Saturday, August 6, 2011

What is positive soil pollution?

n the positive soil pollution there occur an overuse of chemical fertilizers, air pollutants and pesticides along with herbicides and fumigants. The air pollutants have the ability to move down with the rain. The pesticides and weedicides are defined as the chemicals which have the ability to kill the insects, fungi, rodents, algae, weeds so that the agriculture output is increased. The insecticides are most commonly used. They are sprayed on the plants as powders or fine mist. They are mainly broad spectrum and affect the animals and plants. They are also referred as biocides. They may also involve the man. It includes the chlorinated hydrocarbons which involve DDT, DDE, aldrin, endrin and BHC. They are toxic and the dieldrin is the most common toxic form. It is many times toxic and poisonous than DDT. These are always persistent and mobile in the ecosystem. These hydrocarbons are mainly soluble in the fat and aggregate in the living organisms. The zooplankton which acts on many aquatic phytoplankton cells has pesticide in their tissues. Their levels are not static. They keep on changing with as high as 1 part pesticide per million parts of the fat. There are certain fishes which feed on the zooplankton and have further higher levels of pesticide which range around 5 parts per million. The birds which feed on fishes have further higher levels of pesticide which range around 3000 parts per million. This increase in the level of pesticides at the higher trophic levels in the food pyramids is referred as the biological magnification. They affect the brain, liver, heart and may cause cancer in the human beings. They may also affect the birds and lead to the defective egg shell production. The shell of the eggs is very thin and can be broken by the bird’s weight. The developing embryos are also adversely affected. . So, the numbers of birds are decreased. The herbivorous animals feed on the pesticide rich vegetation. The humans feed on their meat and milk and take pesticides in their tissues. There are other groups of chemicals which are included and are known as Organo pesticides. These include the organo phosphorous compounds like malathion, parathion, triothion, ethion and carbamates. They are poisonous and can be degraded. They are difficult to handle and may lead to nausea, vomiting, salivation and diarrhea along with the tremors in muscle. There are another group of pesticides which are known as the inorganic pesticides and contain arsenic and sulphur. They can be poisonous to both the plants and animals. They cannot be degraded. The weedicides are also known as herbicides. They are used to clear the forest so that new buildings can be built. They also help to control the weed in agriculture, horticulture and in the management of forest. They are mainly the inhibitors of metabolism which interfere in the process of photosynthesis. It may lead to the death of plant. They also effect the multiplication of phloem cells which inhibits the transport of organic food. The weeds in Aswan dam were killed by the weedicides. They not only affect the agricultural fields but also have an impact on the fish production in sea. There is a process which is known as ecological boomerang in which there are adverse ecological effects of substances in the later period. It is also known as the ecological backlash. The industrial wastes can be solid or liquid. They are dumped on the soil. It consists of many metals, cyanides, acids, alkalies, solvents and chromates. In the mining areas mine dust is the main source of pollution. It can spread with the help of winds and with the help of purification plants. The waste of these plants also pollutes the environment. It destroys the vegetation along with the poisonous gases and toxic materials. They also affect the animals and plants by causing deformities and diseases. The fertilizers have the ability to enter the crops and may also go to the water table. They become a part of underground water. The nitrogen fertilizers make high concentration of nitrate and nitrite. It occurs in the leaves and fruits. There are canned foods which contain nitrate and may lead to the corrosion of tin present in the can. The tin can also produce the nitrous oxide. The drinking water with the excess of nitrates increases the toxicity. The bacteria change the nitrates and nitrites in the alimentary canal. They enter the blood and combine with the hemoglobin to form met haemoglobin. It forms a condition known as the met haemoglobinaemia which occurs due to the reduced transport of oxygen. They lead to cyanosis in the infants and the breathlessness in adults. The nitrate poisoning can be fatal in the infants. It is treated by the use of methylene blue. The soil deterioration occurs by the use of excessive fertilizers. The populations of natural bacteria like nitrifying; nitrogen fixing is decreased and also destroys the crumb structures. The fertilizers also increase the salt content of soil. There are other pollutants which affect the soil. The air and water pollutants ultimately go to the soil. The weathering of rocks also adds the toxic materials to soil. The lead released by the automobiles also adds to the soil present near the roadside. The surface soil of Bombay has a lead concentration of 41 micro grams per gram as reported by the Khandekar in the year 1984. It can enter the food chain. The water and food chain has the fluoride and in plants it has the ability to combine with the magnesium ions of chlorophyll. It affects the process of photosynthesis and may lead to the death of plant. The fluoride pollution can be indicated by the maize plant. The excess of fluorides lead to a condition known as fluorosis. It leads to the mottling of teeth. It can be followed by the fluorosis of bone. The bones become weak and there is a knocking of knees along with the boat shaped posture. The animals which graze over the fields rich in fluoride show ill health and teeth, weak and swelled bones.

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