| ObjectiveIn order to investigate the exposure level and distribution characteristics of pollutants in drinking water,the drinking water quality of T-city in 2017-2018 was analyzed,,and also the factors affecting water quality was explored,potential hazards of drinking water to residents was assessed.Our work would provide scientific basis for ensuring the safety of drinking water for residents.Method486 samples of finished water,tap water and secondary water in T city from 2017 to 2018 were monitored during dry season(February)and wet season(August).Water samples were categorized according to certain standards(water supply mode,year,water period,production unit,area)and health risk was evaluated by 9 indexes.Excel 2013 was used to establish the database of water quality monitoring results.SPSS 19.0 was used for statistical analysis.Comparisons between classified variables were tested by χ2 test.Pollutant variables showed skewed distribution.Rank sum test was used for comparison.The difference was statistically significant with P<0.05.ResultIn the 2017-2018 year,the overall pass rate of drinking water in T city was 97.3%,and the unqualified indicator was the total number of colonies.The unqualified rate in 2017 was higher than that in 2018(x2=4.366,P=0.037),and that in A water plant was higher than that in B water plant(x2=5.604,P=0.018).The concentration of chloroform in wet season was higher than that in dry season(Z=-2.687,P=0.007),A water plant was higher than that in B water plant(Z=-3.798,P<0.001),zinc concentration in rural area was higher than that in urban area(Z=-2.2,P=0.027),aluminum concentration in 2017 was higher than that in 2018(Z=-2.487,P=0.013),wet season was higher than that in dry season(Z=-6.606,P<0.001),A water plant was higher than that in B water plant(Z=-2.637,P=0.008),fluoride concentration in 2017 was higher than that in 2018(Z=-7.450,P<0.001),wet season was lower than that in dry season(Z=-2.261,P=0.024),A water plant was higher than that in B water plant(Z=-2.963,P=0.003).The carcinogenic risk of 9 pollutants in drinking water in T city from 2017 to 2018 was 6.69×10-7/a,the non-carcinogenic risk was 3.18×10-9/a,and the total health risk was 6.72×10-7/a.Carcinogenic health risk was ranked as chromium(Cr6+)>arsenic>chloroform>lead>carbon tetrachloride,non-carcinogenic health risk was ranked as fluoride>arsenic>chromium(Cr6+)>mercury>chloroform>aluminum>zinc>carbon tetrachloride,and total health risk was ranked as chromium(Cr6+)>arsenic>chloroform>fluoride>carbon tetrachloride>mercury>aluminum>lead>zinc,The proportions of chromium(Cr6+),arsenic and chloroform were 54.7%,41.1%and 3.40%.The total health risk of drinking water in T city was lower than the maximum acceptable level recommended by all agencies,and higher than the negligible level recommended by IAEA(5×10-7/a),the Royal Society of England(1×10-7/a)and the Ministry of Construction and Environment of the Netherlands(1×10-8/a),just on the acceptable risk level of the social population recommended by USEPA(10-7～10-6/a).ConclusionsThe main reason for the disqualification of drinking water in T city is the total number of colonies exceeding the standard.The concentration of pollutants in drinking water in T city was higher than that in dry season,A water plant was higher than that in B water plant,rural area was higher than that in urban area,2017 was higher than that in 2018.The ozone-activated carbon advanced treatment technology in water treatment process has obvious effect on reducing the pollutants in drinking water.It is suggested that A water plant should develop the advanced treatment technology.Galvanized pipe is easy to cause zinc dissolution after long term use.It is recommended to update the old pipe network in time.Overall,drinking water quality of T city is good,long-term drinking will not cause harm to the human health. |
PDF Full Text Request