ThadLuang Marsh before

entering the Mekong. Textile, detergent and paper plants discharge directly into open

drains without any treatment, and contribute wastewaters into ThadLuang Marsh.


15

There are two tanneries although the larger of these has sophisticated treatment

facilities, in practice wastes bypass these and are discharged untreated. The brewery

on the southern shore of ThadLuang passes waste through an oxidation pond.

Because of the importance of ThadLuang with issues directly relating to

Vientiane environment, it is irrefutable that researching water pollution in

ThadLuang is necessary and must be done immediately. Some data published on

pollution in ThadLuang marsh is shown in table 1.1.

Table 1.1: Some data published on pollution in ThadLuang marsh.

Parameters Unit 2002 2003 Standard

(STEA, 2000)

pH (mg/l) 7.8 8.8 6 – 9.5

Temperature o

C 28 32.6 *

Electrical Conductivity (EC) (micro/cm) 266 438 *

Dissolve Oxygen (DO) mg/l 2.8 1.1 >2

Biological Oxygen Demand (BOD) mg/l 39 78.3 4

Ammonia nitrogen (NH3-N) mg/l 0.294 0.389 0.2

Nitrate-Nitrogen (NO3-N) mg/l 3.064 3.991 <5.0

PO4-P (mg/l) 5.4 6.45 30

Total-N (mg/l) 5.6 3.19 *

Total-P (mg/l) * 5.951 *

This table only mentions about some norms such as BOD, COD, EC, DO …

Most scientific research has shown that there is no data on heavy metals pollution

until now. This study will provide more information to this missing part. According

to this table, pH, BOD, Ammonia nitrogen (NH3-N) and PO4-P parameters are much

higher than standard while Dissolve Oxygen (DO) and Nitrate-Nitrogen (NO3-N) are


16

lower. There is sound that water pollution appears compared to Surface Water

Quality Standard in Lao PDR. Also, by the fact that it exist wastewater and sewage

(from the city area) discharged into the marsh. Especially, no sooner do many

factories appear and develop increasing fast than water is polluted by heavy metals is

over allowable limit.

1.3. Toxicity of Cadmium Cd, Copper Cu, Lead Pb, Zinc Zn

1.3.1. Cadmium Cd

The most dangerous form of occupational exposure to cadmium is inhalation

of fine dust and fumes, or ingestion of highly soluble cadmium compounds.

Inhalation of cadmium-containing fumes can result initially in metal fume fever but

may progress to chemical pneumonitis, pulmonary edema, and death. [Ayres, Robert

U, 2003]

Cadmium is also an environmental hazard. Human exposures to environmental

cadmium are primarily the result of fossil fuel combustion, phosphate fertilizers,

natural sources, iron and steel production, cement production and related activities,

nonferrous metals production, and municipal solid waste incineration. However,

there have been a few instances of general population toxicity as the result of long-

term exposure to cadmium in contaminated food and water. In the decades leading up

to World War II, Japanese mining operations contaminated the Jinzū River with

cadmium and traces of other toxic metals.[National Research Council (U.S.), 1969) ]

As a consequence, cadmium accumulated in the rice crops growing along the

riverbanks downstream of the mines. Some members of the local agricultural

communities consuming the contaminated rice developed itai-itai disease and renal

abnormalities, including proteinuria and glucosuria.

The victims of this poisoning were almost exclusively post-menopausal

women with low iron and other mineral body stores. Similar general population

cadmium exposures in other parts of the world have not resulted in the same health

problems because the populations maintained sufficient iron and other mineral levels.

Thus, while cadmium is a major factor in the itai-itai disease in Japan, most

researchers have concluded that it was one of several factors. Cadmium is one of six

substances banned by the European Union's Restriction on Hazardous Substances

(RoHS) directive, which bans certain hazardous substances in electrical and

http://en.wikipedia.org/wiki/Metal_fume_fever

http://en.wikipedia.org/wiki/Pneumonitis

http://en.wikipedia.org/wiki/Pulmonary_edema

http://en.wikipedia.org/wiki/Death

http://en.wikipedia.org/wiki/World_War_II

http://en.wikipedia.org/wiki/Jinz%C5%AB_River

http://en.wikipedia.org/wiki/Itai-itai

http://en.wikipedia.org/wiki/Proteinuria

http://en.wikipedia.org/wiki/Glucosuria

http://en.wikipedia.org/wiki/ROHS


17

electronic equipment but allows for certain exemptions and exclusions from the

scope of the law.

Although some studies linked exposure to cadmium with lung and prostate

cancer, there is still a substantial controversy about the carcinogenicity of cadmium.

More recent studies suggest that arsenic rather than cadmium may lead to the

increased lung cancer mortality rates. Furthermore, most data regarding the

carcinogenicity of cadmium rely on research confounded by the presence of other

carcinogenic substances.

Tobacco smoking is the most important single source of cadmium exposure in

the general population. It has been estimated that about 10% of the cadmium content

of a cigarette is inhaled through smoking. The absorption of cadmium from the lungs

is much more effective than that from the gut, and as much as 50% of the cadmium

inhaled via cigarette smoke may be absorbed. [Jarup, L. (1998)]

On average, smokers have 4-5 times higher blood cadmium concentrations

and 2 - 3 times higher kidney cadmium concentrations than non - smokers. Despite

the high cadmium content in cigarette smoke, there seems to be little exposure to

cadmium from passive smoking. No significant effect on blood cadmium

concentrations has been detected in children exposed to environmental tobacco

smoke.

Cadmium exposure is a risk factor associated with early atherosclerosis and

hypertension, which can both lead to cardiovascular disease.

1.3.2. Copper Cu

Copper toxicity refers to the consequences of an excess of copper in the body.

Copper toxicity can occur from eating acid food that has been cooked in un-coated

copper cookware, or from exposure to excess copper in drinking water or other

environmental sources.

Copper in the blood exist in two forms: bound to ceruloplasmin (85–95%) and

the rest "free" loosely bound to albumin and small molecules. Free copper causes

toxicity as it generates reactive oxygen species such as superoxide, hydrogen

peroxide, the hydroxyl radical. These damage proteins, lipids and DNA.

[Federal

Register, 1976]

http://en.wikipedia.org/wiki/Passive_smoking

http://en.wikipedia.org/wiki/Copper

http://en.wikipedia.org/wiki/Ceruloplasmin

http://en.wikipedia.org/wiki/Albumin

http://en.wikipedia.org/wiki/Reactive_oxygen_species

http://en.wikipedia.org/wiki/Superoxide

http://en.wikipedia.org/wiki/Hydrogen_peroxide



http://en.wikipedia.org/wiki/Hydroxyl_radical

http://en.wikipedia.org/wiki/Protein

http://en.wikipedia.org/wiki/Lipid

http://en.wikipedia.org/wiki/DNA


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Acute symptoms of copper poisoning by ingestion include vomiting,

hematemesis (vomiting of blood), hypotension (low blood pressure), melena (black

"tarry" feces), coma, jaundice (yellowish pigmentation of the skin), and

gastrointestinal distress. Individuals with glucose-6-phosphate deficiency may be at

increased risk of hematologic effects of copper. Hemolytic anemia resulting from the

treatment of burns with copper compounds is infrequent.

Chronic (long-term exposure) effects of copper exposure can damage the liver

and kidneys. Mammals have efficient mechanisms to regulate copper stores such that

they are generally protected from excess dietary copper levels.

The U.S. Environmental Protection Agency's Maximum Contaminate Level (MCL)

in drinking water is 1.3 milligrams per Liter. The MCL for copper is based on the

expectation that a lifetime of consuming copper in water at this level is without

adverse effect (gastrointestinal effect). The U.S EPA lists evidence that copper

causes testicular cancer as "most adequate" according to the latest research at

Sanford-Burnham Medical Research Institute. The Occupational Safety and Health

Administration (OSHA) has set a limit of 0.1 mg/m3 for copper fumes (vapor

generated from heating copper) and 1 mg/m3 for copper dusts (fine metallic copper

particles) and mists (aerosol of soluble copper) in workroom air during an 8-hour

work shift, 40-hour workweek. [Curtis D. Klassen, Ph.D., McGraw-Hill]

1.3.3. Lead Pb

Lead is a poisonous metal that can damage nervous connections (especially in

young children) and cause blood and brain disorders. Lead poisoning typically

results from ingestion of food or water contaminated with lead; but may also occur

after accidental ingestion of contaminated soil, dust, or lead based paint. Long-term

exposure to lead or its salts (especially soluble salts or the strong oxidant PbO2) can

cause nephropathy, and colic-like abdominal pains. The effects of lead are the same

whether it enters the body through breathing or swallowing. Lead can affect almost

every organ and system in the body. The main target for lead toxicity is the nervous

system, both in adults and children. Long-term exposure of adults can result in

decreased performance in some tests that measure functions of the nervous system. It

may also cause weakness in fingers, wrists, or ankles. Lead exposure also causes

small increases in blood pressure, particularly in middle-aged and older people and

can cause anemia. Exposure to high lead levels can severely damage the brain and

http://en.wikipedia.org/wiki/Nephropathy

http://en.wikipedia.org/wiki/Colic


19

kidneys in adults or children and ultimately cause death. In pregnant women, high

levels of exposure to lead may cause miscarriage. Chronic, high-level exposure has

shown to reduce fertility in males. The antidote/treatment for lead poisoning consists

of dimercaprol and succimer.

The concern about lead's role in cognitive deficits in children has brought

about widespread reduction in its use (lead exposure has been linked to learning

disabilities). Most cases of adult elevated blood lead levels are workplace-

related. High blood levels are associated with delayed puberty in girls. Lead has been

shown many times to permanently reduce the cognitive capacity of children at

extremely low levels of exposure.

During the 20th century, the use of lead in paint pigments was sharply reduced

because of the danger of lead poisoning, especially to children. By the mid-1980s, a

significant shift in lead end-use patterns had taken place. Much of this shift was a

result of the U.S. lead consumers' compliance with environmental regulations that

significantly reduced or eliminated the use of lead in non-battery products,

including gasoline, paints, solders, and water systems. Lead use is being further

curtailed by the European Union's RoHS directive. Lead may still be found in

harmful quantities in stoneware, vinyl (such as that used for tubing and the insulation

of electrical cords), and brass manufactured in China. Between 2006 and 2007 many

children's toys made in China were recalled, primarily due to lead in paint used to

color the product. [Stellman, Jeanne Mager (1998).]

Older houses may still contain substantial amounts of lead paint. White lead

paint has been withdrawn from sale in industrialized countries, but the yellow lead

chromate is still in use; for example, Holland Colours Holcolan Yellow. Old paint

should not be stripped by sanding, as this produces inhalable dust.

