Identifying the Sources and Processes of Mercury in Subtropical Estuarine and Ocean Sediments Using Hg Isotopic Composition

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• 作者：Runsheng Yin ; Xinbin Feng ; Baowei Chen ; Junjun Zhang ; Wenxiong Wang ; Xiangdong Li
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：49
• 期：3
• 页码：1347-1355
• 全文大小：470K
• ISSN：1520-5851

文摘

The concentrations and isotopic compositions of mercury (Hg) in surface sediments of the Pearl River Estuary (PRE) and the South China Sea (SCS) were analyzed. The data revealed significant differences between the total Hg (THg) in fine-grained sediments collected from the PRE (8鈥?51 渭g kg^鈥?) and those collected from the SCS (12鈥?3 渭g kg^鈥?). Large spatial variations in Hg isotopic compositions were observed in the SCS (未²⁰²Hg, from 鈭?.82 to 鈭?.10鈥? 螖¹⁹⁹Hg, from +0.21 to +0.45鈥? and PRE (未²⁰²Hg, from 鈭?.80 to 鈭?.68鈥? 螖¹⁹⁹Hg, from 鈭?.15 to +0.16鈥?. The large positive 螖¹⁹⁹Hg in the SCS indicated that a fraction of Hg has undergone Hg²⁺ photoreduction processes prior to incorporation into the sediments. The relatively negative 螖¹⁹⁹Hg values in the PRE indicated that photoreduction of Hg is not the primary route for the removal of Hg from the water column. The riverine input of fine particles played an important role in transporting Hg to the PRE sediments. In the deep ocean bed of the SCS, source-related signatures of Hg isotopes may have been altered by natural geochemical processes (e.g., Hg²⁺ photoreduction and preferential adsorption processes). Using Hg isotope compositions, we estimate that river deliveries of Hg from industrial and urban sources and natural soils could be the main inputs of Hg to the PRE. However, the use of Hg isotopes as tracers in source attribution could be limited because of the isotope fractionation by natural processes in the SCS.