Fundamental of ground water, water quality and environmental concern

Facts about water Water, an essential element for survival and growth of human beings, called as basis of life (World Water

Forum- 2004). Only 2.7% of the total water available on the earth is fresh water out of which ~75.2% lies frozen in polar

regions and ~22.6 % is present as ground water. (Ministry of Water Resources, 2010). India having 2.4% of geographical area and 15% of world population have only 4% of fresh water resource.

Average annual rainfall emanating largely from the south west monsoon is 116 cm which is higher than world average of 110 cm. In spite of this fact, 35% of geographical area of the country is draft prone and this water problem is more enhanced by quality degradation due to industrial and domestic waste (National Institute of Hydrology, 2001).

India is the largest user of ground water in the world, with an estimated use of 231 km3 of ground water every year, more than a quarter of the global level (Ministry of Water Resources, 2010).

Ground water supports ~60% of irrigated agriculture and > 80% of rural and urban water supplies.

Facts about water

Freshwater Readily accessible freshwater

Biota0.0001%

Rivers0.0001%

Atmosphericwater vapor

0.0001%

Lakes0.0007%

Soilmoisture0.0005%

Groundwater0.592%

Ice capsand glaciers

0.592%

0.014%

Industrialization and water problem The rapid pace of agricultural development, industrialization and urbanization has resulted in the

overexploitation and contamination of ground water resources in various parts of the country, resulting in various adverse environmental impacts and threatening its long-term sustainability.

There are 57,000 polluting industries (large and medium) in India generating 13,468 mld of wastewater out of 13,468 mld, ~ 60% is treated and rest 40% untreated are discarded in river, lakes, and streams depleting quality of surface as well as groundwater. 1,00,000 tonne/year of pesticide are consumed in major agricultural region of India which by run-off get added in surface water or get infiltrate to groundwater, thus decreasing its quality (CPCB, 2003).

Water cycle….

http://ga.water.usgs.gov/edu/watercyclegraphichi.html

Fundamentals of Ground water Infiltration: movement of water into soil from matric and gravity forces Percolation: movement due to gravity alone Porosity decreases with depth.►Zone of aeration: Soil surface water table top

Soil water zone►Soil surface through the root zone

Vadose zone►Soil water zone capillary fringe

Capillary fringe:►Water from saturated zone is pulled up

Fundamentals of Ground water(contd…) Zone of saturation: below the water table Aquifer: water-bearing porous soil or rock strata that yield significant

water to wells Aquiclude: any water-bearing soil or rock that are effectively

impermeable Example: shale, slate, clays

Aquitard: water-bearing soil or rock that retards flow of groundwater Example: silts, mudstones

Fundamentals of Ground water(contd…)

Evaporation and transpiration

Evaporation

Stream

InfiltrationWater tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay Confirming permeable rock layer

Fundamentals of Ground water(contd…)►Porosity: total void space in rock or soil as volume

10% for glacial till 20-50% for sands and gravels 33-60% for clays

►Effective porosity: ratio of void space through which water can flow to the total volume

►Permeability: Degree of connectedness of the pores

Fundamentals of Ground water(contd…)►Unconfined aquifers: water is in direct contact with the atmosphere

through porous material Allows for transfer of gases and water

►Confined aquifers : aquifer is separated from the atmosphere by an aquiclude

Also called artesian; these are under pressure

►Perched aquifers : bottom of the aquifer is constrained by an aquitard

Fundamentals of Ground water(contd…)

Water pollution• Increase in overall salinity of the groundwater, • Presence of high concentrations of fluoride, nitrate, iron, arsenic, total hardness and

few toxic metal ions,• Like surface water pollution, groundwater is also susceptible to contamination from

various natural and man-made sources. • Sources of Groundwater Pollution• Due to contamination by microbes, chemicals, hazardous substances and other foreign particles.• Industries which produce toxic effluent.• Agricultural run off.• Sewage• Trace Metals

• Pesticide

Arsenic Nickel Copper Mercury Chromium TotalCadmium Zinc Lead Iron Total

BHC(Total) Dieldrin Carbamate 2.4 DDDT(Total) Aldrin Endosulphan

Kinds of Water Pollution Inorganic Pollutants Organic Pollutants

Each year another 700-800 new chemicals are produced The 20 most abundant compounds in groundwater at industrial waste

disposal sites include TCE, benzene, vinyl chloride…all are carcinogens, and also affect liver, brain, and nervous system

Inorganic Pollutants Examples: Pb in gasoline, Radionuclides Phosphorus, nitrogen (Great Lakes),Other heavy metals.

It have 3 groups 1) Produce no heavlth effects until a threshold concentration is exceeded—e.g., NO3 –ook at ,

50mg/liter; at higher levels: methaemoglobinaemia 2) No threshold—e.g.—genotoxic substances: some natural and synthetic organic compounds,

microorganic compunds, some pesticides, arsenic 3) Essential to diets: F, I, Se—absence causes problems, but too much also causes problems

Inorganic Trace Contaminants: Mercury—methyl Hg and dimethyl Hg in fish—probably most significant path to humans—Minamata

Bay, Japan, 1950’s, Rhine River drains 185,000 sq km—heavily polluted by 1970’s Lead—toxicity has been known for a long time

Tetraethyl lead—anti-knock additive for gas, 1930-1966

Phosphates—mostly a result of sewage outflow and phosphate detergents Additional phosphate grows excess algae…oxygen depletion, Lake Erie…1972 phosphate management

plant…$7.6 billion expense. Nitrates—sewage and fertilizers.

Organic Pollutants: Three classes of compounds

Pesticides and Herbicides Materials for common household and industrial use Materials for industrial use

Pesticide Most present pesticides are 10-100 x more toxic than those used in 1050’s Average lawn receives 10x more pesticides than equivalent area of cropland Each year about 250,000 people are admitted to hospitals and/or emergency rooms with

pesticide poisoning Chlorinated hydrocarbons

DDT, heptachlor, etc—2-15 years Organophosphates

Malathion, methyl parathion—1-2 weeks Carbamates

Carbaryl, maneb, aldicarb—days to weeks Pyrethroids

Pemethrin, decamethrin—days to weeks

HerbicidesContact

Triazines—e.g. atrazine, paraquat(interfere with photosynthesis)

Systemic—phenoxy compounds, N compounds, Alar, glyphosate(create excess growth hormones)

Soil sterilantstrifluralin, dalapon

(kill soil microorganisms)

Disadvantages of Pesticides They accelerate the development of genetic resistance to pesticides

by pest organismsSince 1945, ~1000 species of insects and rodents and 550 species of weeds and plant

diseases

They can put farmers on a financial treadmill Some kill natural predators and parasites that control ‘pests’ They don’t stay put

—only 0.1 to 2% of stuff applied reaches target insect, 5% reaches target plant—the rest—into air, water, humans, wildlife

Disadvantages of Pesticides (contd..) Harm wildlife

USDA, USFWS: each year pesticides wipe out about 20% of honeybee population, damage another 15%, losing US farmers about $200 million/yr. Kill 6-14 million fish, ~67 million birds/year

Threaten human health--Poison 3.5-5 million workers in developing countries, and at least 300,000 in US; cause about 20000-40000 deaths (about 25 in US) per year. Prob greatly underestimated.--In food causes about 4000-20000 cases of cancer/year in US (Nat’l Academy of Sciences); genetic mutations, birth defects, nervous systems disorders, endocrine disorders.

Thank you…