Lead salts used in pottery glazes have on occasion caused poisoning, when

acidic drinks, such as fruit juices, have leached lead ions out of the glaze. It has been

suggested that what was known as "Devon colic" arose from the use of lead-lined

presses to extract apple juice in the manufacture of cider. Lead is considered to be

particularly harmful for women's ability to reproduce. Lead (II) acetate (also known

as sugar of lead) was used by the Roman Empire as a sweetener for wine, and some

consider this to be the cause of the dementia that affected many of the Roman

Emperors.

http://en.wikipedia.org/wiki/Dimercaprol

http://en.wikipedia.org/wiki/Succimer

http://en.wikipedia.org/wiki/Learning_disabilities



http://en.wikipedia.org/wiki/Pigment

http://en.wikipedia.org/wiki/Gasoline

http://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive

http://en.wikipedia.org/wiki/Lead_paint

http://en.wikipedia.org/wiki/Lead_chromate



http://en.wikipedia.org/w/index.php?title=Holland_Colours&action=edit&redlink=1

http://en.wikipedia.org/wiki/Devon_colic

http://en.wikipedia.org/wiki/Cider

http://en.wikipedia.org/wiki/Lead(II)_acetate

http://en.wikipedia.org/wiki/Roman_Empire

http://en.wikipedia.org/wiki/Dementia


20

Lead as a soil contaminant is a widespread issue, since lead is present in

natural deposits and may also enter soil through (leaded) gasoline leaks from

underground storage tanks or through a waste stream of lead paint or lead grindings

from certain industrial operations.

Lead can also be found listed as a criteria pollutant in the United States Clean

Air Act section 108. Lead that is emitted into the atmosphere can be inhaled, or it can

be ingested after it settles out of the air. It is rapidly absorbed into the bloodstream

and is believed to have adverse effects on the central nervous system, the

cardiovascular system, kidneys, and the immune system. [Hong, Youlian and

Bartlett, Roger, ed (2008)].

In the human body, lead inhibits porphobilinogen synthase and ferrochelatase,

preventing both porphobilinogen formation and the incorporation of iron into

protoporphyrin IX, the final step in hemi synthesis. This causes ineffective hemi

synthesis and subsequent microcytic anemia. At lower levels, it acts as a calcium

analog, interfering with ion channels during nerve conduction. This is one of the

mechanisms by which it interferes with cognition. Acute lead poisoning is treated

using disodium calcium edentate: the calcium chelae of the disodium salt of

ethylene-diamine-tetracetic acid (EDTA). This chelating agent has a greater affinity

for lead than for calcium and so the lead chelae is formed by exchange. This is then

excreted in the urine leaving behind harmless calcium.

1.3.4. Zinc Zn

Although zinc is an essential requirement for good health, excess zinc can be

harmful. Excessive absorption of zinc suppresses copper and iron absorption. The

free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate

fish. The Free Ion Activity Model is well-established in the literature, and shows that

just micro molar amounts of the free ion kills some organisms. A recent example

showed 6 micro molar killing 93% of all Daphnia in water. [Barceloux, Donald G.;

(1999)].

The free zinc ion is a powerful Lewis acid up to the point of being corrosive.

Stomach acid contains hydrochloric acid, in which metallic zinc dissolves readily to

give corrosive zinc chloride. Swallowing a post-1982 American one cent piece

(97.5% of zinc) can cause damage to the stomach lining due to the high solubility of

the zinc ion in the acidic stomach.

http://en.wikipedia.org/wiki/Soil_contaminant

http://en.wikipedia.org/wiki/Underground_storage_tank

http://en.wikipedia.org/wiki/Criteria_pollutant

http://en.wikipedia.org/wiki/United_States_Clean_Air_Act



http://en.wikipedia.org/wiki/Porphobilinogen_synthase

http://en.wikipedia.org/wiki/Ferrochelatase

http://en.wikipedia.org/wiki/Porphobilinogen

http://en.wikipedia.org/wiki/Iron

http://en.wikipedia.org/wiki/Protoporphyrin_IX

http://en.wikipedia.org/wiki/Heme

http://en.wikipedia.org/wiki/Microcytic_anemia

http://en.wikipedia.org/wiki/EDTA

http://en.wikipedia.org/wiki/Mole_(unit)

http://en.wikipedia.org/wiki/Daphnia

http://en.wikipedia.org/wiki/Lewis_acid

http://en.wikipedia.org/wiki/Corrosive

http://en.wikipedia.org/wiki/Hydrochloric_acid

http://en.wikipedia.org/wiki/Cent_(United_States_coin)


21

There is evidence of induced copper deficiency at low intakes of 100–300 mg

Zn/day; a recent trial had higher hospitalizations for urinary complications compared

to placebo among elderly men taking 80 mg/day [Fosmire GJ (1990)]. The USDA

RDA is 11 and 8 mg Zn/day for men and women, respectively. Even lower levels,

closer to the RDA, may interfere with the utilization of copper and iron or adversely

affect cholesterol. Levels of zinc in excess of 500 ppm in soil interfere with the

ability of plants to absorb other essential metals, such as iron and manganese. There

is also a condition called the zinc shakes or "zinc chills" that can be induced by the

inhalation of freshly formed zinc oxide formed during the welding of galvanized

materials.

The U.S. Food and Drug Administration (FDA) has stated that zinc damages

nerve receptors in the nose, which can cause anomies. Reports of anomies were also

observed in the 1930s when zinc preparations were used in a failed attempt to

prevent polio infections. On June 16, 2009, the FDA said that consumers should stop

using zinc-based intranasal cold products and ordered their removal from store

shelves. The FDA said the loss of smell can be life-threatening because people with

impaired smell cannot detect leaking gas or smoke and cannot tell if food has spoiled

before they eat it. Recent research suggests that the topical antimicrobial zinc

pyrithione is a potent heat shock response inducer that may impair genomic integrity

with induction of PARP-dependent energy crisis in cultured human keratinocytes

and melanocytes.

In 1982, the United States Mint began minting pennies coated in copper but

made primarily of zinc. With the new zinc pennies, there is the potential for zinc

toxic sis, which can be fatal. One reported case of chronic ingestion of 425 pennies

(over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal

sepsis, while another patient, who ingested 12 grams of zinc, only showed lethargy

and ataxia (gross lack of coordination of muscle movements). Several other cases

have been reported of humans suffering zinc intoxication by the ingestion of zinc

coins.

Pennies and other small coins are sometimes ingested by dogs, resulting in the

need for medical treatment to remove the foreign body. The zinc content of some

coins can cause zinc toxicity, which is commonly fatal in dogs, where it causes a

severe hemolytic anemia, and also liver or kidney damage; vomiting and diarrhea are

http://en.wikipedia.org/wiki/Copper_deficiency

http://en.wikipedia.org/wiki/USDA

http://en.wikipedia.org/wiki/Recommended_Dietary_Allowance

http://en.wikipedia.org/wiki/Zinc_shakes

http://en.wikipedia.org/wiki/Food_and_Drug_Administration

http://en.wikipedia.org/wiki/Anosmia

http://en.wikipedia.org/wiki/Polio

http://en.wikipedia.org/wiki/Heat_shock

http://en.wikipedia.org/wiki/PARP

http://en.wikipedia.org/wiki/Keratinocytes

http://en.wikipedia.org/wiki/Melanocytes

http://en.wikipedia.org/wiki/United_States_Mint

http://en.wikipedia.org/wiki/Cent_(United_States_coin)

http://en.wikipedia.org/wiki/Sepsis

http://en.wikipedia.org/wiki/Lethargy

http://en.wikipedia.org/wiki/Ataxia

http://en.wikipedia.org/wiki/Hemolytic_anemia


22

possible symptoms. Zinc is highly toxic in parrots and poisoning can often be fatal.

The consumption of fruit juices stored in galvanized cans has resulted in mass parrot

poisonings with zinc.

1.4. Analytical methods for determination of heavy metals in water and

sediment samples

1.4.1. Electrochemical methods

1.4.1.1. Polarography

Polarography is a subclass of voltammetry where the working electrode is

a dropping mercury electrode (DME) or a static mercury drop electrode (SMDE)

useful for its wide cathodic range and renewable surface. It was invented by Jaroslav

Heyrovský, who was for this invention awarded by Nobel’s prize in 1959.

Polarography is an voltammetric measurement whose response is determined

by combined diffusion/convection mass transport. Polarography is a specific type of

measurement that falls into the general category of linear-sweep voltammetry where

the electrode potential is altered in a linear fashion from the initial potential to the

final potential. As a linear sweep method controlled by convection/diffusion mass

transport, the current vs. potential response of a polarographic experiment has the

typical sigmoidal shape. What makes polarography different from other linear sweep

voltammetry measurements is that polarography makes use of the dropping mercury

electrode (DME) or the static mercury dropping electrode.

A plot of the current vs. potential in a polarography experiment shows the

current oscillations corresponding to the drops of Hg falling from the capillary. If one

connected the maximum current of each drop, a sigmoidal shape would result. The

limiting current (the plateau on the sigmoid), called the diffusion current because

diffusion is the principal contribution to the flux of electro active material at this

point of the Hg drop life.

The method has been used for the determination of heavy metals. In Vietnam,

Tu Van Mac and Tran Thi Sau has studied about determination of copper, lead and

cadmium in beer in Hanoi by alternating current differential pulse polarography with

sensitivity accounting for 1ppb. [Tu Van Mac, Tran Thi Sau]

Thanh Thuc Trinh, Nguyen Xuan Lang and their colleagues has applied

polarimetry on determination of Zinc, Cadmium, Lead and Copper in some kinds of

http://en.wikipedia.org/wiki/Parrots

http://en.wikipedia.org/wiki/Voltammetry

http://en.wikipedia.org/wiki/Working_electrode


http://en.wikipedia.org/wiki/Jaroslav_Heyrovsk%C3%BD



http://en.wikipedia.org/wiki/Sigmoid_function




23

food and agricultural soil. It is experimented in environment of acetate buffer with

system of 3 polars: hanging mercury drop electrode, reference electrode Ag/AgCl,

auxiliary electrode Pt and electrodeionization potential accounting for -1.05V in 60

seconds [Thanh Thuc trinh, Nguyen Xuan Lang].

1.4.1.2. Voltammetry

Voltammetry is a category of electroanalytical methods used in analytical

chemistry and various industrial processes. In voltammetry, information about

an analyte is obtained by measuring the current as the potential is varied.

Voltammetry experiments investigate the half cell reactivity of ananalyte.

Voltammetry is the study of current as a function of applied potential. These curves I

= f(E) are called voltammograms. The potential is varied arbitrarily either step by

step or continuously and the actual current value is measured as the dependent

variable. The opposite, i.e., amperometry, is also possible but not common. The

shape of the curves depends on the speed of potential variation (nature of driving

force) and on whether the solution is stirred or quiescent (mass transfer). Most

experiments control the potential (volts) of an electrode in contact with the analyte

while measuring the resulting current (amperes). [Zoski, Cynthia G. (2007-02-07)].

Professor Petrovic and his colleagues used Differential pulse stripping

voltametry to determine Cd and Pb in water after separating them from humic acid

by thin layer chromatographic method. [Petrovic and Dewal, 1998]

Selehattin Yilmaz, Sultan Yagmur, Gulsen Saglikoglu, Murat Sadikoglu

studied about direct determination of zinc heavy metal in the tap water carried out by

differential pulse anodic stripping voltammetry technique at the glassy carbon

electrode (GCE). The zinc ions were deposited by reduction at -1.5 V on a bare

glassy carbon surface. Then, the deposited metal was oxidized by scanning the

potential of the electrode surface from -1.5 to -0.8 volt using a differential puls mode.

