Environmental impact of atmospheric inorganic nitrogen wet deposition in the interaction influence area of atmospheric circulation.

The continuous increase in atmospheric wet nitrogen deposition resulting from human activities has had a profound impact on the biodiversity and ecological balance of the Tibetan Plateau. The Three Rivers Headwater Region, situated in the central part of the plateau, influences atmospheric circulation and is an important source of water in China. However, owing to the limited availability of comprehensive monitoring data, the understafnding of nitrogen deposition and its sources in the study area remains limited, hindering our understanding of its temporal and spatial patterns and influencing factors. To address this research gap, this study analyzed 939 precipitation samples from the Three Rivers Headwaters Region. The findings revealed that during the study period, the volume-weighted mean concentrations of NO, NO, and NH were 0.13, 1.26, and 2.53 mg/L, respectively. Nitrogen deposition flux in this region was approximately 15.48 kg·hm·a, surpassing national averages. NH was the primary form of nitrogen deposition within the study area, accounting for 60.91 %. Moreover, there were notable geographical variations in nitrogen deposition, which initially increased but then decreased with increasing altitude and was highest in grassland, at 0.51 kg·hm·a. Local human activities constituted the main source of nitrogen deposition within this region; however, anthropogenic emissions from Central, West, and South Asia were transported to the Three Rivers Headwaters Region through westerly winds and monsoons. In recent years, ongoing animal husbandry development and urban expansion within the study region have contributed to a continuous increase in wet nitrogen deposition and economic growth across Asia has significantly affected atmospheric nitrogen deposition within this area. Consequently, it is essential to propose strict nitrogen emission management requirements and scientific economic development strategies.