Study On Environmental Quality Of Groundwater And Environmental Exposure Health Risk Assessment Of Liangzhou District In Wuwei City

Objectives1.Making evaluation environmental quality of groundwater and analyze the state of groundwater contamination in Liangzhou district of Wuwei City.2.In order to assess groundwater as drinking water sources of residents health risk caused by toxic pollutants in environmental media in this district.3.The study aims to prevent and control groundwater pollution,,and ensure health and safety of residents drinking water in Wuwei City of Liangzhou district,and provide scientific basis for health risk management measures.Methods1.Groundwater environmental quality evaluation method?1?Multivariate statistical analysis:Using correlation analysis,factor analysis,hierarchical cluster analysis of groundwater quality major pollutants and pollution spatial distribution characteristics.?2?Individual indicators evaluation:Using a single factor evaluation on groundwater quality grade,water pollution pollutants and excessive pollution multiples.?3?Comprehensive index evaluation method:Using nemerow index method and improved method to make comprehensive evaluation for groundwater pollution levels and distribution characteristics.2.Groundwater environmental exposure health risk assessment methodsAccording to environmental health risk assessment model of EPA,the exposure of groundwater quality of major toxic pollutants was estimated.Results1.Environmental quality of groundwater assessment results in Liangzhou district of Wuwei City?1?Environmental quality of groundwater assessment results in 2013?1?Factor analysis and cluster analysis showed that important factors were natural geological factors and nitrate pollution factor?F₁?,followed by Organic pollution factor?F₂?and agricultural emission factor?F₃?.Class A of highly polluting space was mainly controlled by F1 and F₂ factors;Class B of under heavy pollution space was controlled by F₁,F₂ and F₃ factors;Class C of light polluted space;Class D of moderately polluted space,was mainly controlled by F₂ and F₃ factors.Class 4 sub-space of groundwater pollution sorted as follows:Class B>Class A>Class D>Class C.Water polluting areas were mainly distributed in the Northeast railway with Jinta river and Xiying river irrigation,which villages and towns were Qingshui,Shuangcheng,Jinsha,Changcheng,Qingyuan,Jiudun,Fafang,Xiashuang,Yongchang and Daliu.?2?Single factor evaluation results showed that groundwater quality monitoring sites proportion of 79.17%were not up to class III standard.Excessive rate of indicators were ammonia?58.33%?,sulfate?41.67%?,nitrite?37.50%?and total hardness?33.33%?.?3?Improved nemerow index evaluation results showed that 70.45%of the regional groundwater quality meet national class III standard,Water of Class IV regions accounted for29.55%,which were distributed in the northeast railway zone with Xiying river,Jinta river and Huangyang river irrigation,which villages and towns were Hongxiang,Shuangcheng,Yongchang,Jiudun,Xiashuang,Jinsha,Daliu,Changcheng,Fafang,Qingshui,Qingyuan,Donghe,Hunagyang and Wu Jiajing.?2?Groundwater environmental assessment results from 2008 to 2013?1?Improved nemerow index results showed that more than half of the regions with groundwater quality meet the national standard III in wet and dry seasons.Grade IV rates were25.40%and 20.32%.There was no statistically significant of water quality exceeded rate between the wet season and dry season.?²=22.165,P>0.05?.?2?Northeastern railway of water quality exceeded rate?29.89%?was higher than the southwest railway zone?19.08%?in wet season,the difference was statistically significant.?²=4.717,P<0.05?.Jinta river irrigation with northeast railway zone excessive rate of water quality?42.19%?was higher than Xiying river irrigation with southwest and northeast railway zone?23.26%and 25.40%?,Jinta river irrigated with southwest railway zone?12.50%?and Huangyang river irrigation with railway northeast zone?20.00%?,and the differences were statistically significant?P<0.05?.?3?Jinta irrigated water quality exceeded rate?29.81%?was higher than the other three irrigation areas in dry season,the difference were statistically significant?P<0.05?.Water quality excessive rate of railway Northeast zone?26.09%?was higher than the railroad southwest zone?12.21%?,the difference was statistically significant?²=9.097,P<0.05?.In addition to standard rate of water quality between Jinta river irrigation with railway northeast zone and Zamu river irrigation with railway northeast zone had no statistical significance?P>0.05?.Excessive rate of water quality in Jinta river irrigation with railway northeast zone?40.63%?was higher than the other six regions,and the differences were statistically significant?P<0.05?.2.Rural drinking water quality assessment results in Liangzhou district of Wuwei City?1?Drinking total pass rate was 47.73%in 2013,indicators with lower passing rate were total hardness?59.09%?,sulfate?61.36%?,total dissolved solids?75.00%?and nitrate?81.82%?,which were lower than 90.00%.?2?Drinking total water pass rate was 78.10%form 2008 to 2013.,the highest quality passing rate was 84.13%in 2011,the lowest water quality passing rate was 65.38%in 2013.Total quality pass rate of wet season?66.03%?lower than dry season?87.93%?,the difference was no statistically significant?