Level, Source Apportionment And Ecological Risk Assessment Of Polycyclic Aromatic Hydrocarbons In Soils From Shanghai

Polycyclic Aromatic Hydrocarbons (PAHs) are persistent organic pollutants(POPs) which are widespread in different environment mediums. PAHs are also thecarcinogens with the largest quantities and which are earliest discovered in nature sofar. Most of them have teratogenicity, carcinogenicity and mutagenicity. POPs in soilmay contaminate the air, surface water and underground water by volatilization,diffusion and transfer. They easily accumulate in organism by bioconcentration andbiomagnification, and finally endanger the health of human beings. Thecontamination levels, spatial distribution, isomeric composition, possible sources andpotential ecological risk of26PAHs from238soil samples in Shanghai weresystematically investigated. The study aimed to understanding the soil contaminationstatus and potential risk posed by PAHs in Shanghai, and to providing the scientificbasis for pollution control and management of PAHs. The main conclusions aresummarized as follows:1. A total of27soil samples collected in Chongming areas of Shanghai, Chinawere analyzed for26PAHs including highly carcinogenic dibenzopyrene isomers.The total concentrations ranged from37.5to1280μg kg-1for Σ26PAHs and27.2to1010μg kg-1for Σ16PAHs, with mean values of271and216μg kg-1, respectively.Most soils were detected lower concentrations, and a small number of soils withhigher concentrations were found in trunk road with heavy traffic. The compositionpattern of PAHs was characterized with high molecular weight PAHs. The correlationanalysis showed that the concentrations of the total PAHs were not significantlycorrected with soil TOC, except a few low molecular weight PAHs had a weakcorrelation with TOC. The source analysis indicated that the PAHs in Chongming soilwere mainly derived from combustion concluding vehicular emission, coal andbiomass combustion. The risk assessment of PAHs showed that most soils PAHsexposure was in a safe range.2. A total of57soil samples collected in main urban areas of Shanghai, Chinawere analyzed for26PAHs including highly carcinogenic dibenzopyrene isomers.The total concentrations ranged from133to8650μg kg-1for Σ26PAHs and83.3to7220μg kg-1for Σ16PAHs, with mean values of2420and1970μg kg-1, respectively.PAHs isomeric ratios, PCA/MLR and PMF indicated that PAHs in urban soils fromShanghai originated mainly from combustion. DB[a,l]P and DB[a,e]P may serve as markers for diesel vehicle emission, while DB[a,h]P is a probable marker of coke taras distinct from diesel emissions. The risk assessment suggested that soil PAHscarcinogenic potential merited attention at present contamination level in urban areas.The carcinogenic potencies of Σ4DBPs made up higher contributions of total potencyequivalents.3. A total of154soil samples collected in suburban areas of Shanghai, Chinawere analyzed for26PAHs including highly carcinogenic dibenzopyrene isomers.The total concentrations ranged from25.1to7280μg kg-1for Σ26PAHs and18.8to6320μg kg-1for Σ16PAHs, with mean values of961and807μg kg-1, respectively.PAHs isomeric ratios, PCA/MLR and PMF indicated that PAHs in suburban soilsfrom Shanghai originated mainly from combustion, and some soils originated fromcoking industry. The risk assessment suggested that soil PAHs carcinogenic potentialmerited attention at present contamination level in suburban areas.