Monitoring cadmium and zinc contamination in freshwater systems with the use of the freshwater river crab, Potamonautes warreni

Abstract

Zn (an essential element) and Cd (a non-essential element) levels were measured in water and sediment samples and in Potamonautes warreni individuals from Germiston Lake, an impacted site, and Potchefstroom Dam, a minimally impacted site. All samples for metal analysis were acid digested in triplicate at 200 to 250°C with 55% nitric and 70% perchloric acids in a ratio of 2:1 (v/v). The results revealed that the Cd levels in the water, sediment and biota were similar at the two sites, but that higher levels of sediment-bound Zn were detected at the impacted site. Cd levels in P. warreni were low and did not differ significantly between the two sites. Zn concentrations, were significantly higher in the organisms from the impacted site, a result which could be exacerbated by the softer water from that site. This might suggest that the levels of Zn were not well regulated by P. warreni. Genderrelated differences were not observed for either metal at either site. While the size and mass of P.

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