This presentation deals with the recent advancement in the field of ground water sampling and analysis technique and water born survey as well as Indian scenario to interpret.
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Ground water sampling & Analysis technique
1. Groundwater Quality Analysis
Dr. V. Arutchelvan & Atun RoyChoudhury
Professor & Head of Civil Engineering, M.E.
Scholar & Research Assistant
Annamalai University
2. Introduction
Indian Ground Water Scenario and Brief Management
Groundwater Quality
– Sampling Plan
– Field Measured Parameters
• pH
• Alkalinity
• Conductance
• Salinity
• Dissolved Oxygen
• Turbidity
– Chemical Equivalence
– Laboratory QA/QC
– Diagrams
• Piper
• Stiff
– Water Quality Classification
– Ground water Quality & Associated Problems
– Irrigation Water
• Sodium
• Salinity
– Arsenic
– Fluoride
– Iron
– Nitrates
Recent Advancements & Remedial Measures
3. • Water is the most important in shaping the
land and regulating the climate. It is one of
the most important compounds that
profoundly influence life.
• In the last few decades, there has been a
tremendous increase in the demand for fresh
water due to rapid growth of population and
the accelerated pace of industrialization.
4. • Groundwater is used for domestic and
industrial water supply and also for irrigation
purposes in all over the world.
• According to WHO organization, about 80% of
all the diseases in human beings are caused by
water.
• Once the groundwater is contaminated, its
quality cannot be restored back easily and to
device ways and means to protect it.
5.
6. Groundwater Quality
• Helps us understand the hydrogeologic
system
• Indicates comingling of groundwater and
surface water
• Helps us interpret groundwater flow dynamics
• Delineates groundwater contamination
7. • Water quality index is one of the most
effective tools to communicate information
on the quality of water to the concerned
citizens and policy makers.
• It, thus, becomes an important parameter for
the assessment and management of
groundwater.
• The more common soluble constituents
include calcium, sodium, bicarbonate and
sulphate ions.
8. WQI Status Possible Usage
0-25
26-50
51-75
76=100
101-150
150
Excellent
Good
Fair
Poor
Very Poor
Unfit for Drinking
Drinking, Irrigation &
Industries
Domestic, Irrigation &
Industries
Irrigation & Industries
Irrigation
Restricted use for Irrigation
Proper Treatment Required
9. • Another common constituent is chloride ion
derived from intruded sea water, connate
water, and evapotranspiration concentrating
salts, and sewage wastes, for example Nitrate
can be a natural constituent but high
concentrations often suggest a source of
pollution.
• Water quality standards are needed to
determine whether ground water of a certain
quality is suitable for its intended use.
10. • Due to increasing urbanization, surface water
is getting over contaminated and more
stringent treatments would be required to
make surface water potable. Therefore, it is
required to additional sources for fulfil the
requirement of water. Because the ground
water sources are safe and potable for
drinking and other useful purposes of human
being. Hence studies of physic-chemical
characteristics of underground water to find
out whether it is fit for drinking or some other
beneficial uses.
17. Sampling and Analysis Plan
• Document written in advance of sampling that
defines:
– Sampling locations and frequency
– How field parameters are measured
– How samples are collected
– Quality control and assurance measures
• Do NOT go to the field without a plan!
18. Groundwater Sampling
• Important Points
– Be sure to take a representative sample
– Make sure sample bottles are properly rinsed
– Filter and preserve samples in the field
– Take field measurements with proper equipment
– Store on ice
– Send to a certified water chemistry laboratory within
24 hours of sampling
– Have a quality control program with duplicates,
blanks, field blanks, or spiked samples
19. Groundwater Sampling Methods
Sampling is the process of obtaining, containerizing, and preserving (if required) a
ground water sample after the purging process is complete.
There are few technical methods, which can be adopted for collection of
representative samples are-
Sampling Wells With In-Place Plumbing
Samples should be collected following purging from a valve or cold water tap as
near to the well as possible, preferably prior to any storage/pressure tanks or
physical/chemical treatment system that might be present.
Sampling Wells Without Plumbing, Within the Limit of Suction
The pump of choice for sampling ground water within the limit of suction is the
variable- speed peristaltic pump. Its use is described in the following sections.
