Soil pollutants, effects and remedies

Soil pollutants

Soil pollution is the addition of harmful substances to the soil that lower its quality and productivity. The main pollutants are:

• Agrochemicals: chemical fertilisers (nitrates, phosphates), pesticides and herbicides (DDT, BHC, malathion).
• Heavy metals: Pb, Hg, Cd, As, Cr from mining, batteries, paints and industrial waste.
• Industrial wastes: fly ash, sludge, acids, alkalis, dyes, tannery waste.
• Solid wastes: plastics, polythene, glass, metal scrap, municipal garbage and e-waste.
• Others: sewage sludge, radioactive wastes, oil spills, acid rain deposition, excess salts from irrigation.

Adverse effects

• Loss of soil fertility and reduced crop yield; soil becomes acidic, saline or toxic.
• Toxic chemicals enter the food chain through plants and are biomagnified, causing cancer, kidney and nerve damage.
• Leaching of pollutants contaminates groundwater and nearby streams (nitrates cause blue-baby syndrome).
• Death of useful soil organisms such as earthworms and nitrogen-fixing bacteria.
• Plastics block water movement and root growth; dumps cause bad smell and spread disease (flies, rats).
• Soil erosion and land degradation.

Possible remedies

• Use fertilisers and pesticides in controlled amounts; adopt organic farming, compost and biofertilisers, and integrated pest management.
• Segregate solid waste and follow reduce, reuse, recycle; compost biodegradable waste and produce biogas.
• Ban or limit polythene; use biodegradable materials.
• Treat industrial effluents before discharge; dispose of hazardous waste in secure landfills.
• Bioremediation and phytoremediation (microbes or plants that absorb metals) to clean polluted soil.
• Afforestation and crop rotation to prevent erosion; public awareness and strict laws.