SOIL CONTAMINATION

 

 

Soil contamination is caused by the presence of man-made chemicals in the natural soil environment. It usually arises from the leakage of underground storage tanks, application of pesticides, oil and fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. These chemicals greatly affect our health and the ecosystem.

 

 

Excavation showing soil contamination at a disused gasworks

 

Health effects

 

In our daily life, we always are in direct contact with soils such as residences, parks, schools and playgrounds. We may also be affected by drinking contaminated water or inhalation of soil contaminants which have vaporized. There are mainly a few kinds of chemical will affect our health.

• Chromium and obsolete pesticides such as mercury, are carcinogenic to populations.
• Lead is especially hazardous to young children since it may damage the development of the brain. Moreover, it may cause kidney damage to all populations.
• Chronic exposure to at sufficient concentrations is known to be associated with higher incidence of leukemia .
• 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 (physical), eye irritation and skin rash for the above cited and other chemicals.

 

Ecosystem effects

 

As we all know, soil contaminants can have significant deleterious consequences for ecosystems. Even though there is only a low concentration of the hazardous contaminant species, radical soil chemistry changes can still arise. These changes can be shown in the alteration of metabolism of endemic microorganisms and arthropods resident in a given soil environment. This results in the destruction of some of the primary food chain, which in turn have major consequences for predator or consumer species.

Besides, even if the chemical effect on lower life forms is small, the lower pyramid levels of the food chain may ingest different chemicals, which normally become more concentrated for each consumer of the food chain. Many of these effects are now well known, such as the concentration of persistent DDT materials for avian consumers, leading to weakening of egg shells, increased chick mortality and potentially species extinction.

 

For agricultural lands, contaminants typically change plant metabolism, resulting in the reduction of crop yields. Moreover, 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.