Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010070, China; College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.
Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010070, China.
Aquat Toxicol. 2024 Jun;271:106928. doi: 10.1016/j.aquatox.2024.106928. Epub 2024 Apr 18.
The significant role of aquatic phytoplankton in global primary productivity, accounting for approximately 50 % on an annual basis, has been recognized as a crucial factor in the reduction of Hg(II). In this study, we compared the efficiency of Hg(II) photoreduction mediated by three types of algae leaching dissolved organic matter (DOM) and humic acid (DOM-HA). Especially, we investigated the potential effects of algae-leached DOM on the photoreduction of Hg(II) and its subsequent uptake by lettuce, which serves as an indicator of Hg bioavailability for aquatic plants. The results revealed that under light conditions, the conversion of Hg(II) to Hg(0) mediated by algae-leached DOM and DOM-HA was 6.4-39.9 % higher compared to dark condition. Furthermore, the free radical quenching experiment demonstrated that the reduction of Hg(II) mediated by DOM-HA was higher than algae-leached DOM, mainly due to its ability to generate superoxide anion (O). Moreover, the photoreduction efficiences of Hg(II) mediated by algae-leached DOM were 29-18 % lower compared to DOM-HA. The FT-IR analysis revealed that the production of -SH from algae-leached DOM led to the formation of strong metal-complexes, which restricts the reduction process from Hg(II) to Hg(0). Finally, the hydroponics experiment demonstrated that algae-leached DOM inhibited the bioavailability of Hg(II) to plants more effectively than DOM-HA. Our research emphasizes the significant functional roles and potential mechanisms of algae in reducing Hg levels, thereby influencing the availability of Hg in aquatic ecosystems.
浮游植物在全球初级生产力中扮演着重要角色，其贡献约占每年的 50%，这被认为是减少汞(II)的关键因素。在这项研究中，我们比较了三种藻类浸提溶解有机质（DOM）和腐殖酸（DOM-HA）介导的 Hg(II)光还原效率。特别是，我们研究了藻类浸提 DOM 对 Hg(II)光还原及其随后被生菜吸收的潜在影响，生菜被用作水生植物对 Hg 生物利用度的指示物。结果表明，在光照条件下，藻类浸提 DOM 和 DOM-HA 介导的 Hg(II)转化为 Hg(0)的转化率比暗条件下高 6.4-39.9%。此外，自由基猝灭实验表明，DOM-HA 介导的 Hg(II)还原比藻类浸提 DOM 更高，主要是因为它能够产生超氧阴离子（O）。此外，藻类浸提 DOM 介导的 Hg(II)光还原效率比 DOM-HA 低 29-18%。FT-IR 分析表明，藻类浸提 DOM 产生的 -SH 导致形成了强金属配合物，从而限制了 Hg(II)到 Hg(0)的还原过程。最后，水培实验表明，藻类浸提 DOM 比 DOM-HA 更有效地抑制 Hg(II)对植物的生物利用度。我们的研究强调了藻类在降低 Hg 水平方面的重要功能作用和潜在机制，从而影响水生生态系统中 Hg 的可用性。