Other acceptable alternatives that may be used under these conditions are the
RediFlo2® electric submersible pump (with Teflon® tubing) and a closed-top
Teflon® bailer.
(variable speed peristaltic pump/ Peristaltic Pump/ Vacuum jug/ RediFlo2
Electric Submersible Pump/ Bailers)
20. Sampling Wells without Plumbing, Exceeding the Limit of Suction
RediFlo2® Electric Submersible Pumps, and Bailers, are suitable sample methods
where the water table is too deep to consider the use of a peristaltic pump for
sampling.
Micro-Purge or No Purge Sampling Procedures
The Micro-Purge or No Purge sampling procedures are usually employed when it
necessary to keep purge volumes to an absolute minimum. Among the Micro-
Purge or No Purge procedures that might be employed are:
Low pump rate sampling with peristaltic or submersible pumps (typical Micro-
Purge sampling), TM
HydraSleeve or Passive diffusion bag (PDB) sampling
21. WELL SAMPLING
• Calculate Well Volume:
– Determine static water level
– Calculate volume of water in the well casing
• Purge the well:
– A minimum of three casing volumes is
recommended.
22. Post Sampling Procedures
• Sample Preservation
Consult the Analytical Support Branch Laboratory Operations and Quality
Assurance Manual (ASBLOQAM) for the correct preservative for the
particular analytes of interest.
All samples preserved using a pH adjustment.
• Filtering
Filtering will usually only be performed to determine the fraction of major
ions and trace metals passing the filter and used for flow system analysis
For the purpose of geochemical speciation modeling.
• Specific Sampling Equipment Quality Assurance Techniques
All equipment used to collect ground water samples shall be cleaned as
outlined in the SESD Operating Procedure for Field Equipment Cleaning
and Decontamination (SESDPROC-205).
• Auxiliary Data Collection
Well Pumping Rate – Bucket/Stop Watch Method
25. Water Uses
Use Typical quality parameters
Public Water Supply Turbidity, TDS, inorganic and
organic compounds, microbes
Water contact recreation Turbidity, bacteria, toxic
compounds
Fish propagation and wildlife DO, chlorinated organic
compounds
Industrial water supply Suspended and dissolved
constituents
Agricultural water supply Sodium, TDS
Shellfish harvesting DO, bacteria
26. Abundance of Dissolved Constituents
in Surface and Ground Water
• Major Constituents
(> 5 mg/L)
–Ca
–Mg
–Na
–Cl
–Si
–SO4
2-
- sulfate
–H2CO3 - carbonic acid
–HCO3
-
- bicarbonate
27. Abundance of Dissolved Constituents
in Surface and Ground Water
• Minor Constituents
(0.01-10 mg/L)
–B
–K
–F
–Sr
–Fe
–CO3
2-
- carbonate
–NO3
-
- nitrate
28. Abundance of Dissolved Constituents
in Surface and Ground Water
• Trace Constituents
(< 0.1 mg/l)
–Al
–As
–Ba
–Br
–Cd
–Co
–Cu
– Pb
– Mn
– Ni
– Se
– Ag
– Zn
– others
29. Water Classification
• How?
– Compare ions with ions using chemical equivalence
– Making sure anions and cations balance
– Use of diagrams and models
• Why?
