18-01-2013, 04:44 PM
SOIL POLLUTION
1SOIL.doc (Size: 72.5 KB / Downloads: 61)
Definition:
Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts,
radioactive materials, or disease causing agents, which have adverse effects on plant growth and animal
health.
Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface.
The organic portion, which is derived from the decayed remains of plants and animals, is concentrated
in the dark uppermost topsoil. The inorganic portion made up of rock fragments, was formed over
thousands of years by physical and chemical weathering of bedrock. Productive soils are necessary for
agriculture to supply the world with sufficient food.
There are many different ways that soil can become polluted, such as:
• Seepage from a landfill
• Discharge of industrial waste into the soil
• Percolation of contaminated water into the soil
• Rupture of underground storage tanks
• Excess application of pesticides, herbicides or fertilizer
• Solid waste seepage
The most common chemicals involved in causing soil pollution are:
• Petroleum hydrocarbons
• Heavy metals
• Pesticides
• Solvents
Types of Soil Pollution
• Agricultural Soil Pollution
i) pollution of surface soil
ii) pollution of underground soil
• Soil pollution by industrial effluents and solid wastes
i) pollution of surface soil
ii) disturbances in soil profile
• Pollution due to urban activities
i) pollution of surface soil
ii) pollution of underground soil
Causes of Soil Pollution
Soil pollution is caused by the presence of man-made chemicals or other alteration in the natural
soil environment. This type of contamination typically arises from the rupture of underground storage
links, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and
fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The
most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other
heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and
intensities of chemical usage.
A soil pollutant is any factor which deteriorates the quality, texture and mineral content of the
soil or which disturbs the biological balance of the organisms in the soil. Pollution in soil has adverse
effect on plant growth.
Pollution in soil is associated with
• Indiscriminate use of fertilizers
• Indiscriminate use of pesticides, insecticides and herbicides
• Dumping of large quantities of solid waste
• Deforestation and soil erosion
Indiscriminate use of fertilizers
Soil nutrients are important for plant growth and development. Plants obtain carbon, hydrogen
and oxygen from air and water. But other necessary nutrients like nitrogen, phosphorus, potassium,
calcium, magnesium, sulfur and more must be obtained from the soil. Farmers generally use fertilizers
to correct soil deficiencies. Fertilizers contaminate the soil with impurities, which come from the raw
materials used for their manufacture. Mixed fertilizers often contain ammonium nitrate (NH4NO3),
phosphorus as P2O5, and potassium as K2O. For instance, As, Pb and Cd present in traces in rock
phosphate mineral get transferred to super phosphate fertilizer. Since the metals are not degradable,
their accumulation in the soil above their toxic levels due to excessive use of phosphate fertilizers,
becomes an indestructible poison for crops.
The over use of NPK fertilizers reduce quantity of vegetables and crops grown on soil over the
years. It also reduces the protein content of wheat, maize, grams, etc., grown on that soil. The
carbohydrate quality of such crops also gets degraded. Excess potassium content in soil decreases
Vitamin C and carotene content in vegetables and fruits. The vegetables and fruits grown on overfertilized
soil are more prone to attacks by insects and disease.
Indiscriminate use of pesticides, insecticides and herbicides
Plants on which we depend for food are under attack from insects, fungi, bacteria, viruses,
rodents and other animals, and must compete with weeds for nutrients. To kill unwanted populations
living in or on their crops, farmers use pesticides. The first widespread insecticide use began at the end
of World War II and included DDT (dichlorodiphenyltrichloroethane) and gammaxene. Insects soon
became resistant to DDT and as the chemical did not decompose readily, it persisted in the
environment. Since it was soluble in fat rather than water, it biomagnified up the food chain and
disrupted calcium metabolism in birds, causing eggshells to be thin and fragile. As a result, large birds
of prey such as the brown pelican, ospreys, falcons and eagles became endangered. DDT has been now
been banned in most western countries. Ironically many of them including USA, still produce DDT for
export to other developing nations whose needs outweigh the problems caused by it.
The most important pesticides are DDT, BHC, chlorinated hydrocarbons, organophosphates,
aldrin, malathion, dieldrin, furodan, etc. The remnants of such pesticides used on pests may get
adsorbed by the soil particles, which then contaminate root crops grown in that soil. The consumption
of such crops causes the pesticides remnants to enter human biological systems, affecting them
adversely.
