chemistry of groundwater influenced by geogenic ... · • high levels of fluoride in drinking...

Chemistry of groundwater influenced by geogenic & anthropogenic

contamination

Sudhakar M. Rao, Department of Civil Engineering and Centre for Sustainable

Technologies, Indian Institute of Science, Bangalore

Sudhakar Rao-IISc

Water Resources In India

Total Water Availability

1869 BCM

Surface Water

Availability 690 BCM

14 Major River Basins

Ground Water

Availability 432 BCM

68% remains untapped

Sudhakar Rao-IISc

Domestic & Industrial use

70 BCM

Agriculture

330 BCM

Replenishable Ground Water

Resource

432 BCM

Quality

deterioration

Domestic pollution

Agricultural pollution

Industrial pollution

Geogenic contamination

Disposal of

wastes, leaching of

sewer

materials,e

tc.

Leaching

of nutrients, pesticides,

fertilisers,

etc.

Disposal of

effluents in streams or

on land

Arsenic

Fluoride

Iron

Hardness

Salinity

Nature of

quality problem

Number of

affected

habitations

Approximate

population at

risk (million)

Affected regions

Excess Arsenic

(0.05-3.2 mg/L)

5,029 25 79 blocks of 8 districts (Bardhaman, Hoogli, Howrah, Malda, Murshidabad, Nadia,

North and South 24 Parganas) of West Bengal, parts of Bhojpur and Patna districts

of Bihar and Ballia district of Uttar Pradesh, parts of Rajnandgaon district of

Chhattisgarh and parts of Assam

Excess Fluoride

(1.5-48 mg/L)

36,988 71 (a) Kerala, Jammu & Kashmir, West Bengal, Orissa, Assam, Bihar and Delhi with

less than 30 per cent of the districts affected.

(b) Punjab, Haryana, Madhya Pradesh, Karnataka, Uttar Pradesh, Tamil Nadu,

Chattisgarh and Maharashtra with 30-70 per cent of the districts affected.

(c) Rajasthan, Gujarat and Andhra Pradesh with 70-100 per cent of the districts

affected.

Excess Iron (1-

20mg/L)

1,38,670

- Prevalent mostly in hilly regions, parts of Assam, Agartala, Bihar, Orissa,

Rajasthan, Tripura, West Bengal, Uttar Pradesh, Punjab, Maharashtra, Madhya

Pradesh, Chhattisgarh, Jharkhand, Tamilnadu and Kerala.

Excess Nitrate

(50-1000 mg/L)

13,958 842.54 Parts of Uttar Pradesh, West Bengal, Rajasthan, Madhya Pradesh, Chandigarh,

Punjab, Haryana, Delhi, Bihar, Maharashtra, Karnataka, Kerala, Orissa, Jammu &

Kashmir, Himachal Pradesh, Gujarat, Tamil Nadu and Andhra Pradesh

Excess Salinity

(Inland and

coastal)

(2000-27000

mg/L)

32,597 - Inland salinity: Inland salinity in ground water is caused due to geogenic sources.

The problem of inland salinity has been observed in arid and semi arid regions of

Rajasthan, Haryana, Punjab, and Gujarat with limited extent in the states of Uttar

Pradesh, Delhi, Karnataka, Maharashtra, Madhya Pradesh and Tamilnadu.

Electrical conductivity in these areas exceeds 4000 micro Siemens/ cm.

Coastal salinity: Problem of coastal salinity in ground water that is caused due to

excessive exploitation of ground water has been observed in Mangrol - Chorwad

areas and Coastal Saurashtra of Gujarat, Minjur area in Tamilnadu, Pondicherry

coast, parts of Orissa, Andhra Pradesh and Kerala coast.

Other reasons

(Heavy metals,

Pesticides,

Fertilizers, etc.)

25,092 - Parts of Andhra Pradesh, Assam, Bihar, Goa, Gujarat, Haryana, Himachal Pradesh,

Karnataka, Kerala, Madhya Pradesh, Maharashtra, Meghalaya, Orissa, Punjab,

Rajasthan, Tamil Nadu, Uttar Pradesh, West Bengal and NCT of Delhi

Total 2,52,334

Sl.No Nature of Quality Problem

No. Habitations affected

1 Excess Fluoride 36,988

2 Excess Arsenic 3533

3 Excess Salinity 32,597

4 Excess Iron 138,670

Geogenic Contamination

Areas of Focus

Water Quality

Impact of geogenic stresses on groundwater bodies

Impact of anthropogenic stresses on ground water

bodies

Why is fluoride in drinking water an environmental problem ?

• High levels of fluoride in drinking water ( > 1.5 mg/L ) leads to dental and skeletal fluorosis.

• Problem is severe where ground water is the major source of drinking water.

• Indian standard specifies ( IS 10500: 1991) desirable and permissible limits of fluoride in drinking water as 1.0 and 1.5 mg/L.

