Division of Environmental Science, The State University of New York College of Environmental Science and Forestry, Syracuse, USA.
Environ Sci Process Impacts. 2019 Apr 17;21(4):677-691. doi: 10.1039/c8em00546j.
Quantifying changes in riparian biogeochemistry following rainfall events is critical for watershed management. Following storms, changes in riparian hydrology can lead to high rates of nutrient processing and export and greenhouse gas (GHG) release. We assessed shifts in hydrology and biogeochemistry 24 and 72 hours post-rainfall following storms of three different magnitudes in an agricultural riparian zone influenced by stream restoration in the Piedmont region of North Carolina, USA. Post-storm changes in water table height, soil moisture, groundwater flow, and lateral hydraulic gradient were related to biogeochemical processing. Though near-field nitrate (NO3-) concentrations were elevated (median: 13 mg nitrogen (N) L-1 across storms), substantial riparian NO3- removal occurred (89-96%). High N removal throughout the study occurred concurrently with release of dissolved solutes (e.g., soluble reactive phosphorus [SRP]) and fluxes of gases (carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]), based on storm timing, magnitude, and intensity. A high intensity, short duration storm of low magnitude lead to release of CO2 across the riparian zone and low SRP removal. A storm of intermediate duration/magnitude towards the beginning of the summer lead to mobilization of near-field NO3- and release of N2O in the upper riparian zone and SRP in the lower riparian zone. Finally, a larger storm of longer duration lead to pronounced near-stream release of CH4. Therefore, it is important to expand research of biogeochemical response to different types of storm events in restored riparian zones to better balance water quality goals with potential greenhouse gas emissions.
量化降雨事件后河岸带生物地球化学的变化对于流域管理至关重要。在风暴之后，河岸带水文学的变化可能导致养分处理和输出以及温室气体（GHG）释放的高速率。我们在美国北卡罗来纳州皮埃蒙特地区评估了受溪流恢复影响的农业河岸带在三次不同规模的风暴后 24 和 72 小时的水文学和生物地球化学变化。地下水水位、土壤湿度、地下水流动和侧向水力梯度的变化与生物地球化学过程有关。尽管近场硝酸盐（NO3-）浓度升高（三次风暴的中位数为 13 毫克氮（N）升-1），但大量的河岸带 NO3-被去除（89-96%）。在整个研究过程中，大量的 N 去除与溶解溶质（例如可溶解性反应磷 [SRP]）和气体（二氧化碳 [CO2]、氧化亚氮 [N2O]和甲烷 [CH4]）的通量同时发生，这取决于风暴的时间、规模和强度。一场低规模高强度、短持续时间的风暴导致整个河岸带释放 CO2 和低 SRP 去除。一场中等持续时间/规模的风暴发生在夏季初，导致近场 NO3-的迁移和上河岸带 N2O 的释放以及下河岸带 SRP 的释放。最后，一场持续时间较长的大风暴导致了近河流 CH4 的显著释放。因此，扩大对恢复河岸带中不同类型风暴事件的生物地球化学响应的研究对于更好地平衡水质目标与潜在温室气体排放非常重要。
