Pollution Characteristics and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Agricultural Soils of Different Land Use Types in Nanjing Suburbs

Abstract

In order to clarify the pollution characteristics of PAHs in suburban agricultural soils, the content of 16 types of PAHs was measured in agricultural soils with different land use types (paddy fields, vegetable fields, and forest land) in the suburbs of Nanjing. The results showed that acenaphthene (Acy) was not detected in any soil samples. The concentration of 15 PAHs in agricultural soil in suburban Nanjing ranged from 24.49 to 925.54 μg·kg-1, with an average concentration of 259.88 μg·kg-1. In different land use types, the order of PAHs concentration in soil from high to low was:forest land>paddy fields>vegetable fields, and the high-ring PAHs content was dominant in general. The effects of different soil physicochemical properties on PAHs showed that there was a certain correlation between soil organic carbon (TOC) and clay (clay) content and PAHs, whereas pH and total nitrogen (TN) had no significant correlation with PAHs. The toxic equivalence method and CSI index method were used for ecological risk assessment, which showed that the ecological risk of PAHs in agricultural soils in suburban Nanjing was relatively small; however, the ecological risk of PAHs in forest land should be given some attention, and supervision should be strengthened. Health risk assessment using incremental lifetime cancer risk (ILCR) showed that the threat to the health of children was slightly greater than that of adults, and the CR of forest land was significantly higher than that of vegetable and paddy fields, though still within an acceptable range. Uncertain health assessments were performed in adults, showing that risk analyses of deterministic health risks underestimated the health risks of PAHs. The results of sensitivity analysis showed that the input parameter that had the greatest impact on the total variance of the total carcinogenic risk CR was the exposure frequency EF (50.7%), followed by the pollutant concentration CS (43.3%).