Anthropogenic effects on sediment quality offshore southwestern Taiwan: Assessing the sediment core geochemical record

Slag material was dumped in two sites off southwestern Taiwan by the China Steel Corporation during 1984-1995. By geochemically analyzing four sediment cores, we investigated the impact of slag on the sediment chemistry. Elemental profiles from the dumping sites show a strong depletion in detrital elements and enrichment in alkaline and redox-sensitive elements, especially for the top similar to 20 cm of sediments. The relative enrichment factor (EF(rel)) exhibits wider range for Ca (0.73-13.33), Fe (0.88-3.03), Mg (0.94-9.58) and Mn (1.22-33.30) due to contamination of sediments by slag. Sediment weathering indicators also show a distinct change with lower values in sediments influenced by dumping due to Ca and Sr addition. Higher EF(rel) for As, Cd and Pb in the top sections of the cores indicate an additional modern/industrial input of these elements since similar to 1950. Our study suggests that slag dumping may have a localized effect on biogeochemical processes by inducing the diagenetic remobilization of certain elements. (C) 2010 Elsevier Ltd. All rights reserved.