State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
J Environ Manage. 2018 Jan 15;206:602-606. doi: 10.1016/j.jenvman.2017.11.012. Epub 2017 Nov 10.
Humic substances (HS) are redox-active and can function as organic terminal electron acceptors in anaerobic microbial respiration, which plays a relevant role on suppressing the emissions of methane (CH) in anoxic systems. However, it is unclear whether or not there is an inherent link between suppression of CH emissions by HS and warming temperature. In this study, we assess the effects of HS additions on CH production in paddy and wetland soils and their responses to increasing temperature by incubation experiments. We show that the intensity of HS to suppress CH production under anoxic condition is positively associated with the temperature, which may be due to the fact that the activities of enzymes involved in methanogenesis have lower temperature sensitivity than those involved in microbial HS reduction, and that the methanogenesis process is less susceptible to increasing temperature compared to the microbial HS reduction process. The hypothetical increase in the effectiveness of pH alteration and HS toxicity caused by warming may be also responsible for the increased inhibition of CH production by HS addition in response to increasing temperature. Our findings highlight the increasingly important role of HS in suppressing CH production in anoxic ecosystems in a future warmer world.
腐殖质（HS）是氧化还原活性的，并且可以作为厌氧微生物呼吸中的有机末端电子受体，在缺氧系统中抑制甲烷（CH）排放方面发挥着相关作用。然而，HS 对 CH 排放的抑制作用与升温之间是否存在内在联系尚不清楚。在这项研究中，我们通过培养实验评估了 HS 对稻田和湿地土壤中 CH 生成的影响及其对温度升高的响应。我们表明，在缺氧条件下 HS 抑制 CH 生成的强度与温度呈正相关，这可能是由于参与产甲烷的酶的活性比参与微生物 HS 还原的酶的活性对温度的敏感性更低，并且与微生物 HS 还原过程相比，产甲烷过程对升温的敏感性较低。由于升温导致 pH 值变化和 HS 毒性增加的假设增加，可能也是由于 HS 对 CH 生成的抑制作用随着温度升高而增加的原因。我们的研究结果强调了在未来更温暖的世界中，HS 在抑制缺氧生态系统中 CH 生成方面的作用越来越重要。