The stripping current arising from the oxidation of metal was connected with the

concentration the metal in the sample. The concentration of zinc heavy metal found

in tap water sample was determined to be 180 mg L-1

using 0.2 mol L-1

acetate buffer

(pH: 3.50) [Selehattin Yilmaz, 2009].

http://en.wikipedia.org/wiki/Electroanalytical_methods

http://en.wikipedia.org/wiki/Analytical_chemistry


http://en.wikipedia.org/wiki/Analyte

http://en.wikipedia.org/wiki/Analyte

http://en.wikipedia.org/wiki/Potential

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Electric_current


24

1.4.2. Spectrophotometric methods

1.4.2.1. Ultraviolet-visible spectrophotometer

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometer (UV-

Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in

the ultraviolet-visible spectral region. This means it uses light in the visible and

adjacent (near-UV and near-infrared (NIR)) ranges. The absorption or reflectance in

the visible range directly affects the perceived color of the chemicals involved. In

this region of the electromagnetic spectrum, molecules undergo electronic

transitions. [ Prabhakar, Dubinskii, Editors and Dekker (2002)]. This technique is

complementary to fluorescence spectroscopy, in that fluorescence deals with

transitions from the excited state to the ground state, while absorption measures

transitions from the ground state to the excited state. UV/Vis spectroscopy is

routinely used in analytical chemistry for the quantitative determination of different

analytes, such as transition metal ions, highly conjugated organic compounds, and

biological macromolecules. Determination is usually carried out in solutions.

Gao Hong – Wen (China) used dithizone combining with Cd separation cells

filter to determination of Cd (II) in sea water by UV/Vis spectroscopy with LOD is

0.006 ppm. [Gao Hong – Wen (1995),]

A.M Garcia Rodriguez, A Garcia de Torres and J.M Cano Pavon studied

about simultaneous determination of iron, cobalt, nickel and copper by UV-visible

spectrophotometry with multivariate calibration. Linear determination ranges of Co,

Ni, Fe and Cu are 0.2–1.3 mg/ml, 0.1–1.2 mg/ml, 0.1–1.1 mg/ml and 0.2–1.2 mg/ml

respectively.A method for the simultaneous spectrophotometric determination of the

divalent ions of iron, cobalt, nickel and copper based on the formation of their

complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH) is

proposed.[A.M Garcia, A Garcia and J.M Cano (1998)]

1.4.2.2. Atomic emission spectroscopy (AES)

Atomic emission spectroscopy (AES) is a method of chemical analysis that

uses the intensity of light emitted from a flame, plasma, arc, or spark at a particular

wavelength to determine the quantity of an element in a sample. The wavelength of

the atomic spectral line gives the identity of the element while the intensity of the

emitted light is proportional to the number of atoms of the element. A sample of a

http://en.wikipedia.org/wiki/Absorption_spectroscopy

http://en.wikipedia.org/wiki/Ultraviolet

http://en.wikipedia.org/wiki/Visible_spectrum

http://en.wikipedia.org/wiki/Near-infrared

http://en.wikipedia.org/wiki/Color_of_chemicals

http://en.wikipedia.org/wiki/Electromagnetic_spectrum

http://en.wikipedia.org/wiki/Molecule

http://en.wikipedia.org/wiki/Molecular_electronic_transition



http://en.wikipedia.org/wiki/Prabhakar_Misra

http://en.wikipedia.org/wiki/Fluorescence_spectroscopy

http://en.wikipedia.org/wiki/Fluorescence

http://en.wikipedia.org/wiki/Excited_state

http://en.wikipedia.org/wiki/Ground_state


http://en.wikipedia.org/wiki/Quantitative_analysis_(chemistry)

http://en.wikipedia.org/wiki/Transition_metal

http://en.wikipedia.org/wiki/Conjugated_system

http://en.wikipedia.org/wiki/Organic_compound

http://en.wikipedia.org/wiki/Chemical_analysis

http://en.wikipedia.org/wiki/Flame

http://en.wikipedia.org/wiki/Plasma_(physics)

http://en.wikipedia.org/wiki/Electric_arc

http://en.wikipedia.org/wiki/Electric_spark

http://en.wikipedia.org/wiki/Chemical_element

http://en.wikipedia.org/wiki/Atomic_spectral_line

http://en.wikipedia.org/wiki/Atom


25

material (analyte) is brought into the flame as a gas or sprayed solution. [Stefánsson

A, Gunnarsson I, Giroud N (2007)]. The heat from the flame evaporates the solvent

and breaks chemical bonds to create free atoms. The thermal energy also excites the

atoms into excited electronic states that subsequently emit light when they return to

the ground electronic state. Each element emits light at a characteristic wavelength,

which is dispersed by a grating or prism and detected in the spectrometer. A frequent

application of the emission measurement with the flame is the regulation of alkali

metals for pharmaceutical analytics

Krzysztof Jankowski , Jun Yao, Krzysztof Kasiura, Adrianna Jackowska,

Anna Sieradzka studied about multielement determination of heavy metals in

water samples by continuous powder introduction microwave-induced plasma atomic

mission spectrometry after preconcentration on activated carbon. The experimental

setup consisted of integrated rectangular cavity TE and vertically positioned plasma

torch. The satisfactory signal stability required for sequential analysis was attained

owing to the vertical plasma configuration, as well as the plasma gas flow rate

compatibility with sample introduction flow rate. The elements of interest (Cd, Cu,

Cr, Fe, Mn, Pb, Zn) were preconcentrated in a batch procedure at pH 8–8.5 after

addition of activated carbon and then, after filtering and drying of the activated

carbon suspension, introduced to the MIP by the CPI system. [Krzysztof Jankowski ,

Jun Yao, Krzysztof Kasiura, Adrianna Jackowska, Anna Sieradzka (2004)].

1.4.2.3. Atomic absorption spectroscopy (AAS)

Atomic absorption spectroscopy (AAS) is a spectroanalytical procedure for

the qualitative and quantitative determination of chemical elements employing the

absorption of optical radiation (light) by free atoms in the gaseous state. In analytical

chemistry the technique is used for determining the concentration of a particular

element (the analyte) in a sample to be analyzed. AAS can be used to determine over

70 different elements in solution or directly in solid samples. The technique makes

use of absorption spectrometry to assess the concentration of an analyte in a sample.

It requires standards with known analyte content to establish the relation between the

measured absorbance and the analyte concentration and relies therefore on Beer-

Lambert Law. In short, the electrons of the atoms in the atomizer can be promoted to

higher orbitals (excited state) for a short period of time (nanoseconds) by absorbing a

defined quantity of energy (radiation of a given wavelength). [B.V L’vov (2005)]

This amount of energy, i.e., wavelength, is specific to a particular electron transition

http://en.wikipedia.org/wiki/Beer-Lambert_Law

http://en.wikipedia.org/wiki/Beer-Lambert_Law

http://en.wikipedia.org/wiki/Wavelength


26

in a particular element. In general, each wavelength corresponds to only one element,

and the width of an absorption line is only of the order of a few picometers (pm),

which gives the technique its elemental selectivity. The radiation flux without a

sample and with a sample in the atomizer is measured using a detector, and the ratio

between the two values (the absorbance) is converted to analyte concentration or

mass using Beer-Lambert Law.

Hüseyin Bağ, A.Rehber Türker , Ramazan Coşkun, Mehmet Saçak, Mustafa

Yiğitoğlu studied about determination of zinc, cadmium, cobalt and nikel by flame

atomic absorption spectrometry after preconcentration by poly(ethylene

terephthalate) fibers grafted with methacrylic acid. The batch adsorption method was

used for the preconcentration studies. Effect of pH, amount of adsorbent,

concentration and volume of elution solution, shaking time and interfering ions on

the recovery of the analytes have been investigated. Recoveries of Zn, Cd, Co and Ni

were 97.3±0.4%, 98.3±0.2%, 94.1±0.3% and 96.5±0.6% at 95% confidence level,

respectively, at optimum conditions. Langmuir adsorption isotherm curves were also

studied for the analytes. The adsorption capacity of the adsorbent was found as 298,

412, 325 and 456 mg/g for Zn, Cd, Co and Ni, respectively. [Hüseyin Bağ, 2000].

Nakashima and his colleagues in Okayama University (Japan) studied about

determination of Cadmium in water by using AAS after separating Cd out of samples

by zirconi oxide. [M.C. Yebra , N. Carro, A. Moreno-Cid (2002)].

In addition, M.C. Yebra , N. Carro, A. Moreno-Cid studied about

determination of copper in sea water by flow-injection- atomic absorption

spectrometry. By using the optimized flow systems, seawater samples were collected

and pre-concentrated in situ by passing them with a peristaltic pump through a mini-

column packed with Amberlite XAD-4 impregnated with the complexing agent 4-(2-

pyridylazo) resorcinol. Thus, copper is pre-concentrated without the interference of

the saline matrix. Once in the laboratory, the mini-columns loaded with copper are

incorporated into a flow injection system and eluted with a small volume of a 40%

(v/v) ethanolic solution of 3 mol l−1

hydrochloric acid into the nebulizer-burner

system of a flame atomic absorption spectrometer. Analysis of certified reference

materials (SLEW-3 and NASS-5) showed good agreement with the certified value.

[Susumu, Masakazu (1983)].

http://en.wikipedia.org/wiki/Radiation_flux


27

Conclusion: Because the objects of our research are surface water and sediment

samples containing heavy metals as Cd, Cu, Pb, Zn… the amount of heavy metals

must be determined exactly in order to evaluate the quality of water. Modern

analytical methods such as GF-AAS, ICP-MS… require expensive equipments and

costly fees. In this case, using F-AAS is a reasonable choice with high sensitivity and

the capability to analyze many elements in complex matrices, providing a good

accuracy and precision result, short time for analyzing and cheap price. The

referenced results obtained by ICP-MS will be also included to recognize the ultra

trace of heavy metal contents in some environmental samples.


28

CHAPTER 2: EXPERIMENTS

2.1. Research Objects and research contents

2.1.1. Research objects

At present, the environmental impact is still poorly understood in Lao PDR. It is lack

of information for herbicide and pesticide management. The may be some problems

have occurred as:

- People are unaware of dangers of heavy metals content in water and sediment.

- High residue levels in water and sediment.

- Threat to farmers’ health and aquatic ecosystems due to misuse and

misunderstand.

- Using polluted surface water for agricultural purpose leads to accumulate

heavy metals.

This research aims to get quantitative determination of four main heavy metals (such

as Pb, Cd, Zn, Cu) in water and sediment samples in the ThadLuang Marsh and

assessments the distribution these heavy metals contents in environmental samples of

studied mash. No sooner do many factories appear and develop increasing fast than

water is polluted by heavy metals is over allowable limit. Owing to not taking part in

biochemical process, heavy metals such as Cd, Pb, Zn, Cu… are accumulated in

human body, which leads to harmfulness for organism. The fact that water is polluted

by heavy metal is often seen in rivers near industrial area, big cities and minerals

exploiting area. The main reason leading to heavy metals pollution is pouring into

water environment a large amount of industrial and untreated wastewater. Pollution

by heavy metals accumulated through foods directly into organism has negative

effects on life environment. In order to reduce consequence of this problem, it is

necessary to cultivate measures of water treatment.

