Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China; Institute of International Rivers and Eco-security, Yunnan University, Kunming, 650091, China.
Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China.
Environ Pollut. 2021 Feb 15;271:116328. doi: 10.1016/j.envpol.2020.116328. Epub 2020 Dec 16.
Biochar substrates and tidal flow (TF) and intermittent aeration (IA) operation modes have recently been applied to improve the treatment performance of constructed wetlands (CWs), but their roles in regulating greenhouse gas (GHG) emissions from CWs are still unclear. In this preliminary study, CO, CH and NO fluxes and associated microbial characteristics in four groups of subsurface-flow CWs, i.e., ceramsite CWs (C-CWs), biochar-amended CWs (B-CWs), intermittently aerated B-CWs (AB-CWs) and tide-flow B-CWs (TB-CWs), were comparatively investigated. The results showed that biochar amendment significantly mitigated CH and NO fluxes from the CWs by supporting higher abundances of mcrA and nosZ genes and higher ratios of pmoA/mcrA and nosZ/(nirK + nirS), thus reducing global warming potential (GWP, a decrease of 55.8%), in addition to promoting total nitrogen (TN) removal by 41.3%, mainly by increasing the abundances and activities of nitrifiers and denitrifiers. The TF mode efficiently improved nitrogen removal, but it greatly increased GHG fluxes since large amounts of GHGs escaped from the empty CW matrix after water draining. IA abated GHG emissions from the CWs, mainly after aeration. TF and IA decreased the abundances of functional bacteria and archaea related to C and N transformation, except nitrifiers, and shaped the microbial community structures. The application of a biochar substrate and IA mode can facilitate the design and operation of CWs in a more ecologically sustainable way.
生物炭基质和潮汐流（TF）和间歇曝气（IA）运行模式最近被应用于提高人工湿地（CWs）的处理性能，但它们在调节 CWs 温室气体（GHG）排放方面的作用仍不清楚。在这项初步研究中，比较了四种地下流 CWs，即陶瓷 CWs（C-CWs）、生物炭改良 CWs（B-CWs）、间歇曝气 B-CWs（AB-CWs）和潮汐流 B-CWs（TB-CWs）中 CO、CH 和 NO 通量及相关微生物特性。结果表明，生物炭的添加通过支持更高丰度的 mcrA 和 nosZ 基因以及更高的 pmoA/mcrA 和 nosZ/（nirK+nirS）比值，显著减轻了 CWs 中 CH 和 NO 的通量，从而降低了全球变暖潜势（GWP，降低了 55.8%），此外还通过增加硝化菌和反硝化菌的丰度和活性，促进了总氮（TN）的去除率提高了 41.3%。TF 模式有效地提高了氮的去除率，但由于大量 GHG 在排水后从空的 CW 基质中逸出，它大大增加了 GHG 的通量。IA 减少了 CWs 中的 GHG 排放，主要是在曝气之后。TF 和 IA 降低了与 C 和 N 转化相关的功能细菌和古菌的丰度，除了硝化菌外，还改变了微生物群落结构。生物炭基质和 IA 模式的应用可以促进 CWs 的设计和运行更加生态可持续。
