ORGANIC-CARBON NORMALIZATION OF PCB, PAH AND PESTICIDE CONCENTRATIONSIN SUSPENDED-SOLIDS

The equilibrium partitioning concept for hydrophobic organic compounds (HOCs) predicts that organic carbon (OC) normalised or organic matter (OM) normalised HOC concentrations are approximately the same for dif ferent solid types sampled at the same time from the same surface wate r. This hypothesis was tested for polyaromatic hydrocarbon (PAH), poly chlorobiphenyl (PCB) and pesticide concentrations in settling solids ( sediment trap) and suspended solids (continuous how centrifuge) taken from Lake Volkerak and Lake Zoom (The Netherlands). It was found that settling solids had significantly higher OC normalised, or OM normalis ed HOC concentrations than suspended solids. Also, the degree of miner alisation as quantified by the OC-N atomic ratio of the organic materi al was significantly higher for the settling solids. The higher degree of mineralisation explains the higher normalised HOC concentrations i n the settling solids, It was concluded that the ageing of organic mat ter during settling in the water column or after burial in sediments, may cause the increased fixation of HOCs onto organic particles. (C) 1 997 Elsevier Science Ltd.