2.1.2. Research contents

In order to gain a completely process, it is necessary to study systematically the

following issues:

- Investigation of optimal conditions for determination of Pb, Cd, Zn, and Cu

in water and sediment using F-AAS.

- Investigation of sample matrix’s effects.

- Investigation of other interferences to analytical results.


29

- Determination of Cd, Cu, Pb, Zn content in water and sediment samples

collected in ThadLuang marsh in May, 2011.

2.2. Chemicals and Apparatus

2.2.1. Chemicals

All reagents were of Merck analytical grade or ultra-pure grade for ICP-MS

measurement. Working solutions of analysed ions were prepared by dilution of

standard solutions of 1000 ppm standard solutions of Zn 2+

, Cu2 +

, Pb+2

, Cd2 +

.

- 2% solutions of HNO3, HCl, CH3COONH4 were prepared from 65% solution

of HNO3 , 36% solution of HCl and 99% solution of CH3COONH4,

respectively.

- 10% solution of HCl, HNO3 was prepared from con.HNO3 68%.

- Super pure water (Resistance >=18.2 MΩ ) and Argon, super pure grade

(>=99.999) for ICP-MS measurement.

All standard reagent solutions were stored in low density polyethylene bottles.

2.2.2. Apparatus

- Beaker 25, 50, 100ml capacity

- Pipettes 1, 2, 5, 10, 25 ml... capicity

- Pipetteman 20, 100, 200, 1000, 5000 μl capicity

- Hopper glass, filter paper, pH indicator...

- Elementary flasks 50, 100, 250 ml... capacity

- Glass volumetric flasks: 25, 50, 100 and 25 ml capacity.

All laboratory glassware and plastic ware, polyethylene sample and reagent bottles

were cleaned by soaking in a detergent solution, rinsed with ultra pure water from a

Millipore Q50

system and soaking in a HNO3 ( 2%), v/v) bath overnight. This was

followed by thorough rinsing with pure and dried before use.

- Calculations: MINITB release 14 for window.


30

2.2.3. Equipments

- AAS- novAA spectrometer with pneumatic nebulisation and mono- element

lamps with hollow cathode made by Analytikjena (Fig. 3)

Figure 2.1: Spectrometer atomic absorption novAA 6800, Shimazhu

2.3 Sampling and Sample Preparation

2.3.1. Study Area

2.3.1.1. Water samples

Eight sampling points were located within marsh were shown in Figure 2.2. The

description of the characteristics of water sampling points is given in table 2.1.


31

Table 2.1: Characteristics of the water sampling points in Thadluang marsh

Sampling point Position Time Potential source of

metal pollution

1. 17°58'34.73"N

102°38'54.35"E

9:56:29AM

28th

May 2011

Market’s waste

2. 17°58'4.86"N

102°38'30.79"E

10:36:37AM

28th

May 2011

Trade waste

3. 17°57'54.09"N

102°39'11.83"E

5:36:23PM

28th

May 2011

Agricultural waste

4. 17°57'8.36"N

102°39'35.47"E

5:04:21PM

28th

May 2011

Agricultural waste

5. 17°56'20.76"N

102°39'33.45"E

4:20:31PM

28th

May 2011

Agricultural waste

6. 17°55'21.34"N

102°39'31.56"E

3:32:22PM

28th

May 2011

Agricultural waste

7. 17°54'30.79"N

102°39'29.47"E

12:27:47PM

28th

May 2011

Agricultural waste

8. 17°52'56.15"N

102°39'27.91"E

2:41:02PM

28th

May 2011

Laos Beer Factory


32

Figure 2.2: The map of Thadluang marsh showing water sampling sites.


33

2.3.1.2. Sediment samples

Five sampling points were located within marsh were shown in Figure 2.3. The

description of the characteristics of sampling points are given in table 2.2

Table 2.2: Characteristics of the sediment sampling points in Thadluang marsh

Sampling

point

Position Time Potential source of metal

pollution

1 17°58'34.73"N

102°38'54.35"E

9:56:29AM

28th

May 2011

Market’s waste

2 17°57'8.36"N

102°39'35.47"E

5:04:21PM

28th

May 2011

Agricultural waste

3 17°55'21.34"N

102°39'31.56"E

3:32:22PM

28th

May 2011

Agricultural waste

4 17°54'30.79"N

102°39'29.47"E

12:27:47PM

28th

May 2011

Agricultural waste

5 17°52'56.15"N

102°39'27.91"E

2:41:02PM

28th

May 2011

Laos Beer Factory


34

Figure 2.3: The map of Thadluang marsh showing sediment sampling sites.


35

2.3.2. Sampling and sample preparation

Surface water and sediment samples were collected from various places in

Thadluang marsh. Sample were collected and prepared for experiments in a standard

ways described in the literatures for these kinds of materials.

All laboratory glassware and plastic ware, polyethylene sample and reagent

bottles were cleaned by soaking in a detergent solution, rinsed with ultra pure water

from a Millipore Q50

system and soaking in a HNO3 ( 2%), v/v) bath overnight. This

was followed by thorough rinsing with pure and dried before use.

2.3.2. 1. Water samples

Surface water of ThadLuang marsh were collected and kept in 100 mL LDPE

bottles and transferred to laboratory in HUS to analyze.

At laboratory, transfer a 100-mL aliquot of well-mixed sample to a beaker.

For metals that are to be analyzed, add 2 mL of concentrated HNO3 and 5 mL of

concentrated HCl. The sample beaker is covered with a ribbed watch glass or other

suitable covers and heated on a steam bath, hot plate or other heating source at 90 to

95oC until the volume has been reduced to 15-20 mL.

After heating, the volume of sample was reduced around 15 mL and samples

were transferd to 25 mL volumetric flasks, well mixed with 5 mL CH3COONH4 10%

and distilled water were added to the mark and shacked well before analyzing.

2.3.2.2. Sediment samples

In order to investigating the pollution of four heavy metals in sediment, 100g

of sediment was taken at 5 different positions in ThadLuang marsh and transferred to

Vietnamese laboratory to analyze.

At laboratory, the amount of 0.05 g of each sample was weighted separately

then 2 ml of 63% solution of HNO3 acid, 5 ml of 32% solution of HCl acid were

added. These samples were brought to the pot boiling on the sand about 2 hours.

After being cooled and adding 2 drops of H2O2 ; 2 mL of H2F2, it is boiled until

appearance of white ash.

The residue was filtered through Whatman paper to 50 mL volumetric flasks and 1%

HNO3 was used to make the volume to 50.00 mL.


36

2.4. Analytical methods for determination of Cu, Pb, Cd, Zn

2.4.1. Flame atomic absorption spectroscopy method (F-AAS):

determination of heavy metal content in sediment samples

2.4.1.1. Principles

The technique of flame atomic absorption spectroscopy (FAAS) requires a

liquid sample to be aspirated, aerosolized, and mixed with combustible gases, such as

acetylene and air or acetylene and nitrous oxide. The mixture is ignited in a flame

whose temperature ranges from 2100 to 2800 oC. During combustion, atoms of the

element of interest in the sample are reduced to free, unexcited ground state atoms,

which absorb light at characteristic wavelengths, as shown in figure 2.4.

Figure 2.4: Operation principle of an atomic absorption spectrometer.

The characteristic wavelengths are element specific and accurate to 0.01-

0.1nm. To provide element specific wavelengths, a light beam from a lamp whose

cathode is made of the element being determined is passed through the flame. A

device such as photomultiplier can detect the amount of reduction of the light

intensity due to absorption by the analyte, and this can be directly related to the

amount of the element in the sample. [Haswell, S.J., 1991].

Different flames can be achieved using different mixtures of gases, depending

on the desired temperature and burning velocity. Some elements can only be

converted to atoms at high temperatures. Even at high temperatures, if excess oxygen

is present, some metals form oxides that do not redissociate into atoms. To inhibit


37

their formation, conditions of the flame may be modified to achieve a reducing, no

oxidizing flame.

Proper nebulization is required to break up an aqueous sample into a fine mist

of uniform droplet size that can be readily burned in the flame. Most instruments

utilize the direct aspiration. During aspiration, the gas flow breaks down the liquid

sample into droplets, and the nebulization performance depends on the physical

characteristics of the liquid. Only about 10% of the sample gets into the flame.

Another option for nebulization is the use of an ultrasonic wave beam, which

generates high frequency waves in the liquid sample. This causes very small liquid

particles to be ejected into a gas current forming a dense fog. [Reynolds, R.J. et al.,

1970].

In a certain limit of concentration, the intensity value depending linearly on

the concentration of the element to be analyzed according to the equation:

Aλ = k.Cb

Where: A λ: absorption intensity spectral lines.

k: constant experimentation.

b: length of absorbing environment. (0<b≤ 1)

C: concentrations of elements necessary to determine the sample

The block diagram of atomic absorption spectrometer with 5 main parts is

depicted in figure 2.5.

Figure 2.5: Block diagram of atomic absorption spectrometer


38

Part 1: Power-ray emission of the resonant element analysis (emission

spectral lines characteristic of the element to be analyzed), to compare the

absorption containing atoms of elements freely. It is the hollow cathode

lamp (HCL), the discharge lamps without electrodes (EDL), or continuous

emission sources were be modulated.

Part 2: The atomic system of samples for analysis. In nuclear engineering

chemical flame, this system includes:

+ Division lead aerosol form into the chamber and make the process

of aerosol chemical form (can create aerosols).

+ Light to atoms of the sample (burner head) to ignite the gas mixture

can form in suspensions containing aerosols.

Part 3: The absorption spectroscopy, it is a monochrome, is responsible

for collection, segregation and choose light (spectral lines) to measure the

optical power to focus on detected by AAS signal absorption spectral lines.

Part 4: System indicator signal absorption of spectral lines (i.e. intensity

spectral lines of absorption or concentration of elements to be analyzed).

This system can are equipped with:

+ The simplest design is a power only energy absorption (E) of spectral

lines,

+ A self-recording machine pic of spectral lines,

+ Or is the number digital

+ Or the computer and printer (printer), or analyzer (Integrator).

Part 5: With the AAS spectrometer also has a modern microcomputers or

microprocessor and software systems. Equipped with this type is

responsible for measurement process control and process measurements,

graphing, calculation of sample concentration analysis, etc...

- Inductively couple plasma – mass spectrometer (ICP-MS) Elan 9000,

Perkin – Elmer, USA.

- Auto sample AS-93plus. Tray as-90/as90b.try

Collect and record the results of measuring the intensity of spectral lines

absorbed.


39

2.4.1.2. The fixed optimal conditions of instrument F- AAS for the

determination of Pb, Cd, Zn, and Cu

Experiments were carried out to find out the optimal conditions of F-AAS for

measuring each element. Wavelength, slit width, current of HCL, burner height and

fuel gas were investigated and followed by catolog of producers. The optimal

conditions were shown in table 2.3. All experiments in this research were conducted

in these conditions.

Table 2.3: The optimal conditions of F-AAS for measuring Pb, Cd, Zn, Cu

Element

Factors

Pb

Cd Zn

Cu

Instrument

parameters

Wavelength (nm) 217.0 228.8 213.9 324.8

Slit width (nm) 0.5 0.5 0.5 0.5

Current of HCL (mA) 8 6 6 12

Burner height (mm) 8 6 6 8

Fuel gas (mL/min) 60 50 50 45


40

2.4.2. Inductive couple plasma - mass spectrophotometry (ICP - Ms) for

the determination of heavy metal contents in surface water samples.