²=0.085,P>0.05?.Except 2010,quality pass rate between wet season and dry season was no statistically significant?²=1.933,P>0.05?.The rest of the year water quality passing rate with dry season was higher than wet period,the differences were statistically significant?P<0.05?.Wet season of total hardness?79.05%?,total number of colonies?81.27%?,sulfate?82.86%?and nitrate?88.25%?and dry season of total hardness?87.94%?,sulfate?88.89%?,which passing rates were lower than 90%.3.Groundwater environmental health risk assessment of exposure results in Liangzhou district of Wuwei City?1?Cross-sectional survey dates in 2013 and monitoring datas from 2008 to 2013 showed that non-carcinogens?nitrates,nitrites and ammonia?through drinking water route caused personal annual risk index and total risk index were higher than the dermal route.And indexes were less than the threshold value of 1.0,which was acceptable risk of the body.?2?Non-carcinogenic caused personal total risk index through drinking water route in 2013,which followed the decreasing order:Huangyang river irrigation>Jinta river irrigation>Xiying river irrigation>Zamu river irrigation;railroad northeast zone>railroad southwest zone.Non-carcinogenic caused personal total risk index which followed the decreasing order:Nitrate>ammonium>Nitrite.Nitrate caused personal total risk index is the highest in Xiying river irrigation;Railroad southwest zone>Railroad northeast zone;Nitrite caused personal total risk index is the highest in Huangyang river irrigation;Mmonia caused personal total risk index is the highest in Zamu river irrigation;Nitrite and ammonia caused personal risk index with railway northeast zone>railway southwest zone.?3?Nitrate caused personal risk index from 2008 to 2013,which followed the decreasing order:wet season>dry season,Railroad northeast zone>Railroad southwest zone.?1?Nitrate caused personal risk index in wet season which followed the decreasing order:Jinta river irrigation>Xiying river irrigation>Zamu river irrigation>Huangyang river irrigation.?Jinta,Zamu,Xiying,?river irrigation with railway northeast zone>?Xiying,Zamu,Huangyang?river irrigation with railway southwest zone>Huangyang river irrigation with railway northeast zone>Jinta river irrigation railway southwest zone.?2?Nitrate caused personal risk index in dry season which followed the decreasing order:Jinta river irrigation>Xiying river irrigation>Zamu river irrigation>Huangyang river irrigation;?Jinta,Zamu,and Huangyang?irrigation with railway northeast zone>?Xiying,Huangyang,Jinta;Zamu?river irrigation with railway southwest zone>Zamu river irrigation with railway northeast zone.Conclusions1.Cross-sectional survey dates in 2013 and monitoring datas from 2008 to 2013 showed that more than half of the regions with groundwater quality meet the national standard III in Liangzhou district of Wuwei City.There is class IV poor water quality in some areas,the water pollution was affected by natural ecological factors and human activities factors.Groundwater pollutants had obvious environmental topography and hydrogeological characteristics of distribution,water quality was gradually worse with the Xiying river,Jinta river,Zamu river and Huangyang river from southwest to northeast direction in wet sease and dry season.Water pollution is most serious in Jinta river irrigation with with railway northeast zone,followed by water pollution is more serious in Xiying river irrigation with railway northeast zone with.The main pollutants were including ammonia,sulphate,nitrite and the total hardness.Drinking water passing rate fluctuations each year is not similar,and werelower than 90%Total passing rate of wet dry season was less than dry season.Lower passing rate indexes were including total hardness,sulphate,total bacteria,total dissolved solids and nitrates.2.Non-carcinogens?nitrates,nitrites and ammonia?was mainly through drinking water route caused health risk in Liangzhou district of Wuwei City.Nitrate is the main danger factor of residents health.Nitrate caused personal risk index was higher in Xingying and Jinta river irrigation with railway northeast zones,which were within acceptable range of the human health,and less harmful effects on health.If population chronically exposed to groundwater as drinking water in nitrogen pollution environment,it will pose potential health risks of residents.And the harmful effects can not be ignored.Great important attentions should be paid to relevant departments.