Study On The Atmospheric Deposition Of Nitrogen In The City Of Dalian

In this study, atmospheric dry deposition samples were collected by a Denuder Long-Term Atmospheric (DELTA) sampling system and were used for monthly reactive nitrogen concentrations analysis, the wet atmospheric deposition samples were collected continuously in rainy days which were measured by rain gauge in the year of2011and2012in agricultural zone at Lushunkou District and in the city of Dalian which is along the boundaries of Yellow and Bohai Sea. After using continuous flow analytical system to measure the active ammonium and nitrate nitrogen concentrations in gaseous, particulate and rain, respectively, the concentrations of each month were transformed into fluxes. Based on the datum of concentrations and fluxes, the monthly and seasonal change trend of active nitrogen was quantified. The conclusion is listed bellow:1. The features of atmospheric nitrogen deposition in the years of2011(1) The content of total inorganic reactive nitrogen by atmospheric deposition was26.25kg·hm-2, which is equal to55.85kg·hm-2·a-1usage of CO(NH)2and154.41kg·hm-2·a-1usage of NH4HCO3, and dry and wet atmospheric deposition were8.64and17.61kg·hm-2, respectively. According to the settlement way to analyze,the priority deposition was by wet deposition, rating at67.09%; according to the settlement of composition, the nitrate nitrogen proportion was higher, rating at52.61%.(2) The total flux and annual concentration of inorganic active nitrogen by wet atmospheric deposition was17.61kg·hm-2and10.97mg·L-1, respectively. The amounts of active nitrogen depositing in summer accounted for half of nitrogen depositing among the whole year. According to the component analysis, wet subsidence nitrate nitrogen for a high proportion. The fluxes of wet deposition nitrogen with rainfall was significantly positive correlation, and the greater the rainfall, the fluxes of deposition nitrogen is larger.(3) The total fluxes of inorganic active nitrogen by dry atmospheric deposition was8.64kg·hm-2, and it showed that the contents in both autumn and winter were greater than that in both spring and summer. The ammonium nitrogen was deposited higher by dry deposition by component analysis2. The features of atmospheric nitrogen deposition in the years of2012(1) The content of total inorganic reactive nitrogen by atmospheric deposition was29.48kg·hm-2, which is equal to62.72kg·hm-2·a-1usage of CO(NH)2and173.41kg·hm-2·a-1usage of NH4HCO3, and dry and wet atmospheric deposition were9.51and19.97kg·hm-2, respectively. According to the settlement way to analyze,the priority deposition was by wet deposition, rating at67.74%; according to the settlement of composition, the nitrate nitrogen proportion was higher, rating at57.73%.(2) The total flux and annual concentration of inorganic active nitrogen by wet atmospheric deposition was19.97kg·hm-2and6.44mg·L-1, respectively. It was in July and August with high rainfall that deposited more active nitrogen. According to the component analysis, wet subsidence nitrate nitrogen for a high proportion. The fluxes of wet deposition nitrogen with rainfall was significantly positive correlation, too.(3) The total fluxes of inorganic active nitrogen by dry atmospheric deposition was9.51kg·hm-2, and it showed that the contents in both autumn and winter were greater than that in both spring and summer. The dry deposition of nitrate nitrogen proportion was higher by component analysis.3. Compared with nitrogen deposition conditions in the year of2011and2012(1) The annual volume of rainfall and frequency in the year of2012were increased compared to in2011. The amounts of total inorganic nitrogen in2012was higher than in2011by2.36kg·hm-2,which was as0.13times as much. And the greater the annual rainfall, the greater the nitrogen fluxes in settlement.(2) The annual total fluxes of nitrogen were26.25and29.48kg·hm-2in the two years, respectively, which both have already more than the standard of healthy ecosystems. This study did not consider of NO2--N and organic nitrogen, while the deposition of them were less, it may also lead to underestimate the concentration and fluxes of deposition nitrogen.