基于MixSIAR模型与通量核算法解析白坭河流域地表水氮素来源OA

This study investigates the Baini River Basin using the MixSIAR model to quantify nitrate contributions from wastewater effluent(M&S),sewer leakage(SL),agriculture(AG),soil nitrogen(SN),and urban runoff(UR),with flux calculation used to verify model reliability.Results show that wastewater effluent is the dominant source(67.5%),followed by soil nitrogen(13.7%),agriculture(12.6%),sewer leakage(4.7%),and urban runoff(1.1%).Source contributions show spatiotemporal variations.In the wet season,wastewater effluent accounts for 54.0%,while agriculture and soil nitrogen contribute 18.3%and 19.5%,respectively.In the normal season,wastewater effluent rises to 61.8%,while agriculture and soil nitrogen decline.Spatially,the main channel and downstream tributaries are dominated by wastewater effluent(55.4%and 57.1%),whereas agricultural input rises at the watershed boundary(25.7%).Isotopic and dissolved oxygen data indicate limited denitrification in the basin,and wastewater effluent and untreated sewage leakage are the main sources of riverine nitrogen.Therefore,sewer network maintenance,stormwater-sewage separation,and sewage overflow control should be strengthened.