CLIMATE CHANGE: EFFECTS ON CONCENTRATION OF HEAVY

METAL IN AQUATIC ENVIRONMENTSADHU, H.

JOOMAN, U.BRASSE, C.

LONG, P.B.G.

ABSTRACT

• Heavy metals are metallic element that has a relatively high density. Common examples are lead, copper and mercury. Heavy metals have biological, chemical and industrial applications. They are of natural occurrence or present in everyday commodities such as paint dust, batteries and cells; however, some have detrimental toxicological effects on health and environment. In this study, the effects of copper on aquatic environment were under investigation. Fish species of Tilapia and water from Citron River were used to set up aquatic ecosystems in laboratory. Copper sulphate pentahydrate (CuSO4. 5H2O) in the range of 0.05 to 0.22PPM were used as independent variable. Data logger (Data Harvester 2.7) was taken to record change in parameters. Little significant effect on temperature (28.2±1.3 oC), pH (5.6 ±0.3) and oxygen concentration (32.2 ±1.9%) on the aquatic system was noted. Conductivity of the system and breathing rate of fish were increased by 368.3% and 76.6% respectively. Minimum lethal dose of copper sulphate on Tilapia was found to be 0.2PPM after 105min. Alarmingly, the survey prior to investigation revealed that 10% of students do not know what are heavy metals and 17% believed that heavy metals have no effect on environment. Students should be met more aware of the danger of heavy metals.

Key words: Heavy metal copper, aquatic environment,

INTRODUCTION• The term “heavy metals” refers to any metallic element that has a

relatively high density and is toxic or poisonous even at low concentration (Lenntech, 2004). Heavy metals include lead (Pb), cadmium (Cd), zinc (Zn), mercury (Hg), arsenic (As), silver (Ag) chromium (Cr), copper (Cu) iron (Fe), and the platinum group elements.

• Heavy metals occur as natural constituents or in common day commodities such as batteries, cells, paints etc.

• They are toxic to health and the environment• They have importance biological, chemical and industrial applications.• Veerappapillay (2000) , Chuckowree (2003) , Ramessur (2002) and

Petersson (2005) have studied different aspect of heavy metals in Mauritius.

AIMS AND OBJECTIVES

• The aim of this study was to investigate the effects of heavy metal copper on aquatic environment.

• It was to be determined whether copper ions affect the oxygen concentration, pH, conductivity and temperature of aquatic ecosystem.

• The lethal dose of copper and the impact on the breathing rate of Tilapia were to be determined.

• The perceptions of students on heavy metals were to be examined also.

METHODOLOGY

• A survey was carried out in order to determine the perceptions of students on aspect of heavy metals on environment. A sample consisting of 30 students from upper six classes were selected. Questionnaire was used to collect data. Analysis was carried using Microsoft Excel

• Samples were collected in a Labourdonais river located at Long Mountains, situated in the district of Pamplemousses (fig 3.1) . The river receives water from Citron River. Drift and fabric nets were used to collect species of fish (Fig 3.2).

Figure 3.1: The sampling site showing the bridge of River Citron, Long Mountain. The river is located in the region of Long Mountains found in the district of Pamplemousses

(Photo: Mr. Long)

Figure 3.2: Equipment used for samplings. Jeri Can, Drift Net and fabric net (Photo: Mr. LONG)

• Sensors (Data harvester 2.7) were used to determine the oxygen concentration, pH, conductivity and temperature of the water collected (fig 3.3, 3.4). The presence of copper ions in the water was also investigated using NaOH precipitation method.

Figure 3.3: Sensors used (Photo: Mr. Long)

Figure 3.4: Home page of data harvester

• Six large glass beakers (2dm3) were chosen. The beakers were labeled A, B, C, D, E and Z ( fig 3.5).

• 1000ml of river water collected was added in each beaker.

• Different amount of Copper sulphate pentahydrate (CuSO4. 5H2O) was then added. The concentrations added are shown in table 3.2.

*1 ppm= 1mg of CuSO4. 5H2O in 1000ml of river water

Table 3.2: Concentration of copper sulphate used

Beaker Concentration of CuSO4. 5H2O/ppm*

Z 0.00

A 0.05

B 0.10

C 0.15

D 0.20

E 0.25

• Sensors were used to determine the temperature, the oxygen concentration, the pH and the conductivity of the water before fish was added. This was denoted t=0

• One fish was added to each beaker. • At 30 minutes interval for 2 hours sensors were used to determine

the temperature, the oxygen concentration, the pH and the conductivity of the water against (See fig 3.6).

• Six digital stop watches were used to record time; one for each beaker.

• The breathing rate was determined by counting the number of gill beat produced per minutes.

