Characteristics, sources and environmental implications of atmospheric wet nitrogen and sulfur deposition in Yangtze River Delta

Nitrogen (N) and sulfur (S) deposition rates have changed rapidly in China during recent years. But few studies have simultaneously measured wet N and S deposition rates on different land use types in the same region. In present study, 238 precipitation samples were collected between May 2016 and April 2017 using wet-only autosamplers, and the wet N and S deposition rates were measured at three sites with different land use types (urban, agriculture, and lake) in the Yangtze River Delta (YRD), Eastern China. The annual wet deposition rates of total N (TN), ammonium (NH4+), nitrate (NO3-), dissolved organic N (DON), water-insoluble particulate N (WIPN), and sulfate (SO42-) were 16.87-26.64, 6.38-10.81, 5.92-11.11, 1.43-1.96, 2.23-2.67, and 9.07-22.53 kg N (S) ha(-1) yr(-1), respectively. The wet N and S deposition rates were in the order: agriculture > urban > lake sites, and the seasonal variations in wet N and S deposition were similar at all sites. DON and WIPN contributed 6.4-11.8% and 10.7-16.2% of the total wet N deposition, respectively. Chemical N fertilization and fossil fuel were important sources of wet N and S deposition. Annual wet N and S deposition are important nutrient sources that stimulate the eutrophication and soil/water acidification in the YRD. To minimize the environmental cost of wet N and S deposition in the YRD, it is critical to investigate the sources of N and S.