Partitioning of Metals in Sediment and Porewater from Rivers in Southern Taiwan

in International Symposium (Abstract oral presentation), 國際研討會(摘要口頭發表)
標題Partitioning of Metals in Sediment and Porewater from Rivers in Southern Taiwan
AuthorsChi-Ying Hsieh, 謝季吟, Kuo Wen-Chien 巫欣澤, Ching-Jen Ho 何建仁, & C.H. Tsai 蔡政紘
出版日期May 21 2016 12:0

The distribution and partitioning characteristics of six metals (Cr, Ni, Cu, Zn, Pb, and Cd) in porewater and sediment from eight rivers (YS, DB, SY, AGD, HJ, LK, WR, and DG) were investigated in southern Taiwan. Total metals concentrations in sediments ranged from below the limits of detection to 910.60 mg/kg and were dominated by copper and zinc. Maximum concentrations of Cr, Ni, Cu, Zn, and Pb in porewaters were 0.212, 0.256, 0.126, 3.609, and 0.045 mg/L, respectively. Cd levels in porewaters were all below the detection limit. Particle size analysis showed that the HJ, ER, and DG rivers contained high quantities of silt and clay while LK and AGD river sediments were composed primarily of sand. Furthermore, signi?cant correlations (p < 0.05) were found between Cu concentrations and clay content (< 2 μm) using the Spearman rank correlation analysis. However, the metals Cu, Pb, and Cd were most easily adsorbed onto particles < 20 μm in size and Zn was preferentially adsorbed on sand (20 μm ~ 2 mm), while particle size had little effect on the adsorption of Cr and Ni. Total organic carbon (TOC) concentrations varied from 0.47 to 5.46%. Furthermore, signi?cant relationships were observed between TOC content and Ni, Cu, Zn, Pb, and Cd concentrations. Our results confirmed that heavy metals concentrations in sediments were influenced more by organic matter content than other factors. In addition, the sediment-porewater partition coef?cients (Koc) of heavy metals play important roles in metals partitioning between sediment particles and porewater. Measured Koc values varied by an order of magnitude among the various metal compounds in the different rivers. The highest log Koc value was obtained for Cu in all rivers, and the lowest log Koc values were for Zn from rivers YS, DB, AGD, LK, WR, and DG. The lowest values were for Cr and Ni from the SY and HJ rivers. Overall, the Koc values for metals, in decreasing magnitude, were Cu>Pb>Ni>Cr>Zn. Zn was the most easily remobilized heavy metal in porewaters and Cu the most easily adsorbed in sediments.

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