– Helps define origin of the water
– Indicates residence time in the aquifer
– Aids in defining the hydrogeology
– Defines suitability
30. What is Chemical Equivalence?
• Chemical analysis of groundwater samples
– Concentrations of ions are reported by
• weight (mg/L)
• chemical equivalence (meq/L)
• Takes into account ionic charge
• Equivalent Concentration
32. Formula weight
• Formula weight
– Multiply atomic weight by # of atoms and add together
• E.g.,
– Formula weight of water
H2O = 2*(Atomic Wt of H) + 1*(Atomic Wt of O)
2*(1.008) + 1*(16) = 18.01
Atomic Weight (Relative atomic mass) is a dimensionless physical quantity, the ratio
of the average mass of atoms of an element to 1/12 of the mass of an atom of
carbon-12
33. Ion Balance
• If all ions are correctly determined by a lab
sum of cations should equal sum of anions (all in
meq/L)
• Errors in analysis and chemical reactions in
samples
5% difference is considered acceptable
> 5%, question the lab results
34. Calculating Equivalence
Parameter
Sandstone Aquifer
mg/L Meq/L
Na+
19 0.827
Cl-
13 0.367
SO4
2-
7 0.146
Ca2+
88 4,391
Mg2+
7.3 0.6
HCO3
-
320 5.245
Total Anions 5.758
Total Cations
5.818
% Difference 1%
For instance:
The atomic wt. of Sodium
(valence of one) = 22.989
And its charge is one
Dividing the concentration of
sodium in the sample (19 mg/L)
by its “combining wt.” = 0.827
meq/L or its equivalent
concentration.
35. Use of Diagrams
• There numerous types of diagrams on which
anions and cations (in meq/L) can be plotted.
• It is a graphical representation of the chemistry
of a water samples in hydro geological studies
These include:
Piper - comparing the Ionic compounds of the set of water samples
but does not lend to spatial comparison
Stiff – for geographical applications, the stiff diagram are more
applicable because they can be used as marker on a map
Pie – statistical graphical representation
37. Stiff Diagrams
• Concentrations of
cations are plotted to
the left of the vertical
axis and anions are
plotted to the right
(meq/L)
• The points are
connected to form a
polygon.
• Waters of similar
quality have
distinctive shapes.
39. Pie Diagrams
Igneous Volcanic
Na
Ca
Mg
Cl
SO4
HCO3
NO3
Sandstone Aquifer
Na
Ca
Mg
Cl
SO4
HCO3
NO3
Shale with Salts
Na
Ca
Mg
Cl
SO4
HCO3
NO3
Calcium bicarbonate waterCalcium bicarbonate water Magnesium bicarbonateMagnesium bicarbonate
waterwater
Sodium chloride waterSodium chloride water Sodium-calcium bicarbonateSodium-calcium bicarbonate
water with nitrateswater with nitrates
Alluvium
Na
Ca
Mg
Cl
SO4
HCO3
NO3
40. Average Composition of
Sea Water and Mississippi River water
Parameter
Sea water
(mg/L)
Mississippi River
water (mg/L)
Na 10,500 20
Cl 19,000 24
SO4 2,700 51
Ca 410 38
Mg 390 10
HCO3 142 113
Na
Cl
SO4
Ca Mg HCO3
Sea water (mg/ L)
Na
Cl
SO4
Ca
Mg
HCO3
Mississippi River water (mg/ L)
42. Aquatic Freshwater Protection Criteria
(USEPA Guidelines)
Criteria Recommended Standard
pH 6.5-9.5
Alkalinity 20 mg/L or more
Dissolved Oxygen
30 day average 5.5 mg/L
(warm water fish)
Suspended Solids
Should not reduce Photosynthesis by
more than 10% in the water
43. Drinking Water Criteria
(USEPA Guidelines)
Criteria Recommended Standard Reason
Coliform Bacteria 0 colonies/ml Health
pH 6.5-8.5 Aesthetic
Barium 2 mg/L
Health
Nitrate 10 mg/L Health
Total Dissolved
Solids
500 mg/L Taste
44. Basic Water Quality Parameters
• pH
• Specific conductance (EC)
• Salinity
• Total dissolved solids (TDS)
• Turbidity
• Dissolved oxygen (DO)
• Biochemical oxygen demand (BOD)
• Temperature
• Total Hardness
47. pH
• Measures hydrogen ion
concentration
• Negative log of hydrogen ion
concentration
• Ranges from 0 to 14 std. units
• pH
– 7 neutral
– 0 - 7 acidic
– 7 - 14 alkaline
Thanks to Phil Brown
48. Solubility of Specific Ions
Based on Water pH
Toxic metals less available in water at pH 6 to 8.Toxic metals less available in water at pH 6 to 8.
