Investigation And Trend Of Surface Water Quality In Gansu Province (2011-2015)

Water is the lifeblood of the national economy.Gansu is located in the western hinterland of China,the mainland geography center.Gansu is a fragile natural ecological province,the forest coverage rate is low,the water and soil loss area is wide,the mountainous area,the plateau,the Gobi and the desert occupy the main part,the land desertification,the problem of land desertification,degradation and salinization is serious.Part of the regional and river environmental problems highlighted.Gansu water environment pollution and water resource shortage restricts the sustainable development of economy and society,optimizing the development and efficient utilization of water resources,strengthen the management of drinking water sources and water quality of major rivers is a long-term strategic task.In this paper,the pollution factors of "Surface Water Environmental Quality Standard"(GB3838-2002)were selected by site sampling and automatic station monitoring in 67 sections of 15 rivers and 17 reservoirs in Gansu Province.From 2011 to 2015,Based on the data of 5 years,the single factor evaluation,comprehensive pollution index,pollution sharing rate and sperman rank correlation coefficient were used to analyze and evaluate the surface water quality and water quality of 5 years in Gansu Province.Analyze the causes of pollution from economic indicators,industry distribution,industrial emissions,and ecological environment.Research shows that the Gansu river water quality remained stable,the overall environmental quality of surface water has shown signs of improvement,COD,BOD and dissolved oxygen 3 pollution are the main pollutant from 2011-2015.Gansu River included,the Yangtze River,the Yellow River,the inland river three watershed,The Yellow River river water quality stability of the whole process to reduce the degree of pollution,chemical oxygen demand,biochemical oxygen demand and ammonia nitrogen pollution factor as the main pollutants.The water quality of the Yangtze River Basin is excellent.Inland river basin pollution level has been reduced,the comprehensive pollution index decreased,volatile phenol,biochemical oxygen demand and oil pollution factors as the main pollutants.In addition,this paper analyzes the reservoirs in Gansu Province,showing that the water quality of 17 reservoirs improved year by year,and the three pollution factors,dissolved oxygen,pH and chemical oxygen demand,were the main pollutants.In 2011,there were 15 water quality reservoirs of Class and above,and 16 water quality reservoirs in Gr? ade and above in ?2012-2015.The main reasons for the quality of water environment in Gansu Province are as follows: 1.Although the province's wastewater emissions increased,but the main pollution indicators of chemical oxygen demand,total ammonia emissions reduced year by year,the rate of industrial wastewater discharge standards strict requirements every year;2.The main emission industry of chemical oxygen demand is the quantity of agricultural and sideline food processing,Ammonia and nitrogen emissions mainly for the chemical raw materials and chemical products manufacturing industry,the two industry pollutant emissions decreased year by year;3.Gansu Province,five years the overall population growth rate is slow;4.2011-2015 in Gansu Province,the per capita GDP growth rate accounted for decreased year by year;5.continue to change the industrial structure of Gansu Province,the proportion of the second industry is gradually reduced,the proportion of the third industry increased year by year;6.The increase of vehicle ownership in Gansu has caused oil pollution in surface water;7.2011 to 2015,the province's ecological environment quality remained stable."13th Five-Year Plan " period is our country build a well-off society in the extra period,environmental protection situation and tasks require complex and arduous,correct understanding of environmental quality in the current and future environmental protection forecast main problems,help to break the constraints of resources and environment,so as to achieve the overall goal of improving environmental quality.Gansu Province,as a less developed province,scientific research on water environment quality and trends in the past 2011-2015 years,is of great significance to promote the Gansu province " 13 th Five-Year Plan " and even longer period of time the work of environmental protection.