Bioaccumulation of Endosulfan from Contaminated Sediment by Vallisneria spiralis

Abstract

Endosulfan (C₉H₆Cl₆O₃S) is a non-persistent organochlorine insecticide that is used widely in agriculture to control invertebrate pests. It is a cyclodiene ester pesticide with two isomers (α and β). These have half-lives of only a few days in water but the toxic biological metabolite, endosulfan sulfate, has an aqueous half-life of several weeks (Peterson and Batley 1993). It is a hydrophobic compound that can be sorbed to soil and sediment, having in this situation a longer environmental half-life (Rao and Murty 1980). Batley and Peterson (Leonard et al. 1999) have ranked it between pesticides with highest potential for impact on the riverine environment. Although the longer persistence of endosulfan in soil suggests that field runoff during storm events may be the major source of endosulfan in fish kills (Leonard et al., 1999). In an artificial stream study Hose et al. (2002) found a NOEC value for benthic macroinvertebrates of 6.14 µg/L with interstitial water that corresponded with a nominal spiked concentration of 2 mg endosulfan/Kg. The authors found significant changes in the abundance of several macroinvertebrate taxa which could result in significant effects on macroinvertebrates populations and communities.