| Taiyuan is currently facing a serious problem of ambient PM2.5 pollution.Due to the small particle size and the complex compostion of PM2.5,which it is more likely to enter the body to affect people's health,it was regarded as the main study object.This paper focused on study volatile arsenic and mercury and polycyclic aromatic hydrocarbons of PM2.5.PM2.5 samples were collected on filters during day-night in different seasons.We determined the contents of arsenic?mercury and PAHs by using atomic fluorescence spectrophotometer and high performance liquid chromatography with fluorescence-ultraviolet detector?HPLC-FLD?.This paper adopted ratio method,enrichment factor method,backward trajectory,Monte Carlo simulation,lifetime cancer risk assessment?ILCR?and life expectancy loss?LL?and so on to conduct health risk assessment,with results providing scientific support for city management and supplying data for the study on the relationship between environment and health.The main results are as follows:1.Results of total content of arsenic and mercury of PM2.5 in winter showed that the concentrations of total mercury and arsenic value were 1.52 ± 0.80 ng/m3 and 34.58 ± 17.66 ng/m3,respectively.Correlation analysis of PM2.5,total arsenic and total mercury and meteorological factors and statistical test results showed that other factors were negatively correlated to wind speed?P<0.05?;there was no significant correlation between relative humidity and PM2.5?P>0.05?;relative humidity had significant relationship to total arsenic and mercury concentrations?P<0.05?.There was a significant difference between the diurnal concentration of total arsenic and mercury?P<0.05?,and concentrations during the night was higher than the daytime,indicating that coal combustion was the main source of arsenic and mercury.2.The bioavailability analysis of different forms of arsenic and mercury showed that organic matter bound state of arsenic had the highest ratio and the proportion of residue state was lowest; Fe-Mn oxides bound state of mercury had the had the highest ratio and the proportion of exchangeable state was lowest.The Potentially available state of arsenic and mercury had the highest ratios.The biological activity coefficients of arsenic and mercury were 38.11%and 33.02%,which has a strong physiological activity.The carcinogenic and non carcinogenic risk evaluation of arsenic and Mercury indicating that they would not cause carcinogenic effect.The source analysis showed that pollution comes mainly from anthropogenic pollution sources,and coal combustion and vehicle exhaust were regarded as the main pollution sources.3.The results of average concentrations of EPAHs in different seasons showed that they were ranged from 10.36 ng/m3 to 215.93 ng/m3,with concentrations during the night was higher than the daytime.There was a significant difference between the diurnal concentration of PAHs in spring?autumn and winter?P<0.05?.The distribution of different categories of PAHs exhibited strong seasonal variation:4-ring PAHs were dominant in spring and winter,and percentages of 5-ring and 6-ring PAHs were higher in summer and winter.The results of ratio method showed that the main PAH sources are coal and wood combustion and vehicle emissions.The hybrid single-particle lagrangian integrated trajectories?HYSPLIT?model was used to back trace air masses on different representative days,with results indicating that long-range transportation will have a certain impact on the concentration of polycyclic aromatic hydrocarbons.Finally,a risk assessment of PAHs was performed based on BaPeq values and individual cancer risk ratios,with results suggesting that the toxicity of PAHs was high during winter and spring time in Taiyuan.The values of incremental lifetime cancer risk?ILCR?showed that PAHs in winter and spring had a certain impact on human health.The Sensitivity analysis showed that particulate phase concentrations of each individual PAH?Cp?and exposure duration?ED?were the most influential variables for all three age groups in inhalation exposure;the dermal adsorption fraction?AB?and the particle-to-skin adherence factor?AFd?were the most influential variables for all three age groups in dermal contact exposure;The results of LL showed that values of male and female adults were higher in winter.In summary,we should pay more attention to arsenic,mercury and polycyclic aromatic hydrocarbons in Taiyuan,with the biological activity coefficients of arsenic and mercury were relative high and PAHs had potential carcinogenic risk.It is necessary to take effective measures to remove the above pollutants to reduce the environmental emissions of arsenic,mercury and PAHs. |
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