49. Alkalinity
• “acid neutralizing capacity”
• Important because it buffers the water against
changes in pH
• For most waters, alkalinity includes the
bicarbonate ion (HCO3
-
)
• Other ions such as orthophosphate (HPO4
-
),
borates, may contribute to alkalinity but in
small amounts
50. Conductivity
• Measures electric
conductivity (EC) of water
• Higher value means water
is a better electrical
conductor
• Increases when more salt
(e.g., sodium chloride) is
dissolved in water
• Indirect measure of salinity
• Units are μmhos/cm at 25o
C or μsiemens/cm
Thanks to Phil Brown
52. Conductivity at Barton Springs
• Specific conductance is an indication of the hardness of water. The
specific conductance declines in spring water when rainfall enters the
aquifer and later discharges in the spring. Below is a graph demonstrating
this effect in Barton Springs. Rainfall is indicated in red, and specific
conductance in blue.
53. Salinity
• Classification of Ground Water
• Composition Based on Total Dissolved
Solids Content
Salts in Sea Water
Type of Water Dissolved salt content (mg/l)
Fresh water < 1,000 mg/l
Brackish water 1,000 - 3,000 mg/l
Moderatly saline
water
3,000 - 10,000 mg/l
Highly saline water 10,000 - 35,000 mg/l
Sea water > 35,000 mg/l
54. Dissolved Oxygen
• Amount of gaseous oxygen
(O2) dissolved in water
• Oxygen gets into water by
diffusion from the
surrounding air, by
aeration, and through
photosynthesis
• DO range from 0-18 mg/l
• Need 5-6 mg/l to support a
diverse population
• DO < 2 mg/l - Hypoxia
Thanks to Phil Brown
55. Turbidity• Measured in Nephelometric
Turbidity Units (NTU)
• Estimates light scattering by
suspended particles
• Photocell set at 90o
to the
direction of light beam to
estimate scattered rather
than absorbed light
• Good correlation with
concentration of particles in
water
Thanks to Phil Brown
YSI 556 MPS
HF Scientific MicroTPI
– Turbidity Meter
56. Total Dissolved Solids
• One measure of the quality of the water in
lakes, rivers, and streams is the total amount
of solids dissolved in the water. High amounts
of dissolved solids can indicate poor water
quality. The same is true for drinking water.
Methods:
• Gravimetric method.
• Electrical Conductivity.
57. Gravimetric method.
• Gravimetric means "by weighing". Balances
require gravity to weigh something. You will
weigh the total dissolved solids after water is
boiled away. This will be done using just one
water sample.
Procedure:
• To measure TDS using this method, the water
sample is first passed through a filter that blocks
anything bigger than 2 microns ( 2 micrometers
or 2 millionths of a meter).
58. • This ensures the test measures dissolved solids
not solids suspended in the water. Such things as sediment or
specks of plant material are filtered out and therefore not
counted in the "total dissolved solids“
• A certain amount of the filtered water is then weighed out
and the water is boiled away leaving the dissolved solids
behind as a solid residue. This residue is weighed. This is
called the gravimetric method because a balance is used.
Balances need gravity to find the mass. So that's why it's
called a gravimetric method.
59. Nitrate
Sources:
• Fertilizers and manure
• Decayed vegetable
• Animal feedlots
• Municipal wastewater and sludge disposal to
land
• Industrial discharges
• Leachates from refuse dumps
• Septic systems
60. Methods for Nitrate Estimation
Ultraviolet Spectrophotometric Method
• Filter the sample.
• Add 1 ml of 1N HCl per 50 ml of sample.
• Read absorbance or transmittance at 220 nm
and 275 nm.
• Set 0 absorbance or 100% transmittance with
distilled water.
61. Nitrate Electrode Method
• Useful for Nitrate concentration range of 0.14
to 1400 mg/L
• NO3-N
• Interferences
• Chloride and bicarbonate with weight ratios to
NO3-N >10 or >5 respectively
• NO2, CN, Sulphide, Br, I, Chlorite and Chlorate
62. Phenoldisulphonic Acid (PDA) Method
• Nitrate reacts with Phenoldisulphonic acid to
produce nitro derivatives that in alkaline
solution rearranges its structure to form
yellow colour compound with characteristics
that follows
• Beer’s law
• Chloride interferes seriously which can be
overcome by precipitation of chloride with
Ag+ as AgCl
63. Presence of Nitrate
• Nitrate is a very common constituent in the ground water, especially in
shallow aquifers due to anthropogenic activities. High concentration of Nitrate
in water beyond the permissible limit of 45 mg/l causes health problems.
