State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
College of Applied Arts and Science of Beijing Union University, Beijing, 100191, China.
Environ Pollut. 2021 Jan 15;269:116141. doi: 10.1016/j.envpol.2020.116141. Epub 2020 Dec 1.
Lakes in arid regions are experiencing mercury pollution via air deposition and surface runoff, posing a threat to ecosystem safety and human health. Furthermore, salinity and organic matter input could influence the mercury cycle and composition of bacterial communities in the sediment. In this study, the effects of salinity and algae biomass as an important organic matter on the genes (merA and hgcA) involved in the mercury cycle under mercury contamination were investigated. Archaeal merA and hgcA were not detected in sediments of lake microcosms, indicating that bacteria rather than archaea played a crucial role in mercury reduction and methylation. The high content of mercury (300 ng g) could reduce the abundance of both merA and hgcA. The effects of salinity and algae biomass on mercury cycling genes depended on the gene type and dose. A higher input of algae biomass (250 mg L) led to an increase of merA abundance, but a decrease of hgcA abundance. All high inputs of mercury, salinity, and algae biomass decreased the richness and diversity of bacterial communities in sediment. Further analysis indicated that higher mercury (300 ng g) led to an increased relative abundance of mercury methylators, such as Ruminococcaceae, Bacteroidaceae, and Veillonellaceae. Under saline conditions (10 and 30 g L), the richness of specific bacteria associated with mercury reduction (Halomonadaceae) and methylation (Syntrophomonadaceae) increased compared to the control. The input of algae biomass led to an increase in the specific bacterial communities associated with the mercury cycle and the richness of bacteria involved in the decomposition of organic matter. These results provide insight into mercury cycle-related genes and bacterial communities in the sediments of lakes in arid regions.
干旱地区的湖泊正在通过空气沉积和地表径流遭受汞污染，对生态系统安全和人类健康构成威胁。此外，盐度和有机物输入会影响沉积物中汞循环和细菌群落的组成。在这项研究中，研究了盐度和藻类生物量（一种重要的有机物）对汞污染下汞循环相关基因（merA 和 hgcA）的影响。湖泊微宇宙沉积物中未检测到古菌 merA 和 hgcA，表明细菌而非古菌在汞还原和甲基化过程中发挥了关键作用。高含量的汞（300ng/g）会降低 merA 和 hgcA 的丰度。盐度和藻类生物量对汞循环基因的影响取决于基因类型和剂量。藻类生物量（250mg/L）的高输入会导致 merA 丰度增加，但 hgcA 丰度降低。所有高输入的汞、盐度和藻类生物量都会降低沉积物中细菌群落的丰富度和多样性。进一步分析表明，较高的汞（300ng/g）会导致更多的汞甲基化剂相对丰度增加，如 Ruminococcaceae、Bacteroidaceae 和 Veillonellaceae。在盐度条件下（10 和 30g/L），与汞还原（Halomonadaceae）和甲基化（Syntrophomonadaceae）相关的特定细菌的丰富度与对照相比有所增加。藻类生物量的输入导致与汞循环相关的特定细菌群落和参与有机物分解的细菌的丰富度增加。这些结果为干旱地区湖泊沉积物中的汞循环相关基因和细菌群落提供了新的见解。
