ASSESSMENT OF CADMIUM IN AQUATIC SEDIMENT USING DIALYSIS SAMPLERS WITH ION-EXCHANQE-RESIN COLLECTION

Simultaneously extracted metals (SEM) and acid volatile sulfide (AVS) show the potential for toxicity on the basis of their ratio. According ly, we spiked cadmium in a range for which Cd/AVS ratios were from 0.2 to 10 in the sediment with its weight about 8 kg in each batch. Dialy sis samplers with a cation ion-exchange resin (Dowex 50W-X4) collectio n were used in a laboratory for the determination of free cadmium conc entrations in pore water of the collected sediment. When equilibrium w as reached among cadmium in pore water, sediment, and ion-exchange res in, cadmium exchanged onto resin phase was regenerated with 1 N hydroc hloric acid (OPTIMA grade) and determined using an atomic absorption s pectrophotometer (Zeeman 5000) with a graphite furnace accessory. Cadm ium determined using the dialysis sampler is considered as free cadmiu m which is related to the metal bioavailability toward aquatic biota T he developed methodology provides a new technique for assessment of fr ee metal in aquatic sediment systems.