Harmful effects of soil pollution
Ecological changes have a direct impact on living organism. The environment has deteriorated owing to industrial stress, urbanization, population density and numerous other villains which make the earth as a paradise for infectious agents. Such chronically accumulated environment contaminates our air, water, food and soil, etc., thereby severely affecting the health. Nearly 80% of the diseases particularly in developing world can be linked with soil and water. About 90% of the pollution load in river system is due to faecal matter. The soil is highly polluted by several pathogenic organisms and hazardous industrial effluents. Soil pollution is the result of urban-technological revolution and speedy exploitation of every bit of natural resources.
We can discuss the harmful effect of soil pollution under following headings:
1) Effects of industrial pollutants
i) Industrial wastes consist of a variety of chemicals which are extremely toxic to living being. Different industries release different harmful toxins. These toxins enter in the food chain causing a number of undesirable effects.
ii) Industrial effluents when discharged through sewage system will poison the biological purification mechanism of sewage treatment causing several soil and water-borne diseases.
iii) Metallic contaminants (Hg, Zn, Cd, etc.,) destroy bacteria and beneficial microorganisms in the soil.
iv) Soluble salts are responsible for cost damage. These cause crop loss, soil loss, and metallic corrosion.
v) Some of the trade wastes contain pathogenic bacteria, e.g., Anthrax bacilli bacteria from tannery wastes.
2) Effects of urban waste products
i) In India million tonnes of waste is dumped along highway and other places. These wastes spread several chronic diseases. The wastes including building materials, sludge, dead animal skeletons, and thrown away garbage pile up at public places and cause obstruction in daily life.
ii) Sewage is the good medium for the growth of pathogenic bacteria, viruses, etc. Vibrio cholerae found in sewage causes cholera.
iii) Solid wastes result in offensive odor and cause clogging of ground water filters. Suspended matter in sewage can blanket the soil, thereby interfering with the soil moisture.
iv) The use of polluted ground water containing human excreta, sewage sludge decrease soil fertility by killing microorganisms.
3) Effects of radioactive pollutants: The problem of radioactive wastes dumped into the soil is more complicated. Radioactive elements can remain active in soil for long times. Harmful effects of radioactive pollutants are:
i) Radioactive pollutants can produce great human misery when food containing radionuclides is taken by man, some of them concentrate in specific body organs and cause undesirable diseases.
ii) Radiation actually affects the soil and soil fertility. These radiations kill plant species. Variations in radio sensitivity among tree and shrubs are due to differences in their chromosome number and size.
iii) A recent report indicates that a large number of induced radio nuclides as Carbon-14, Fe-55, Mn-54, Co-57, etc., get concentrated in biological systems.
4) Effects of modern agro-technology
i) Effects of fertilizers
a) Potassium fertilizers in soil decrease the valuable nutrient ascorbic acid (vitamin C) and carotene in vegetables and fruits.
b) Excessive use of nitrogenous fertilizers in land leads to accumulation of nitrate in the soil. This excess accumulation can cause diarrhea and cyanosis in children.
c) Phosphate fertilizer is considered detrimental to crop production.
d) Cereal crops like jawar, maize, etc., grown on alkaline soil absorb higher amounts of fluorides and are responsible for the spread of fluorosis.
ii) Effects of pesticides
a) Pesticides retained in soil concentrate in crop, vegetables, etc., which taint them to such an extent that they are not usable.
b) Pesticides like DDT, endrin, etc., are known to seep gradually through soil into ground water and contaminate drinking water supplies.
c) Organo phosphates pesticides cause extreme muscular weakness, tremors and dizziness in poisoned animals.
d) Longer lasting effects of pesticides are visible in animals and man where they affect the tissues and interfere in the normal metabolic activities.