Sources, effects and control measures of soil pollution?

Question

Please answer in full details and in point form

Answer 1

There are thousands of contaminant sources and pollutant types, but the following list is illustrative (pollutants indicated by parentheses):

* Petroleum hydrocarbons from rupture of underground storage tanks (benzene, ethylbenzene, toluene, xylene, alkanes, alkenes, MTBE)
* Spillage or leakage of solvents and dry cleaning agents (acetone, trichloroethylene, formaldehyde) and perchloroethylene
* Leaching of contaminants from solid waste disposal sites (lead, mercury, chromium, cadmium, bacteria, hydrocarbons)
* Water runoff which carries pollutants and may deposit them at a point of percolation
* Percolation into soils from pesticides and herbicides uses (wide variety of chemicals including DDT, lindane, organochlorines, organophosphates, carbamates, cyclodienes)
* Deposition of dust from smelting operations and coal burning power plants (zinc, cadmium, lead, mercury)
* Lead deposition from lead abatement or construction demolition (lead)
* Leakage of transformers (Polychlorinated Biphenyls (PCB)).


The major concern is that there are many sensitive land uses where people are in direct contact with soils such as residences, parks, schools and playgrounds. Other contact mechanisms include contamination of drinking water or inhalation of soil contaminants which have vaporized. There is a very large set of health consequences from exposure to soil contamination depending on pollutant type, pathway of attack and vulnerability of the exposed population. Chromium and many of the pesticide and herbicide formulations are carcinogenic to all populations. Lead is especially hazardous to young children, in which group there is a high risk of developmental damage to the brain and nervous system, while to all populations kidney damage is a risk.

Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia. Mercury and cyclodienes are known to induce higher incidences of kidney damage, some irreversible. PCBs and cyclodienes are linked to liver toxicity. Organophosphates and carbamates can induce a chain of responses leading to neuromuscular blockage. Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervous system. There is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals. Clearly at sufficient dosages a large number of soil contaminants cause death.

Effects occur to agricultural lands which have certain types of soil contamination. Contaminants typically alter plant metabolism, most commonly to reduce crop yields. This has a secondary effect upon soil conservation, since the languishing crops cannot shield the earth's soil mantle from erosion phenomena. Some of these chemical contaminants have long half-lives and in other cases derivative chemicals are formed from decay of primary soil contaminants

Control Measures

The following measures can be used to control land pollution:

1. anti-litter campaigns can educate people against littering;
2. organic waste can be dumped in places far from residential areas;
3. inorganic materials such as metals, glass and plastic, but also paper, can be reclaimed and recycled.
4. Establishment of factories and laboratories away from farms, while fixing filters on chimneys. In addition treatment of water used by these factories is needed before it is drained.
5. Proper use of pesticides and fertilizers.
6. Greater care about security measures for atomic reactors. Nuclear explosions should be carried out in places far enough to ensure security of living organisms and safety of the cultivable soil. Such experiments should be as few as possible for the safety of mankind.
7. Proper drainage of the cultivated soil and treatment of sewage water in order to be reused.