2.4.2.1. Principles:

The plasma sources developed for atomic emission spectrometry have

also been shown to be very suitable ion sources for mass spectrometry. This

is particularly true for electrical discharges at pressures in the 1±5 mbar range

and sources at atmospheric pressure since the powerful vacuum systems became

available, with which the pressure difference between the mass spectrometer (of the

order of 10-5 mbar) and the source can be bridged.

Elemental mass spectrometry, however, goes back to the use of high-

vacuum arcs and sparks, with which ultratrace and survey analyses of metal samples

could be performed. Spark source mass spectrography with high resolution sector

field mass spectrometers, is still very useful for a survey characterization of

electrically-conducting solids down to the ng/g level. The spectra can be recorded

on photographic plates, which are a permanent document and at least enable semi-

quantitative analyses to be made. At the ng/g level this approach is suitable for the

quality control of materials required in micro- electronics. The technique has

become very useful since computer-controlled densitometers have been available,

which automatically record the blackenings of the elemental lines on the photoplates

and convert them into logarithmic intensities, these being proportional to the

logarithmic concentrations.

Spark source mass spectrometry requires expensive sector-field mass

spectrometers and despite the possibility of automated read-out of the spectra,

highly skilled laboratory personnel for data evaluation are also required. This

situation arises from the fact that high-vacuum sparks are very powerful sources

producing vast amounts of multiply charged ions making the spectra line rich. The

analytical precision achievable in spark mass spectrometry is low, however,

special precautions such as the use of rotating electrodes have been found to be

helpful. Spark source mass spectrometry has been used for the analysis of compact

metals, from which electrodes could be made by turning-of or by fixing

drillings in electrode holders. In the case of metals of low melting point, such as

gallium, liquid nitrogen cooled electrodes of the gallium were used. For electrically

conducting as well as non-conducting powders electrodes were pressed from

mixtures with gold powder, which is ductile and leads to electrodes that are


41

electrically and heat conductive. The method is very powerful for dry solution

residues as a result of its sensitivity and has been used for impurity detection in

liquid aliquots obtained from trace ± matrix separations in the analysis of high-purity

materials.

In ICP-MS (Fig. 6 ) the ions formed in the ICP are extracted with the

aid of a conical water-cooled sampler into the first vacuum stage where a pressure

of a few mbar is maintained. A supersonic beam is formed and a number of collision

processes take place as well as an adiabatic expansion. A fraction is sampled from

this beam through the conical skimmer placed a few cm away from the

sampler. Behind the skimmer, ion lenses focus the ion beam now entering a vacuum

of 10-5

. This was originally done with the aid of oil diffusion pumps or cryopumps,

respectively, but very quickly all manufacturers switched to turbo molecular pumps

backed by roughing pumps.

The sampler and the skimmer are usually made of stainless steel and are both

conically shaped with different cone angles. The sampler can also be made of copper,

which has a better heat conductivity. In the case of HF containing solutions, platinum

samplers can also be used. This is particularly worthwhile for the analysis of

geological samples subsequent to wet chemical dissolution and removal of the

silicates. The distance between the sampler and skimmer is critical with respect to the

maximum power of detection and minimal ionization interferences. This also applies

to the power transmission to the Rf coil, where considerable differences were

found for coils powered centrally and coils powered at one of the ends. The

processes in the intermediate stage together with their influence on the ion

trajectories in the interface and also behind the second aperture (skimmer) are very

important for the transmission of ions and for related matrix interferences, this

being the topic of fundamental diagnostic studies.


42

Figure 2.6: Instrumentation for low-resolution ICP-MS.

(a): nebulizer; (b): sampler; (c): ion optics; (d): quadrupole;

(e): electronics; (f ): detector; (g): RF-generator; (h): roughing pump;

(i): turbo molecular pump: ( j): quadrupole RF generator.

2.4.2.2. Experimental conditions for determination of Cu, Pb, Cd and Zn

in surface water samples

The experimental conditions for determination of Cu, Pb, Cd and Zn using

ICP- MS techniques were fixed as in table 2.4.

Table 2.4: The experimental conditions for determination of Cu, Pb, Cd and Zn

using ICP- MS techniques

Gas flow rate Nebulizer 0.90 L/min

Makeup gas flow rate 2.0 L/min

Plasma gas flow rate 15.0 L/min

Pressure vacuum pump (Quantitative ) 1.2 – 1.3. 10-5

Torr

Pressure vacuum pump ( Standby) 2.0 – 3.0. 10-6

Torr

Sample flush 40s

Sample flush speed -48 +/- rpm


43

Read delay 15s

Delay and analysis speed -26 +/- rpm

Wash 60s

Wash speed -48 +/- rpm

Cooling water power 1750W

ICP RF power 1000W

Lens voltage 5,75V

Analog stage voltage -1850V

Pulse stage voltage 1000V

Sweeps/reading 10

Readings/replicate 1

Replicates 3

Detector mode Dual

Other parameters Automatic

2.4.3. Quality control of analytical methods

- Blank samples: - Reagents’ blank were carries out through the entire sample

preparation procedure.

- Method blanks: method blanks reflect laboratory contamination from both the

determinative and preparatory method. Field blanks (e.g., trip blanks and

equipment or rinsate blanks) account for accumulative field and laboratory

activities were used to parellaly analyses.

Blank determinations for total a metal were carried out in the same manner as the

samples using the same acid concentrations.

- Spiked samples: A surface water or sediment sample to which known

concentrations of specific analytes have been added in such a manner as to

minimize the change in the matrix of the original sample. Every spiked


44

sample analyzed should have an associated reference to the spike solution

and the volume added.

- Certified reference material (CRM): For calibration and validation of

analytical procedures (FAAS and ICP-MS), CRM- MESS3- sediment was

applied.


45

CHAPTER 3: RESULTS AND DISCUSSION

3.1. Optimizations of some chemical factors influencing to absorbance in

F- AAS method

3.1.1. Study the effects of sample matrix and matrix modifier to F-AAS

In F-AAS measurement, type of acid that is used to acidify water samples to

prevent the formation of hydroxo complex, or hydrolysis…and acid concentration

can also reduce or increase the spectrum absorbance in F-AAS. On the other hand,

matrix modifiers (compounds added to the sample before injection or injected to the

atomizer together with the sample) will affect the thermal processes taking place in

the atomizer to minimize losses of analyte during pyrolysis and to enable more

effective matrix components removal. Some modifiers can change the sample matrix

to evaporate the matrix components at lower temperature; other type of modifiers

work as an analyte stabilizer. Therefore, the effect of concentrations of nitric acid

and ammonium acetate were investigated. First, a specific concentration of HNO3

was fixed and the concentrations of NH4CH3COO were gradually varied from 0%-

2%. The investigates were carried out with each solution containing : 3.0 ppm Pb2 +

solution, 0.5 ppm Cd2+

solution, 1.0 ppm Zn2+

solution, and 2.0 ppm Cu2+

solution,

separately. The results (including abs and RSD to check the working stability of

apparatus) were shown in table 3.1.


46

Table 3.1: Investigation of HNO3 and NH4CH3COO effects on analysis of Pb,

Cd, Cu and Zn

NH4CH3COO

/ HNO3

0.5% 1.0% 1.5% 2.0%

A RSD(%) A RSD(%) A

RSD(%) A RSD(%)

Pb

0 0.03594 1.19 0.02980 1.07 0.03215 2.02 0.03253 0.80

0.5% 0.02977 1.57 0.02432 0.92 0.02556 0.97 0.02257 2.44

1.0% 0.02698 1.03 0.02723 1.92 0.02645 1.40 0.02739 0.84

2.0% 0.02942 0.89 0.02772 1.78 0.02856 0,73 0.02843 1.45

Cd

0 0.02401 2.45 0.09536 1.33 0.1830 1.09 0.1814 0.88

0.5% 0.02005 1.57 0.07944 2.26 0.1872 1.46 0.1658 0.89

1.0% 0.01565 1.03 0.08564 1.61 0.1902 0.83 0.1521 0.73

2.0% 0.01314 0.89 0.09634 0.47 0.1870 0.64 0.08140 4.04

Zn

0 0.08007 0.08 0.04197 0.87 0.03626 1.58 0.04403 0.64

0.5% 0.06398 0.06 0.03485 0.95 0.03250 1.29 0.04025 1.02

1.0% 0.05265 0.05 0.03292 0.40 0.03366 0.90 0.04356 0.56

2.0% 0.04638 0.05 0.03310 1.76 0.03633 0.77 0.04637 1.31

Cu

0 0.03651 1.59 0.03032 1.91 0.02508 2.03 0.02904 1.73

0.5% 0.03242 1.29 0.02565 1.89 0.02264 1.71 0.01994 2.36

1.0% 0.03345 0.40 0.02822 0.88 0.02550 1.57 0.02321 1.44

2.0% 0.03407 3.16 0.02945 3.57 0.02650 2.18 0.02509 1.82

Based on above results, the first conclusion will be extracted that there may

not be great interferences of HNO3 and NH4 CH3COO concentration to the signal of

absorbance. In order to evaluate the exact effect of HNO3 and CH3COOONH4 to the

absorbance of Pb, Zn, Cd and Cu measurements, the analysis of variance (ANOVA)

with two ways was used. The ANOVA table is expressed in table 3.2.


47

Table 3.2: Two- way ANOVA table for evaluating effects of HNO3 and

NH4CH3COO

Pb Source DF SS MS F P

HNO3 3 0.0000252 0.0000084 3.13 0.080

NH4CH3COO 3 0.0001109 0.0000370 13.77 0.001

Error 9 0.0000242 0.0000027

Total 15 0.0001602

S = 0.001638 R-Sq = 84.92% R-Sq(adj) = 74.87%

Cd Source DF SS MS F P

HNO3 3 0.0640037 0.0213346 41.21 0.000

NH4CH3COO 3 0.0014856 0.0004952 0.96 0.454

Error 9 0.0046596 0.0005177

Total 15 0.0701488

S = 0.02275 R-Sq = 93.36% R-Sq(adj) = 88.93%

Cu Source DF SS MS F P

HNO3 3 0.0000252 0.0000084 3.13 0.080

NH4CH3COO 3 0.0001109 0.0000370 13.77 0.001

Error 9 0.0000242 0.0000027

Total 15 0.0001602

S = 0.001638 R-Sq = 82.91% R-Sq(adj) = 76.85%

Zn Source DF SS MS F P

HNO3 3 0.0002419 0.0000806 41.41 0.000

NH4CH3COO 3 0.0000553 0.0000184 9.46 0.004

Error 9 0.0000175 0.0000019

Total 15 0.0003147

S = 0.001396 R-Sq = 94.43% R-Sq(adj) = 90.72%

The results revealed that HNO3 concentrations could significantly affect to

absorbances of Cd and Zn while concentration of NH4CH3COO caused statisticaly


48

significant infuence to Pb, Cu and Zn measurements (Pvalue < 0.05). Therefore matrix

of samples should be kept at 2% HNO3 and 1% NH4CH3OO because of having

maximum absorption and lower relative standard deviation.

