Ecology M. Saadatian Soil pollution 1

Soil pollution

SOIL POLLUTANTS Plastics Agro chemicals Fertilizers Heavy metals

Plastics Major part of global domestic and industrial waste Not easily biodegraded Waste plastic accumulates much thus adds to severe pollution problem Takes several years to disintegrate – 400 years to degrade mineral water bottles In USA, plastics are 7% in weight and 30% of the volume Use of biodegradable plastic solves the problem of pollution

Agrochemical pollution Include pesticides, herbicides, fungicides Pesticides applied reach the soil ultimately Accumulation of pesticide residues in biosphere creates ecological stress causing soil, water and food contamination Persisting chemicals are hazardous to human health Total remediation is impossible Reduction of residue levels through redeeming technology (desirable)

Fertilizer pollution Continuous application – Deterioration in soil properties, cultivated soils lose their characteristics Application of Amm. sulphate, Amm. chloride & Urea reduce soil pH Crops – potato, grapes, citrus, beans – sensitive to chloride toxicity Application of organic manures and biofertilizers reduce the soil from pollution

Heavy metal pollution Metals with atomic number greater than 23 or more than 5 gm per ml (eg. Hg – 70gm ml -1 ) They are hazardous, not acceptable to biological system Toxic to man & other life forms Most are slow poison, accumulate in the body and cause serious disorders Common toxic metals- Hg, Pb, As, Cr, Cd

Heavy metal (forms)SourceEffect Mercury – Hg ++ Methyl mercury fungicides, electrical and electronic industries, PVC, plastics, paints Irreversible neurological damage in man, Minamata disease Lead - Pb 2+, Pb 4+ Automobile exhaust of leaded petrol, batteries, pipes, soldering Mutation in algae and bacteria, blackening in fish, gradual paralysis in man Arsenic – As ++, Arsenic trioxide, Sodium arsenate Herbicide, fungicide, wood preservative – Agrochemicals (70%), paints, bullets (20%), glass wares (5%) Accumulate in hair, nail, skin lesions, act as oxidative uncoupler, damage to kidney, respiratory and nervous disorders

Contd. Chromium – Cr +6 & CrO 3 Tanneries, electroplating and metal finishing processes, Khaki dyeing textiles Toxic to aquatic organisms, absorbed through intestinal tract in man Cadmium - Cd Pigment and stabilizer for PVC, plastics, tyres, rechargeable cells, electroplating, coal oil, phosphate rocks Bones become brittle – Itai Itai disease in Japan, gastro enteric distress and pain

Control of soil pollution Use of pesticides and fertilizers should be minimized. Cropping techniques should be improved to prevent growth of weeds. Special pits should be selected for dumping wastes. Controlled grazing and forest management. Wind breaks and wind shield in areas exposed to wind erosion 11

Bioremediation The use of naturally occuring microorganisms such as bacteria, fungi & plants to break down or degrade toxic chemical compounds that have accumulated in the environment It is a method that treats the soils and renders them non-hazardous, thus eliminating any future liability that may result from landfill problems or violations.

Factors affecting bioremediation Microbial factors Temperature favorable for organisms Availability of water (Moisture content) Availability of nutrients (N,P,K) C: N (carbon: nitrogen) ratio of the contaminant material< 30:1 pH Availability of Oxygen in sufficient quantity in soil.

Water pollution Water pollution occurs when harmful substances are released into the water in large quantities which cause damage to people, wildlife, or habitat or indirectly into water bodies without proper treatment to remove harmful compounds.

Effects of water pollution Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily. An estimated 700 million Indians have no access to a proper toilet, and 1,000 Indian children die of diarrhea sickness every day. Some 90% of China's cities suffer from some degree of water pollution, and nearly 500 million people lack access to safe drinking water.

Examples of water pollutant  oil & grease from cars  fertilizers  animal waste  grass clippings  septic systems  sewage & cleaners from boats  household cleaning products  litter

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