1SOIL.doc (Size: 72.5 KB / Downloads: 61)
Definition:
Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts,
radioactive materials, or disease causing agents, which have adverse effects on plant growth and animal
health.
Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface.
The organic portion, which is derived from the decayed remains of plants and animals, is concentrated
in the dark uppermost topsoil. The inorganic portion made up of rock fragments, was formed over
thousands of years by physical and chemical weathering of bedrock. Productive soils are necessary for
agriculture to supply the world with sufficient food.
There are many different ways that soil can become polluted, such as:
• Seepage from a landfill
• Discharge of industrial waste into the soil
• Percolation of contaminated water into the soil
• Rupture of underground storage tanks
• Excess application of pesticides, herbicides or fertilizer
• Solid waste seepage
The most common chemicals involved in causing soil pollution are:
• Petroleum hydrocarbons
• Heavy metals
• Pesticides
• Solvents
Types of Soil Pollution
• Agricultural Soil Pollution
i) pollution of surface soil
ii) pollution of underground soil
• Soil pollution by industrial effluents and solid wastes
i) pollution of surface soil
ii) disturbances in soil profile
• Pollution due to urban activities
i) pollution of surface soil
ii) pollution of underground soil
Causes of Soil Pollution
Soil pollution is caused by the presence of man-made chemicals or other alteration in the natural
soil environment. This type of contamination typically arises from the rupture of underground storage
links, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and
fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The
most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other
heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and
intensities of chemical usage.
A soil pollutant is any factor which deteriorates the quality, texture and mineral content of the
soil or which disturbs the biological balance of the organisms in the soil. Pollution in soil has adverse
effect on plant growth.
Pollution in soil is associated with
• Indiscriminate use of fertilizers
• Indiscriminate use of pesticides, insecticides and herbicides
• Dumping of large quantities of solid waste
• Deforestation and soil erosion
Indiscriminate use of fertilizers
Soil nutrients are important for plant growth and development. Plants obtain carbon, hydrogen
and oxygen from air and water. But other necessary nutrients like nitrogen, phosphorus, potassium,
calcium, magnesium, sulfur and more must be obtained from the soil. Farmers generally use fertilizers
to correct soil deficiencies. Fertilizers contaminate the soil with impurities, which come from the raw
materials used for their manufacture. Mixed fertilizers often contain ammonium nitrate (NH4NO3),
phosphorus as P2O5, and potassium as K2O. For instance, As, Pb and Cd present in traces in rock
phosphate mineral get transferred to super phosphate fertilizer. Since the metals are not degradable,
their accumulation in the soil above their toxic levels due to excessive use of phosphate fertilizers,
becomes an indestructible poison for crops.
The over use of NPK fertilizers reduce quantity of vegetables and crops grown on soil over the
years. It also reduces the protein content of wheat, maize, grams, etc., grown on that soil. The
carbohydrate quality of such crops also gets degraded. Excess potassium content in soil decreases
Vitamin C and carotene content in vegetables and fruits. The vegetables and fruits grown on overfertilized
soil are more prone to attacks by insects and disease.
Indiscriminate use of pesticides, insecticides and herbicides
Plants on which we depend for food are under attack from insects, fungi, bacteria, viruses,
rodents and other animals, and must compete with weeds for nutrients. To kill unwanted populations
living in or on their crops, farmers use pesticides. The first widespread insecticide use began at the end
of World War II and included DDT (dichlorodiphenyltrichloroethane) and gammaxene. Insects soon
became resistant to DDT and as the chemical did not decompose readily, it persisted in the
environment. Since it was soluble in fat rather than water, it biomagnified up the food chain and
disrupted calcium metabolism in birds, causing eggshells to be thin and fragile. As a result, large birds
of prey such as the brown pelican, ospreys, falcons and eagles became endangered. DDT has been now
been banned in most western countries. Ironically many of them including USA, still produce DDT for
export to other developing nations whose needs outweigh the problems caused by it.
The most important pesticides are DDT, BHC, chlorinated hydrocarbons, organophosphates,
aldrin, malathion, dieldrin, furodan, etc. The remnants of such pesticides used on pests may get
adsorbed by the soil particles, which then contaminate root crops grown in that soil. The consumption
of such crops causes the pesticides remnants to enter human biological systems, affecting them
adversely.