Concentration And Health Risk Assessment Of Polycyclic Aromatic Hydrocarbons(PAHs) In Suburban Vegetable Soils From Changchun City

Most of Polycyclic Aromatic Hydrocarbons(PAHs) compounds are regarded as hard-degraded and carcinogenicity, and they could be accumulated in body and harmful to human health through the food chain. With the rapid development of industry, lots of PAHs compounds entered into the agricultural soils in suburban areas of industrial city through various ways and caused serious pollution problems by long-term accumulation. Vegetable is one of the important economic plants in suburban farming. Studies of the pollution levels, distributing characteristics and health risk of PAHs are crucial for the safe vegetable production and human health.In this study, we choosed suburban vegetable soils of Changchun City as the research subject and investigated the contents, sources, and distributing characteristics of 16 kinds of PAHs compounds in soils through field investigation, field sampling and laboratory analysis. Besides, according to the Environmental Quality Standard for Soils(GB15618—2008), Risk Assessment Guidance for Superfund Volume I Human Health Evaluation Manual(EPA/540/1-89/002) and Technical guidelines for risk assessment of contaminated sites(HJ 25.3—2014), the pollution levels and health risk of 16 PAHs compounds were classified and evaluated, respectively. The main results of this study are as follows:(1) The total content of 16 PAHs compounds in the suburban vegetable soils from Changchun is 20642.91 μg·kg-1, which is markedly higher than the other cities from China. The average contents of 16 PAHs compounds follow the order of Chrysene(CHR)>Benzo[ghi]perylene(Bghi P)>Pyrene(PYR)>Benz[a]anthracene(Ba A)>Phenanthrene(PHE)>Benzo[k]fluoranthene(Bk F)>Fluoranthene(FLA)>Benzo[a]pyrene(Ba P)>Benzo[k]fluoranthene(Bb F)>Indeno[1,2,3-cd]pyrene [1,2,3-cd](Icd P)>Anthracene(ANT)>Dibenz[a,h]anthracene(Dah A)>Fluorene(FLO)>Acenaphthylene(ACY)>Acenaphthene(ACE)>Naphthalene(NAP).(2) The contents of 4~6-rings accounted for more than 90% of the total PAHs compounds content in the suburban vegetable soils from Changchun, which were mainly from the burning of woods, coals, and macromolecule compounds. The spatial distribution of PAHs compounds had much difference because of human activities and weather conditions.(3) The average contents of 16 PAHs compounds exceeded national secondary standard variously, and the order of over-standard rate is as follow: Ba A > CHR > Ba P > Bghi P > Bb F > Icd P > Dah A = PYR > Bk F > PHE > FLA. Among the compounds 11 kinds of PAHs were in light pollution, expecially for Ba A and CHR, the rates of polluted soils were 82.4% and 80.4%, respectively.(4) The order of exposure risk indexes of 16 PAHs compounds for different pathways was: Orally> Cutaneously > Inhalation. Among the 16 PAHs compounds, the Hazard Indexes(HI)of 9 non-carcinogenic PAHs compounds were much lower than 1, indicating none carcinogenic hazards for these compounds. Besides, the cancer indexes(CI) of 6 carcinogenic PAHs compounds were lower than 10-6 lower accept for Ba A with the values between 10-6 and 10-4, but the cancer risk of these 7 compounds were at the acceptable level.