Soil Pollution - Practice Questions & MCQ

The sol or earth has been recognised as the mother of all plants, animals and human beings. It is very essential either directly or indirectly for the survival and maintenance of various biological species including man, as it produces food for all. The chief components of the soil are inorganic matter(90-95%) and organic matter(5-10%). Besides, the soil contains water and air. The composition of soil varies considerably from place to place.
The soil has become the dumping ground of most of the waste products, i.e, domestic, human, animal, industrial and agricultural. Every year the solid wastes dumped into the soil are increasing at an alarming rate all over the world. Different kinds of poisonous materials are being used these days and the whole earth is increasingly being poisoned and polluted as a consequence. The problem of soil pollution has been aggravated by the use of agrochemicals such as pesticides, fungicides, insecticides, fertilizers and manures. Besides, the soil is polluted by deadly pathogenic organisms.

During World War II, DDT was found to be of great use in the control of malaria and other insect-borne diseases. Therefore, after the war, DDT was put to use in agriculture to control the damages caused by insects, rodents, weeds and various crop diseases.

These days, the pesticide industry has shifted its attention to herbicides such as sodium chlorate (NaClO₃ ), sodium arsenite (Na₃AsO₃ ) and many others. During the first half of the last century, the shift from mechanical to chemical weed control had provided the industry with a flourishing economic market. But one must remember that these are also not environment friendly.

Most herbicides are toxic to mammals but are not as persistent as organo-chlorides. These chemicals decompose in a few months. Like organo-chlorides, these too become concentrated in the food web. Some herbicides cause birth defects. Studies show that corn fields sprayed with herbicides are more prone to insect attack and plant disease than fields that are weeded manually.

Pesticides and herbicides represent only a very small portion of widespread chemical pollution. A large number of other compounds that are used regularly in chemical and industrial processes for manufacturing activities are finally released in the atmosphere in one or another form.

Control of soil pollution: 
(i) The use of chemical fertilizers can be reduced by applying biofertilizers and manures. Biological methods of pest control can also reduce the use of pesticides and thereby minimise soil pollution.
(ii) Recycling and recovery of materials appears to be a reasonable solution for reducing soil pollution. Materials such as paper, glass and some kinds of plastics can be recycled. This would decrease the volume of refuse and help in the conservation of natural resources. For example, recovery of one tonne of paper can save 17 trees.
(iii) Control of land loss can be attempted through restoring forest and grass cover to check soil erosion and floods. Crop rotation or mixed cropping can improve the fertility of the land

Industrial wastes: Industrial solid wastes are also sorted out as biodegradable and non-degradable wastes. Biodegradable wastes are generated by cotton mills, food processing units, paper mills, and textile factories. Non-biodegradable wastes are generated by thermal power plants which produce fly ash; integrated iron and steel plants which produce blast furnace slag and steel melting slag. Industries manufacturing aluminium, zinc and copper produce mud and tailings. Fertilizer industries produce gypsum. Hazardous wastes such as inflammables, composite explosives or highly reactive substances are produced by industries dealing in metals, chemicals, drugs, pharmaceuticals, dyes, pesticides, rubber goods etc. 

The disposal of non-degradable industrial solid wastes, if not done by a proper and suitable method, may cause serious threat to the environment. New innovations have led to different uses of waste material. Nowadays, fly ash and slag from the steel industry are utilised by the cement industry. Large quantities of toxic wastes are usually destroyed by controlled incineration, whereas small quantities are burnt along with factory garbage in open bins. Moreover, solid wastes if not managed effectively, affect the components of the environment.

Waste Management

Solid waste is not the only waste, which you see in your household garbage box. Besides household discards, there are medical, agricultural, industrial and mining wastes. The improper disposal of wastes is one of the major causes of environmental degradation. Therefore, the management of wastes is of utmost importance.

Green Chemistry

Green chemistry is a way of thinking and is about utilising the existing knowledge and principles of chemistry and other sciences to reduce the adverse impact on environment. Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment. The byproducts generated during a process, if not used gainfully, add to the environmental pollution. Such processes are not only environmental unfriendly but also cost-ineffective. The waste generation and its disposal both are economically unsound. Utilisation of existing knowledge base for reducing the chemical hazards along with the developmental activities is the foundation of green chemistry.