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  • 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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 2

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 3

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 4

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 5

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 6

    Major Ions in Water

    Major and Secondary Constituents of Groundwater

    Sources

    Water Characterisation

    Water Quality Consequences

    Ion Balancing

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 7

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 8

    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+)

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 9

    Sources (1)

    Atmospheric Gases Dissolved by Rain and their Reactions

    - Oxygen

    - Nitrogen

    - Carbon dioxide

    - Nitrogen oxides (NOx)

    - Sulphur oxides (SOx)

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 10

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 11

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 12

    Water Characterisation (2)

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 13

    Water Characterisation (3)

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 14

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 15

    Hardness Classification

    Hardness (mg/Las Ca CO3)

    Classification

    0 - 75 Soft 75 - 150 Moderately hard

    150 - 300 Hard Over 300 Very hard

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 16

    Other Major Ions Major Ions in Water

    - Sodium high levels often associated with pollution

    - Potassium generally low (

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 17

    Health Effects

    - Nitrate

    - Fluoride

    - Sodium

    - Potassium

    - Chloride

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 18

    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

  • Hydrology Project Training Module File: 28 Major Ions in Water.doc Version 05/11/02 Page 19

    Irrigation Water Quality (2)

    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 05/11/02 Page 20

    Irrigation Water Quality (3)

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