Beside the effects of HNO3 as an acidic medium, the others of acidic media

affecting on adsorption line intensity of Cu and Pb such as HCl and H2SO4 acid were

investigated through the mesurements of Cu and Pb in seperated solutions of 2.0

ppm. The results are presented in Table 3.3:

Table 3.3: Influence of types of acid media HCl, HNO3 and H2SO4 effects on Cu2+

and Pb2+

analysis

Concentration of

acid (%)

Absorption of Cu (Abs)

HCl HNO3 H2SO4

Cu2+

0 0.1550 0.1550 0.1550

1 0.1543 0.1525 0.1500

2 0.1530 0.1510 0.1480

3 0.1515 0.1490 0.1450

4 0.1502 0.1470 0.1430

5 0.1488 0.1455 0.1402

Concentration of

acid (%)

Absorption of Pb (Abs)

HCl HNO3 H2SO4

Pb2+

0 0.0645 0.0645 0.0645

1 0.0635 0.0600 0.0569

2 0.0628 0.0578 0.0535

3 0.0610 0.0561 0.0510

4 0.0590 0.0549 0.0468

5 0.0578 0.0536 0.0425


49

These results show that HCl and HNO3 acids had a smallest effect to the

absorbances. The faster concentrations of acid increased, the more quickly intensity

of adsorption line decreases. However, if the concentration of each acid is too small,

hydrolytic process will happen, relating to the obstacle of atomization. Therefore, 1%

concentration of acids is the reasonable ones. Also, HCl acid represents good

stability and dissolubility. So, 1% solution of HCl acid was accepted.

3.1.2. Calibration curves of Pb, Cd, Zn and Cu measurements.

3.1.2.1. The limit of linearity of Pb, Cd, Zn and Cu measurements

In order to investigate the linear ranges of the determination of Pb2+

,Cd2+

,

Zn2+

, and Cu2+

concentrations, series of their standard solutions with the

concentrations fluctuating from 0.2 to 3.5ppm in the case of Pb2+

, from 0.05 to

1.25ppm with Cd2+

and Zn2+

, from 0.1 to 1.75ppm with Cu2+

were prepared. The

absorbance of each metal atom was measured in the experimental conditions

determined above. The results obtained were depicted in table 3.4.

Table 3.4: The absorbance of each metal atom (after subtracting the

absorbance of the blank solution) vs. their concentrations

No Pb2+

Cd2+

Zn2+

Cu2+

C(ppm) Abs C(ppm) Abs C(ppm) Abs C(ppm) Abs

1 0.2 0.0034 0.05 0.017 0.05 0.0078 0.1 0.00531

2 0.5 0.0094 0.125 0.0332 0.125 0.0177 0.25 0.01267

3 1.0 0.0189 0.25 0.0732 0.25 0.039 0.5 0.02363

4 2.0 0.0387 0.50 0.1421 0.5 0.0761 1.0 0.04512

5 2.5 0.0471 0.75 0.2143 0.75 0.1143 1.25 0.05503

6 3 0.049 1.00 0.2365 1.00 0.1244 1.5 0.05641

7 3.5 0.0504 1.25 0.2456 1.25 0.1271 1.75 0.05709

Using Origin 6.0 software, the scater plots expressing the ralationship between

absorbances of Pb, Cd, Zn and Cu and concentrations were described in figure


50

3.53.02.52.01.51.00.50.0

0.05

0.04

0.03

0.02

0.01

0.00

C-Pb, ppm

Ab

s- P

b

1.41.21.00.80.60.40.20.0

0.25

0.20

0.15

0.10

0.05

0.00

C- Cd, ppm

Ab

s- C

d

1.41.21.00.80.60.40.20.0

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

C- Zn, ppm

Ab

s- Z

n

1.81.61.41.21.00.80.60.40.20.0

0.06

0.05

0.04

0.03

0.02

0.01

0.00

C- Cu, ppm

Ab

s- C

u

Figure 3.1: The investigation of linear ranges for the determination of Pb, Cd, Zn and

Cu using F-AAS

The experimental results provided that the limit of linearity (LOL) of four

heavy metal concentrations is up to 2.5 ppm with Pb; 0.75 ppm with Cd and Zn; 1.25

ppm with Cu measurements.


51

3.1.2.2. Calibration curves for the determination of Pb, Cd, Zn and Cu in

solutions

The calibration curves of Pb, Cd, Zn and Cu were determined by measuring 5

standard solutions of separate analyte. The sequences were as follows: method blank

was first and then analysed standard solutions with concentrations varied from 0 ppm

to 2.5 ppm for Pb2+

, 0.0ppm to 1.25ppm for Cu2+,

0.0ppm to 0.75ppm for Cd2+

and

Zn2+

. The results were shown in table 3.5.

Table 3.5: The absorbance of each heavy metal standard solutions in the

linear range of concentrations

No Pb2+

Cd2+

Zn2+

Cu2+

C(ppm) Abs C(ppm) Abs C(ppm) Abs C(ppm) Abs

1 0.2 0.0034 0.05 0.017 0.05 0.0078 0.1 0.00531

2 0.5 0.0094 0.125 0.0332 0.125 0.0177 0.25 0.01267

3 1.0 0.0189 0.25 0.0732 0.25 0.039 0.5 0.0236

4 2.0 0.0387 0.5 0.1421 0.5 0.0761 1.0 0.04512

5 2.5 0.0471 0.75 0.2143 0.75 0.1143 1.25 0.05503

By using Origin 6.0 software, the calibration curves (included the parameters for

the linear regressions) measurement of Pb, Cd, Zn and Cu concentration obtained

in figure 3.2.

0.0 0.5 1.0 1.5 2.0 2.5

0.00

0.01

0.02

0.03

0.04

0.05

Parameter Value Error

------------------------------------------------------------

A -2.34476E-4 3.83332E-4

B 0.01914 2.52323E-4

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99974 4.95223E-4 5 <0.0001

-------------------------------------------------------

Ab

so

rba

nce

Concentration of Pb (ppm)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0.00

0.05

0.10

0.15

0.20

0.25


------------------------------------------------------------

A 7.65512E-4 0.00171

B 0.28416 0.00405

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.9997 0.00233 5 <0.0001

------------------------------------------------------------

Ab

so

rba

nce

Concentration of Cd (ppm)


52

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0.00

0.02

0.04

0.06

0.08

0.10

0.12


------------------------------------------------------------

A -2.14458E-4 6.81429E-4

B 0.15282 0.00161

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99983 9.29006E-4 5 <0.0001

------------------------------------------------------

Ab

so

rba

nce

Concentration of Zn (ppm)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0.00

0.01

0.02

0.03

0.04

0.05

0.06


------------------------------------------------------------

A 0.00161 4.51406E-4

B 0.04313 5.94264E-4

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99972 5.83167E-4 5 <0.0001

---------------------------------------------------

Ab

so

rba

nce

Concentrationof Cu (ppm)

Figure 3.2: The calibration curves for the determinations of Pb, Cd, Zn and Cu in

standard solutions

In order to determine the linear regressions, the following parameters should be

calculated:

- Degree of freedom f= n-2 = 5-2= 3 for each case.

- The table value for t at confidence level of 95% and 3 degree of freedom

t(0.95;3) = 3.112

- The confidence interval for a and b calculated by error (SA and SB) from the

Origin 6.0 software results are as follows:

ΔA = t (0.95; 3). SA and ΔB = t (0.95; 3). SB

So that the complete regressions describing the linear relationships between

absorbance and concentrations of analytes have the following forms:

Abs= (a±a) + (b± b)xC

Where: Absi is the absorbance when spectrum of heavy metal measured(Abs)

C is the concentration of analytes including Pb, Cd, Zn and Cu (ppm)

By replacing the values included in the figure 8 to the general equation, the linear

regressions of heave metal Pb, Cd, Zn and Cu with good correlation coefficients

were obtained as follows

Abs Pb = -(0.0002 ± 0.0012) + (0.0191± 0.0008). CPb


53

AbsCd = (0.0007 ± 0.0053) + (0.2841 ± 0.0126). CCd

AbsZn = -(0.0002 ± 0.0021) + (0.1528 ± 0.0050). CZn

AbsCu = (0.0016 ± 0.0014) + (0.04313± 0.0019). CCu

3.1.3. Limit of detection (LOD) and Limit of quantitation (LOQ)

Limit of detection and limit of determination are often used as quality criteria

for analytical methods.

- Limit of detection (LOD): is the lowest quantity of a analyst that can be

distinguished from the absence of that substance (a blank value) within a

stated confidence limit.

- Limit of quantitation (LOQ): is the lowest concentration of analyst in a

sample that can be determined with suitable precision and accuracy under the

stated experimental conditions.

The values LOD and LOQ are often calculated from S/N-ratios or calibration

functions and are not obtained in real samples. Therefore they are not useful as

criteria in routine analysis. Calculations from standard addition can be a helpful tool.

Using the statistics, limit of detection can be computed by the formula:

LOD = 3x Sy / b

Where:

Sy: the standard deviation of the calibration curve

b: the slope of the calibration curve Limit of quantitation of F-AAS method

from the calibration curve:

LOQ = 10 x Sy / b


54

From the formulas of calibration curves of Pb, Cd, Cu, Zn, the LOD and LOQ

values could be calculated as depicted in table 3.6.

Table 3.6: LOD and LOQ of the determination of Pb, Cd, Zn and Cu using F-

AAS method

Analyte

No.

Pb Cd Zn Cu

Sy 2.652E-4 0.00233 9.290E-4 5.832E-4

B 0.01942 0.28416 0.15282 0.04313

LOD (ppm) 0.04 0.02 0.02 0.04

LOQ (ppm) 0.14 0.08 0.06 0.14

For the determination of trace elements in river sediments, the above value of

LOD and LOQ can be suitable for using this analytical method. But for the very low

concentration of Pb, Cd in surface water of river, the more sensitivity such as ICP-

MS should be applied.

3.1.4. Effect of interferences to the determination of Pb, Cd and Cu, Zn by

FAAS.

In environmental samples, Pb, Cu, Cd, Zn usually coexist with the same level

of content. These elements can be affected to the absorbance when analyze each one.

Therefore, the effect of other analysts has to be investigated before analyzing by

FAAS. The error of interferences is calculated by the following formula:

%𝑋 = 𝐴𝑡 − 𝐴𝑖

𝐴𝑡× 100%

Where:

+ % X: error.


55

+ Ai: The value of the measured intensity of absorption when on interference

present (Abs)

+ At: Absorption intensity value found when the other analytes being exist

(Abs)

The precision of measurements was determined by the quantity of S2

and

value of RSD (%) and were calculated as follows:

𝑆2 = (𝐴𝑡−𝐴𝑖)

2

𝑛−1 𝑆 = 𝑆2 %𝑅𝑆𝐷 =

𝑆

𝐴𝑡𝑏. 100

Where:

+ Atb: The average absorbance.

+ n: number of measurements.

+ S or SD: standard deviation.

+ %RSD : relative standard deviation.