Fluoride concentration in 15 districts of Karnataka

27.87

44.92

13.77

7.54 4.26 3.93

0

10

20

30

40

50

60

Pe

rce

nt

1-2 2-3 3-4 4-5 5-6 6-8

Fluoride concentration (mg/L)

Occurrence in GW

Physical Features of Karnataka

Total Geographical Area = 1,92,000 sq.kms.

Forms part of the Deccan plateau.

The Coastal plain:

320 km long and

between 13 and 65

km wide

Western mountain range:

Elevations range from 1500

m to1900 m

The Northern Plains:

Entirely a plateau and

ranges between 400

to 600 m

Southern Plains:

Entirely a plateau

and rugged

Most part of the State is underlained by

crystalline rocks such as gneisses,

granites, schists, basalts, charnokites and

small portion of coastal area is having

alluvium.

Major portion of the State is underlained

by crystalline basement aquifers and small

portion of the coastal area and narrow

strip of river courses are occupied by

deltaic and alluvial valley fills.

The crystalline rocks do not have primary

porosity.

The weathered and fractured horizons act

as the water bearing zones and supply

water to wells and bore wells.

The thickness of the weathered zone

extends from a few meters to as much as

30m depending on the rock formation and

topography.

The weathered horizon is followed by

fractured zone which extends upto 150m

in some areas.

Hydrogeology

Rainfall

Average annual rainfall in the

state is 1138 mm spread over

55 rainy days.

Varies from as low as 569 mm

in the Northern plains to as

high as 4029 mm in the

Western costal area.

About 2/3rd of the geographical

area (comprising of the

Northern and Southern plains)

of the State receives less than

750 mm of rainfall (semi-arid).

Limited surface water resources and

erratic rainfall has increased the

dependence on the groundwater

resources.

Exploitation of ground water in the dry

Northern and Southern plains is

higher as compared to Coastal and

Western mountain range regions.

More than 3 lakh dug-wells have

dried, shallow bore wells have failed

and yield in deep bore wells are

declining.

Area irrigated by ground water

extraction structures is decreasing.

More than Rs.2000 crores invested

by individual farmers on dug wells,

pumpsets and other developmental

works have become infructuous.

Districts with overdeveloped groundwater utilization

Status of Groundwater Exploitation

28%

32%

19%

21%

Fluoride

Iron

Nitrate

Brackishness

Habitations affected by groundwater

quality problems

Status of Groundwater

Contamination

Kolar District

No.of

Station

Analyzed

Fall (m) ) with No.of stations

and percentage Total

Rise (m) with No.of stations and

percentage Total

0-2

(m) %

2-4

(m) %

>4

(m) %

0-2

(m) %

2-4

(m) %

>4

(m) %

37 10 27 10 27 8 21.6 76 8 21.6 1 2.7 0 0 24.3

The groundwater levels in 76% of the observation wells monitored by

CGWB show fall in groundwater levels and were less when compared to

corresponding period of last 10 years.

Dark and grey taluks

13.60%2.91%

26.86%

8.52%

48.10% FluorideIronNitrateBrackishnessUnaffected

Decline in the depth of groundwater level from 1978 to 1996 = 5.2m

Tumkur District

No.of

Station

Analyzed




percentage Total

0-2

(m) %

2-4

(m) %

>4

(m) %

0-2

(m) %

2-4

(m) %

>4

(m) %

20 11 55 3 15 5 25 95 0 0 1 5 0 0 5

The ground water levels in 95% of the observation wells monitored by CGWB

show fall in groundwater levels and were less when compared to

corresponding period of last 10 years.


12.00%

27.17%

17.80%10.67%

32.37%FluorideIronNitrateBrackishnessUnaffected

Decline in the depth of groundwater level from 1978 to 1996 = 5.96 m

Chitradurga District

No.of

Station

Analyzed




percentage Total

0-2

(m) %

2-4

(m) %

>4

(m) %

0-2

(m) %

2-4

(m) %

>4

(m) %

14 7 50 3 21.4 1 7.1 79 3 21.4 0 0 0 0 21.4

The groundwater levels in 79% of the observation wells monitored by CGWB

show fall in groundwater levels and were less when compared to groundwater

levels corresponding period of last 10 years.

37.91%

6.36%9.20%25.20%

21.33% FluorideIronNitrateBrackishnessUnaffected

Decline in the depth of groundwater level from 1978 to 1996 = 8.44 m


Mamatha & Rao, 2009, Env. Earth Sci

Granitic and gneissic rocks underlie the study area.

The faults and fractures in these rock formations are occupied by fluoride bearing minerals.

Common fluorine bearing minerals are fluorite, apatite, amphiboles, cryolite and micas that tend to occur in crystalline (granite, granitic gneiss) and sedimentary (limestone, sandstone) rocks

Fluoride from these minerals leaches to the

groundwater.

