Effects Of Atmospheric Nitrogen Deposition On Beili Lake In Hangzhou

To study the pollution situation of urban landscape lake, this article studied the affects of atmospheric nitrogen deposition to the Beili Lake of West Lake in Hangzhou. The main contents of this article are to study the factors of atmospheric nitrogen deposition and the regular pattern of the changes of nitrogen deposition every month, and to analysis the nitrogen deposition contribution to the Beili Lake.The study showed that the NO_x density differed a lot in different position aroud the Beili Lake, it was caused by local pollution of automobile. Wind direction also influenced the NO_x density, the wind from urban area could raise NO_x density. The NO_x washout of rainfall related to the quantity and durance of rainfall. The farmfeild aroud Hangzhou city influenced the NH₄⁺-N density around the Beili Lake from all directions. The Beili Lake is in the south of Hangzhou city, so the influence of southern wind to the NH₄⁺-N density aroud the Beili Lake was much greater. The TSP density in the wind from urban area was higher than that of the wind from hill area.The rainfall was sufficient in 2010 except April, May and November. In wet deposition, 95.5% of TN was TDN. And TN density had a negative correlation with the quantity of rainfall, while TN deposition flux had a correlation with the quantity of rainfall. In wet deposition the density and flux of NH₄⁺-N were higher than those of NO₃^--N. In dry deposition, 82% of TN was TDN. The main factors of TN deposition flux in dry deposition were wind direction as well as the types and density of N in different directions of wind. In total deposition, 90.1% of TN was TDN. Wet deposition was the main deposition mode. The main factor of total deposition was rainfall. NH₄⁺-N was the main component of TN.NH₄⁺-N of deposition had a great contribution to Beili Lake, at about more than 50% of that of lake. In summer, NO₃^--N of deposition accounted for more than 10% in NO₃^--N of lake. The change pattern of TN of deposition opposed to that of TN of lake. Atmospheric deposition contributed 10% of TN to the lake. In a word, in summer, atmospheric deposition was an important source of TN in Beili Lake.