Major Ions in Water.pdf

World Bank & Government of The Netherlands funded
Training module # WQ - 28
Major Ions in Water
New Delhi, September 1999
CSMRS Building, 4th Floor, Olof Palme Marg, Hauz Khas,New Delhi 11 00 16 IndiaTel: 68 61 681 / 84 Fax: (+ 91 11) 68 61 685E-Mail: dhvdelft@del2.vsnl.net.in
DHV Consultants BV & DELFT HYDRAULICS
withHALCROW, TAHAL, CES, ORG & JPS

Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 1
Table of contents
Page
1. Module context 2
2. Module profile 3
3. Session plan 4
4. Overhead/flipchart master 5
5. Evaluation sheets 22
6. Handout 24
7. Additional handout 29
8. Main text 32

1. Module contextThis module presents the major inorganic ions which are significant to water quality.Modules in which prior training is required to complete this module successfully and otheravailable, related modules in this category are listed in the table below.
While designing a training course, the relationship between this module and the otherswould be maintained by keeping them close together in the syllabus and placing them in alogical sequence. The actual selection of the topics and the depth of training would, ofcourse, depend on the training needs of the participants, i.e. their knowledge level and skillsperformance upon the start of the course.
No. Module title Code Objectives1. Basic water quality concepts WQ - 01 Discuss the common water quality
parameters List important water quality issues
2. Basic chemistry conceptsa WQ - 02 Convert units from one to another Discuss the basic concepts of
quantitative chemistry Report analytical results with the
correct number of significant digits.
3. Basic Aquatic ChemistryConcepts
WQ - 24 Calculate ion concentrations fromionisation constants
a - prerequisite

2. Module profile
Title : Major Ions in Water
Target group : HIS function(s): Q2, Q3, Q5, Q6, Q7, Q8
Duration : 1 session of 60 min
Objectives : After the training the participants will Know the major ions in water and their sources Understand the significance of major ion concentrations
Key concepts : Sources of major ions in water Ion balance Hardness, SAR Health effects
Training methods : Lecture and discussion
Training toolsRequired
: Board, flipchart, OHS,
Handouts : As provided in this module,
Further readingand references
: Water Quality Monitoring, ed. J. Bartram and R. Balance Water Quality Assessment, ed. D. Chapman, E&FN SPON,
London

3. Session plan
No Activities Time Tools1 Preparations2 Introduction:
Introduce the session Suggest a number of common aquatic ions and
ask the participants whether these would be majoror secondary constituents of groundwater
Following discussion use overhead to confirm
10 min OHS
3 Introduction to Major Ions Discuss major cations and anions Talk about how ions become dissolved in water Discuss the sources of major ions Show how it is possible to characterise waters
graphically
10 min OHS
4 Individual Major Ions Discuss calcium and magnesium and what their
presence means in water Discuss the concept of hardness and what that
means in terms of water quality List other major ions and ask the participants what
their presence in water indicates Follow up by showing overhead of various major
ions Discuss sar, %Na, RSC and how it is used to
assess potential irrigation waters. Talk about thedifference between Indian and International SARstandards. Show USDA classification
15 min OHS
5 Ion Balancing Talk about the technique of ion balancing and why
it is so useful to the chemical analyst and waterquality expert
Show how ion balancing can be done and discussthe acceptability of errors
15 min OHS
6 Wrap up and Evaluation 10 min Addl.Handout

4. Overhead/flipchart masterOHS format guidelines
Type of text Style SettingHeadings: OHS-Title Arial 30-36, with bottom border line (not:
underline)
Text: OHS-lev1OHS-lev2
Arial 24-26, maximum two levels
Case: Sentence case. Avoid full text in UPPERCASE.
Italics: Use occasionally and in a consistent way
Listings: OHS-lev1OHS-lev1-Numbered
Big bullets.Numbers for definite series of steps. Avoidroman numbers and letters.
Colours: None, as these get lost in photocopying andsome colours do not reproduce at all.
Formulas/Equations
OHS-Equation Use of a table will ease horizontal alignmentover more lines (columns)Use equation editor for advanced formattingonly

