Professor, Institute of Marine Science and Technology, National Kaohsiung Marine University

Speech Title: Spatial and temporal variations of heavy metal concentration in water and sediment of Houjing River, Taiwan

Abstract: Contamination of heavy metals in aquatic environment has attracted global attention due to their significant adverse effects on aquatic ecosystems as well as human health. This study assessed spatio-temporal variations of eight heavy metals As, Cd, Cr, Cu, Pb, Ni, Zn and Hg in water and sediment samples collected at 12 sites in Houjing River, one of the most seriously polluted rivers in Taiwan. Results showed that the highest total concentration was found at the water and sediment samples nearby Nanzi Export Processing Zone (0.04-0.45 mg/L, 122-1486 mg/kg dry wt.), followed by the sites nearby Dashe Industrial Park (0.03-0.05 mg/L, 167-737 mg/kg dry wt.) and Renwu Industrial Park (0.03-0.24 mg/L, 195-427 mg/kg dry wt.), respectively. Regarding temporal variation of heavy metal concentration from 2014-2017, Dashe site tended to decrease but others had the reversal trends. The sediment core profiles reveal that As, Cr, Cu, Zn and Hg concentrations have increased in the past two decades. Ecological risk assessment was evaluated using multi-element indices include modified degree of contamination, Nemerow pollution index and the ecological risk index values. Results indicated that the heavy metal pollution in water possess low level of risk to the ecosystem. However, heavy metal contamination in sediment at Dashe, Zhuwai, and Renwu sites fell within the "moderately to heavily” and “severe" categories. Therefore, future suitable pollution prevention and control strategies need to be concerned, and remediation may be required.