| In recent years, global environmental issues have been aggravated. As a key factor of ecosystems balance and environment changes, the nutrient variations caused by human activities has drawn more and more attention from academia. And as a main nutrient in environment, the nutrient deposition is an important part in ecological cycle. Influenced by human activities, the sorts and degrees of pollutions produced by nitrogen deposition present some temporal and spacial variations, making the study of nitrogen deposition complicated. By implementing the method of sectorization to investigate the distribution and influence factors temporally and spacially, we can control the pollution in a specific way. As a result, in this thesis the area for research will be divided into four zones:agricultural region, industrial estate, urban and village. By sampling and analyzing the dust and rain among these areas, we can study the temporal and spacial distribution and influence factors of nitrogen deposition in Chongzhou. Based on the results, in addition with the water condition in agriculture region, the nitrogen contribution and pollution of atmosphere deposition to water will be discussed in this thesis.The main result is summarized as following:(1) The annual wet deposition fluxes of TN, NH4+-N, NO3--N, DON in research regions are 64.68kg/(hm2-a),26.90kg/(hm2·a),14.56kg/(hm2·a),23.23kg/(hm2·a),The annual dry deposition fluxes are 33.58kg/(hm2·a),16.66kg/(hm2·a),4.24kg/(hm2·a), 12.68kg/(hm2·a), The annual total deposition fluxes are 98.18kg/(hm2·a), 43.44kg/(hm2·a),18.76kg/(hm2·a),35.98kg/(hm2·a); For all different compounds of nitrogen, the NH4+-N deposition dominates in both wet and dry deposition; On the other hand, in terms of deposition types, the wet deposition dominates all the sectorizations under research, and its ratio is far higher than the dry deposition.(2) The dry deposition flux of atmospheric nitrogen shows some spatial variations: the sequence of dry deposition flux of TN is industrial>agricultural>urban>village (p<0.05), the sequence of dry deposition flux of NH4+-N is agricultural Other functional areas (p<0.05), the sequence of dry deposition flux of NO3-N is industrial? Other functional areas (p<0.05), DON shows no difference in different functional areas (p<0.05); The nitrogen density in rainfall also shows some spatial variations, The density of TN shows industrial>agricultural>urban>village (p<0.05), The density of NH4+-N shows agricultural Other functional areas (p<0.05), The density of NO3--N shows industrial>urban>Other functional areas (p<0.05), DON shows no difference in different functional areas (p<0.05); Limited by dimension of research area, there is no apparent spatial difference on wet deposition flux of nitrogen and total deposition flux of nitrogen.(3) The dry deposition flux of atmospheric nitrogen also shows some variation. The seasonal variation of TN, N03'-N, DON of dry deposition in different functional areas are nearly the same:peak in winter, followed by spring and fall, The seasonal variation of NH4+-N of dry deposition in industrial, agricultural and urban shows Spring, Winter>Fall>Summer (p<0.05), The seasonal variation of NH4+-N of dry deposition in village shows Winter>Spring, Fall>Summer (p<0.05); The seasonal variation of TN, NO3--N, DON of rain concentration in different functional areas are nearly the same:dry season> wet season (p<0.05); The seasonal variation of TN, NH4+-N, NO3--N, DON of wet deposition in different functional areas are nearly the same:Summer>Fall, Spring>Winter (p<0.05).(4) The nitrogen densities of various states in precipitation are highly correlated to the rainfall. Continuous rainfall and the duration of previous rain will also affect the nitrogen density in precipitation. The more rainfall, the higher wet deposition flux of atmospheric nitrogen will be, both of which show a positive correlation(p<0.05), precipitation procedure also has a significant influence on wet deposition flux of nitrogen. What's more, the precipitation is able to clean the atmosphere.(5) The deposition of atmospheric TN in agricultural area contributes to target water in amount of 3474.05kg/a, per unit area (hm2) get 34.60kg/a. |
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