The composition, spatial patterns, and influencing factors of atmospheric wet nitrogen deposition in Chinese terrestrial ecosystems

Abstract

Atmospheric nitrogen (N) deposition is an important component of the global N cycle, and is a key source of biologically available N. Understanding the spatio-temporal patterns and influencing factors of N deposition is essential to evaluate its ecological effects on terrestrial ecosystems, and to provide a scientific basis for global change research. In this study, we monitored the monthly atmospheric N deposition in rainfall at 41 stations from the Chinese Ecosystem Research Network through measuring total N (TN), total dissolved N (TDN), ammonium (NH4+–N), and nitrate (NO3−–N). The results showed that the atmospheric wet deposition of TDN, NH4+–N, and NO3−–N were 13.69, 7.25, and 5.93kgNha−1yr−1, respectively. The deposition of TN and total particulate N (TPN) was 18.02 and 4.33kgNha−1yr−1 respectively, in 2013. TPN accounted for 24% of TN, while NH4+–N and NO3−–N made up 40% and 33%, respectively, confirming the assumption that atmospheric wet N deposition would be underestimated without particulate N in rainfall. The N deposition was higher in Central and Southern China, and lower in North-west, North-east, Inner Mongolia, and Qinghai–Tibet regions. Precipitation, N fertilizer use, and energy consumption were significantly correlated with wet N deposition (all p<0.01). Models that included precipitation and N fertilizer can explain 80–91% of the variability in wet N deposition. Our findings reveal, for the first time, the composition of the wet N deposition in China at different scales and highlight the importance of TPN.