Factors involved in the dynamics of pesticides in soils: the effect of temperature and period of contact on leachability and adsorption of pesticides by soils

Abstract

The effect of soil temperature on Ieachability and adsorption of pyrolan, γ‐HCH, α‐endosulphan, β‐endosulphan and dieldrin by Gezira soil from the Sudan, was studied. It was found that even when subjected to high temperatures (45°C) and prolonged leaching (60+ days), dieldrin and endosulphan isomers did not leach below 17 cm depth, but pyrolan and γ‐HCH exhibited leaching. In general, the leaching of pyrolan was greater than that of γ‐HCH. With the exception of pyrolan, the pesticide adsorption decreased progressively with temperature. Pyrolan adsorption was only slightly affected by temperature as most of the compound was either degraded or recovered from the leachate. Unaccountable losses of all pesticides increased with temperature. The effect of different periods of contact and temperature on adsorption of pesticides by a sandy clay loam from Northern England was also investigated.