The Surface Water Pollution Investigation And Evalution Of Yanhe River And Qingjianhe River

In the past few years, surface water was seriously deteriorated by the exploitation of petroleum and the expansion of urbanization in the Northern Shaannxi province and lack of water resource has been continuously aggravated. So the quality of surface water in Yan'an city has been paid more attention by experts and residents. By collecting previous monitoring data, field investigating, location sampling and indoor testing, the detailed water quality of Yanhe and Qingjianhe River have been evaluated. The samples were collected both in low water and normal water period at 30 sampling spots. Approximately 400 bottles of surface water, 1 bottle of fountain and 1 bottle of well water were collected. Total of 17 indexes: pH, salinity, Hardness,Cr⁶⁺,As,Cd,Pb,ammonia nitrogen,volatile phenol,oil,COD,chloride,sulfate, nitrate nitrogen, total phosphorus, cyanide, fluoride were chosen to analyze the pollution degree. Main pollution factors and situation of different pollution area were then analyzed and the main reasons of pollution were found out. In addition, careful investigation was carried out both in the Upper and Lower reaches of WangYao Reservoir, which is the water source of Yan'An city, after the "8.29"XingZihe river leakage accident. By comparing the water quality of Beiluohe River to the Yanhe and Qingjianhe River, the similarities and differences situation of water pollutions between two regions are as follows:(1) The surface water quality of main drainage areas in Yanhe and Qingjianhe River are the poor category V. The major pollutants are volatile phenol, total phosphorus, ammonia nitrogen, petroleum and COD in normal water period. In low water period the major pollutants are total phosphorus, volatile phenol, ammonia nitrogen and chloride. The pollution in Low-flow period is more serious. The key factor of surface water quality in Low-flow period is the oil.(2) The main reasons for the pollution in Yanhe and Qingjianhe River are:â‘ leaks during the process of crude oil exploitation and transportation, illegal discharges of waste oil and waste water during the process of oil refining, as well as the frequent oil spills, all of them make the water seriously contaminated.â‘¡The increase of population in urban and rural areas makes the rapid emission of sewage. But the capacities of municipal wastewater treatment plants are inadequate. Large amounts of untreated sewage discharged directly into rivers and overloaded the river' s pollutant carrying capacity.â‘¢Nitrogen and phosphorus in soil and agricultural fertilizer are vulnerable to loose and runoff into the river because of its location on the Chinese Loess Plateau where soil eroded seriously, and worsen the river water quality.(3) A few oil pollutants were detected in Wangyao Reservoir because the vestigial oil residue on the river bank and mud left over by the accident entering into the reservoir with rainfall.(4) Arsenic, cadmium, lead, fluoride, nitrate, cyanide, fluoride and pH in surface water of Yanhe and Qingjianhe River are the same with Beiluohe Rive, and nearly all the samples are lower than the standard.(5) Volatile phenol pollution degree is similar in surface water of Yanhe, Qingjianhe and Beiluohe River. Total phosphorus, ammonia nitrogen, COD pollution degree in surface water of Yanhe and Qingjianhe River is larger than Beiluohe River because of the large population.