Zhang Yan, Lin Yule, Yang Ping, Yang Hong, Chen Guanpeng, Liu Wenjing, Tong Chuan, Lin Yongxin, Sun Dongyao, Lin Wenbo, Tang Kam W
School of Geographical Sciences, Fujian Normal University, Fuzhou, 350117, China; Fujian Provincial Key Laboratory for Subtropical Resources and Environment, Fujian Normal University, Fuzhou, 350117, China; Fujian Minjiang Estuary Wetland Ecosystem National Observation and Research Station, National Forestry and Grassland Administration, Fuzhou, 350215, China.
Fujian Provincial Key Laboratory for Subtropical Resources and Environment, Fujian Normal University, Fuzhou, 350117, China.
Environ Res. 2025 Aug 15;279(Pt 1):121746. doi: 10.1016/j.envres.2025.121746. Epub 2025 Apr 29.
Man-made habitats such as sewage outfalls, farmlands and aquaculture ponds are known as hotspots for greenhouse gas production and emissions, but their climate influence extends out to neighboring areas through a network of drainage ditches, which are often overlooked in greenhouse gas assessments. This study analyzed the concentrations and diffusive fluxes of CO and CH in urban sewage ditches, agricultural ditches, and aquaculture ditches within a subtropical estuary in southeastern China. Urban ditches had higher combined concentration (μmol L) of CO (30.7) and CH (8.8) than agricultural and aquaculture ditches, likely because of their high dissolved organic carbon levels and mcrA gene abundances. The estimated diffusive flux was 0.2-0.5 mmol m h for CO and 30.1-258 μmol m h for CH among all three ditch types. Emissions tended to be highest in summer and lowest in winter. On average, dissolved CO and CH concentrations in ditch waters were equivalent to 18.9 % and 11 % of the respective dissolved gas concentrations in the sources they drained from (i.e. farmlands, sewage outfalls and aquaculture ponds), suggesting strong outgassing as the water entered the ditches. Overall, drainage ditches are stronger emission sources than natural rivers and streams.
诸如污水排放口、农田和水产养殖池塘等人工栖息地被认为是温室气体产生和排放的热点地区，但其对气候的影响通过排水沟网络延伸至邻近区域，而排水沟在温室气体评估中往往被忽视。本研究分析了中国东南部亚热带河口地区城市排水沟、农业排水沟和水产养殖排水沟中CO和CH的浓度及扩散通量。城市排水沟中CO（30.7）和CH（8.8）的总浓度（μmol/L）高于农业排水沟和水产养殖排水沟，这可能是由于其溶解有机碳含量高以及mcrA基因丰度高。在所有三种排水沟类型中，CO的估计扩散通量为0.2 - 0.5 mmol·m⁻²·h⁻¹，CH为30.1 - 258 μmol·m⁻²·h⁻¹。排放量往往在夏季最高，冬季最低。平均而言，排水沟水中溶解的CO和CH浓度分别相当于它们所排放源（即农田、污水排放口和水产养殖池塘）中各自溶解气体浓度的18.9%和11%，这表明水进入排水沟时会发生强烈的脱气现象。总体而言，排水沟是比天然河流和溪流更强的排放源。
