The degradation of fertile soils through chemical processes is known as soil pollution. This can have serious implications for both global food security and human health.
Sources of Land and soil pollution
1.Industrial wastes-
- It includes Slag from blast furnace, fly-ash, lime sludge, brine mud, metal scraps, copper slag from large industries or ash, waste from tanneries, dyes, scrapes of wool, plastics and many other wastes from small scale industries
2.Domestic wastes -
- Kitchen garbage, other household rubbish, broken bottles and crockery, waste tin cans, plastic bottles, cloth rags, pieces of papers, straw-board boxes, ash etc.
3.Nuclear plant waste-
- Radioactive and hazardous wastes.
4.Rural waste-
- Pesticides, herbicides, agricultural runoffs.
5.Urban waste-
- Municipal, sewage, industrial effluents, domestic effluents, hospital waste
Types of Soil Pollution
A.Positive soil pollution-
- Reduction in the productivity of soil due to the addition of undesirable substances like pesticides, herbicides, fertilisers, etc. is called positive pollution.
- These pollutants have cumulative effect and kill the soil organisms.
B.Negative soil pollution
- It is caused by the removal of useful components from soil by erosion, deforestation and improper methods of agriculture
Persistent organic pollutants
POPs are chemicals that remain intact in the environment for-
- Long periods or Long Duration.
- Become widely distributed geographically.
- Accumulate in the fatty tissue of living organisms.
- Toxic to humans and wildlife.
- Fat-soluble pollutants may be retained for a long time and bio magnify.
- Fatty tissues of organisms such as fishes are tested for the detection and measurement of such pollutants.
- In mammals often mother’s milk is tested for the pollutants since it has a lot of fat in it.
Pollutants that are not biodegradable have the potential to accumulate and magnify in the higher levels of the food chain.
The dirty dozen
The 12 POPs identified by the UNEP under the Stockholm Convention called the dirty dozen
These can be placed in 3 categories:
1.Pesticides-
- Aldrin, chlordane, DDT, dieldrin, endrin , heptachlor , hexachlorobenzene , mirex , toxaphene.
2.Industrial chemicals-
- Hexachlorobenzene, polychlorinated biphenyls (PCBs);
- Furans and Dioxins.
Banned in India-
Aldrin, chlordane, DDT(Restricted use), dieldrin, endrin, heptachlor, Polychlorinated Biphenyls (PCBs), Toxaphene.
Two of these chemicals are produced Unintentionally and these are-
- Furans- Furans are a type of chemical compound that can be found in various sources such as the production of PCBs, waste incinerators, and vehicle emissions.
- Dioxins- These are produced unintentionally due to incomplete combustion of plastic, polyethylene etc., as well as during the manufacture of pesticides and other chlorinated substances.
Various measure to control soil pollution
- Proper dumping of unwanted materials.
- Recycling and Reuse of wastes.
- Cropping techniques should be improved to prevent growth of weeds.
- Use of chemical fertilizers should be reduced by the use of bio fertilizers and manures.
- Use of cattle dung and agricultural wastes in biogas plants should be encouraged.
Important one liner on Soil Pollution.
What are the sources of industrial waste that contribute to soil pollution?
Answer: Slag from blast furnace, fly-ash, lime sludge, metal scraps, plastic waste, and many others.
How does positive soil pollution affect soil productivity?
Answer: Positive soil pollution reduces soil productivity due to the addition of harmful substances like pesticides and herbicides.
What are persistent organic pollutants (POPs)?
Answer: POPs are chemicals that remain intact in the environment for a long time and are toxic to humans and wildlife.
What are the 12 POPs identified by the UNEP under the Stockholm Convention?
Answer: The "dirty dozen" POPs are Aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene, PCBs, furans, and dioxins.
How can we control soil pollution?
Answer: We can control soil pollution by proper dumping of waste, recycling and reusing waste, improving cropping techniques, reducing chemical fertilizer use, and encouraging the use of biogas plants.