State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210003, China.
Department of Ecological Sciences and Engineering, College of Environment and Ecology, Chongqing University, Chongqing, 400045, China; Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, Fukuka, 819-0395, Japan.
J Environ Manage. 2023 Mar 1;329:117091. doi: 10.1016/j.jenvman.2022.117091. Epub 2022 Dec 28.
The application of reservoirs in the upper reaches of rivers will change the hydrological rhythm of river-connected wetlands in the lower reaches, causing changes in the distribution of wetland vegetation. The differences of carbon and nitrogen sequestration and emission potential in different vegetations may lead to the dynamics of greenhouse gas emissions from wetlands during hydrological periods. For a wetland connected to the Yangzi River, China, the dynamic changes of vegetation and water areas were identified by remote sensing, and the water level, the emission fluxes of greenhouse gases and the functional bacteria of carbon and nitrogen in soil were measured in-situ. Compared with drought period, the area of phragmites zone in flooding period increased by 28.2%, while the areas of carex and phalaris zones decreased by 42.9%. The carbon and nitrogen accumulation in the soil of phragmites zone is the highest, while the cumulative amount of phalaris is the lowest. The emission fluxes of CH and NO in mud/water and various vegetations were positively correlated with water level and reached the maximum during flooding period. Although the global warming potential of mud/water was highest than that of vegetations, carex zone had the highest warming potential among vegetation zones. CH contributes 8-37 times as much as NO to global warming potential in the wetland. The increase of flooding time promoted the emissions of CH and NO in the wetland. The anaerobic condition caused by flooding stimulated the activities of denitrifying and methanogenic bacteria, thus increasing the emission of greenhouse gases. The sequestrations and emissions of carbon and nitrogen regulated by a reservoir in the upstream suggest that the operation of water conservancies should be considered to alleviate the greenhouse gas emission from river-connected wetland.
河流上游水库的应用会改变下游河网湿地的水文节律，导致湿地植被分布发生变化。不同植被的碳氮固存和排放潜力的差异可能导致湿地在水文期内温室气体排放的动态变化。对于中国长江流域的一个湿地，通过遥感识别了植被和水域的动态变化，并在现场测量了水位、温室气体排放通量和土壤中碳氮功能细菌。与干旱期相比，洪泛期芦苇带面积增加了 28.2%，而苔草带和灯心草带面积减少了 42.9%。芦苇带土壤的碳氮积累量最高，而灯心草的累积量最低。泥/水和各种植被中 CH 和 NO 的排放通量与水位呈正相关，在洪泛期达到最大值。尽管泥/水的全球变暖潜势高于植被，但苔草带在植被带中具有最高的变暖潜势。CH 对湿地全球变暖潜势的贡献是 NO 的 8-37 倍。洪水时间的增加促进了湿地中 CH 和 NO 的排放。洪水引起的厌氧条件刺激了反硝化菌和产甲烷菌的活性，从而增加了温室气体的排放。上游水库对碳氮的固存和排放的调节表明，水利工程的运行应考虑减轻河网湿地的温室气体排放。
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