Estimation Of Nitrogen Input And Distinguishing Potential Ecological Risk In Shenzhen

With the rapid development of society,the decline of environmental quality which is caused by human activities has brought about a series of ecological problems,and these ecological problems are serious threats to the social sustainable development.At present,nitrogen and nitrogen compound have been widely applied to the fields including ecological research,biological research,environmental research and chemical research,but the nitrogen-related research focuses on the direct discharge areas in China,like water environment,the risk assessment focuses on human health.There are few discussions of gradual change risk caused by long-term human activities,and most of them emphasize specific human activities or industrial form,this influence the assessment of nitrogen input causes by human activities.In this paper,Shenzhen city,the typical urbanization city is the research area,the nitrogen input of human activities is the breakthrough point.The nitrogen input(1991-2014)is estimated according to the three types of activities such as industrial production,residents’ living and agricultural production.At the same time,the difference of nitrogen input space is analyzed by land-use,and the ecological risk(2000-2014)of urbanization in Shenzhen is analyzed through these areas’ nitrogen input keep high and the increased grade areas.The main research contents and conclusions are as follows:(1)The research quantitative estimation of nitrogen input from 1991 to 2014 based on statistical yearbook.From 1991 to 2014,the total nitrogen input in Shenzhen showsa trend which is increasedat first and then decreasing,and it is affected by nitrogen input of residents’ living.The nitrogen input of agricultural production is decreased year by year.The nitrogen input of industrial production decreases first and then increases,the turn of the change is in 2001.Thenitrogen input of the residents’ living increased first and then decreased,the nitrogen input of industrial production and residents’ livingare affected by the sewage discharge.Based on the correlation analysis of socioeconomic factors related to urbanization,it is shown that the nitrogen input in the agricultural production is affected by the added value of the primary industry,the population and the agricultural land area.The input nitrogen input of the residents’ living is affected by the added value of tertiary industry.The total nitrogen input of the city is affected by GDP,while the nitrogen input of the industrial production is affected by the change of the industrial structure.(2)Using ArcGIS to combine nitrogen input with remote sensing data to analyze the spatial differences and gradation changes of nitrogen inputs.In the spatial difference of nitrogen input,from 2000-2003 the high input area of nitrogen input is concentrated in the southwest of the Shenzhen city in the Luohu District and Futian District,which are the city’s social and economic concentrated activities areas in this period.In 2006,the areas of the high value nitrogen input spread to the whole city.In 2010,high nitrogen input areas including the business districts of Yantian District and Futian District,the city’s nitrogen input is in a balanced state in 2014.The low input area of nitrogen input is concentrated in the eastern part of the city in the nitrogen input gradation.(3)The heterogeneity of nitrogen input spatial distribution and the fluctuation of time change caused the imbalance of nitrogen input ecological risk in Shenzhen,and there are potential ecological risks in the densely populated areas of the eastern part of the city,the traffic land is especially obvious,which brings some threat to Shenzhen city.The nitrogen load pressure has an upward trend in Shenzhen during the study,if things continue this way,it will bring great pressure on the Shenzhen environment,ecological risk continue to increase.