Abstract:
Concentrations of cadmium and zinc in water, sediments and mussel Hyriopsis myersiana from the lower Ping River were studied during March 1992 to February 1993. It appears that the mean concentrations of cadmium and zinc in water were 1.51 and 40.51 microgram per litre, respectively. The concentrations of cadmium and zinc in water during the dry season were statistically higher than those of the wet season at the significant level of 0.05. The mean concentrations of cadmium and zinc in sediments from the Ping River were 0.83 and 90.66 microgram per gram dry weight, respectively. The high values were found in sediments around the waste water discharged area of zinc smelting plant (Padaeng Industry Co. Ltd.) at Changwat Tak. The concentrations of cadmium and zinc in the core sediments showed the highest values at the level of 5-10 centimeter depth around the same area. Ranges of cadmium and zinc concentration in mussel from the Ping River were 3.60-5.56 and 73.44-126.91 microgram per gram wet weight, respectively. The concentrations of cadmium in mussel near the discharged area of zinc smelting plant were found to be statistically higher than the Food Standard Limits at the significant level of 0.01.