Sources of Soil Pollution – Natural and Anthropogenic

Soil is a natural medium of inorganic and organic nutrients and has an inbuilt system of spontaneous recycling of matter. It is affected by changes in the atmospheric conditions as well as water contents and microbial population.

Soil pollution is defined as an undesirable change in the natural, physical, chemical or biological components of the soil.

Sources of Soil Pollution

The various sources of soil pollution may be categorised into two groups: Natural sources and Anthropogenic sources.

Natural Sources

1. Plant Residues

Normally plants, on death and decay, contribute organic matter to the soil and thereby increase soil fertility. Sometimes residues from crops, fields and orchards carry plant pathogens and pests. Burning of crops yields residues with CO (8.3%), NO (1.5%), hydrocarbons (5,3%) and particulate matter (8.5%).

2. Animal Residues

Animal wastes, such as faecal matter, urnine, blood, slaughter house waste in the form of liquid or particulate matter, bodies of dead animals etc. are all indiscriminately dumped into the soil. Excessive organic contents are harmful for healthy growth of roots as they create hypertonic conditions in the soil causing wilting or stunted growth of the plants.

Anthropogenic Sources

1. Domestic

Domestic sewage is wastewater generated from the household activities. It is 99.9 percent pure ater; remaining 0.1 percent are pollutants which are both organic and inorganic materials. Organic materials are food and vegetable waste, excreta, faecal matter whereas inorganic materials such as phosphates and nitrates come from soaps and detergents.

2. Agriculture

It is undoubted that extensive use of fertilizers and pesticides, collectively called as agro-chemicals, increases the agricultural output. These, mostly artificial chemicals, move into the waterbodies alongwith rainfall and groundwater by leaching. Such chemicals are persistent and may after gain entry into the food chain causing numerous problems in the animals.

3. Industries

Most of the industries are situated along the banks of the river for convenience and disposal of effluents. Often these effluents comprise acids, bases, dyes, paints, and a range of other chemicals. Detergents form white foam. The industrial waste can be mercury, lead, cadmium, chlorides, fluorides, ammonia etc. Such addition alters the pH of water and turns it into a condition that is fatal to aquatic forms. The industries regularly discharge heavy amount of superheated water used in the thermal power plants, oil refineries, nuclear power plants, etc. such high temperature injuries and kills the aquatic flora and fauna. High temperature also reduces the amount of oxygen dissolved in water that may harm or even kill the aquatic life, the condition is called as thermal pollution.

4. Radioactive Waste

High concentrations can be lethal, whereas low concentrations of radioactive substances can cause malignancy and various forms of sickness. Two most important contributors in Europe are Sellafield and Ca La Hague.

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