Water Quality Change Of Shandian River In Zhenglan Banner Yuan Capital Site

In recent years,Zhenglan Banner of Inner Mongolia has promoted its urbanization,improved its level of industrialization and boosted rapidly its development on grassland tourism industry with local characteristics,which has increasingly improved the quality of life of farmers and herdsmen but also affected the natural environment to varying degrees.In order to protect the ecological environment around the Yuan Capital Site,a world cultural heritage,this paper monitors and analyzes specifically the water quality of Zhenglan Banner Yuan Capital Site reach of Shandian River.According to the climate characteristics and the river water supply in Zhenglan Banner,the monitoring time is set within July to September within 2013-2016,the precipitation concentration period,and the samples are taken once a month.The sampling site is the area with abundant water and stable flow rate,and it is closest to the upper reach of the Yuan Capital Site and most influenced by human activities.According to the basic monitoring items in Table 1 of "Standard of Surface Water Environment Quality(GB3838-2002)" and combining the local actual possible pollution sources,16 monitoring factors are selected:dissolved oxygen,pH,COD,BOD5,volatile phenol,fluoride,sulfide,ammonia nitrogen,hexavalent chromium,copper,zinc,lead,cadmium,arsenic,mercury and petroleum.And according to the classification of functional areas of surface water in the Standard,the results of the above factors are evaluated by V class standard limits.The conclusion is:during the four years from 2013 to 2016,the overall water quality of Zhenglan Banner Yuan Capital Site reach of the Shandian River changed slightly.But some detection factors changed obviously and exceeded the limits.(1)Physical and chemical indicators:pH value basically increased year by year and exceeded the limits in 2016;dissolved oxygen showed a downward trend year by year.(2)Reductive comprehensive indicators:biochemical oxygen demand(BOD5)and chemical oxygen demand(COD)increased basically year by year and exceeded the limits in 2013,2015 and 2016.(3)Heavy metallic detection factors:hexavalent chromium,copper,zinc,lead,cadmium and mercury kept basically unchanged for four years,and the test results of them reached the standard and mostly below the detection limit.(4)Other non-metallic detection factors:volatile phenol,sulfide,ammonia nitrogen,arsenic and petroleum changed slightly and reached the standard during the four years.But the fluoride increased year by year and exceeded the limit in 2016.This paper summarizes the possible causes for exceeding the limits and the changing trend of some detection factors through the discussion of the above monitoring results.It also analyzes and investigates the problems one by one according to the causes,to put forward some suggestions and measures specifically for protecting the water quality of this reach.