INFLUENCE OF SUSPENDED-SOLIDS AND BACK-DIFFUSION ON ORGANIC CONTAMINANT UPTAKE BY SEMI-PERMEABLE MEMBRANES (SPMDS)

The organic contaminant uptake efficiency by a semi-permeable membrane device (SPMD) was assessed by carrying out simple equilibration tests under variable natural suspended solids concentrations. C-14-radiolab elled methylnaphthalene was used to trace total contaminant partitioni ng between dissolved, solids-sorbed and SPMD dialysate phases. At susp ended solids loads typical of most natural waters (<100 mg l(-1))there was no effect on SPMD uptake efficiency, however, at high solids conc entrations such as may occur at interfaces between water column and be d sediments or during high river flow or tidal resuspension, reduced S PMD uptake occurred. Over an extended SPMD exposure period back diffus ion of contaminants from SPMD dialysate will occur following a decline in ambient concentrations. (C) 1997 Elsevier Science Ltd.