Huang Shuyuan, Zhao Yuhan, Lv Supeng, Wang Weiguo, Wang Weili, Zhang Yuanbiao, Huo Yunlong, Sun Xiuwu, Chen Yaojin
Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China.
Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China; College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China.
Chemosphere. 2021 Jun;272:129716. doi: 10.1016/j.chemosphere.2021.129716. Epub 2021 Feb 3.
Isotope signatures of mercury (Hg) were determined for Hg fractions in seawater, sediments, porewaters, core sediments and fish from the Yundang Lagoon, Xiamen, China. Sequential extraction was used to extract Hg fractions in sediments and the purge-trap method was used to preconcentrate Hg in seawater. A large variation in mass dependent fractionation (δHg: -2.50‰ to -0.36‰) was observed in the lagoon. Seawater and fish samples showed positive mass-independent fractionation (ΔHg: -0.06‰-0.45‰), while most of sediment and porewater samples displayed insignificant mass-independent fractionation (ΔHg: -0.10‰-0.07‰). Ancillary parameters (total organic carbon, sulfide, pH, Eh, water content and grain size) were also measured in the sediments to investigate correlations with Hg isotopes. Three sources (domestic sewage, sediments and atmospheric deposition) were identified as the main sources of Hg in the lagoon seawater. Photochemical reaction was the main process causing isotope fractionation in seawater. Through Hg partitioning and deposition, light isotopes were enriched from dissolved Hg to particulate Hg, then to sediments, and then to porewaters. Finally, Hg isotope signatures were used to identify the Hg sources and fractionation processes in core sediments from different depths. Our results demonstrate that Hg isotopes are powerful tools for tracing Hg sources and arriving at a better understanding of Hg biogeochemical cycling in the lagoon after long-term interventions.
对中国厦门筼筜湖海水中的汞（Hg）组分、沉积物、孔隙水、岩芯沉积物和鱼类进行了汞同位素特征分析。采用连续提取法提取沉积物中的汞组分，采用吹扫捕集法对海水中的汞进行预浓缩。在该泻湖中观察到质量依赖分馏存在很大差异（δHg：-2.50‰至-0.36‰）。海水和鱼类样品显示出正的质量非依赖分馏（ΔHg：-0.06‰-0.45‰），而大多数沉积物和孔隙水样品显示出不显著的质量非依赖分馏（ΔHg：-0.10‰-0.07‰）。还对沉积物中的辅助参数（总有机碳、硫化物、pH值、氧化还原电位、含水量和粒度）进行了测量，以研究与汞同位素的相关性。确定了三个来源（生活污水、沉积物和大气沉降）为泻湖海水中汞的主要来源。光化学反应是导致海水中同位素分馏的主要过程。通过汞的分配和沉积，轻同位素从溶解态汞富集到颗粒态汞，然后到沉积物，再到孔隙水。最后，利用汞同位素特征识别不同深度岩芯沉积物中的汞来源和分馏过程。我们的结果表明，汞同位素是追踪汞来源和更好地理解长期干预后泻湖汞生物地球化学循环的有力工具。
