Pesticides decreasing contamination

The threat of pesticides impact on the environment in Russia and other CIS countries has not diminished because they were used less in the 1990s. The long-term influence of pesticides on the soil not only has not decreased, but has become more apparent. Until recently, OCP soil contamination, significantly exceeding MPC, has been observed in the Krasnodar Krai, in the Republics of Central Asia, Moldova, Kazakhstan, in Ukraine, and in other regions [35]. DDT and its metabolites cause the most significant environmental problems, especially where perennial and industrial crops are grown. 

For any on-slte disposal system, there are at least four criteria that should be met to decrease the chance of environmental contamination and either eliminate or decrease the need for disposal at a permanent facility. First, the disposal system would need to concentrate the large volume of waste to Increase ease of handling and permanent disposal. Secondly, the disposal system would be required to contain the pesticide wastes to avoid environmental contamination or risks to human health. Thirdly, the system should prevent toxic levels from vaporizing Into the air. Finally, the disposal system should degrade and detoxify the pesticide wastes In the containment, particularly If buildup of the wastes to toxic levels Is a potential problem. 

Fish were killed at the 1000 ppm level and daphnids succembed at 100 and 1000 ppm levels. Sediment additions substantially reduced the toxicity at lower treatment levels. Sediment additions decreased total by 6 to 13% in fish, 20 to 40% in algae, 45 to 50% in snails and 55% in daphnids (10 ppm rate). Measureable levels of DDT not diffuse through 1 cm or more of untreated soil into water in one year. Covering pesticide contaminated sediment with soil and sediment in situ is an effective contamination control method under certain aquatic conditions. 

U.S. Geological Service report of a survey of pesticides in the nation s waters concluded that pesticides were common in surface and shallow groundwaters in both urban and agricultural areas, but investigators were not able to determine whether contamination is decreasing or increasing. 

It is therefore reasonable to assume that the evaporation rate of residue is proportional to the gross area of spray deposit for a pesticide remaining exposed on a leaf surface. The pesticide will be lost at a constant rate, under constant conditions of ventilation, until the contaminated area decreases significantly. 

The contamination decreased significantly after cleaning and casing of the well, although no change was introduced to the adjacent backfill. Hence, the pesticides were fixed on the soil. 

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