Pollution Characterization, Source Apportionment And Health Risk Assessment Of Polycyclic Aromatic Hydrocarbons In Airborne Particulate Matters

The particulate-bound polycyclic aromatic hydrocarbons?PAHs?,has led to the eager research in academia due to its great threaten to human health.Given the current situation and deficiency of particulate-bound PAHs,this study would conduct several works as follows:First of all,in the case of the application of ultrasonic extraction technolog y to PAHs extraction from environmental samples,this study investigates the effects of extraction solvents and time on the extraction efficiency of PAHs.The results show that,binary solvents have better PAHs extraction performance than single solvents.For those extracted out PAHs,three of the single solvent provide average recovery rate of PAHs as 48.38±61.97%,34.03±21.92%,67.66±60.76%,respectively.In the application of three of the single solvents,the ratio of 5+6-ring PAHs to the total PAHs is 46%,which is the highest,followed by 4-ring PAHs and then 2+3-ring PAHs.In the case of binary solvent,among the various series of binary solvent combination,n-hexane/DCM?1:1,v/v?,DCM/acetone?3:1,v/v?,acetone/n-hexane?3:1,v/v?provides better recovery rates as 112.08±39.23%,89.39±58.55%,68.04±59.68%,respectively.When applying binary solvent,the relationship among ratios of PAHs with different ring numbers to the total PAHs are as follows:5+6-ring PAHs>2+3-ring PAHs>4-ring PAHs.When using different volumes of extraction solvent?30 mL,45 mL,60 mL?,the extraction efficiency of PAHs are as follows:86.83±60.04%,78.42±66.46%,86.58±63.77%.When applying different extraction time?2 circles,4 circles,and 6 circles?,the extraction efficiencies of PAHs are as follows:89.34±72.13%,77.21±59.98%,85.01±53.03%.Secondly,with regard to particulate pollution and particulate-bound organic pollution in the regional atmospheric environment,this study selects the Anderson Type Non-viable particulate sampler designed based on particulate cumulation mechanism of human respiratory system(eight stage sampler?the zeroth sampling stage,S0;the first sampling stage,S1;...;the seventh sampling stage,S7?and an auxiliary stage sampler(the F^th sampling stage,SF))to collect air particulates.With the particulate sampler,this study plants to recognize the concentration level and size distribution of particulate and particulate-bound PAHs.A.During the sampling period,the PM₁₀-bounded and PM_2.1-bounded 15PAHs has the average concentration as 9.45±2.95 ng/m³,6.30±1.22 ng/m³.Specifically,air particulate with particle size between 1.1-2.1?m?S5?collects the highest PAHs concentration.In terms of PM₁₀,the relationship between the ratios of PAHs with different ring numbers to the total PAHs as follows:3-ring PAHs>5+6-ring PAHs>4-ring PAHs.The ratios relationship of PAHs with different ring numbers to the total PAHs in PM_2.1.1 has the similar rule,but the ratio of 4-ring PAHs to the total PAHs decreased and 3-ring PAHs to the total PAHs increased.3-ring PAHs distributed in nine ranges of particle sizes is in the form of unimodal characteristic and the concentration of it peaks at the air particulate with particle size between 9.0-10.0?m?S0?.4-ring PAHs show unimodal characteristic among the various particle sizes and peaks at 0.65-1.1?m?S6?while5+6-ring PAHs show bimodal characteristic and peaks at 1.1-2.1?m?S5?and 0.65-1.1?m?S6?.The results indicated that PAHs with lower aromatic rings prefer to distribute among coarse particulate while PAHs with higher aromatic rings intended to cumulate among fine particulate.Thridly,with regard to the PAHs concentration in diverse air particulate,this study conducts source apportionment for particulate-bound PAHs and further investigate the effects of gas/particulate partitioning on the PAHs source apportionment.The results of positive matrix factorization?PMF?model show that particulate-bound PAHs have four major pollutant sources and their contribution ratios as follows:biomass burning source?9.58%?,coal combustion source?10.60%?,vehicle emission source?59.66%?and“air-surface exchange”source?20.16%?.The total PAHs?measured particulate-bound PAHs and calculated gas-phase PAHs?have three major pollutant sources and their contribution ratios as follows:biomass burning source?93.33%?,coal combustion source?0.06%?and vehicular emission source?6.61%?.The sourse apportionment results of the total PAHs did not reported the fourth pollute source since it considered the gas/particulate partitioning.Though relative analysis,biomass burning source had low corelation between the two data since it often exhaust low-ring PAHs.These results indicated that it is necessary to apply both particulate-phase PAHs concentration and gas-phase PAHs concentration to the source apportionment with the consideration of gas/part iculate partitioning.Fourthly,from the starting point of reconginzing the effect sof particulate-bound PAHs on the health of human respiratory system,this study analyzes the health risk assessment of PAHs distributed among air particulate with diverse p article sizes to human respiratory system.The results show that,during sampling period,the 85-h average total BaPeq of seven carcinogenic PAHs among all the sampling stages is5.18 ng/m³ and peaks at air particulate with particle sizes between 0.65-3.3?m?S4?S5?S6?.This study also conducts incremental life cancer risk?ILCR?among diverse age group?children?1-12 years old?,teenager?13-19 years old?and adult?20-79years old??and gender group?male and female?.PAHs distributed at air particulate matter with particle size between 0.65-2.1?m?S5?S6?had the ILCR value higher than 10^-5,indicating the potential carcinogenic risk to human inhalation health.In the case of age,the ILCR values of PAHs follow the sequence as:adult>teenager>children.In the case of gender,female has higher ILCR values of PAHs than male.Therefore,in the regional environment the concentration of PAH is high on the atmospheric particles,and causes a threat on human respiratory system due to the distribution of particle size.In the process of its source apportionment,the factor of gas/particulate partitioning is crucial and inclusive,in favor of veritable scientific foundation for environmental administrator.