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 km 3 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 Biota % Biota % Rivers % Rivers % Atmospheric water vapor % Atmospheric water vapor % Lakes % Soil moisture % Groundwater 0.592% Groundwater 0.592% Ice caps and 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….

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 Infiltration Water table Infiltration Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such 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

Kinds of Water Pollution Inorganic Pollutants Organic Pollutants

Each year another 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 exceedede.g., NO 3 –ook at, 50mg/liter; at higher levels: methaemoglobinaemia 2) No thresholde.g.genotoxic substances: some natural and synthetic organic compounds, microorganic compunds, some pesticides, arsenic 3) Essential to diets: F, I, Seabsence causes problems, but too much also causes problems Inorganic Trace Contaminants: Mercurymethyl Hg and dimethyl Hg in fishprobably most significant path to humansMinamata Bay, Japan, 1950s, Rhine River drains 185,000 sq kmheavily polluted by 1970s Leadtoxicity has been known for a long time Tetraethyl leadanti-knock additive for gas,

Phosphatesmostly 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. Nitratessewage 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 x more toxic than those used in 1050s 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, etc2-15 years Organophosphates Malathion, methyl parathion1-2 weeks Carbamates Carbaryl, maneb, aldicarbdays to weeks Pyrethroids Pemethrin, decamethrindays to weeks

Herbicides Contact Triazinese.g. atrazine, paraquat (interfere with photosynthesis) Systemicphenoxy compounds, N compounds, Alar, glyphosate (create excess growth hormones) Soil sterilants trifluralin, dalapon (kill soil microorganisms)

Disadvantages of Pesticides They accelerate the development of genetic resistance to pesticides by pest organisms Since 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 dont stay put only 0.1 to 2% of stuff applied reaches target insect, 5% reaches target plantthe 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 million workers in developing countries, and at least 300,000 in US; cause about deaths (about 25 in US) per year. Prob greatly underestimated. --In food causes about cases of cancer/year in US (Natl Academy of Sciences); genetic mutations, birth defects, nervous systems disorders, endocrine disorders.

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