Major Ions in Water
Major and Secondary Constituents of Groundwater
Sources
Water Characterisation
Water Quality Consequences
Ion Balancing

Major constituents (1.0 to 1000 mg/L)
Secondary Constituents(0.01 to 10.0 mg/L)
Sodium Iron Calcium Strontium Magnesium Potassium Bicarbonate Carbonate Sulphate Nitrate Chloride Fluoride Silica Boron

Major Cations and Anions in Water
CATIONS ANIONS Calcium (Ca2+) Bicarbonate (HCO3
-)/Carbonate (CO3
2-) Magnesium (Mg2+) Sulphate (SO4
2-) Sodium (Na+) Chloride (Cl-) Potassium (K+)

Sources (1)
Atmospheric Gases Dissolved by Rain and their Reactions
- Oxygen
- Nitrogen
- Carbon dioxide
- Nitrogen oxides (NOx)
- Sulphur oxides (SOx)

Sources (2)
Calcium Amphiboles, feldspars, gypsum, aragonite, calcite,pyroxenes, dolomite, clay minerals
Magnesium Amphiboles, olivine, pyroxenes, dolomite,magnesite, clay minerals
Sodium Feldspars, clays, halite, mirabilite, industrial wastes Potassium Feldspars, feldspathoids, some micas, clays Bicarbonate/Carbonate
Limestone, dolomite
Sulphate Oxidation of sulphide ores, gypsum, anhydrite Chloride Sedimentary rock, igneous rock

Water Characterisation (1)
Mg
Na + K
Ca
Cl
SO4
CO3 + HCO3
Equ
ival
ents
pe
r m
illio
n->
A B D C
Bar Graphs for 4 different samples

Water Quality Consequences
Calcium and Magnesium
- Cause hardness when combined with HCO-3, CO2-3, SO2
-4 etc
- Ca2+ normally below 15 mg/l
- Ca2+ can be above 100 mg/l in carbonate-rich rocks
- Mg2+ normally between 1 and 50 mg/l depending upon rock type

Hardness Classification
Hardness (mg/Las Ca CO3)
Classification
0 - 75 Soft 75 - 150 Moderately hard
150 - 300 Hard Over 300 Very hard

Other Major Ions Major Ions in Water
- Sodium high levels often associated with pollution
- Potassium generally low (

Health Effects
- Nitrate
- Fluoride
- Sodium
- Potassium
- Chloride

Irrigation Water Quality (1)
Sodium Adsorption Ratio (SAR) - in milliequivalents/L
( )SAR
Na
Ca Mg=
+
+
+ +2 2 2
International SAR Standards Indian SAR Standard SAR < 3: suitable for irrigation SAR > 26 unsuitable for irrigation SAR 3 9: use may be restricted SAR > 9 unsuitable for irrigation

Percent Sodium = Na+/ (Ca++ + Mg++ + Na+ + K+) x 100
- should be less than 60
Residual Sodium Carbonate
RSC = (CO3-- + HCO3
-) - (Ca++ + Mg++)
> 2.5 not suitable
1.25 - 2.5 marginal
< 1.25 safe

Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/

Major Ions in Water.pdf

Text of Major Ions in Water.pdf

Acids, bases and ions in aqueous solution

Heavy metal ions

Marketing ions

Ions in Aqueous Solution

TOPIC V: Ions in Aqueous Solutions

Ions in Aqueous Solution & Colligative Properties

Qualitative Analysis Identifying Ions in Solution Qualitative Analysis Identifying Ions in Solution

Monatomic Ions

Ions in Solution

Lecture 2 - Major Ions in Sea Water What is the composition of seawater? What defines Major Ions? What are their concentrations? What are their properties?

Complex Ions

Acids and Bases Chapter 19. Ions in Solution  Aqueous solutions contain H + ions and OH - ions  If a solution has more H + ions than OH - ions it is