Circulation of Pesticides in the Biosphere

Abstract

In the USSR emphasis is focused on studying pesticide circulation in the environment, especially to determine the regularities of their migration and accumulation in living beings. Over 500 laboratories for systematically estimating pesticide residues in plant and animal products, water, drinking watersupplies, atmospheric air and working area air are established at the National Sanitary and Epidemiology Stations. Summarizing research results permits us to elicit the main reasons for excessive pesticide pollution of separate environmental units and work out scientific standards for each pesticide use. Establishment of time-keeping between the last pesticide application and harvest of the crop is of particular interest. These measures prevent appearance of intolerable pesticide residues in foods. The best time for the next work after pesticide application in fields, gardens, etc. is controlled. Sanitary standards for distance between target and populated areas have been established. The capacity of pesticide storage in food chains is determined. The main pesticide cumulator is soil from which chemicals transfer through root systems into plants. Heptachlor is found in carrot in concentrations of 1 mg/kg at a level of some thousandths of milligrammes in the soil. Pesticides are migrating from soil to underground water, natural water and atmospheric air. A secondary pollution risk is possible. Concentrations of some thousandths of mg/l in water, some hundredths and tenths of mg/kg in zoophytoplankton, about 5 mg/kg in fish have been detected. Pesticide concentrations of 1-2 mg/kg of body weight in hare, 5-8 mg/kg in wolf have been identified. Only a proportion of such chemicals is placed on target areas. The rest of the aerosol is carried away by the wind over a distance to higher atmospheric layers resulting in precipitations. To prevent danger it is necessary to select pesticides strictly precluding any prolonged persistent and stable preparations.

Pesticides in the atmosphere; distribution, trends, and governing factors

“…Air currents produced by the aircraft have a major effect on the trajectories of the fine particles released and can increase their drift potential. In general, spray drift from aerial applications is about five times greater than from ground-rig applications (Ware and others, 1969;Medved, 1975). Orchard radial and axial fan mist-blowers direct the spray up and away from the ground in an effort to cover the entire tree or crop canopy.…”

the Determination of diazinon residues in artificially polluted soils.

“…Moreover, the environmental factors like temperature in particular, precipitation, humidity and wind are among the other factors affecting pesticides' persistence (Edwards, 1975). The rate of dispersal and the persistence time of pesticides in soil depend on the physico-chemical and biological properties of the soil (Medved, 1975). Kabir et al, (2008) observed that diazinon left residue up to 6 d after spray of 3 supervised fields at the field dose 1.5 ml.l -1 of water, however the level of residue was above the maximum residue limit (MRL) which established by FAO 1970.…”