Atmospheric Wet Deposition of Organic Carbon and Dissolved Nitrogen in City, Countryside and Nature Reserve of Subtropical China

The atmospheric wet deposition was higher in subtropical China because of rapid economic growth in past decades and high humidity weather. One-year measurement of wet deposition of organic carbon (C) and dissolved nitrogen (N) was carried out at three sites (Changsha city, Huitong agriculture county, and Dashanchong nature reserve) in Hunan Province. Taking the nature reserve as the control, we make a comparative analysis of the characteristics in atmospheric wet deposition between city and countryside. The concentrations and wet depositions of total and each component of C and N were the lowest in the nature reserve, indicating that human activities significantly increase the atmospheric wet deposition. The concentrations and the wet deposition fluxes of particulate organic C,NO3--N, and dissolved organic N (DON) were the highest in the city, whereas the corresponding values of dissolved organic C (DOC) andNH4+-N were the highest in the countryside. Except for DON, the concentrations of DOC,NH4+-N, andNO3--N changed significantly with rainfall characteristics (rainfall amount, intensity, and weather conditions). Our study supplements the wet deposition data as a baseline for exploring future changes in subtropical China. Meanwhile, the lowest wet depositions in nature reserve imply that the reduction of anthropogenic emission is essential to minimizing the adverse effects of the increased atmospheric deposition.