Potential Contamination of Heavy Metals in Fish along Pong and Chi Rivers

摘要

Levels of heavy metals including Cd, Co, Cr, Cu, Ni, Pb and Zn in fish from 8 predetermined sampling sites along the Pong and Chi Rivers were investigated. Fish were randomly collected from each site and categorized as herbivorous and carnivorous. The sites, marked A, B, C, D, E, F, G, H, located downstream between Ubolratana reservoir and Mahasarakham weir covering a river length of about 180 km. The livers of the fish were immediately separated, processed and analyzed by atomic absorption method. The hepatic levels of Cd, Co, Cr, Cu, Ni, Pb and Zn of the herbivorous fish were 0.0874-3.2477, 6.7-84.98, 3.68-43.2, 60.3-1,620.6, 2.6-41.5, 0-6.32 and 86.8-5923 μg/g dried weight; those of carnivorous being 766-1.7976, 8.51-47.69, 2.68-34.7, 135-807.6, 1.39-15.8, 0.5-13.86 and 6603.3-3,106 μg/g dried weight, respectively. The overall results suggest that site B exhibited the highest levels of the heavy metals accumulated in the fish livers, and, that the herbivorous fish showed higher levels of metal contaminants than the carnivorous. The highest hepatic cadmium content of herbivorous fish was found at site H, whereas those for carnivorous fish were at site B. Both herbivorous and carnivorous fish from site B also contained the highest hepatic Pb levels. Investigation of heavy metals contained in fish should be one of the key indicators that reflect the severity of heavy metal contamination in natural water resources.