Pollution Patterns, Sources And Sinks Of PAHs In Air Of Hangzhou

Polycyclic aromatic hydrocarbons (PAHs)are a kind of widespread persistentorganic pollutants in environment.They are mainly from the uncompletedcombustion of organics,and have the carcinogenic property to humans.In order tocontrol PAH pollution in air efficiently,it is necessary to obtain the occurrences,sources and sinks for PAHs in air.In the dissertation,pollution level,phasedistribution,health risk and influence of life styles for PAHs in indoor (includingpublic places and residential homes)air in Hangzhou were investigated.Emissionamounts and fingerprints of the typical PAH sources such as cigarette smoke,mothball,candle smoke and straw smoke were studied.Furthermore,patterns andsources of PAHs in dry and wet deposition including dust,rain and snow werediscussed,and PAH deposition fluxes in Hangzhou were estimated.The mainconclusions of the dissertation were as follows:1.Concentrations of 15 PAHs in air of public place such as shopping center,supermarket,station,hotel and temple were 1.55-36.5μg/m³ in spring and summer.PAHs were mainly in vapor phase (98±1.4%),and particulate PAHs mainlydistributed on PM_2.5,which accounted for 71.3±10.1% of total particulate phase,andfollowed by PM_2.5-10fraction (17.6±9.1%)and PM＞10 fraction (11.1±5.8%).Naphthalene (NA)was the largest contributor to the total health risks associatedwith the inhalation of PAHs (62.4%).In addition,the average contribution of vaporphase,PM_2.5fraction,PM_2.5-10fraction and PM＞10 fraction to total health risks were79.3%,18.4%,1.4% and 0.9%,respectively.2.Concentrations of 16 PAHs in residential air were 0.425-36.2μg/m³ insummer and winter.The ratios of total PAH concentrations in summer to those inwinter were 1.5-14.6.PAH pollution levels:kitchen＞bedroom＞work room＞living room.Concentrations of total PAHs in smoking residential air were 2.3 timeshigher than those in nonsmoking residential air.In nonsmoking residences,mothballemission,cooking practice and unknown source (may be background concentrations)were the sources of indoor PAHs,however outdoor environment was the fate ofindoor PAHs,and they accounted for 71.5±2.2%,32.8±21.4%,6.2±2.0% and-10.5±2.5% of PAHs in residential air,respectively.3.Emission amounts,influence factors and fingerprints of the typical PAHsources were studied.Emission amounts of 16 PAHs in cigarette smoke,candlesmoke,rice and bean straw smoke were 6109 ng/cig,101-141μg/kg,14.4-16.1μg/gand 4.57-10.7μg/g,respectively.Concentrations of NA in mothball were nd-255 μg/g.NA was the most abundant one in cigarette smoke,candle smoke and strawsmoke,which accounted for 40.2%,76.0% and 35.1% of total PAH concentrations,respectively.3-ring PAHs accounted for 35.3%,17.7% and 46.5% of total PAHconcentrations in these sources,respectively.4.PAHs in rain and snow were mainly from the particles in air.The estimateddry and wet deposition fluxes of PAHs in Hangzhou were 233 kg/yr and 462 kg/yr,respcetively.