64. Chlorides
Source:
• Dissolution of salt deposits
• Discharges of effluents
• Oil well operations
• Sewage discharges
• Irrigation drainage
• Sea water intrusion in coastal area
65. • Methodology : An Argentometric Method
Principle
• Chloride is determined in a natural or slightly
alkaline solution by titration with standard silver
nitrate, using potassium chromate as an
indicator. Silver chloride is quantitatively
precipitated before red silver chromate is
formed.
• Chloride mg/L = (A-B) x N x 35.45 x 1000ml
sample
• Where A = ml AgNO3 required for sample
• B = ml AgNO3 required for blank
• N = Normality of AgNO3 used
66. Fluoride
Significance:
• Dual significance in water
• High concentration of F-
causes dental
Fluorosis
• Concentration < 0.8 mg/L results in dental
Carries
• Essential to maintain F-
concentration
between 0.8 mg/L to 1.0 mg/L in drinking
water
67. Methods:
• Colorimetric SPADNS Method
Principle:
• Under acidic conditions fluorides (HF) react with
zirconium
• SPADNS solution and the lake (colour of SPADNS
reagent) gets
• bleached due to formation of ZrF6 . Since
bleaching is a function of
• fluoride ions, it is directly proportional to the
concentration of fluoride.
• It obeys Beer’s law in a reverse manner.
68. Ion Selective Electrode Method
Principle:
• The fluoride sensitive electrode is of the solid
state type, consisting of a lanthanum fluoride
crystal; in use it forms a cell in combination
with a reference electrode, normally the
calomel electrode.
• The crystal contacts the sample solution at
one face and an internal reference solution at
the other.
69. • A potential is established by the presence of
fluoride ions across the crystal which is
measured by a device called ion meter or by
any modern pH meter having an expanded
milli volt scale.
• Calculate mg F-
/ L present in the sample using
standard curve.
70. Presence of Fluoride
85 % of rural population of the country uses ground water for drinking and
domestic purposes, which contains a high concentration of fluorides (> 1.5 mg
/litre).
71. Sulphate
Significance:
• Occurs in natural water
• High concentration of Sulphate laxative effect
• (enhances when sulphate consumed with
magnesium)
• Problem of scaling in industrial water supplies
• Problem of odour and corrosion in wastewater
treatment due to its reduction to H2S
72. Spectorphotometric Method
Principle:
• Sulfate ions are precipitated as BaSO4 in acidic
media (HCl) with Barium Chloride.
• The absorption of light by this precipitated
suspension is measured by
• Spectrophotometer at 420 nm or scattering of
light by Nephelometer
Calculate:
• mg / L SO4 = mg SO4 x 1000
• ml sample
73. Ammonia
• Ammonia is present naturally in surface and
wastewaters. Its concentration is generally
low in ground waters because it adsorbs in soil
particles and clays and is not leached readily
from soils.
• It is produced largely by de-amination of
organic nitrogen containing compounds and
by hydrolysis of urea.
74. • The graduated yellow to brown colors produced
by nessler-ammonia reaction absorb strongly
over wide wavelength range
• Low ammonia concentration of 0.4 to 5 mg/L can
be measured with acceptable sensitivity in
wavelength region from 400 to 425 nm with
1cms light path
• A light path of 5 cm extends measurements of
ammonia concentrationsrange of 5 to 60 μg/L
75. • In the chlorination of water, chlorine reacts
with ammonia to form mono and
dichloramines (combined residual chlorine)
• Ammonia concentration in water vary from
less than 10μg in some natural surface and
ground waters to more than 30 mg/L in some
wastewaters.
76. Methods for Ammonia Estimation
Nesslerization Method:
• Direct nesslerization method is useful for
purified natural water and highly purified
wastewater effluents with very light color and
having NH3-N concentrations more than 20
μg/L.
• Applicable to domestic wastewater only when
errors of 1 to 2 mg/L are acceptable.