GW Chemistry

GW Chemistry

Mamatha & Rao, 2009, Env. Earth Sci Tumkur

Gibb’s diagram

Kolar

Gibb’s diagram

Mamatha & Rao, 2009, Env. Earth Sci Kolar

Mamatha & Rao, 2009, Env. Earth Sci Tumkur

Nexus between groundwater quality and sanitation practice

Sudhakar Rao,IISc, 18th November 2011, IUC,

28

Problem Statement


29


30


31

Groundwater serves as a decentralized source of “safe drinking water” for millions of rural and urban people. It accounts for nearly 80 per cent of the rural domestic water needs, and 50 per cent of the urban water needs of the country.

Kumar and Shah 2004, Groundwater contamination


32

• Sources going dry or lowering of the ground water table.

• Sources becoming quality affected. • Systems outliving their lives. • Systems working below rated capacity due to poor operation and maintenance. • Increase in population resulting into lower per capita availability. • Emergence of new habitations. • Acute seasonal shortages • Over-exploitation of resources

Issues Impacting SGWM in Indian Context:

Report of Working group on 11th Plan for DDWS 2007-2012 Sudhakar Rao,IISc, 18th November 2011, IUC,

33

http://ddws.gov.in/sites/upload_files/ddws/files/pdf/pdf/XI_Plan_Approach_Now.pdfhttp://ddws.gov.in/sites/upload_files/ddws/files/pdf/pdf/XI_Plan_Approach_Now.pdfhttp://ddws.gov.in/sites/upload_files/ddws/files/pdf/pdf/XI_Plan_Approach_Now.pdf

63% of the urban population in India has got access to sewerage and sanitation facilities (47% from sewer and 53% from low cost sanitation) as on March 2004. As a consequence, open defecation is prevalent widely in rural areas but also significantly in urban

areas too.

Sanitation coverage

11th Plan Document on Drinking Water Supply & Sanitation


34

http://ddws.gov.in/sites/upload_files/ddws/files/pdf/pdf/XIPlan_BHARATNIRMAN.pdfhttp://ddws.gov.in/sites/upload_files/ddws/files/pdf/pdf/XIPlan_BHARATNIRMAN.pdf

Case study


35

Background & Scope

36

The population is 60,000 and supply is ~ 5 MLD and entirely through GW.

To develop a sustainable water management plan towards the future needs.

To efficiently manage the groundwater resources in terms of quantity &

quality.

Geochemical & Microbiological surveys were performed simultaneously.

.


36

Karnataka State

Mulbagal Town

Groundwater Management

under IUWM


37

Table 5: Bore-well details of pump-house series

Pump-house series Supplying bore-wells

Seeganahalli pump house (SPH) M-101, M-107, M-108, M-110, M-200

Kalikamba pump house (KPH) M-202, M-203, M-204, M-205, M-206, M-

207, M-209 , M-210

Someshwarapalya pump house (SOPH) M-304, M-305, M-306, M-308, M-309, M-

310, M-316, M-317

Busal Kunte pump house (BPH) M-111, M-217, M-221

RMC pump house (RMCPH) M-237, M-239, M-240, M-242

The remainder 47 bore-wells contribute to the Inner town series. These bore-well numbers are: M-114, M-115, M-116, M-117, M-118, M – 119, M – 120, M-121, M-122, M-123, M-124, M – 225, M-226, M-227, M-228, M-229, M-230, M-231, M- 233, M-234, M-235, M-236, M-244, M-245, M-300, M-312, M-313, M-314, M-400, M-401, M-402, M – 403, M-404, M-405, M-406, M-407, M-408, M-410, M-411, M-412, M-413, M-414, M- 415, M-417, M-419, M-421 and M-422 respectively.


38

Cation/Anion balance

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8 9 10

Sample number

Cati

on

/An

ion

Bala

nce

Cation/Anion balance

28.4.09 samples

0

50

100

150

200

250

300

350

400

450

0 50 100 150 200 250 300 350 400 450

Nit

rate

, mg

/L

BW No.

ITS OTS

Permissible limit =45 ppm

0

200

400

600

800

1000

1200

1400

1600

1800

0 50 100 150 200 250 300 350 400 450

MP

N/1

00

mL

BW No.

Total Coliforms

ITS OTSColiform organisms should not bedetectable in 100 ml of any two

0

200

400

600

800

1000

1200

1400

1600

1800

0 50 100 150 200 250 300 350 400 450

MP

N/1

00

mL

BW No.

E. Coli

ITSOTS

No sample should contain E. Coli in 100 ml;

0

500

1000

1500

2000

2500

0 50 100 150 200 250 300 350 400 450

TDS,

mg

/L

BW No.

