In groundwater, salinity is increasing due to various reasons. Main sources and mitigations are described in this presentation.

1. INDIAN INSTITUTE OF TECHNOLOGY ROORKEE
Salt as a Soil-water System Contaminant
Presented By:
Shubham Tiwari
En. No. 18917004

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Outline of the presentation
• Introduction
• It’s Origin in Ground water Objective
• Salinity measurement and unit conversion
• Effects of salinity
• Mitigation Method for Groundwater Salinity
• Conclusion

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Introduction
What are salts?
• Natural mineral components of soil that occur in
various quantities throughout the landscape.
• Soil and water are classed as saline when these
salts present in quantities sufficient to adversely
affect
Major ions
• The major cations Ca2+, Mg2+, Na+, K+
• major anions SO42-, Cl-, HCO3-, CO32-, NO3-
Salinity is the measure of all the salts dissolved
in water. Salinity is usually measured in parts per
thousand (ppt or ).
• Average ocean salinity is 35ppt
• Average river water salinity is 0.5ppt or less Fig 1 : Reference FAO united nation
(Sarwar and Eggers 2006)

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It’s Origin in Ground water
Source: www.e-education.psu.edu

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It’s Origin in Ground water
• Erosion of salt deposits and sodium bearing
rock minerals
• Naturally occurring brackish water of some
aquifers
• Salt water intrusion into wells in coastal areas
• Infiltration of surface water contaminated by
road salt
• Irrigation and precipitation leaching through
soils high in salinity
• Infiltration of leachate from landfills or
industrial sites.
Source: On-farm and Community Scale Salt
Disposal Basins on the Riverside Plain, 2000

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Salinity measurement and unit conversion
• Groundwater salinity is
subdivided according to Total
dissolved solids in the following
categories:
Type of Saline water Total Dissolved Solids
(mg/L)
Fresh Water 0 - 1,000
Brackish Water 1,000 – 10,000
Saline Water 10,000 – 1,00,000
Brine > 1,00,000
Source. Revelle (in Todd and Mays, 2005)
Electrical Conductivity
•Soil and water salinity is often
measured by electrical conductivity
(EC).
•EC units are deciSiemens per metre
(dS/m)
• Simple relationships are used to
convert EC to TDS, or vice Versa:
TDS (mg/L or ppm) = EC (dS/m) x
640 (EC from 0.1 to 5 dS/m)
TDS (mg/L or ppm) = EC (dS/m) x
800 (EC > 5 dS/m)

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Effects of salinity
• Unavailability of drinking water
Saline water cannot be used for drinking purpose by human
beings or Animals. In areas where available groundwater is
saline main source of drinking water is only dependent on
surface water or rainfall.
• Reduction in productivity and Fertility of the crops
Salinity can affect soil physical and hydraulic properties, due
to which a huge reduction in productivity and fertility of the
area can be observed

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Effects of salinity
Figure 3: Study Area of Panjab
Source: Gleick (2003)

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Mitigation Methods for Groundwater Salinity
Freshwater Lens in Saline
Groundwater
Washing Saline soil through Ditch
Drainage System
Safe Disposal and Use of Saline
Drainage Effluents
Changing the pumping pattern to
control seawater intrusion
Artificial recharge
Injection barrier

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Conclusion
• The existence of saline water on the mainland is very harmful to the
society.
• The wells in many parts of north India can no longer being used as
source of drinking water due to high concentration of chloride, sodium
and sulphate ions.
• Sea water intrusion is considered as one of the factor causing the
increase of saline water contamination in fresh water.
• Generally, sea water intrusion is faced coastal urban area due to
groundwater over pumping.
• From some proposed method to control sea water intrusion, i.e.: (1)
changing pumping pattern, (2) artificial recharge, (3) extraction barrier,
(4) injection barrier and (5) sub-surface barrier

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References
• Gleick, P. H. Global freshwater resources: soft-path solutions for the 21st century. Science (Washington, DC, U. S.) 2003,
302 (5650), 1524−1528
• Martínez, D.; Bocanegra, E. Hydrogeochemistry and cationexchange processes in the coastal aquifer of Mar Del Plata,
Argentina. Hydrogeol. J. 2002, 10 (3), 393−408.
• Jorreto, S.; Pulido-Bosch, A.; Gisbert, J.; Sanchez-Martos, F.; ́ Frances, I. The fresh water-seawater contact in coastal
aquifers ́ supporting intensive pumped seawater extractions: a case study. C. R. Geosci. 2009, 341 (12), 993−1002

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Thanks