Characteristics Of Organic Pollution And Health Risk Assessment Of Dawu Water Source Area In Zibo City

The Dawu water source is a large-scale karst groundwater source in northern China,which plays an important role in the economic development of Zibo City.However,due to historical reasons,a large number of petrochemical enterprises are located upstream of the Dawu water source,causing a certain degree of organic pollution to groundwater and seriously threatening the water safety of local residents.Therefore,it is of great practical significance to have a deep understanding of the distribution characteristics and pollution status of organic matter in groundwater and carry out health risk assessment for the rational development and utilization of groundwater resources and pollution prevention in this area.This paper mainly conducts a systematic study on the detection,distriibution,and degree of pollution of organic pollution in Dawu water source area of Zibo City.Based on this,a health risk evaluation index system and evaluation model for groundwater pollution in the study area are constructed.Health risk assessment of groundwater organic pollution was conducted in key polluted areas centered on the Hougao-Xixia Lot.The main understanding and conclusions is as follows:(1)A total of 180 groundwater sampling sites were set up in the study area,and the results of 89 organic indexes tests on water samples showed that a total of 46 organic indexes were detected,including halogenated hydrocarbons,chlorobenzene,monocyclic aromatic hydrocarbons,polycyclic aromatic hydrocarbons and organochlorine pesticides.The detection concentration and detection rate of pollutants from halogenated hydrocarbons were the highest.At least one organic index was detected in 128 groups of samples,and the total organic detection rate was 71.11%.The highest single organic matter detection was chloroform,with the detection rate of 47.78%,the total groundwater exceeded the standard rate of 16.11%,and the organic matter with more exceeding the standard were 1,1,2-trichloroethane,l,2-dichloropropane,carbon tetrachloride,benzene,etc.(2)The groundwater in the study area was screened for priority control of pollutants.Using a combination of potential hazard index and weighted scoring method,comprehensive consideration of toxicological data,detection frequency and average concentration,the priority control pollutants for groundwater in the research area were selected as chloroform,carbon tetrachloride,1,1,2-Trichloroethane,1,1-dichloroethylene,trichloroethylene,tetrachloroethylene,1,2-dichloropropane and benzene.The concentration distribution of the selected priority pollutants is significantly affected by human activities and has a certain consistency in space.(3)Carry out organic pollution assessment of groundwater.Will select eight kinds of priority pollutants as the evaluation factors,using the single factor pollution index method and Nemcrow pollution index method to evaluate the organic pollution in the groundwater in the study area,the results show that the groundwater in the study area have been varying degrees of organic pollution,the degree of organic pollution in the groundwater in the upper reaches of the Zihe River in the south of the study area is low,and the organic matter pollution in the groundwater in the Hutian-Jinling-Linzi line in the north of the study area is quite common,and an obvious local heavy pollution area is formed in the area of Hougao-Xixia in the southwest of Jinling Town.(4)Carry out health risk assessment of groundwater pollution.Based on NAS"Four-step Method",combined with field investigation and data collection in the study area,the exposure parameters that are more suitable for residents in the study area are selected and calculated,the exposure path,exposure model and evaluation index are established,and the health risk evaluation model of groundwater pollution suitable for the study area is constructed.The health risk assessment of groundwater pollution was carried out for 8 kinds of target pollutants in the key pollution areas from two exposure ways of drinking water and breathing.The results showed that 21 of the 29 sampling points had non-carcinogenic risks exceeding the limit of 1,with an overrun rate of 72.4%,while the carcinogenic risks were all greater than 10-6,and all had carcinogenic risks.Both for non-carcinogenic risk and carcinogenic risk,benzene has the highest contribution rate,with contribution rates of 47.74%and 65.28%respectively;the risks arising from drinking water pathways are the main contribution values of the total risks from the two exposure pathways.