Characterization of spatial and temporal distribution of nitrogen and source analysis of nitrate in a typical water diversion receiving basin:A case study on upper reaches of Fenhe Reservoir
This study investigated the temporal and spatial distribution characteristics of nitrogen in the upstream basin of the Fenhe River Reservoir in the receiving area of the Wanjiazhai Yellow River Diversion Project.It identified the sources of nitrate and analyzed the impact of Yellow River water diversion on the local basin.Results indicated that the mean concentration of total nitrogen(TN)in each county of the basin was 3.67mg/L throughout the four seasons,with nitrate-nitrogen(NO3--N)accounting for over 70%of TN on average.Spatially,Ningwu County had the highest mean TN concentration,which gradually decreased downstream.Temporally,TN concentrations were higher in autumn and winter and lower in summer,with nitrogen carried by Yellow River water during the diversion period being the primary nitrogen source in the basin.Qualitative analysis revealed that the mixing process of various pollution sources was the main factor affecting nitrogen migration.Quantitative calculations using the MixSIAR model showed that the average contribution rates of various sources to NO3--N were as follows,from highest to lowest:wastewater discharge and point sources(39.3%)>livestock manure(18.7%)>chemical fertilizers(18.2%)>soil organic nitrogen(17.7%)>atmospheric nitrogen deposition(6.1%).In Yellow River water,the contribution rates of wastewater discharge and point sources in autumn and chemical fertilizers in spring to nitrate were significantly higher than those in local tributaries,indicating a greater impact of Yellow River water diversion on the nitrate sources in downstream sections of the main stream.
nitrateupper reaches of Fenhe Reservoirnitrogen and oxygen isotopesyellow water diversionMixSIAR modelsource identification
NETL
NSTL
万方数据
