State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China.
Environ Res. 2023 Oct 1;234:116593. doi: 10.1016/j.envres.2023.116593. Epub 2023 Jul 7.
Currently, little is available on how mercury (Hg) methylation couples with soil organic matter decomposition in degraded permafrost in high northern latitudes, where the climate is becoming warmer rapidly. Here, we revealed the complex interactions between soil organic matter (SOM) mineralization, dissolved organic matter (DOM) and methylmercury (MeHg) production based on an 87-day anoxic warming incubation experiment. Results supported remarkably promotion effects of warming on MeHg production, by 130%-205% on average. Total mercury (THg) loss under warming treatment depended on marsh types but showed an increasing trend on the whole. Warming yielded higher proportions of MeHg to THg (%MeHg), increased by 123%-569%. As expected, greenhouse gas emission was significantly enhanced by warming. Warming also strengthened fluorescence intensities of fulvic-like and protein-like DOM, with contributions to total fluorescence intensities of 49%-92% and 8%-51%, respectively. DOM and its spectral features explained 60% variation of MeHg, and the explanation increased to 82% in conjunction with greenhouse gas emissions. The structural equation model implied that warming, greenhouse gas emission, and humification of DOM had positive effects on Hg methylation potential, while microbial-derived DOM showed negative effects on MeHg. These results showed that accelerated Hg loss and increased methylation covaried with greenhouse gas emission and DOM formation under warming conditions in permafrost marsh.
目前，关于在高纬度地区迅速变暖的退化永久冻土中，汞 (Hg) 甲基化如何与土壤有机质分解耦合，知之甚少。在这里，我们通过为期 87 天的缺氧增温孵育实验，揭示了土壤有机质（SOM）矿化、溶解有机质（DOM）和甲基汞（MeHg）产生之间的复杂相互作用。结果表明，增温对 MeHg 产生有明显的促进作用，平均增幅为 130%-205%。增温处理下总汞（THg）损失取决于沼泽类型，但总体呈上升趋势。增温使 MeHg 对 THg 的比例（%MeHg）增加了 123%-569%。不出所料，增温显著增强了温室气体排放。增温还增强了富里酸和蛋白类 DOM 的荧光强度，分别占总荧光强度的 49%-92%和 8%-51%。DOM 及其光谱特征解释了 MeHg 变化的 60%，而与温室气体排放相结合后，解释度增加到 82%。结构方程模型表明，在永久冻土沼泽中，增温和温室气体排放以及 DOM 的腐殖化对 Hg 甲基化潜力有积极影响，而微生物衍生的 DOM 对 MeHg 有负面影响。这些结果表明，在变暖条件下，Hg 的加速损失和甲基化增加与温室气体排放和 DOM 的形成有关。