The experimental results is illustrated in table 3.7

Table 3.7: Result of errors and repeatability of the measurements

Pb (2ppm)

Element

(1ppm)

Abs % X

RSD %

Ai = Pb 0.02786

3.07 At = Pb + Cd 0.02895 3.9

At = Pb + Zn 0.02819 1.2

At = Pb + Cu 0.02984 3.9

Cd (2ppm)

Other element (1ppm)

Abs % X

RSD %

Ai = Cd 0.3681

6.13

At = Cd + Pb 0.3988 8.3

At = Cd + Zn 0.4164 13.1


56

At = Cd+ Cu 0.4232 14.9

Zn (2ppm)

Other

element (1ppm)

Abs % X

RSD %

Ai Zn 0.09381 0.92

At = Zn + Pb 0.09548 1.8

At = Zn + Cd 0.09500 1.2

At = Zn + Cu 0.0958 2.1

Cu (2ppm)

Other element

(1ppm)

Abs %X

RSD %


57

The obtained results showed that the relative error followed the Gaussian distribution

law. The beginning and the end of the linear error of greater suffering in the

concentration between the baseline errors is minimal. But all these errors are less

than the allowable limit of the analysis of ultra-traces is 15%.

In addition, many other cations do not have any affects on the absorbance of

Cu, Pb, Zn and Cd. The fact shows that the samples contain these cations’

concentration much smaller than the concentration of the 4 elements investigated. In

a word, there is no other cation in the samples effects directly on the analytic results.

3.2. Determination of Pb, Cu, Zn, Cd in surface water samples using ICP-

MS

In river water samples, the concentrations of four heavy metals (Pb, Cu, Zn,

Cd) are usually lower than the limit of detection of F-AAS method. Therefore, ICP-

MS techniques with very low limit of detection, and high selective and simultaneous

determination need to be applied to analyze. All the experimental conditions of ICP-

MS method were followed by instructors and manufacturer and were applicable as

the previous studies at Chemical Faculty, HUS.

3.2.1. Calibration curves for the determination of Cu, Zn, Pb and Cd in

water samples.

Four standard solutions of each analyte including Cu, Zn, Pd and Cd in 1%

HNO3 media were prepared and the analytical signal (cps) were obtained at

experimental conditions (part 2.4.2.2). Because of the large dynamic range with the

range of concentration changing from ppt to ppm, it is not necessary to investigate.

Based on the experimental results, the calibration curves of four metals were

investigated and illustrated in figure 3.3.

Ai = Cu 0.02143

4.69 At = Cu + Pb 0.02214 3.3

At = Cu + Cd 0.02391 11.6

At = Cu + Zn 0.02226 3.8


58

0 50 100 150 200

0

20000

40000

60000

80000

100000

120000

140000

160000

180000


------------------------------------------------------------

B 843.71621 7.29638

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99979 1647.21236 4 <0.0001

------------------------------------------------------

Inte

nsity(c

ps)

Concentration of Cu (ppb)

0 50 100 150 200

0

10000

20000

30000

40000

50000

60000


------------------------------------------------------------

B 264.20003 2.92194

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99968 662.57934 4 <0.0001

-------------------------------------------------------

Inte

nsity

(cp

s)

Concentration of Cd (ppb)

0 50 100 150 200

0

50000

100000

150000

200000

250000

300000

350000


------------------------------------------------------------

B 1627.84069 18.16054

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99964 4113.33566 4 <0.0001

---------------------------------------------------------

Inte

nsity

(cp

s)

Concentration of Pb (ppb)

0 50 100 150 200

0

10000

20000

30000

40000


------------------------------------------------------------

B 200.02019 2.70788

------------------------------------------------------------

R SD N P

------------------------------------------------------------

0.99992 607.20934 4 <0.0001

-----------------------------------------------------

Inte

nsity(c

ps)

Concentration of Zn (ppb)

Figure3.3: Calibration curves for the determination of Cu, Cd, Pb and Zn using ICP-MS

The concentrations of Cu, Cd, Pb and Zn in real samples were exploited by standard

method.


59

3.2.2. Method validation

Accuracy and repeatability of the analytical process for total metals were

checked using estuarine sediment certified reference material (CM-MESS 3) from

National Institute of Standard and Technology (NIST), during which satisfactory

accuracy and repeatability were realized, with recovery between 85% and 113% as

shown on table 3.8.

Table 3.8: Accuracy and recovery of CRM using FAAS and ICP-MS

Metal

LOD (ppm)

Value

(±SD)

(mg/kg)

Recovery

(±SD)

(mg/kg)

RSD (%)

FAAS

Cu 0.14 33.9 ± 1.6 97 1.3

Pb 0.14 21.1 ± 0.7 113 7.8

Cd 0.08 0.24 ± 0.01 87 9.1

Zn 0.06 159 ± 8 91 2.7

ICP-MS

Cu 0.015x10-3

33.9 ± 1.6 101 4.4

Pb 0.042x10-3

21.1 ± 0.7 110 3.1

Cd 0.012x10-3

0.24 ± 0.01 85 2.0

Zn 0.011x10-3

159 ± 8 92 10.3


60

3.3. Total concentrations of Cu, Pb, Cd, Zn in surface water and sediment

of ThadLuang marsh

3.3.1. Water sample:

The absorbance of each sample for each metal was measured by using ICP-MS. The

obtained results were showed in table 3.9.

Table 3.9: The concentration of Pb, Cd, Zn, Cu in surface water samples of

ThadLuang marsh (g/L)

Sample Pb Cd Zn Cu

W1 37.0±0.4 71.7±0.8 25.1±0.3 159±1

W2 29.1±0.3 55.9±0.6 82.5±1.1 34.5±0.3

W3 10.1±0.1 45.6±0.5 86.9±1.1 45.9±0.4

W4 28.2±0.3 66.0±0.7 60.1±0.8 42.3±0.4

W5 17.1±0.2 43.6±0.5 96.3±1.3 44.3±0.4

W6 31.7±0.4 65.2±0.7 106±1 65.7±0.6

W7 56.6±0.6 32.9±0.4 155±2 40.3±0.3

W8 15.1±0.2 76.7±0.8 85.2±1.1 82.2±0.7

3.3.2. Sediment sample

Using the F-AAS, the contents of four elements in the sediment samples were

calculated from the absorbance and the amount of sample (0.05 gram of each

sediment) taken and the following equation:

m (µg) = (Cx. Vo.) 1

0.05

Where: Cx (ppm) concentrations of metals in 25 mL volumetric


61

flask.

V0 is the initial sample volume= 25 mL.

Table 3.10 shows the results of contents of four heavy metals analyted.

Table 3.10: Heavy metal content (mg/kg) in sediment collected in Thadluang

marsh.

Sample Element (mg/kg)

Pb Cd Zn Cu

S1 421.1±74.1 123.4±78.0 287.8±61.0 157.6±79.8

S2 417.2±74.1 134.6±77.7 60.45±60.1 95.3±82.6

S3 423.6±74.0 14.68±85.8 121.0±57.6 65.7±84.3

S4 450.6±73.8 163.9±77.2 313.5±62.8 232.6±77.5

S5 446.0±73.8 170.8±77.2 146.2±57.1 176.2±79.1

3.4. Surface Water Quality Standard

The proposed Surface Water Quality Standard is shown in the following table. Since

such standard has not been stipulated so far in Lao PDR, it is newly provided.

Table 3.11: Proposed Surface Water Quality standard

No. Substances Symbol Unit Standard

Value

Method of

Measurement

1. Color, Odor and Test - N -

2. Temperature ◦C N’ Thermometer

3. pH - 5-9 Electronic pH Meter

4. Dissolved Oxygen DO mg/l 6 Azide Modification

5. COD COD ml/l 5 Potassium permanganate

6. BOD5 BOD5 mg/l 1.5 Azide Modification at

20 degree C, 5 days

7. Total Coliform Bacteria Coliform

Bacteria

MPN/100 ml 5,000

Multiple Tube

Fermentation 8. Faecal Coliform Bacteria Faecal

Coliform

MPN/ 100 ml 1,000

9. Nitrate-Nitrogen NO3-N mg/l <5.0 Cadmium Reduction


62

No. Substances Symbol Unit Standard

Value

Method of

Measurement

10. Ammonia-Nitrogen NH3-N mg/l 0.2 Distillation

Nesslerization

11. Phenols C6H5-OH mg/l 0.005 Distillation, 4-Amin

anti-Pyrenees

12. Copper Cu mg/l 0.1

Atomic Absorption

Direct Aspiration

13. Nickel Ni mg/l 0.1

14. Manganese Mn mg/l 1.0

15. Zinc Zn mg/l 1.0

16. Cadmium Cd mg/l 0.005

17. Chromium, Hexavalent Cr+6

mg/l 0.05

18. Lead Pb mg/l 0.05

19. Mercury Hg mg/l 0.002 Atomic Absorption Cold

Vapour

20. Arsenic As mg/l 0.01 Atomic Absorption

Direct Aspiration

21. Cyanide CN- mg/l 0.005 Pyridine-Barbituric

22. Alpha ¬ Radioactivity- α Becquerel l/l 0.1

Gas Chromatography

23. Beta ¬ Radioactivity- β Becquerel l/l 1.0

24. Total Organ chlorine mg/l 0.05

25. DDT C14H9Cl5 mg/l 1.0

26. Alpha -BHC α BHC mg/l 0.02

27. Dieldrine C12H8Cl6O mg/l 0.1

28. Aldrin mg/l 0.1

30. Endrin mg/l None

Source: The Draft Agreement of National Standard of Environment in Laos, March 2009

Following the results, heavy metals distributed along the That Luang Marshland

were shown in the Table 3.9. The concentration of Pb, Cd, Zn, Cu in surface water

samples of That Luang marsh (g/L) in this study collected on May, 2011 represent

for rainy season.

The heavy metal concentrations higher than the standard value were witnessed in

Pb2+

accounting for 56.6±0.6 (g/L) of the water samples point 7, 37.0±0.4 (g/L)

of the water samples point 1, 31.7±0.4 4 of the water samples point 6. Concentration

for the Cd2+

accounting for 76.7±0.8 (g/L) of the water sample point 8, 71.7±0.8

(g/L) of the water sample point 1, 66.0±0.7 (g/L) of the water sample point 4,

65.2±0.7 (g/L) of the water sample point 6. Concentration for the Zn2+

accounting

for 155±2 (g/L) of the water sample point 7, 106±1 (g/L) of the water sample


63

point 6, 96.3±1.3 (g/L) of the water sample point 5. Concentration of Cu2+

accounting for 159±1 (g/L) ) of the water sample point 1, 82.2±0.7 (g/L) of the

water sample point 8, 65.7±0.6 (g/L) of the water sample point 6.

The heavy metal concentration higher than the standard value were seen in the

concentration of Pb2+

with 450.6±73.8 (mg/kg) of the sediment samples point 4,

446.0±73.8 (mg/kg) of the sediment samples point 5. Concentration of Cd2+

with

163.9±77.2 (mg/kg) of the sediment sample point 4, 170.8±77.2 (mg/kg) of the

sediment sample point 5. Concentration of Zn2+

with 146.2±57.1 (mg/kg) of the

sediment sample point 5, 287.8±61.0 (mg/kg)) of the sediment sample point 1,

313.5±62.8 (mg/kg) of the sediment sample point 4. Concentration of Cu2+

with

157.6±79.8 (mg/kg) of the sediment sample point 1, 232.6±77.5 (mg/kg) of the

sediment sample point 4, 176.2±79.1 (mg/kg) of the water sample point 5.

