Contribution of Atmospheric Wet Deposition to Nutrients in the Yangtze Estuary
大气湿沉降对长江口水域营养盐的贡献

The 31 wet deposition samples were collected at Chongming Island from June 2004 to May 2005 in the Yangtze Estuary, and dissolved species of nutrients (NH+4,NO-3,NO-2,PO3-4 and SiO2-3) in the rainwater were analyzed by Spectrophotometry. The results showed that there were significant differences among monthly average concentration of nutrient elements, and the nitrogen content in the rainwater was rather high. The wet deposition flux was 52.02 mmol/(m2·a) for the total inorganic nitrogen (TIN), 0.17 mmol/(m2·a)for phosphate and 0.10 mmol/(m2·a)for silicate. The wet deposition fluxes for TIN were larger than that for PO3-4 and SiO2-3. NH+4 was the dominant form of TIN, occupying 70.9% of TIN. The proportion of nutrients in the wet deposition and seawater had obvious differences. The rainwater can change the nutrients structure, salinity, pH, phytoplankton production and biologic community in the surface seawater, and this phenomenon may lead to the red tide directly.