Trace metals, PCBs, and PAHs in benthic (epipelic) diatoms from intertidal sediments; a pilot study

Mobile benthic diatoms were harvested from sheltered sediment by spreading lens cleaning tissues and covering them with planktonic gauze of mesh 80 um. The organisms migrated into the gauze from which they were easily washed. Collection took place at 4 sites on the Scheldt estuary. Sediment samples and specimens of Baltic tellin, ragworm, shrimp and livers from flounders were also taken. Homogenized samples were freeze-dried, extracted, cleaned-up and analysed by chromatographic techniques for PCB and PAH. Heavy metals were analysed by atomic absorption spectrophotometry after acid digestion. The dominant species of diatoms was Navicula phyllepta. Bioconcentration factors for all parameters in diatoms were less than 1. Concentrations of PCB, PAH, cadmium, copper and zinc in the diatoms were comparable with other benthic organisms, despite their short lifespan and high turnover rate.