• Care and precaution were strictly considered. Manipulation of copper ions was carried as per MSDS of copper (MSDS, 2010)

Figure 3.5: The beakers with Tilapia (Photo: Mr. LON G)

Figure 3.6: Students measuring time and other parameters (Photo: Mr. LONG)

RESULTS OF SURVEY

• 17 % do not know what is heavy metals (fig. 4.1)• 27% only know that copper is a heavy metal (fig. 4.2)• 11.90% seem not to know the effect of heavy metals at

all (fig. 4.3)• 31.9 % stated that heavy metals are present in rivers

(fig. 4.4)• 10% stated that heavy metals are not dangerous (fig.

4.5)• 63% stated that heavy metals are dangerous to the

environment (fig 4.6)

83%

17%

Fig. 4.1. Do you know what is a heavy metal?

Yes No

Mag-nessium

23%

Calcium30%

Copper27%

I donot know20%

Fig 4.2. Which one of the following is a heavy metal?

Cause diseases to humans

Good for environment

Bad for the environment

I do not know

26.20%

23.80%

38.10%

11.90%

Fig 4.3. Which of the following is/are likely ef-fect(s) of heavy metals?

Motor vehicle smokes

In air In rivers I donot know

25.50% 23.40% 31.90% 19.10%

Fig. 4.4. Where can we have heavy metals?

Yes90%

No10%

Fig. 4.5. Can heavy metals kill organisms?

Yes63%

No37%

Fig 4.6. Can heavy metals damage the environment?

RESULTS OF PRE TESTING OF SAMPLES

• .The fish as an average mean length of 5.7 cm (fig. 4.7)Figure 4.7: Tilapia

• The pre test of the sample of water collected revealed the absence of copper ions in the water. All three sites (R1, R2 and R3) show the absence of copper ions. The result is represented in figure 4.8. The blue precipitate indicates the presence of copper ion.

• The temperature, the oxygen concentration, conductivity and pH of the water sample R1, R2 and R3 were also analysed. The result is represented in table 4.1

Figure 4.8: Pre test for copper ions in sample of river water. R1, R2 and R3 are samples

collected at 3 different sites along the bank of the river. +C is the positive control and –C the

negative control

Sample Temperature/ oC

Oxygen

concentration/

%

Conductivity/

μS

pH

R1 27.6 32.3 12 5.9

R2 27.8 33.2 12 6.1

R3 28.0 33.2 12 5.7

Table 4.1: Parameters analysis of water sample R1,

R2 and R3

RESULTS OF CHANGES IN PARAMETERS OF THE AQUATIC ENVIRONMENT.

• There was a 76.6% decrease in the breathing rate of the fish as time goes by and concentration of copper sulphate increases. The standard deviation was 26.6. (fig 4.9)

• During the experiment, the oxygen concentration shows a slight decrease with both increasing concentration of copper sulphate and with time (fig 4.10).

• The conductivity of the aquatic environment showed a net increased of 368.3%. (fig 4.11)

• Little change was noted on pH over time and over increase in concentration of Cu2+. The standard deviation was only 0.3. (Fig. 4.12)

• Little change was noted in the temperature of the aquatic system. The mean temperature was 28.1oC (fig. 4.13)

• It was noted that a concentration of copper sulphate in order of 0.25ppm cause the fish to die within 80minutes. The mortality was less obvious in the other concentration; fish also died at 105min at 0.2ppm.

Figure 4.9: Decrease (-76.6%) in the breathing rate of fish as concentration of Cu2+ increases.

t=0min t=30min t=60 min t=90 min t=120 min0

5

10

15

20

25

30

35

40Oxygen conc. (%)

0 ppm 0.05 ppm 0.1 ppm 0.15 ppm 0.2 ppm 0.25 ppm

Figure 4.10: Showing a decrease in

concentration of oxygen in the aquatic

environment as concentration of Cu2+ and time increases.

The SD was 1.9.

t=0min t=30min t=60 min t=90 min t=120 min

0

20

40

60

80

100

120

Conductivity

0 ppm0.05 ppm0.1 ppm0.15 ppm0.2 ppm0.25 ppm

Figure 4.11: Increase in conductivity with increase in copper concentration. SD 16.7.

t=0min t=30min t=60 min t=90 min t=120 min

01234567

pH

0 ppm0.05 ppm0.1 ppm0.15 ppm0.2 ppm0.25 ppm

Figure 4.12: Change in pH when time and

concentration of copper sulphate increased.

t=0min

t=30min

t=60 m

in

t=90 m

in

t=120 m

in26

27

28

29

Temperature0 ppm0.05 ppm0.1 ppm0.15 ppm0.2 ppm0.25 ppm

Tem

pera

ture

/oC

Figure 4.13: Change in temperature with increase in Cu 2+ concentration

DISCUSSION • Copper sulphate pentahydride was used because it is highly soluble and is not a toxic

heavy metal to man (Damgaard, 2003; OSHA, 2004). It is easily available also.• The aquatic system set up consisted of glass beakers with same volume of water and

approximately same sized and number of fish. So the variable volumes, number and sized were controlled. Water sample from river was used in order to have same starting level. A control with no copper added was used to facilitate comparison of results.