Water and sediment samples were determined by Inductively coupled plasma mass

spectrometry (ICP-MS) and Flame- Atomic absorption spectroscopy (F-AAS) shown

the result that in water samples were detected concentration of in any point which

mean that its concentration of Pb2+

, Cd2+

, Zn2+

and Cu2+

less than the concentration

of surface water of standard parameter, but for sediment samples were found out

higher accumulation of Pb2+

from 450.6±73.8 (mg/kg) and Cd2+

from 170.8±77.2

(mg/kg) residue in the both point S5, Zn2+

from 313.5±62.8 (mg/kg) and Cu2+

232.6±77.5 (mg/kg) residue in the both point 4 than other point, but we don't have

sediment of standard parameter for compare, due to the location of this area near the

agriculture area and Beer Lao factory .

Heavy metal contents accumulate in the surface water and sediment compartment in

other point, even though the location of this area is very near from ThadLuang

marshland, this point has many canals from the village run to this area. The villagers

mostly worked in paddy field around the canal. This can anticipate that heavy metal

contents contaminated this area come from paddy field, market, factory and other

farm activity.


64

3.4. Application of GIS to find out spatial distribution of heavy metals

Figure 3.4 : The Map of water quality of Thadluang Marsh.


65

Figure 3.5: The Map of sediment quality of Thadluang Marsh.


66

CHAPTER 4: CONCLUSION

Water quality for drainage canals and marshes have been getting worse and water

have been increasing due to increasing discharge of domestic wastewater from urban

areas, resulting from improved living standards, rapid economic and population

growth. Urban areas are facing higher population growth rates than the national

average, representing rural urban migration. Present development trends have

stimulated the urbanization process due to increased growth in the industry and

tourism sectors of the city, combined with rural to urban migration that lead to an

increase in environmental problems, degradation of wetland areas and wastewater

management problems.

In this thesis, I studied and received some significant results

- Application of Inductively coupled plasma mass spectrometry (ICP-MS) and

Flame- Atomic absorption spectroscopy (AAS) to analyze

- Investigation of optimal conditions of some chemical factors influencing to

absorbance in F- AAS method

+ Studying the effects of sample matrix and matrix modifier to F-AAS:

matrix of samples should be kept at 2% HNO3 and 1% NH4CH3OO

+ The limit of linearity of Pb, Cd, Zn and Cu measurements: the limit of

linearity (LOL) of four heavy metal concentrations is up to 2.5 ppm with Pb; 0.75

ppm with Cd and Zn; 1.25 ppm with Cu measurements.

- By F-AAS method, the amount of Pb2+

, Cd2+

, Zn2+

and Cu2+

in 5 sediment

samples taken in ThadLuang marsh was determined. Moreover, the

determination of the amount of these 4 elements in 8 water samples was taken

place by ICP Ms, so the extent of pollution is also estimated. The amount of the

heavy metal in water fluctuates from 10 to 159µg/L while the changing is seen

in sediment from 14.68 to 450.6mg/kg. They are in the range of standard values.

From this analysis it can find the way or support the project to establish the factory

or the system for waste water treatment for Vientiane’s city. It can use these data’s to

make or produce the artificial lake for treat the wastewater by using the necessary

plants or bio-treatment in another places.


67

REFERENCE

Agricultural Statistics. Year Book 2003 and 2004, Vientiane Capital, April 2005.

Department of Planning, Ministry of Agriculture and Forestry.

Ayres, Robert U.; Ayres, Leslie; Råde, Ingrid (2003). The life cycle of copper, its co-

products and byproducts, pp. 135–141.

A.M Garcia Rodriguez, A Garcia de Torres and J.M Cano Pavon (1998), Talanta

Volume 47, Issue 2, p.p 463-470.

Barceloux, Donald G.; Barceloux, Donald (1999). "Zinc". Clinical Toxicology 37,

p.p 279–292.

B.V L’vov (2005), Fifty years of atomic absorption spectrometry, J. Anal Chem., 60:

382–392.

Casarett & Doull's Toxicology, The Basic Science of Poisons, Fifth Edition, Edited

by Curtis D. Klassen, Ph.D., McGraw-Hill, New York. pp 715.

Federal Register / Vol. 65, No. 8 / Wednesday, January 12, 2000 / Rules and

Regulations, pp. 1976.

Fosmire GJ (1990). "Zinc toxicity". Am. J. Clin. Nutr. P. 51.

Gao Hong – Wen (1995), Talanta Volume 42, Issue 7, Pages 891-895.

Hüseyin Bağ, A.Rehber Türker , Ramazan Coşkun, Mehmet Saçak, Mustafa

Yiğitoğlu (2000), “Determination of zinc, cadmium, cobalt and nikel by flame

atomic absorption spectrometry after preconcentration by poly(ethylene

terephthalate) fibers grafted with methacrylic acid”, Spectrochimica Acta Part B:

Atomic Spectroscopy, volume 55, Issue 7, p.p 1101-1108.

Hong, Youlian and Bartlett, Roger, ed (2008). Routledge Handbook of Biomechanics

and Human Movement Science London: Routledge. p. 250.

Haswell, S.J., 1991, Atomic Absorption Spectrometry; Theory, Design and

Applications. Elsevier, Amsterdam.

Jarup, L. (1998). "Health effects of cadmium exposure - a review of the literature and

a risk estimate". Scandinavian Journal of Work, Environment and Health, pp. 11–51.

http://books.google.com/books?id=gGHOz1G3AqwC&pg=PA135

http://books.google.com/books?id=gGHOz1G3AqwC&pg=PA135

http://www.sciencedirect.com/science/journal/00399140

http://www.sciencedirect.com/science?_ob=PublicationURL&_hubEid=1-s2.0-S0039914000X00379&_cid=271360&_pubType=JL&view=c&_auth=y&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=2bf88137f4dceed55049513713a2f582

http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=2407097


http://www.sciencedirect.com/science?_ob=PublicationURL&_hubEid=1-s2.0-S0039914000X00057&_cid=271360&_pubType=JL&view=c&_auth=y&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=bda9b202908e88d7c339b4383497bb0d



http://www.sciencedirect.com/science?_ob=PublicationURL&_hubEid=1-s2.0-S0584854700X00705&_cid=271413&_pubType=JL&view=c&_auth=y&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=b7469892508fee40b61edffa7c7332ec

http://books.google.com/?id=p7Ne5IjK5H0C&pg=PA250

http://books.google.com/?id=p7Ne5IjK5H0C&pg=PA250


68

JICA, (2009). The Study on Improvement of Water Environment of Water

Environment in Vientiane City.

Krzysztof Jankowski , Jun Yao, Krzysztof Kasiura, Adrianna Jackowska,

Anna Sieradzka (2004), “Multielement determination of heavy metals in

water samples by continuous powder introduction microwave-induced plasma atomic

emission spectrometry after preconcentration on activated carbon”, Spectrochimica

Acta Part B: Atomic Spectroscopy, Volume 60, Issue 3, p.p 369-375.

MRC. (2006). Environment Training Program Case Studies: Vientiane Urban

Wetland Conservation and protection, Lao PDR.

M.C. Yebra , N. Carro, A. Moreno-Cid (2002), “Optimization of a field flow pre-

concentration system by experimental design for the determination of copper in sea

water by flow-injection- atomic absorption spectrometry”, Spectrochimica Acta Part

B: Atomic Spectroscopy, Volume 57, Issue 1, p.p 85-93.

National Research Council (U.S.), Panel on Cadmium, Committee on Technical

Aspects of Critical and Strategic Material (1969). Trends in Usage of Cadmium:

Report. National Research Council, National Academy of Sciences-National

Academy of Engineering, pp. 1–3.

Petrovic and Dewal, Analytical letters, vol. 31, No 12, 1998, pp. 2077-2091.

Prabhakar Misra and Mark Dubinskii, Editors, Marcel Dekker (2002) "Ultraviolet

Spectroscopy and UV Lasers", Analytical Chemistry, Physical and Biology

magazine, part II, 4, pp. 4-5.

Reynolds, R.J. et al., 1970, Atomic Absorption Spectroscopy. Barnes & Noble Inc.,

New York.

Research of Integrated Water Quality Treatment by Biology-Physical and Chemical

Characteristics in Thadluang, Faculty of Science, NUOL, Marsh, 2002.

Science Technology and Environment Agency (STEA) (STEA, 2004).

STO (2009). Report of Project Implementation on Efficiency Wastewater Treatment

in That Luang Marsh. Science and Technology Office, Vientiane.

Stellman, Jeanne Mager (1998). Encyclopaedia of Occupational Health and Safety,

International Labour Organization. pp. 81.2–81.4.



http://www.sciencedirect.com/science?_ob=PublicationURL&_hubEid=1-s2.0-S0584854705X03883&_cid=271413&_pubType=JL&view=c&_auth=y&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=f233cb43d20ffd494e79ad0be1f3f509



http://www.sciencedirect.com/science?_ob=PublicationURL&_hubEid=1-s2.0-S0584854700X03692&_cid=271413&_pubType=JL&view=c&_auth=y&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=56c28b30a77af1ce973708ebff91cff8

http://books.google.com/?id=okArAAAAYAAJ



http://en.wikipedia.org/wiki/Prabhakar_Misra

http://books.google.com/?id=nDhpLa1rl44C&pg=PT644


69

Stefánsson A, Gunnarsson I, Giroud N (2007). "New methods for the direct

determination of dissolved inorganic, organic and total carbon in natural waters by

Reagent-Free Ion Chromatography and inductively coupled plasma atomic emission

spectrometry". Anal. Chim. Acta 58, pp. 69–74.

Susumu Nakashima and Masakazu Yagi (1983), “Determination of nanogram

amounts of cadmium in water by electrothermal atomic absorption spectrometry after

flotation separation”, Anal.Chem Acta, Volume 147, p.p 213-318 .

Selehattin Yilmaz, Sultan Yagmur, Gulsen Saglikoglu, Murat Sadikoglu (2009) ,

“Direct Determination of Zn Heavy Metal in Tap Water of Canakkale (TURKEY) by

Anodic Stripping Voltammetry Technique” , Int. J. Electrochem. Sci., 4, pp. 288 –

294.

The Draft Agreement of National Standard of Environment in Laos, March 2009.

The Agreement on National Environmental Standards in Lao, December 7, 2009,

Prime Minister Office and WREA in Lao PDR.

Tu Van Mac, Tran Thi Sau, Determination of heavy metals in beer by polarimetry,

Analytical Chemistry, Physics and Biology magazine, part III, 4, pp. 2-3 .

Thanh Thuc trinh, Nguyen Xuan Lang, Determination of Zinc, Cadmium, Lead and

Copper in some kinds of food and agricultural soil by polarimetry, Analytical

Chemistry, Physical and Biology magazine, part III, 3, pp. 8-9.

Would Bank, 2007, “Lao PDR Environment Monitor 2005.

Zoski, Cynthia G. (2007-02-07). Handbook of Electrochemistry, Elsevier Science.,

pp. 85-87.

http://en.wikipedia.org/wiki/Handbook_of_Electrochemistry

Documents

Investigation the heavy metal contents in surface water and sediment collected