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  • br Moreover BaP also serves as an index chemical for

    2020-08-28


    Moreover, BaP also serves as an index chemical for deriving relative potency factors to estimate the carcinogenicity of other PAH congeners. The total BaPeq of 15 PAHs ranged from 10.3 to 358 ng/g in soil with a mean of 98.3 ng/g dw, and the levels of seven carcinogenic BaPeq ac-counted for above 90% of the total priority PAHs. Compared with the previous studies, as shown in Table 2, the mean value of the Bapeq for the 15 PAHs in this study was higher than the values reported from Novi sad (39 ng/g) of Serbia, Ahvaz (85.3 ng/g) of Iran, and Shanghai
    Table 2
    Concentrations of PAHs (ng/g dry weight) in soil compared to other studies.
    (48 ng/g) of China, Xinzhou (34 ng/g) and the coke production Heparan Sulfate (44.6 ng/g) of Shanxi, China. But it was lower than those in Deli (220 ng/g) of India, Nanjing (130 ng/g) of China, Changzhi for in-dustrial district (432 ng/g) and agricultural soil (151 ng/g), and Southeast of Shanxi (459 ng/g) nearby chemical plants in Shanxi, China. Overall, Shanxi suffered severely from heavy contamination of PAHs at industrial area while it was in the contaminated level at agri-cultural areas.
    3.2. Potential emission sources
    The isomer rations have been shown as a useful indicator of PAH source (Yunker et al., 2002). Four diagnosis ratios, Ant/(Ant + Phe) vs Fla/(Fla + Pyr) and BaA/(BaA + Chr) vs IcdP/(IcdP + BghiP), were chosen for the soil source in the present study (Tobiszewski and
    Country Area Soil type Sample PAHs Mean (Range) BaPeq Mean a (Range) Reference
    Beijing Rural
    a BaPeq: Benzo[a]pyrene equivalent concentrations.
    b Not reported.
    c nd: Not detected.
    d 7C: BaPeq based on 7 carcinogens.
    Fig. 2. Diagnostic ratios for source analysis of PAHs from the surface soil in Shanxi, China.
    There are two types of anthropogenic sources of PAHs: petrogenic and pyrogenic. The ratios of Ant/(Ant + Phe) and BaA/(BaA + Chr) are often used to distinguish between pyrogenic and petrogenic sources. The values of Ant/(Ant + Phe) < 0.1 and BaA/(BaA + Chr) < 0.2 correspond to petrogenic sources. In the present study, all the Ant/ (Ant + Phe) ratios were > 0.1 (Fig. 2A) and most of BaA/(BaA + Chr) ratio > 0.1 except for two site (Fig. 2B), indicating that pyrogenic sources were the primary source of PAHs in the surface soil from Shanxi province, China.
    Moreover, the ratios of Fla/(Fla + Pyr) and IcdP/(IcdP + BghiP) are also used to distinguish the polluted sources. The value of Fla/ (Fla + Pyr) < 0.4 indicates petrogenic sources, and the value 0.4–0.5 is for fossil fuel combustion and > 0.5 is for grass, wood, and coal combustion. Similarly, the value of IcdP/(IcdP + BghiP) < 0.2 in-dicates petrogenic sources, and the value 0.2–0.5 is for petroleum combustion and > 0.5 is for grass, wood, and coal combustion. As shown in Fig. 2, for the 28 of these 33 sites, the values of Fla/ (Fla + Pyr) are greater than 0.5; for the 27 of these 33 sites, the ratios of IcdP/(IcdP + BghiP) are greater than 0.5. In addition, the ratio of low molecular-weight/HMW (LMW/HMW) can also be used as an in-dicator for the source identification. All of the LMW/HMW ratios were > 0.1, suggesting that the pyrogenic was the primary source of  Ecotoxicology and Environmental Safety 182 (2019) 109381
    PAHs. Since some isomeric ratios can indicate the mixed and contra-dictory results for source identification, the interpretation of such re-sults should integrate the other information and local investigations. The results from the ratios were consistent with four diagnosis ratios, suggesting that pyrogenic sources from the combustion of grass, wood, and coal were the main pollution sources in the surface soil from Shanxi. This could be explained by the fact that coal is still the main energy source in Shanxi. The main source of PAHs in soil is atmospheric deposition (Bozlaker et al., 2008), while coal burning is a significant air pollution source, with global, regional and local impacts on air quality, public health and climate (Chen et al., 2017). Therefore, the restriction of coal burning and the natural gas for substitution will be imperative in the future.
    3.3. Cancer risk of PAHs via ingestion, dermal and inhalation
    Table 3
    Total incremental lifetime cancer risks (ILCR) of soil contaminated by PAHs for humans via inhalation, dermal contact, and ingestion based on the BaP equivalents. ILCR is presented as the number of expected cases in excess Heparan Sulfate of 1 in a million (10−6).
    No. Sites Childhood
    Adolescence Adulthood
    Male Female Male Female Male Female
    Table 4
    The analysis of variance for the total incremental lifetime cancer risk (ILCR) among the 11 cities. ILCR is presented as the number of expected cases in excess of 1 in a million (10−6).