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Soil Pollution

Definition, Causes, Types, Effects

What is Soil Pollution?

Soil pollution or soil contamination is a part of land degradation caused by acid rain water, excess and wrong use of agricultural fertilizer, insecticides ( the chemical compounds kill insect), and herbicides (chemical substances kill plants) to affect the natural soil environment. The important fact, all the soil contains different types of harmful or toxic polluted substances for human beings and other living organisms. However, the natural concentration of such substances in unpolluted substances is very low and does not threaten the surroundings of our ecosystem. Soil pollution effect or damage a living organism, when the concentration of one or more of such toxic molecule is large enough.

Sources of Soil Pollution

Different types of polluting substances or sources responsible for soil pollution in our environment or ecosystem. Acid rain, repeated or excessive use of fertilizer, the inadequate drainage system in agricultural fields, spraying of insecticide, and herbicides are the main factors responsible for soil pollution. The different types of sources and their effect are discussed below in this learning chemistry topic.

Soil pollution or contamination is a part of land degradation caused by acid rain, use fertilizer, insecticides, herbicides

Acid Rain

We know that the air of our environment contains gas sulfur dioxide (SO2) and nitrogen dioxide (NO2). Sulfur dioxide present in the air undergoes photolytic or catalytic oxidation to form sulfur trioxide (SO3) which reacts with rainy water or moisture to form sulfuric acid rain ( SO3 + H2O → H2SO4) is responsible for soil and water pollution. NO2 also reacts with rainy water or moisture in presence of oxygen or ozone produces nitric acid (HNO3) rain. The sulfuric acid and nitric acid formed by the above formula come down to the atmosphere to damages standing crops of soil.

Repeated or Excess Use of Fertilizer

Repeated and excess use of the same fertilizer pollutes the soil of our environment. For example, when we used ammonium sulfate [NH4(SO4)] fertilizer for the production of crops into the soil, again and again, the ammonium ion (NH4+) used up by crops but sulfate ion (SO4-2) get accumulated into the soil responsible for pollution. Therefore, the sulfate ion makes the soil highly acidic, hence the soil unfit for plant growth. If we use sodium nitrate (NaNO3) or potassium nitrate (KNO3) again and again, the nitrate ion (NO3) is used up by successive crops but sodium and potassium ions get accommodated into the soil. These cations make the soil alkaline and hence the soil cannot be used for high production of food.

Drainage System in Agricultural Field

We use a lot of water for irrigation along with fertilizer, but there should be a good drainage system for the outlet of unused water, otherwise, the soil becomes highly saline (salt-containing) which effects the growth of plants and responsible for soil pollution. Therefore, the inadequate drainage system in the agricultural field is another source of soil pollution.

Insecticides and Herbicides Pollution

When we speared different types of insecticides and herbicides to save the fruits and vegetable plants from harmful insects and herbs, the insecticides and herbicides enter into the living tissue of the growing plants in our environment. The insecticides and herbicides cause soil pollution and toxic effects on our health, when we eat these grains, fruits, or vegetable, it may damage our heart, kidney, etc. Therefore, we advised that before eating these types of polluted foods growing from soil pollution, they should be washed with a sufficient quantity of water.