Formation and biorelease of bound residues of pesticides in two Brazilian soils. I. [¹⁴C] - lindane

Abstract

Soil contamination after pesticide applications is often frequent, and the use of radiolabelled molecules had proved the existence of non extractable or bound residues which remain firmly bound to the soil matrix. The extent of bound residues formation varies according to the applied compound, but it may constitute a significant part of residues remaining in the soil. The extractable and bound residues formation of ¹⁴C-lindane were studied immediately and three months after the application. Metabolism, biorelease, and possible bioavailability of bound residues to bean plants were investigated by the use of biometer flasks. The results show that the formation and biorelease of lindane bound residues varied according to the soil type and with the aging time of the compound in the soil. There is a gradual binding because bound residues formed immediately after the application were released easier than the bound residues formed after a time of interaction of lindane with the soils. However, although some biorelease had occurred mainly by the microflora action, some bound residues remained as still bound even after the microflora and rhizosphere action, being thus, inactivated.