Water Quality Investigation And Risk Assessment Of Rural Water Sources In Northeast China

Northeast China is a typical alpine region where shallow groundwater is the drinking water source for most villages and towns.At the same time,Northeast China is also the main agricultural production area in China.The non-point source pollution caused by the extensive use of pesticides and fertilizers is bound to have a certain impact on shallow groundwater and bring unsafe factors to drinking water in villages and towns.Taking northeast province town water as the research object,selected the 180counties in the province water samples and typical agricultural areas of 47 samples,for each sample’s hardness,Na⁺,Ca²⁺,NH₄⁺-N,NO₃^--N,CN^-,F^-23 routine water quality indexes such as analysis,in view of the typical agricultural areas of water samples and analysis of organic pollutants existing conditions,Conduct pollutant traceability,water quality survey and health risk assessment to identify typical pollutants and their hidden risks to human health.The main conclusions are as follows:The analysis of the water samples of the whole province shows that the order of the over-standard rate of non-metallic substances from high to low is:NH₄⁺-N>NO₃^--N>F^-,the qualified rate of NH₄⁺-N and NO₃^--N are 72.22%and 78.89%respectively,and the order of the over-standard rate of metal elements from high to low is:The qualified rates of Mn>Fe>As>Pb,Fe and Mn were 76.67%and 61.11%,respectively.The indexes with a higher proportion of V type water include Mn,Fe,NH₄⁺-N,NO₃^--N.Water rock action accounted for 60.52%,agricultural activities accounted for 31%,and mineral factors accounted for 8.34%.The results of risk assessment showed that the HQ values of non-carcinogenic risk of hazardous substances to adults and children in drinking water in villages and towns in this province ranged from 0.101 to 13.256 and from 0.12 to16.33,and the HQ values of non-carcinogenic risk exceeding the limit 1 accounted for12.7%and 20.0%,respectively.The carcinogenic risk entropy Rs of adults and children were 0-2.565×10^-4 and 0-1.578×10^-4,respectively,and the proportion of medium and low risk samples was 25.6%and 18.9%,respectively.The non-carcinogenic risk mainly came from NO3-,and the carcinogenic risk mainly came from AS.The analysis of typical regions showed that the qualified rate of Mn and NO₃^--N indexes was the lowest,both of which were 77%.The organic substances,such as atrazine,petroleum,animal and vegetable oils and 2,4-dit-butyl phenol were detected.The main controlling effect of inland water in the region is water-rock action,which is mainly caused by silicate dissolution.80.9%of NO₃^-comes from chemical fertilizer pollution,and 17%comes from soil nitrogen.The influencing factors of water quality are agricultural activity 30.2%,water-rock action 52%and mineral action17.8%.The drinkability ranges from 14 to 300 corresponds to"good"to"unfit for drinking",18 water samples are"poor"and 1 water sample is"unfit for drinking".The risk analysis showed that children aged 6 months to 6 years were exposed to the highest entropy of non-carcinogenic risk,and children aged 0-9 years had the highest carcinogenic risk,and their carcinogenic risk RS ranged from 1×10^-5 to 7.44×10^-4.The contribution rate of non-carcinogenic risk was mainly caused by F-and NO₃^--N,while the carcinogenic risk was mainly caused by As.