[Characteristics of Nitrogen Transport and Its Source Trace in Loess Plateau's Dam Watershed in Alternating Wet and Dry Seasons:A Case Study of Yangjuangou Watershed].

In this study,we wanted to explore the impacts of N wet deposition on N export and trace the N source by isotopic method through monitoring N wet deposition in Loess Plateau's Dam Watershed in alternating wet and dry seasons,through measuring N wet deposition,rainfall-runoff and base flow process and analyzing concentration change of different forms of N.The results showed that there were 11 rainfall events in the 2015 wet season,in which N wet deposition load reached 814.18 kg and N deposition flux was about 4.26 kg·hm,while there were three rainfall events in the 2015 dry season,in which N wet deposition load reached 155.58 kg and N deposition flux was 0.83 kg·hm,so it presented a great seasonal variability.By collecting the dynamic process of four rainfall events,we found that,different rainfall intensity had different influence on N export process.The contribution of N wet deposition of four rainfall events to N export in watershed was 16.94 kg.The ratio that N output load of rainfall and river in watershed N output load was 14.45%-64.84%,which showed that the contribution of rainfall to watershed N transport was big.The variation range of δ N in Loess Plateau's Dam Watershed was big,which was -0.844‰-12.791‰,and the δ O was within the range of 8.166 ‰-15.115 ‰ in the dam watershed.