Research On The Characteristics Of Organic Contamination Of Groundwater And Health Risk Assessment In North Henan Plain

Groundwater resources are an important part of the drinking water sources in the North Henan Plain,but water resource in the area is not only relatively scarce,but also organic contamination of underground water is intensifying along with the growing urbanization and industrialization.On the basis of three field sampling survey and experiment analysis in the laboratory,this article analyzes the organic pollution characteristics of groundwater in research area and has evaluation on organic pollution.It carries out health risk assessment on Puyang oil-field region because of its severe pollution..The study arranged 41 sampling points in the research area and tested 37 kinds of organic pollution components.Results indicate that the pollution groups with higher concentration can be divided into 10 kinds,mainly benzene series and hydrocarbons.In the dry season,the detection rate of toluene is the highest(90.24%),with the maximum detectable concentration of 15.98ug/L;in the wet season,toluene remains the highest detection rate of 92.68%,with the maximum detectable concentration of 17.98ug/L.Compared with the dry season,the detection rate of benzene series in the wet season has increased;chloroform is special,with less detection rate of wet season than dry season.All pollution components in the research area don't exceed the limit of “Drinking Water Hygienic Standard(GB5749-2006)”,and the detection is characterized by a higher detection rate but a lower excessive rate.Toluene has a wider distribution in the research area,which is concentrated in the area of Qi County ~ Tangyin County ~ Neihuang County,the Yuanyang County(in the southern Xinxiang),and Puyang oil-field in the northeast part of the research area;the main detection points of trichloroethylene and chloroform focus on Puyang oilfield;the other four kinds of hydrocarbons organics are dotted with sporadic distribution and the regularity is poor.It uses organic pollution evaluation methods of single factor pollution index method and comprehensive pollution index method to evaluate the groundwater organic pollution in research area respectively.The evaluation results show that: toluene pollution is the most serious in groundwater of research area.Its organic contamination level is heavy pollution and the area in Puyang oil-field forms an obvious seriously polluted area.To further understand the risk level of organic pollution on human health,the article is based on NAS “Four-step Method” to select exposure factors more suitable for Chinese people from 5 kinds of target pollutants in groundwater of the key research area and carries out health risk assessment from 3 kinds of exposure pathways: drinking water,breathing and skin contact.The evaluation results show that in the dry season and the wet season,the non-carcinogenic risk in 9 sampling sites of assessment district is less than the limit of 1.0 and the carcinogenic risk is greater than 10-6.In the dry season,the lowest non-carcinogenic risk is D005 and the highest is D006;the minimum and maximum of carcinogenic risk are D005 and D006 respectively.In the wet season,the minimum and maximum of non-carcinogenic risk are D004 and D006 respectively;the lowest and highest of cancer risk are D001 and D006 respectively.In the five kinds of pollutants,the benzene of cancer risk account for the highest percentage of total non-carcinogenic risk.During the risks brought by three kinds of exposure pathways,the breathing has the greatest risk,followed by drinking water,and the skin contact has the minimum risk.