Soil Pollution
The adulteration of soil (land) by the addition of unwanted substances that harm its quality and the life it supports is known as soil pollution. These pollutants can be solid, liquid, or gaseous materials that degrade the soil's physical, chemical, and biological properties.
Sources of Pollution
1. Industrial waste: The industrial wastes are the major cause of soil pollution because the wastes are toxic due to presence of cyanides, chromates, acids, alkalies, metal like nickel, cadmium, mercury and lead. Some industries like paper industries Sugar mills, textile mills and distilleries, chemical industries & cement industries are also responsible for soil pollution. The wastes of these industries are not bio-degradable.
2. Urban and domestic waste: The urban and domestic wastes referred as soil refuse, containing garbage, and rubbish, paper pieces, glass, plastics polythene bags, cans detergents and cakes. These substances emit gases, toxic hydrocarbons and pathogenic microbes cause to disease.
3. Agricultural chemicals: The fertilizers, pesticides, herbicides insecticides and fungicides are commonly used to save and increase the yield of crops but they have polluted the soil. Some time the entry of these chemicals in food chain has cause to adverse effects on health of consumers.
4. Fertilizers: The fertilizers increase the yield crop it has no doubt but the excessive use has adverse effects. It disturb the pH of soil, ionic balance and the presence of certain elements. So they have a number of health hazards. The nitrites cause to cancer in human body.
5. Pesticides: The chemicals are used to kill or to stop the growth of unwanted organisms and entry of these chemicals into food and water cause cause effect on the health of animals and human beings.
6. Insecticides: Some chemicals like DDT, BHC, aldrin, dieldrin are used to kill the insects, the use of DDT is banned by the Government because It is not biode gradable. It also effects the next crop in the field due to observed by the soil. Some bio degradable organ phosphates, carbonates may be used in place of insecticides.
7. Herbicides: The compounds used to control the growth of weeds, some inorganic compounds like sodium chlorate and sodium arsenite (Na3AsO3) were commonly used as herbicids. These one toxic in nature. So Now-adays organic herbicide Triazines are preferred.
8. Fungicides: Fungicides are used to chock the growth of fungi. Fungi is one those plants in which chlorophyll is not present i.e. they can not make their food by the process photosynthesis. They live an dead organic matters as saprophytes. Organic compounds of mercury have been used as fungicides. Many people in Iraq resulted to death due to eating breads made from grains that been treated with methyl mercury fungicide. It’s use have many disastrous consequences because these compounds breakdown in soil.
Environmental and Ecosystem Effects:
Reduced Soil Fertility: Pollutants can kill beneficial soil microorganisms, like bacteria and fungi, that are essential for nutrient cycling and decomposition of organic matter.
Altered Soil Structure and pH: Acid rain and certain chemical pollutants can lower the soil's pH, making it unsuitable for many plant species. This also affects the availability of nutrients.
Bioaccumulation and Biomagnification: Persistent pollutants, such as DDT and heavy metals, are absorbed by plants and animals and then move up the food chain. Bioaccumulation is the buildup of a substance in an organism, and biomagnification is the increasing concentration of the substance as it moves to higher trophic levels.
Water Contamination: Pollutants from the soil can leach into groundwater or be carried by runoff into rivers and lakes, affecting aquatic ecosystems and drinking water sources.
Control of Soil Pollutions:
The following steps have been suggested to control the soil pollutions:
(i) The use of chemical fertilizers can be reduced by applying bio-fertilizers and manures.
(ii) Re cycling and recovery of materials appears to be a reasonable solution for reducing soil pollutions. Materials like papers, gas and some kinds of plastics can be recycled.
(iii) Control of land loss can be attempted through restoring forests and grass cover to check soil erosion and flood.
(iv) Proper methods should be adopted for the disposal of solid wastes.
(v) Promote the reclamation and safe disposal of hazardous and electronic waste.
(vi) Regularly monitor and remediate contaminated hotspots, especially in industrial and mining areas.
Common Soil Pollutants:
| Type of Pollutant | Examples | Effects |
|---|---|---|
| Heavy Metals | Lead, Mercury, Cadmium, Arsenic | Toxic to plants and animals; causes neurological and developmental issues in humans |
| Organic Compounds | Petroleum hydrocarbons, PAHs, pesticides | Carcinogenic; disrupts microbial activity and soil fertility |
| Non-biodegradable Waste | Plastics, glass, construction debris | Long-term contamination; physical blockage of soil pores |
| Biological Waste | Sewage, animal waste, pathogens | Spread of disease; eutrophication of nearby water bodies |
| Radioactive Substances | Uranium, Radium, Cesium | Long-lasting contamination; harmful radiation exposure |