State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
Sci Total Environ. 2020 Jun 15;721:137760. doi: 10.1016/j.scitotenv.2020.137760. Epub 2020 Mar 5.
Methanotrophs play a crucial role in mitigating methane (CH) emission by oxidizing produced CH in paddy soils; however, ecological drivers of methanotrophic community in the soils around heavy metal contaminated areas remain unclear. In this study, we evaluated the effects of heavy metal pollution and soil properties on the abundance, diversity and composition of methanotrophic community in paddy soils from two typical mercury (Hg) mining regions in southwest China. The results of random forest and structure equation models suggest that both heavy metal content and soil nutrients greatly influenced the attributes of methanotrophic community. In general, the abundance and diversity of methanotrophs were negatively related to soil Hg content, but showed positive correlation with soil organic carbon content. However, the other metals (cadmium (Cd), nickel (Ni), lead (Pb), arsenic (As), zinc (Zn)) had inconsistent associations with the microbial indexes of methanotrophic community in the soil. Elevated levels of heavy metal and nutrients in the soils shifted the community composition of methanotrophs. For example, Pb, As and Zn contents had negative associations with the relative abundance of Methylocaldum. In addition, changes in the relative abundance of ecological clusters within the co-occurrence network of methanotrophs were related to metal contents and soil properties. Together, our findings provide novel insights into understanding ecological drivers of methanotrophic community in paddy soils around Hg mining regions, with important implications for mitigating CH emissions in terrestrial ecosystems.
甲烷营养菌在氧化稻田土壤中产生的甲烷以减轻甲烷（CH）排放方面发挥着关键作用；然而，重金属污染地区周围土壤中甲烷营养菌群落的生态驱动因素仍不清楚。在这项研究中，我们评估了重金属污染和土壤特性对来自中国西南两个典型汞（Hg）矿区稻田土壤中甲烷营养菌群落丰度、多样性和组成的影响。随机森林和结构方程模型的结果表明，重金属含量和土壤养分都极大地影响了甲烷营养菌群落的属性。一般来说，甲烷营养菌的丰度和多样性与土壤汞含量呈负相关，但与土壤有机碳含量呈正相关。然而，其他金属（镉（Cd）、镍（Ni）、铅（Pb）、砷（As）、锌（Zn））与土壤中甲烷营养菌微生物指标的相关性不一致。土壤中重金属和养分水平的升高改变了甲烷营养菌的群落组成。例如，Pb、As 和 Zn 含量与 Methylocaldum 的相对丰度呈负相关。此外，甲烷营养菌共生网络中生态类群相对丰度的变化与金属含量和土壤特性有关。总之，我们的研究结果为理解汞矿区周围稻田土壤中甲烷营养菌群落的生态驱动因素提供了新的见解，对减轻陆地生态系统中 CH 排放具有重要意义。
