Institute of Geosciences, University of Campinas, Campinas, Brazil.
Institute of Geosciences, University of Campinas, Campinas, Brazil.
Mar Pollut Bull. 2021 Dec;173(Pt B):113031. doi: 10.1016/j.marpolbul.2021.113031. Epub 2021 Oct 14.
The mercury (Hg) cycle in estuaries has been globally discussed, although Holocene deposition in mangrove sediments remains unknown. Herein, a sediment core from a mangrove system in southeastern Brazil was C-dated to evaluate millennial Hg deposition. The highest Hg concentrations (1010-2540 ng g) in surface sediments were explained by emissions from a chlor-alkali industry (1964 CE). However, Hg levels were also high in pre-industrial periods, associated to fine grain-size and algal organic deposition. Less anomalous Hg concentrations in bottom sediments indicate Holocene ages (~1940-3324 cal yr BP), potentially associated to Serra do Mar mountains weathering. This study reveals the capacity of mangrove to retain Hg over millennial time scales, acting as significant and long-term Hg sinks. Therefore, the use of Hg as an Anthropocene marker must be considered cautiously in coastal systems that act as Hg sinks in times when environmental changes were not caused by human activities.
尽管全球范围内已经对河口的汞（Hg）循环进行了讨论，但对于红树林沉积物中的全新世汞沉积仍知之甚少。本文通过对巴西东南部红树林系统中的一个沉积物岩芯进行 C 年代测定，以评估千年尺度的汞沉积。表层沉积物中最高的汞浓度（1010-2540ng g）是由氯碱工业（1964 年）排放引起的。然而，在工业前时期，汞浓度也很高，与细颗粒和藻类有机沉积有关。底层沉积物中较少异常的汞浓度表明全新世时期（约 1940-3324 年 cal yr BP），可能与 Serra do Mar 山脉风化作用有关。本研究揭示了红树林在千年时间尺度上保留汞的能力，充当重要的长期汞汇。因此，在那些当环境变化不是由人类活动引起时充当汞汇的沿海系统中，必须谨慎使用汞作为人类世的标记物。
