<br>影响河口沉积物中汞和甲基汞的通量和硅藻吸收的特性,Environmental Pollution

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影响河口沉积物中汞和甲基汞的通量和硅藻吸收的特性
Environmental Pollution ( IF 7.6 ) Pub Date : 2024-02-27 , DOI: 10.1016/j.envpol.2024.123604
Kathleen J Gosnell ₁ , Nashaat Mazrui ₂ , Robert P Mason ₃

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汞（Hg）是一种显著且持久的全球污染物。离子汞可甲基化成有害甲基汞（CH3Hg），这种汞在海洋热带网络中会生物放大，对人类和生物体构成健康风险。沉积物 Hg 甲基化速率是可变的，产生的 CH3Hg 的输出通量取决于沉积物特性和环境因素。因此，关于沉积物中 CH3Hg 的形成和通量，以及这如何导致浅层生态系统中沿海生物的生物累积负担，仍然存在不确定性。从美国东部的 3 个河口位置收集岩芯，以研究沉积物特性如何影响 Hg 和 CH3Hg 进入食物链的基础。将无机 200Hg 和 CH3199Hg 的稳定同位素注入单个岩心的沉积物中，培养的硅藻仅限于上覆水域。对重复的核心进行了五种不同的处理，并加标：（1）无 Hg 同位素（对照）;（2）无机物 200Hg;（3） CH3199Hg;（4） 200Hg 和 CH3199Hg 同位素，（5） 200Hg 和 CH3199Hg 都进入上覆水域（不是沉积物）。实验核心在温度和光照受控条件下孵育 3 天。这些结果表明，上层沉积物特征导致 Hg 循环的高度可变性。值得注意的是，含有丰富泥炭状有机物质（∼28 %LOI）的沉积物具有最高的孔隙水 DOC （3206 μM）并显示硫还原细菌带，产生最大的甲基化率（1.97 % day-1）和随后的硅藻吸收 CH3200Hg （细胞配额 0.18 amol/cell）在上覆水中。

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Properties influencing flux and diatom uptake of mercury and methylmercury from estuarine sediments

Mercury (Hg) is a conspicuous and persistent global pollutant. Ionic Hg can be methylated into noxious methylmercury (CH3Hg), which biomagnifies in marine tropic webs and poses a health risk to humans and organisms. Sediment Hg methylation rates are variable, and the output flux of created CH3Hg are dependent on sediment characteristics and environmental factors. Thus, uncertainties remain about the formation and flux of CH3Hg from sediment, and how this could contribute to the bioaccumulative burden for coastal organisms in shallow ecosystems. Cores were collected from 3 estuarine locations along the Eastern USA to examine how sediments characteristics influence the introduction of Hg and CH3Hg into the base of the food chain. Stable isotopes of inorganic 200Hg and CH3199Hg were injected into sediments of individual cores, with cultured diatoms constrained to overlying waters. Five different treatments were done on duplicate cores, spiked with: (1) no Hg isotopes (control); (2) inorganic 200Hg; (3) CH3199Hg; (4) both 200Hg and CH3199Hg isotopes, (5) both 200Hg and CH3199Hg into overlying waters (not sediment). Experimental cores were incubated for 3 days under temperature and light controlled conditions. These results demonstrate that upper sediments characteristics lead to high variability in Hg cycling. Notably, sediments which contained abundant and peaty organic material (∼28 %LOI), had the highest pore water DOC (3206 μM) and displayed bands of sulfur reducing bacteria yielded the greatest methylation rate (1.97 % day−1) and subsequent diatom uptake of CH3200Hg (cell quota 0.18 amol/cell) in the overlying water.

更新日期：2024-02-27

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