Zhou Xingzi, Johnston Sarah Ellen, Bogard Matthew J
Department of Biological Sciences, University of Lethbridge, Lethbridge, AB Canada.
Present Address: Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK USA.
Biogeochemistry. 2023;162(2):237-255. doi: 10.1007/s10533-022-01002-x. Epub 2022 Dec 11.
Wetlands have been used to treat anthropogenic effluents for decades due to their intense biogeochemical processes that transform and uptake nutrients, organic matter, and toxins. Despite these known functions, we lack generalizable knowledge of effluent-derived dissolved organic matter (DOM) cycling in wetlands. Here, we quantify the cycling of DOM in one of Canada's more economically important wetland complexes (Frank Lake, Alberta), restored to hydrologic permanence in the 1980s using urban and agro-industrial effluents. Optical analyses and PARAFAC (parallel factor analysis) modelling showed a clear compositional change from more bioavailable and protein-like DOM at effluent input sites to more aromatic and humic-like at the wetland outflow, likely due to DOM processing and inputs from marsh plants and wetland soils. Microbial incubations showed that effluent DOM was rapidly consumed, with the half-life of DOM increasing from as low as 35 days for effluent, to 462 days at the outflow, as a function of compositional shifts toward aromatic, humic-like material. Long-term averaged dissolved organic carbon (DOC) export was low compared to many wetlands (10.3 ± 2.0 g C m yr). Consistent with predictions based on water residence time, our mass balance showed Frank Lake was a net source of DOM across all measured years, but shifted from a source to sink among wet and drought years that respectively shortened or lengthened the water residence and DOM processing times. Overall, Frank Lake processes and transforms effluent DOM, despite being a longer-term net source of DOM to downstream environments.
The online version contains supplementary material available at 10.1007/s10533-022-01002-x.
几十年来，湿地一直被用于处理人为废水，因为其强烈的生物地球化学过程能够转化和吸收营养物质、有机物质及毒素。尽管有这些已知功能，但我们对湿地中源自废水的溶解有机物质（DOM）循环缺乏可推广的认识。在此，我们对加拿大一个经济上较为重要的湿地复合体（艾伯塔省的弗兰克湖）中的DOM循环进行了量化，该湿地在20世纪80年代利用城市和农业工业废水恢复了水文永久性。光学分析和PARAFAC（平行因子分析）建模表明，从废水输入点处生物可利用性更强、类似蛋白质的DOM，到湿地流出点处更具芳香性和类似腐殖质的DOM，其组成发生了明显变化，这可能是由于DOM的处理以及沼泽植物和湿地土壤的输入所致。微生物培养表明，废水DOM被迅速消耗，随着组成向芳香性、类似腐殖质物质的转变，DOM的半衰期从废水的低至35天增加到流出点处的462天。与许多湿地相比，长期平均溶解有机碳（DOC）输出较低（10.3±2.0 g C m⁻² yr⁻¹）。与基于水停留时间的预测一致，我们的质量平衡表明，在所有测量年份中，弗兰克湖都是DOM的净源，但在湿润年和干旱年之间发生了从源到汇的转变，湿润年和干旱年分别缩短或延长了水停留时间和DOM处理时间。总体而言，尽管弗兰克湖是下游环境中DOM的长期净源，但它仍对废水DOM进行处理和转化。
在线版本包含可在10.1007/s10533-022-01002-x获取的补充材料。
