Methane emissions and methanogenic community investigation from constructed wetlands in Chengdu City

• DOI: 10.1016/j.uclim.2021.100956
• Publication Date: 2021-08-27T12:36:55Z
• Authors: Ke Zhang; Jingting Wang; Xiaoling Liu; Xiaoying Fu; Hongbing Luo; Mei Li; Bing Jiang; Jia Chen; Wei Chen; Bo Huang; Liangqian Fan; Lin Cheng; Xiaochan An; Fenghui Chen; Xiaohong Zhang
• Keywords: Microcosm; Diversity index

Abstract This paper aims to investigate the methane emissions from typical urban and rural constructed wetlands (CWs) associated with methanogen diversity using Illumina sequencing in microcosms from five different CWs planted with Cyperus alternifolius L. The results show that the average CH4 flux in summer in these five CWs was 0.33 gCH4 m−2 day−1, with a range of 0.01–1.52 g CH4 m−2 day−1 ((GWP: global warming potential) = 0.28–42.72 kg CO2eq m−2 year−1). Redundancy analysis (RDA) shows that methane fluxes were mostly impacted by local temperature (Ymethane = 4.66 Xtemp - 102.63, R2 = 0.81), which is considered to be a key environmental factor. The dissolved oxygen of all CWs showed a significantly negative correlation with CH4 emissions (R2 = −0.99, p = 0.01). Both the species richness index and species diversity index showed that Methanobacteria was the predominant class, with percentages ranging from 16.47% to 26.66% in the five CWs. The percentage of Methanomicrobia was 15.42–24.98% in the five CWs, and Methanococci was only found in the FengHuang constructed wetland. Other findings suggest that Methanomicrobiales in the Anlong Village constructed wetland was a dominant order and similar to a local paddy ecosystem in the Chengdu Plain.