Adsorption of selected pesticides on a rigid PVC lysimeter

Lysimeters have traditionally been made out of stainless steel and tenon to monitor soil solutions and groundwater, The possibility of adsorption of o rganic chemicals to polyvinyl chloride (PVC) Lysimeters, a more economical alternative to stainless steel, has led to debate over their suitability fo r groundwater sampling. The adsorption of different pesticide chemistries, chloroacetanilide (alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethy l)acetamide)), s-triazine (atrazine (6-chloro-N-ethyl-N'-1-methylethyl)-1,3 ,5-triazine-2,4-diamine)), chloronicotinyl (imidacloprid (1-[(6-chloro-3-py ridinyl)methyl]-N-nitro-2-imidazolidinimine)), organophosphorus (isofenphos (1-methylethyl 2-[[ethoxy[(1-methylethyl)amino]phosphinothioyl]oxy]benzoat e)), sulfonylurea (nicosulfuron (2-[[[[(4,6-dimethoxy-2-pyr-imidinyl)amino] carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridine carboxamide)), and azole ( triadimefon (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)-2-b utanone)), on a lysimeter constructed from rigid PVC was determined to eval uate the suitability of PVC material for use in groundwater sampling. Among all pesticides tested, only isofenphos demonstrated slight adsorption (9% of applied) on the lysimeter; adsorption was rapid and isophenfos was not e asily desorbed with methanol and water, None of the other pesticides adsorb ed to the lysimeter, When selecting a lysimeter, potential adsorptive inter actions between other pesticide chemistries and the materials used in the l ysimeter construction should be evaluated.