77. Ammonia Selective Electrode Method
• The ammonia selective electrode uses a hydro-
phobic gas permeable membrane to separate the
sample solution from an electrode internal
solution of ammonium chloride
• Dissolved ammonia is converted to NH3(aq) by
raising pH to above 11 with a strong base, which
diffuses through membrane and changes the
internal solution pH that is sensed by a pH
electrode
78. • The fixed level of chloride in the internal
solution is sensed by a chloride ion-selective
electrode that serves as the reference
electrode.
• Applicable to the measurement of 0.03 to
1400 mg NH3-N/L in potable and surface
waters and domestic and industrial wastes.
• High concentrations of dissolved ions affect
the measurements but color and turbidity do
not.
79. Titrimetric Method
• The method is used only on samples that have
been carried through preliminary distillation.
• Titrate ammonia in distillate using standard
0.02N Sulphuric acid with boric acid indicator
solution.
80. Phosphates
• Phosphate occurs in traces in many natural
waters, and often in appreciable amounts
during periods of low biologic productivity.
Waters receiving raw or treated sewage
agricultural drainage, and certain industrial
waters normally contain significant
concentrations of phosphate.
81. Methods for Phosphorus Estimation
Vanadomolybdo phosphoric Acid Method
• In a dilute orthophosphate solution, ammonium
molybdate reacts under acid conditions to form a
heteropoly acid. In the presence of vanadium,
yellow vanadomolybdo phosphoric acid is
formed. The intensity of yellow color is
proportional to phosphate concentration.
• Minimum detectable concentration is 0.2 mg P/L
in 1 cm cell.
82. Procedure
• Sample pH adjustment if pH > 10
• Removal of excessive color by shaking with
activated carbon
• Colour development with vanadate-
molybdate reagent
• Measurement of color absorbance at
wavelength of 400 to 490 nm
83. Stannous Chloride Method
• Molybdo phophoric acid is formed and reduced by
stannous chloride to intensely colored molybdenum
blue.
• This method is more sensitive than above method and
minimum detectable concentration is about 3 μg P/L.
• Procedure
• Sample pH adjustment if pH > 10
• Color development with molybdate reagent
• Measurement of color absorbance at wavelength of
690 nm
84. Limit of Iron and Manganese in
Drinking Water
• As per WHO guidelines for domestic water, iron
should not
• exceed the limit of 0.3 mg/l
• Above 200mg/l iron is toxic to human health
• Manganese concentration as per WHO guideline
is 0.05 mg/l
• However average manganese level in drinking
water range from 5 to 25 ug/l
• At concentration exceeding 0.15 mg/l,manganese
imparts undesirable taste
85. Iron and Manganese
• Presence of excess of iron and manganese in water
causes discoloration, turbidity and deposits.
• Iron and manganese bearing water have astringent
metallic or bitter taste.
• Precipitation of iron and manganese imparts colour to
water from yellow to brownish black, which becomes
objectionable to consumers.
• Manganese concentration ranging from 8-14 mg/l is
toxic to human.
• Excess of iron facilitates growth of iron bacteria which
causes blocking of pipes, meters etc.
86. Methods for Detection of Iron and
Manganese in Water
• Atomic Absorption spectrophotometer (AAS)
• Inductively Coupled Plasma (ICP)
• Colorimetric method
• In colorimetric method iron is detected at
wavelength 510 nm and manganese is detected
at 525 nm.
• 1. Iron:- Phenanthroline method
• 2. Manganese:- Persulphate method Periodate
method
87. Presence of Iron
High concentration of Iron (>1.0 mg/l) in ground water has been
observed in more than 110 thousands habitations in the country.
89. ANALYSIS OF WATER SAMPLES
• Field:
– pH, specific conductance, temperature,
dissolved oxygen, and alkalinity
• Laboratory:
– Cations: sodium, calcium magnesium,
potassium, and iron
– Anions: bicarbonate, carbonate, sulfate, and
chloride
– Trace Metals, Radioactivity
90. Ground water Quality &
Associated Problems
Indian Sub- Continent is endowed with diverse geological formations from
oldest Achaeans to Recent alluviums and characterized by varying climatic
conditions in different parts of the country.
