LAUSR

Abstract Atmospheric N deposition patterns play an important role in the nitrogen cycles of arid ecosystems. This study observed a significant spatiotemporal variation in inorganic N concentrations in precipitation from 2013 to 2016 at eight sampling sites in the Hexi Corridor, northwestern China. Mean mNO3–/Cl– and mNH4+/NO3– values were 1.62 and 0.98 from late autumn to early spring, respectively, indicating that inorganic N in precipitation is most likely principally controlled by NO3– in response to coal-fired heating and low wind speeds. However, mean mNO3–/Cl– and mNH4+/NO3– were 0.91 and 2.69 from late spring to early autumn, respectively, suggesting that the primary contributor is NH3 from agricultural soils and fertilizers. Mean annual mNH4+/NO3– values in the eastern sectors of the Hexi Corridor ranged from 0.57 to 1.55, but those in the central and western sectors ranged from 1.53 to 3.59. The ratios of NH4+-N deposition flux to total wet deposition of inorganic N flux were > 50% in the Corridor’s central and western sectors, but