Comparison of marine sampling methods for organic contaminants: Passive samplers, water extractions, and live oyster deployment

Abstract

Laboratory and field trials evaluated the efficacy of three methods of detecting aquatic pesticide concentrations. Currently used pesticides: atrazine, metolachlor, and diazinon and legacy pesticide dieldrin were targeted. Pesticides were extracted using solid-phase extraction (SPE) of water samples, titanium plate passive samplers coated in ethylene vinyl acetate (EVA) and eastern oysters (Crassostrea viginica) as biosamplers. A laboratory study assessed the extraction efficiencies and precision of each method. Passive samplers yielded the highest precision of the three methods (RSD: 3–14% EVA plates; 19–60% oysters; and 25–56% water samples). Equilibrium partition coefficients were derived. A significant relationship was found between the concentration in oyster tissue and the ambient aquatic concentration. In the field (Housatonic River, CT (U.S.)) water sampling (n = 5) detected atrazine at 1.61–7.31 μg L−1, oyster sampling (n = 2×15) detected dieldrin at n.d.–0.096 μg L−1 SW and the passive samplers (n = 5×3) detected atrazine at 0.97–3.78 μg L−1 SW and dieldrin at n.d.–0.68 μg L−1 SW.