The main ground water quality problems in India are as follows-
Inland Salinity (Rajasthan, Haryana, Gujarat, Andhra Pradesh, Maharashtra,
Tamil Nadu etc.)
Coastal Salinity (The Indian subcontinent has a dynamic coastline of about
7500 km length, which stretches from Rann of Kutch in Gujarat to Konkan
and Malabar coast to Kanyakumari)
3 probable cases of coastal salinity
Saline water overlying fresh water aquifer
Fresh water overlying saline water
Alternating sequence of fresh water and saline water aquifers
91. Sodium and Irrigation
• Sodium reacts with soil to reduce permeability.
• Alkali soils - High sodium with carbonate
• Saline soils – High sodium with chloride or sulphate
• Neither support plant growth
• Sodium Adsorption Ratio (SAR) is a measure of the suitability of water
for use in agricultural irrigation, as determined by the concentrations of solids dissolved in
the water. It is also a measure of the sodicity of soil, as determined from analysis of water
extracted from the soil.
92. Sodium and Irrigation
• Low-sodium water
– Used on all soils with little danger of harmful levels of
exchangeable sodium.
• Medium-sodium water
– appreciable sodium hazard in certain fine-textured soils
• High-sodium water
– harmful levels of exchangeable sodium in most soils
– require special soil management such as good drainage,
leaching, and additions of organic matter.
• Very high sodium water
– unsatisfactory for irrigation unless special action is taken,
such as addition of gypsum to the soil
93. Salinity and irrigation
• Low salinity water
– used for most crops
• Medium salinity water
– used with moderate amount of leaching (potatoes,
corn, wheat, oats, and alfalfa)
• High salinity water
– Cannot be used on soils having restricted drainage.
• Very high salinity water
– Can be used only on certain crops and then only if
special practices are followed
94. Arsenic in Groundwater
• Long-term exposure to arsenic from drinking
water is directly linked to:
– Cancer of the skin, lungs, urinary bladder and kidneys.
– Acute gastrointestinal and cardiac damage as well as
vascular disorders such as Blackfoot disease.
– Sub-lethal effects include diabetes, keratosis, heart
disease and high blood pressure.
• Toxicity is dependent on diet and health, but is
cumulative. Arsenic is excreted very slowly by the
body through deposition in the hair and nails.
95. BACKGROUND
• Arsenic (As)
– toxic metal widespread in groundwater
• Occurs widely in aquifers
– deltaic sediments near mountain uplift zones
– deep sandy aquifer layers originating as riverine, lake
or coastal deposits.
– Ganges, Mekong and Red River deltas, sandy alluvial
deposits in South Asia, South East Asia, South
America, and in many parts of North America and
Europe.
96. Chemistry
• Arsenic has the ability to switch between two
valency forms,
– As3+
and As5+
.
• As3+
– more soluble and more likely to be absorbed than As5+
– This switching property makes detection and
measurement difficult and frequently unreliable
97. Arsenic Contamination
• Associated with fluctuating water tables and
flooding cycles particularly in
– Acidic sulfate soils or
– Iron and/or manganese-enriched layers,
– saline-layered aquifers
• Levels in water supplies can vary through a
year adding to the difficulties of identification
and monitoring.
98. Drinking Water Standards
• Worldwide 50 ppb limit (1942)
• US EPA
– Acceptable mortality = 1 death per 1,000 people
for carcinogens
– Lifetime risk from exposure to 50 ppb As
• 13 cancer-related deaths per year per 1000 people
(1992)
– Current standard = 10 ppb standard
99. Arsenic in the United States
• USGS analyzed US water quality data
• 10 ppb level exceeded by 8% of public ground
waters tested
• EPA estimates that the 10 ppb rule affects
about 4,000 water systems
• "Hotspots" of high concentration
– Central New England
– Midwest
– Western states.
103. Instrument set up
• Warm up for 30 min
• Check the alignment of plasma torch
• Make Cu/Mn ratio adjustment
• Calibrate instrument using calibration standards
and blank
• Aspirate the standard and blank for 15s
• Rinse with calibration blank for at least 60s to
eliminate anycarryover from previous standards
• Ensure the concentration values within the 5%
error
104. Analysis of samples
• Analysis the samples using calibration blank.
