Soil Pollution
Soil Pollution

Soil Pollution

Soil Pollution: Environment for UPSC

  • Soil pollution is defined as the ‘addition of substances to the soil, which adversely affects physical, chemical and biological properties of soil and reduces its productivity.
  • It is a build-up of persistent toxic compounds, chemicals, salts, radioactive materials, or disease-causing agents in the soil which have adverse effects on plant growth, human and animal health.

Causes and Sources of Soil Pollution

Plastic bags

  • They accumulate in soil and prevents germination of seeds. They stay in the soil for centuries without decomposing (non-biodegradable).
  • Burning of plastic in garbage dumps release highly toxic and poisonous gases like carbon monoxide, carbon dioxide, phosgene, dioxins, and other poisonous chlorinated compounds.
  • Toxic solid residue left after burning remains in the soil. The harmful gases enter soils through chemical cycles.

Industrial sources

  • They include fly ash, metallic residues, mercury, lead, copper, zinc, cadmium, cyanides, thiocyanates, chromates, acids, alkalies, organic substances, nuclear wastes etc.
  • A large number of industrial chemicals, soil and are known to create many health hazards including cancer.

Pesticides

  • Pesticides are chemicals that include insecticides, fungicides, algicides, rodenticides, weedicides sprayed in order to improve the productivity of agriculture, forestry, and horticulture.
  • Chlorohydrocarbons (CHCs) like DDT, endosulfan, heptachlor accumulate in soil and cause biomagnification. Some of these pesticides like DDT and endosulfan are banned by most of the countries.

Fertilizers and manures

  • Excessive use of chemical fertilizers reduces the population of soil-borne organisms and the crumb structure of the soil, productivity of the soil and increases the salt content of the soil.

Discarded materials

  • It includes concrete, asphalt, rungs, leather, cans, plastics, glass, discarded food, paper, and carcasses.

Radioactive Wastes

  • Radioactive elements from mining and nuclear power plants, find their way into the water and then into the soil.

Other pollutants

  • Many air pollutants (acid rain) and water pollutants ultimately become part of the soil and the soil also receives some toxic chemicals during weathering of certain rocks.

Effects of soil pollution

Agriculture

  • Reduced soil fertility due to an increase in alkalinity, salinity or pH.
  • Reduced crop yield due to reduced fertility.
  • Reduced nitrogen fixation due to the reduced number of nitrogen fixers.
  • Increased erosion due to loss of forests and other vegetation.
  • Runoff due to deforestation cause loss of soil and nutrients.
  • Deposition of silt in tanks and reservoirs due to soil erosion.

Health

  • Health effects are similar to the effects of water pollution.

Environment

  • Ecological imbalance.
  • Foul smell and release of gases.
  • Waste management problems.

Control measures

  • More or less the same as for water pollution
  • Indiscriminate disposal of solid waste should be avoided.
  • To control soil pollution, it is essential to stop the use of plastic bags and instead use bags of degradable materials like paper and cloth.
  • Sewage should be treated properly before using as fertilizer and as landfills.
  • The organic matter from domestic, agricultural and other waste should be segregated and subjected to vermicomposting which generates useful manure as a byproduct.
  • The industrial wastes prior to disposal should be properly treated for removing hazardous materials.
  • Biomedical waste should be separately collected and incinerated in proper incinerators.
  • Use of biopesticides, biofertilizers. Organic farming.
  • Four R’s: Refuse, Reduce, Reuse, and Recycle.
  • Afforestation and Reforestation.
  • Solid waste treatment.
  • Reduction of waste from construction areas.
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