The Study Of Surface Water Quality In YangZhou Based On Geographic Information System (GIS)

This article proceed from researching surface water quality in YangZhou,according to the area of YangZhou City,other technical requirements and workload size,using Grid GIS method divided YangZhou City into 196 grids(14×14),with measuring NO3-N,NH3-N,PO4-P,COD,Cu,Cd,Pb,Zn such as other index in October 07, Jaunary 08,April 08,July 08,studied the nutrient elements in surface water,the distribution and level of heavy metal, do detail comparison from space,time,and speculated the possible source of pollutants.Main researches as follows:(1)On the space.The highest pollution value of nutrient element NO3-N is 11.962ppm,the totally feature space distribution of NO3-N:East area is high while west area is low,and rural area is high while urban area is low;The standard rate of PO4-P is 47%,the highest pollution value is 3.567ppm,most of the standard rate is residential area, primary origin is the sewage contained PO4-P;The standard rate of COD in the water is from the sewage and the waste water of aquaculture;There is basically no Cd pollution in the water,the content of Cu is slightly higher,the water of the sampling points YZ046,YZ070,YZ115,YZ127 endanger the survival of the fish,the highest pollution value is 0.7ppm;The pollution of Pb is mainly from coal-fire flue gas,by dry and wet sedimentation into the water body;The pollution of Zn is along the coast of the HuaiSi River,the highest pollution value is 43.34ppm.According to the author sampled along the same river,found the difference between the migration of kinds of heavy metal:the sewage containing Zn can be self-purification in short-range and the pollution of other heavy metal Cu,Cd,Pb is farther.(2)On the time.It is found the comparison by the same indicators at different time:the NH3-N content in the water in August is significantly higher than in January,the seasonal differences of heavy metals are also large.Except to Cd contenting little in the water changed not so obviously,other heavy metals Cu,Pb,Zn are totally higher in the wet period than in the dry season.While PO4-P,COD don't change so significantly. According to the above research,it carries out the risk assessment for the environmental quality of surface water body of YangZhou.This article uses classic Hakanson ecological risk index method and Muller geological accumulation index method(Igeo),evaluates the environment effects of heavy metals in water.There's little heavy metal pollution in the water of YangZhou,YZ023,YZ038,YZ069,YZ172,YZ188 have different levers of pollution,also have a great impact in the region.The city center is polluted least by the heavy metal.Based on the above conclusions,it carries out the regular monitoring,controlling the source,cleaning up the triage, establishing a rational industrial distribution such as other technical and management measures for the environment quality of YangZhou City,it contributes to the improving the water quality of this region and supporting the decision of surface water quality on the South-to-North Water Diversion.