• Analyse samples alternately with analyses of
calibration blank.
• Rinse at least for 60s.
• Examine each analysis of the calibration blank to
verify that carry over memory effect is no more.
• Make appropriate dilutions of the sample to
determine concentrations beyond the linear
calibration.
105. Lab Procedures
• Preparing your filters
• Rinse three filters with 20-30 mL DI to
remove any solids that may remain from the
manufacturing process. Place the filters in
separate, labeled aluminum weight pans, dry
them in a 104oC oven for 30 minutes, place
them (filter and pan) in a desiccator, and
obtain a constant weight by repeating the
oven and desiccation steps.
106. • 2.Filter 100.mL of sample through each pre-
weighed filter.
• 3.Place each paper in its aluminum weight pan
in the 104o
C oven for 1 hour. Cool the filter
and pan in a desiccator and obtain a constant
weight by repeating the drying and
desiccation steps.
• Calculation:
• TSS mg/L=
• (average weight from step 3 in g - average
inital weight from step 1 in g)(1000mg/L)/
(sample volume in L)
107. Research Institutes in India
• Rajiv Gandhi National Ground
Water Training & Research
Institute, India
Rajiv Gandhi National Ground Water
Training & Research Institute was
established during IX thFive Year Plan
at Raipur as a training wing of Central
Ground Water Board, Ministry of
Water Resources, Government of
India and is running continuously
since 1997.
The RGNGWTRI is envisaged to
function as a `Centre of Excellence’ in
training ground water resources
personnel.
108. Recent Advancements &
Remedial Measures
In order to nullify the ill effects of the anthropogenic activities, which
causes depletion and contamination of ground water, the following
measures can be implemented-
Heliborne Survey
Aquifer Mapping
Participatory Ground Water Management
Artificial Ground Water Recharge etc.
109. Heliborne Survey
• In India airborne geophysical
surveys have been conducted for
mineral prospecting and
geological mapping by RSAS (GSI),
NGRI, NRSC and AMD.
111. Aquifer Map for Cuddalore District
• The aquifer disposition and
aquifer characterization has been
brought by analysis of 45
lithologs (includes 11 lithologs
generated during the pilot
project), 22 electrical logs
(includes 9 generated in the
project) , 56 hydrograph of
dugwells (53 established in
project study), 35 piezometric
head (15 piezometers established
in project), 61 hydrochemical
data (46 dugwells and 15 zone
wells established in the pilot
project).
112. Participatory Ground Water
Management
• The scarcity of water resources and ever increasing demand of
these vital resources require identification, quantification and
management of ground water in a way that prevents
overexploitation and consequent economic and environmental
damage, while satisfying demand for water supply of competing
sectors.
• Participatory ground water management is essential at grass root
level to enable the community and stake holders to monitor and
manage the ground water as common pool resources themselves.
• It is imperative to have the aquifer mapping activity with a road
map for groundwater management plan to ensure its transition into
a participatory groundwater management programme for effective
implementation.
113. Artificial Ground Water Recharge
• The artificial recharge to ground
water aims at augmentation of
ground water reservoir by modifying
the natural movement of surface
water utilizing suitable civil
construction techniques.
Artificial recharge techniques normally
address to the following issues:
To enhance the sustainability in areas
where over-development has depleted
the aquifer.
Conservation and storage of excess
surface water for future requirements.
To improve the quality of existing ground
water through dilution.
114. Model Bill
A Bill to regulate and control the Development and Management of Ground Water and matters
connected therewith or incidental thereto.
Workflow-
Establishment Of A Ground Water Authority
Staff Of The Authority
Powers To Notify Areas To Regulate And Control The Development And
Management Of Ground Water
Grant Of Permit To Extract And Use Ground Water In The Notified Area
Registration Of Existing Users In Notified Areas
Registration Of User Of New Wells In Non-notified Area
Registration Of Drilling Agencies
Power To Alter, Amend Or Vary The Terms Of The Permit/ Certificate Of
Registration
Cancellation Of Permit / Certificate Of Registration
Bar To Claim Compensation
Delegation Of Powers And Duties