Characteristics Of Atmospheric Active Nitrogen And Sulfur Dry And Wet Deposition In Taiyuan City And Surrounding Areas

In recent years,the urbanization process has accelerated in Taiyuan.The emission of nitrogen oxides has increased in the air due to the development of industry,transportation and agriculture.The study is on wet and dry deposition of atmodpheric N and S in Taiyuan city and surrounding farmland,will provide a scientific theory for nitrogen pollution control in city and comprehensive management of nitrogen and sulfur resources at farmland.Therefore,the atmospheric nitrogen and sulfur deposition were monitored from 2016 to 2018 in Taiyuan City and surrounding areas.The changes of nitrogen and sulfur deposition in Dongyang Demonstration Base of Shanxi Academy of Agricultural Sciences,Yuci District,Jinzhong City and Hecun Village,Yangqu County and Taoyuan in Taiyuan city center and Shanglan in the suburbs of Taiyuan were quantified,which will be benifit for environmental sustainable development of Taiyuan City.The main results and new progress were summarized as follows:?1?Researches on N deposition and precipitation were conducted from June 2016 to May 2018 at Dongyang and Hecun.The results showed that the average N wet precipitation rate was 12.9 kg/hm²,and the total dry deposition rate of gaseous active nitrogen?NH₃ and NO₂?was 14.6 kg/hm² at Dongyang.The particle form of NH₄⁺-N and NO₃^--N by gravity was 2.9 kg/hm²,and the ratio of ammonium nitrogen was the higher in N deposition.The deposition rate of NH₃,NO₂,HNO₃,particulate NH₄⁺ and particulate NO₃^-averaged 6.1,2.9,3.3,2.1,1.4 kg/hm²,respectively,and total dry deposition was 15.8 kg/hm² in Hecun.All this results indicated that ammonia had a significant influence on N deposition of the study area.The deposition rate of NH₃ in Dongyang was 1.9 times that of Hecun,and that of HNO₃ and NO₂ was 40% of the total dry deposition in Hecun.It can be concluded that the atmospheric active nitrogen at Dongyang is mainly affected by agricultural sources,and for Hecun the influence of transportation sources was similar to agricultural sources.In the future,it should be conducted more scientifically fertilization and reduce the volatilization of nitrogen fertilizer,and should concern the influence of surrounding industrial and transportation gas emissions on N deposition in these areas.?2?The reaserch on temporal variation of atmospheric N and S wet deposition were conducted form June to October in 2016,at Dongyang experimental base of Shanxi Academy of Agricultural Sciences.The deposition rates of SO₄^2--S,NH₄⁺-N and NO₃^--N were 34.5,7.9 and 2.5 kg/hm²,respectively.The deposition rate of SO₄^2--S was 4.3 times and 14 times that of NH₄⁺-N and NO₃^--N,respectively.S deposition accounted for 77% of the total deposition,and inorganic nitrogen accounted for 23%,of which NH₄⁺-N accounted for a high proportion.The concentration and deposition rate of SO₄^2--S and NO₃^--N were extremely significant?P<0.01?and significantly linearly correlated?P<0.05?,the correlation coefficients were 0.688 and 0.619,respectively,indicating that they have the same source.The concentration ratios of SO₄^2--S/NO₃^--N and NH₄⁺-N/NO₃^--N were 13.94 and 3.20,which indicated the type of acid rain was sulfuric acid type.In general,N deposition mainly based on agricultural sources at Dongyang,and surrounding transportation and combustion of living fuel had similar effects on the deposition of SO₄^2--S and NO₃^--N.High-sulfur deposition should be paid more attention to its effect on the supply of sulfur in farmland ecosystems.and also could provide important data for relevant environmental departments.?3?The reaserch on temporal and spatial variation of atmospheric nitrogen wet deposition was conducted using rain gauge from January 2016 to December 2017,at Taoyuan,Shanglan and Hecun of Taiyuan City.The concentration of NO₃^--N and NH₄⁺-N averaged from 1.3 mg/L to 18.4 mg/L and from 1.6 to 3.6 mg/L,respectively.The average concentration of NH₄⁺-N showed a stable state during the different season,but NO₃^--N was high in winter and spring.Annual wet deposition of inorganic N?IN?averaged 40.0,48.3,14.2 kg/hm²,respectively,in these three sites.The wet deposition rates of NH₄⁺-N were 8.8,5.3,8.2 kg/hm² and accounted for 22%,11%,57% of the IN deposition,and that of NO₃^--N were 31.2,43.0,6.0 kg/hm² and accounted for 78%,89%,43% of the IN deposition at Taoyuan,Shanglan and Hecun of Taiyuan,respectively.The average concentration ratio of NH₄⁺-N/NO₃^--N was 0.54,0.30 and 1.31,respectively,in these three sites.In addition,the difference between nitrogen wet deposition and rainfall in Taoyuan and Shanglan areas of the city was not significant,and Hecun reached a very significant level,indicating that the factors affecting the two-point wet deposition of the urban area were more complicated than the farmland.These results revealed that the atmospheric nitrogen wet deposition of the Taoyuan and Shanglan mainly came from industry and transportation,while that of Hecun originated from agriculture.Above all,in the future such high deposition rates of N wet deposition should be controlled according to its own characteristics in Taiyuan area.