BayCEER Workshop 2008

Slugs - Bioaccumulating Terrestrial Molluscs for Monitoring of Herbicides in Agro-Ecosystems

About 50% of the globally applied pesticides (2.4 million tons a^-1) are herbicides. Less than 0.1% reach the target, large amounts enter the environment and may adversely affect non-target species. Wildlife can be exposed by direct overspray, drift and by contact with contaminated soil, vegetation or prey. The aim of the present work is to use slugs (e. g. Deroceras reticulatum) as bioindicators for monitoring herbicides in relation to agricultural practices. Slugs are abundant on cultivated land; they are polyphagous molluscs, easy to sample, relatively stationary, sufficiently large, and their life-cycle takes place in close contact to the soil to absorb nutrients and contaminants. Twelve herbicides, representatives of the triazine, triazinone, phenylurea, chloracetamide and hydroxy-benzonitrile classes, have been determined in slugs, soils and surface waters. Slug and soil samples were freeze-dried and subjected to accelerated solvent extraction (ASE), followed by solid phase extraction (SPE) to obtain purified concentrates. Liquid chromatography coupled to electrospray tandem mass spectroscopy (LC-ESI-MS/MS) was used for separation and quantification.