| Objective:In recent years,more and more attention has been paid to ambient fine particulate matter(PM2.5)pollution.Except the negative influence on atmospheric visibility,the inhalation risk of fine particulate matter(PM2.5)to human health should not be ignored.As an important building materials productive city in China,with highly developed petrochemical industry and pharmaceutical enterprise,Zibo was among the cities with large pollutant emission amount in spatial distribution.In order to find the characteristics of ambient pollution from September 2016 to December 2018 in Zibo city,the concentrations of PM2.5,water soluble inorganic ions and metallic elements were detected in this study.The inhalation exposure and risk assessment of metallic elements in ambient PM2.swere carried out by using US EPA Health Risk Assessment Modal.The causes and prevention measures of haze were explored for the future work of environmental management.Methods:Two sampling sites were set up.The sampling site in Zhangdian District was located in the downtown area with developed transportation and trade around.The sampling site in the High-tech District was located in the suburbs,designated as control area.From the tenth day to the sixteenth day of each month,a total number of 390 atmospheric PM2.5 samples were collected from the roof of a 15-meter high building in Zhangdian District and the High-tech District respectively from September 2016 to December 2018.The concentrations of PM2.5,water soluble inorganic ions and metallic elements were detected through weighing method,ion chromatography and inductively coupled plasma mass spectrometry respectively.Excel 2007 was used to build the database,and SPSS 18.0 was used for statistical analysis.Results:1.During the whole research period from September 2016 to December 2018,there was no significant difference in the average concentrations of PM2.5 between two districts,with a concentration of 83.6 ?g/m3 in Zhangdian District and 85.4 ?g/m3 in the High-tech District.The concentration of As in Zhangdian District was 10.5 ng/m3,higher than 7.5 ng/m3 of the High-tech District(P<0.05).The concentration of Cd in Zhangdian District was 3.1 ng/m3,higher than 2.8 ng/m3 of the High-tech District(P<0.05).The concentration of Sb in Zhangdian District was 3.0 ng/m3,higher than 2.3 ng/m3 of the High-tech District(P<0.05).However,the concentration of Al in the High-tech District was 244 ng/m3 higher than 215 ng/m3 of Zhangdian District(P<0.05).2.The average concentrations of PM2.5 in two districts were both above 120?g/m3 in the autumn and winter of 2016,after that the average concentrations of PM2.5 in two districts were both below 90 ?g/m3 in 2017 and 2018.The concentration of PM2.5 was relatively higher in winter and spring,compared to it in summer and autumn.The average concentration of PM2.5 of Zhangdian District in 2017 and 2018 were respectively 2.3 times and 1.9 times of the annual PM2.5 concentration limit of 35 ?g/m3 in China.The average concentration of PM2.5 of Zhangdian District was 79.5?g/m3 in 2017,ranging from 11 ?g/m3?307 ?g/m3,while it was 66.9 ?g/m3 in 2018,ranging from 21 ?g/m3-248 ?g/m3.According to the PM2.5 daily guidelines of 75 ?g/m3,the occurrence rates of exceeding were 42.2%and 27.4%respectively.3.The average concentration of PM2.5 and its components from September to December of 2017 was the lowest in the year 2016,2017and 2018.The average concentration of PM2.5 in September,October and November were all above 140?g/m3 in 2016,and decreased to less than 80 ?g/m3 in 2017,finally increased to less than 100?g/m3 in 2018,showing a trend of decreasing rapidly and then increasing slowly.4.Water soluble inorganic ions are the main components of PM2.5 in Zhangdian District.Their total mass concentration ranges from 19.6 ?g/m3 to 63.3 ?g/m3,with a proportion ranging from 39.7%to 55.1%.During the research period,as the top three ions,the average concentrations of NO3-,SO42-,NH4+ were 13.4 ?g/m3,12.8 ?g/m3 and 10.3 ?g/m3,respectively.The proportion of SO42-in PM2.5 in summer was the highest,while the proportion of NO3-in PM2.5 in summer was the lowest,thus leading to a ratio of NO3-versus SO42-far below 1 in summer.5.The concentration of A1 was the highest in the 11 elements of Sb?Al?As?Cd?Cr?Hg?Pb?Mn?Ni?Se?T1 in the research,and was apparently higher in spring than it in other seasons.Followed by the concentration of Pb,which showed characteristics of relatively higher in winter and lower in summer,decreasing year by year.6.The chronic non-carcinogenic risk of As is relatively higher,followed by Mn.Both of their hazard quotient(HQ)were very close to 1.The lifetime carcinogenic risk of As is relatively higher(10-5),followed by Cd(10-6).7.Enrichment factor analysis showed that the enrichment factors of Ni,Mn and Cr were between 10 to 20,reminding that Ni,Mn and Cr were affected by both natural sources and anthropogenic pollution.The enrichment factors of Cd,Se,Pb,Sb,T1 and As were all higher than 100,indicating that these elements were seriously affected by anthropogenic pollution.Conclusions:1.The concentration of As,Cd,Sb in PM2.5 of Zhangdian District was higher than it in the High-tech District.However,as the control area,the concentration of Al in PM2.5 of the High-tech District was higher than it in Zhangdian District,the downtown area.It showed that the construction of Zibo high speed railway north station increased the concentration of A1 in the atmosphere.More attention should be paid to the prevention and control of dust pollution at the construction site and the surrounding areas.2.In Zibo city,during the research period the average concentration of PM2.5 from September to December of 2016 was the highest,it decreased in 2017 and 2018,but still far above the yearly guidelines of 35,g/m3.We still have a long way to go in the prevention and control of PM2.5.3.We should vigorously develop public transportation and encourage people to choose green and environment-friendly ways to travel,so as to reduce PM2.5 pollution caused by vehicle exhaust in spring autumn and winter.4.The chronic non-carcinogenic risk of As and Mn is relatively higher,the lifetime carcinogenic risk of As and Cd is relatively higher.That should be pay more attention.5.The consumption of coal is directly related to PM2.5 and its components'concentrations.The establishment of corresponding limits in laws and the implementation of environmental protection measures,together with the development of pollutant removal technology will decrease the emission of pollutants.We should continue to develop coal utilization technologies cleanly and efficiently and accelerate the pace of new energy sources development and utilization. |
PDF Full Text Request