• During the experiment, the oxygen concentration shows a slight decrease with both increasing concentration of copper sulphate and with time. With a standard deviation of 1.9 this demonstrates that all the results were near to the mean. Therefore, copper ions of different concentrations and time seem not to affect concentration of oxygen in the water.

• Breathing rate is an important parameter to determine the condition of the fish. It has been noted that the breathing rate was slower at higher concentrations of copper than at lower concentrations. There was a net decrease of 76.6% in breathing rate. This confirms the view of (Duruibe et al, 2007) that heavy metals are toxic to fish. Copper ions are strong non competitive inhibitor of enzymes and they can easily denatured protein by destruction of ionic bonds (Duruibe et al, 2007)

• The data obtained during study period concurred with observations elsewhere. It was noted that a concentration of copper sulphate in the order of 0.25ppm cause the fish to die within 80mins. The mortality was less obvious in the other concentration; fish dies at 105min at 0.2ppm. PAN (2006) approximately, similar results were obtained. Gholami et al, 2010 revealed that white fry were killed at a copper concentration of 0.4 mg per liter.

• pH is the concentration of proton in a solution. Change in pH can affect enzymatic activities and protein structures (Duruibe et al, 2007). Little change (pH5.6 ±0.3) was noted on pH over time and over increase in concentration of Cu2+. The conductivity shows an increase of about more than 300%. This is normal because as concentration of copper was increased more copper ions would be present in the water. Little change in temperature was noted. The mean temperature was 28.1.

LIMITATIONS OF THE STUDY• No replications were carried. Replication would have given more

accurate results• The data logger is not very portable. It would have been suitable if

the pre testing of samples was done in situ• The sensors used have their own limitations. For instance due to

charged particles distribution, the pH and conductivity sensor could not be used at the same time. In addition only 3 sensors could be used at any moment because only 3 slots are present on the data harvester. So cross contamination could have occurred during manipulation.

• It would have been desirable if all fish were of the same size. • It would have been desirable if other statistical package used to

analyse data.

IMPROVEMENTS AND RECOMMENDATIONS

• As there was no access to better equipment, it was not feasible to investigate the possible influence of the copper ions on the physiology of the fish. Neither has a standard been used when carrying test on the samples.

• It would have been possible to collect a sufficient number of samples to work with statistically if another approach had been used. To increase validity, more powerful statistics should have been applied; such as analysis of variance and student T test. Standard error of sample should have been determined. Powerful statistical packages could have been used, such as Data log pro.

• Due to limitation of sensors, accurate results could not have been obtained. More sophisticated sensors which can be used in situ should have been used. Other aquatic species should have been included but due to ethical issues on organism right and protection of biodiversity this has not been possible.

• Survey with more questions should have been given to respondents; due to lack of time this was not possible. Other method to collect data could have also been used, such as interview. Larger sample size could have been used.

• • Information on the danger of heavy metals should be made

available to students in order to increase their awareness on the topic. This could be done by using poster, essay, elocutions and debate contest on heavy metals. Science and other subjects should infuse topic related to heavy metals in their lessons.

CONCLUSIONS• The data obtained during this study demonstrated that at

concentration 0.2ppm copper ions were found to be lethal to fish after 105min. The results provide also some background information of copper with the aquatic environment; copper ions have little effects on temperature (28.2±1.3 oC) , pH (5.6 ±0.3) and oxygen concentration (32.2 ±1.9%) of the aquatic system used. Conductivity of water and breathing rate of fish were however affected with increasing concentration of the heavy metal and with time. There was a decrease of 76.6% in breathing rate of fish and an increase of 368.3% in conductivity of water system. The survey revealed that students are not aware of heavy metals and their toxicology on environment, organisms and human health.

ACKNOWLEDGEMENTS

• In the elaboration of this project, special thanks must go to the following persons: Mr. Ramen, Mr. Shadobaccus, Mr. Busgeeth, Mrs. Ransurn, Miss. Shahabun, Students of Form IIO, Upper six Science and form IVR.

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• Duruibe, J. O., Ogwuegbu, M. O. C. and Egwurugwu, J. N. (2007). Heavy metal pollution and human biotoxic effects. International Journal of Physical Sciences Vol. 2 (5), pp. 112-118, [accessed April 20, 2012] http://www.academicjournals.org/IJPS

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