ITS

OTS

Permissible limit = 2000 mg/L

Desirable limit = 500 mg/L

0

1

2

3

4

5

6

7

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00

NO

3, m

eq

/l

TZ-, meq/l

4

4.5

5

5.5

6

6.5

7

7.5

8

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

pH

Anion/Cation

Geochemical classification & Mechanisms

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

10 100 1000 10000

EC, micromhos/cm

SA

R

10 100 1000 10000

ITS PHS

C1, low C2 medium

C3 medium-highC4high

C5

V. high

C1-S1C2-S1

C3-S1

C4-S1

C4-S2

Classification-USDA

Aquachem software

5

2

6

1

3

2

1CaHCO3 type

2NaCl type

3 Mixed CaNaHCO3

4Mixed CaMgCl

5CaCl type

6NaHCO3 type

4

Hydrochemical facies GroundWater Chart Calibration Plots-USGS Software

1CaHCO3 type

2NaCl type

3 Mixed CaNaHCO3

4Mixed CaMgCl

5CaCl type

6NaHCO3 type

4

1 2

6

3

5

Hydrochemical facies Hydrochemical facies

GroundWater Chart Calibration Plots-USGS Software

1

10

100

1000

10000

100000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Cl/Cl+HCO3

TD

S,

mg

/L

Rock weathering

dominance

Evapo-

crystallization

dominance

Atmospheric

precipitation

dominance

PHS series

Geochemical mechanisms Gibb’s diagram

Gibb's chart

1

10

100

1000

10000

100000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Na/Na+Ca

TD

S, m

g/L

Rock weathering

dominance

Evapo-

crystallization

dominance

Atmospheric

precipitation

dominance

Geochemical mechanisms

PHS

Gibb’s diagram

1

10

100

1000

10000

100000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Cl/Cl+HCO3

TD

S, m

g/L

Rock weathering

dominance

Evapo-

crystallization

dominance

Atmospheric

precipitation

dominance

ITS series


Gibb's chart, ITS

1

10

100

1000

10000

100000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Na/Na+Ca

TD

S, m

g/L

Rock weathering

dominance

Evapo-

crystallization

dominance

Atmospheric

precipitation

dominance

`


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 10 20 30 40 50 60

Sample Number

F, m

g/L

ITS Mulbagal

PHS Mulbagal

Kolar - Tumkur Series

F Distribution

SI=logIAP-logKsp

SI= 0, Mineral is in equilibrium SI> 0, Solution is over-saturated with mineral SI

Samp

le No.

Ca, moles/l HCO3,

moles/l

IAP log

IAP

Ksp log

Ksp

SITheoretic

al

1 0.0007734 0.0028 2.17E-06 -5.66 1*10-8

-8 2.34

2 0.0045908 0.0084 3.85E-05 -4.41 1*10-8

-8 3.59

3 0.0061377 0.0072 4.42E-05 -4.35 1*10-8

-8 3.65

4 0.0058882 0.0063 3.72E-05 -4.43 1*10-8

-8 3.57

5 0.0049650 0.0067 3.31E-05 -4.48 1*10-8

-8 3.52

6 0.0028942 0.0065 1.87E-05 -4.73 1*10-8

-8 3.27

7 0.0033183 0.0074 2.47E-05 -4.61 1*10-8

-8 3.39

8 0.0035678 0.0041 1.46E-05 -4.84 1*10-8

-8 3.16

9 0.0011227 0.0032 3.59E-06 -5.45 1*10-8

-8 2.55

Calculations of SI calcite from Ca and HCO3 concentrations. Excel calculations

Source: http://www.sswm.info)

Pathogens: Bacteria (0.4 to 2.5μ) and viruses (0.01 to 0.25 μ)

Most nitrogen is excreted as urea, which readily degrades to ammonium. Nitrate is formed by the sequential, microbially-catalysed oxidation of ammonia to nitrite and then to nitrate

Biologically active layer : removes pathogens and reduces porosity

Ben Cave and Pete Kolsky 1999, London School of Hygiene and Tropical Medicine


66

Pit latrine, ventilated improved pit latrine and pour flush toilets.

http://www.sswm.info/

Pathogen movement and removal by soil Bacteria travel depends on velocity of groundwater flow. During travel, fraction die or retained (adsorbed or screened) on soil matrix. Key factor for removal of bacteria and viruses from groundwater: effluent residence time between contamination source and point of water abstraction. Unsaturated zone is most important line of defence against faecal pollution of aquifer as it is less permeable Probable survival time for coliforms in anaerobic groundwater environment is 4-7 days.

Ben Cave and Pete Kolsky 1999, London School of Hygiene and Tropical Medicine


67

E Coli Attenuation

One log removal of E Coli needed 4 m of decline in groundwater level


68

Thank You

chemistry of groundwater influenced by geogenic ... · • high levels of fluoride in drinking...

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