Atmospheric Deposition Of Nitrogen And Its Effect On The Water Environment In The Hangjiahu Area

Nitrogen deposition has become a main part of the global nitrogen cycle.As a considerable source of nutrients in the environment,atmospheric deposition of nitrogen and phosphorus is an important way for nitrogen and phosphorus loss in ecosystem and also has a certain role in promoting the growth of plants.However,excessive nitrogen and phosphorus deposition of atmosphere have a risk of productivity and stability of terrestrial and aquatic ecosystem.Since the industrial development,a sharp increase of the consumption of chemical fertilizer and fossil fuels led to a surge of anthropogenic emissions of nitrogen.This study focuses on analyzing and comparing the data of atmospheric nitrogen and phosphorus deposition,which was obtained from five typical sites locate in Hangjiahu area?Hangzhou,Jiaxing and Huzhou?during September 2013 and August 2014.Also,this study evaluates the value of atmospheric nitrogen and phosphorus deposition flux and discusses the temporal variation of influence factors,atmospheric deposition.Furthermore,atmospheric deposition of nitrogen and phosphorus which effect the regional water environment were estimated by analyzing the sources of atmospheric deposition in Jiaxing area,providing basic data and scientific basis for pollution control in Hangjiahu area.?1?The deposition flux of atmospheric nitrogen,phosphorus in Hangjiahu area is relatively high,which was 4884.70 and 65.46kg/?km²·a?respectively.The deposition of atmospheric nitrogen and phosphorus to the surface were 64745.96 and 871.21 tons,respectively,equivalent to 56.8 and 19.8%,of the whole nitrogen,phosphorus emissions from non-point source.Nitrogen,phosphorus of atmospheric deposition into the river were 11547.22 and 155.46 tons,respectively,accounted for 32 and 7.7% of nitrogen andphosphorus into the river from the non-point source.?2?The main form of nitrogen deposition is wet deposition,however,it dependences the area,which can be 53.1% to 70.8% and average value is 60.7%.During the period of May 2013 to August 2014,deposition flux of TN wet from JiaXing Station was up to 4545kg/km²,among which,NH₄⁺-N,NO₃^--N and DON accounted for the TN proportion were 39%,19% and 42% respectively.Ddeposition flux of TN wet from Huangdian station was 3417kg/km²,among which,NH₄⁺-N,NO₃^--N and DON accounted for the proportion of TN were 33%,19% and 48%respectively.NH₄⁺-N and DON deposition are the main part of atmospheric nitrogen wet in Jiaxing station.For the rainfall in summer,the concentration of TN from JiaXing Station change relatively gentle,which is around 1.71³.96mg/L.The rainfall in Wangdian station,TN concentration decreased gradually along with time.In the rainfall,NH₄⁺-N and NO₃^--N concentration form these two stations had the same trend with TN concentration.For TP concentration,these two stations also decreased from month to month.According to the analysis result of wet deposition in Hangzhou and Jiaxing,wet deposition flux of phosphorus and nitrogen is mainly influenced by precipitation,and it increases with the increase of rainfall,the highest concentration of TN and TP in the light rain.The atmospheric wet deposition flux among different levels of rainfall followed heavy rain,moderate rain and light rain.The main form of phosphorus deposition is dry deposition.Dry deposition accounted for the total settlement ratio is between 59.62⁷0.57%,with an average of67.0%?3?Atmospheric deposition of nitrogen and phosphorus had temporal and spatial differences.In Hangjiahu area,nitrogen deposition is much higher in summer and autumn,while phosphorus deposition is much higher in autumn and winter.The wet deposition flux of atmospheric nitrogen among different seasons was followed spring?summer?autumn?winter.The wet deposition flux of atmospheric phosphorus among different seasons was followed autumn ? summer ? spring ? winter,atmospheric nitrogen,phosphorus dry deposition is much higher in autumn and winter.In the space,atmospheric deposition fluxes of nitrogen and phosphorus in Jiaxing was the highest,which was 5368.4 and 74.92kg/?km²·a?respectively,followed by Huzhou,respectively 4950.74 and 67.22kg/?km²·a?,and the lowest one is in Hangzhou,which was 4334.96 and 54.26kg/?km²·a?respectively.The atmospheric wet deposition flux of nitrogen and phosphorus among different areas was inn sequence of Huzhou,Jiaxing and Hangzhou,the atmospheric dry deposition fluxes of nitrogen and phosphorus among different areas was in sequence of Jiaxing,Huzhou and Hangzhou.?4?Backward trajectory in Jiaxing showed that the precipitation is mainly affected by the natural and anthropogenic sources and the content of nutrients by the continental air mass effect of precipitation is higher than that of the marine air masses of precipitation.Normally,the highest atmospheric wet deposition flux of nitrogen appears in summer and autumn for Jiaxing,which was effected by the air mass come mainly from the southwest and southeast direction.While the highest wet deposition flux of atmospheric phosphorus appears in autumn for Jiaxing,which was effected by the air mass is mainly from the southeast.Atmospheric dry deposition in spring and summer mainly influenced by marine air masses,hence dry deposition flux was low in these two seasons,and high dry deposition fluxes in autumn and winter may be caused by the air pollutants contained dust and anthropogenic.?5?The critical load of nutrient nitrogen deposition in Hangzhou,Jiaxing and Huzhou were 2.03,1.3 and 1.83keq/?hm2·a?respectively,which exceeded the critical load of 0.55,2.42 and 1.68keq/?hm2·a?respectively.Effect of atmospheric nitrogen deposition on nitrogen export flux in spring and summer than in autumn and winter is more significant,effects of atmospheric nitrogen deposition flux of nitrogen from Huzhou than Hangzhou and Jiaxing is more significant.