Spatial Distribution Characteristics and Source Apportionment of Soil PAHs in Shizuishan City Based on GIS and PMF Model

Abstract

With the acceleration of urbanization and industrialization, the content and pollution of polycyclic aromatic hydrocarbons (PAHs) in urban soils have been sources of widespread concern. Taking Shizuishan City as an example, the spatial distribution characteristics of PAHs in 156 surface soil samples (0-20 cm) from eight urban functional areas were analyzed. Single factor and Nemero composite indices, as well as a lifetime cancer risk increment model were used to evaluate PAHs pollution in soils. The sources of PAHs were analyzed using the positive matrix factorization (PMF) model. The results showed that the mean value of PAHs in the surface soil of Shizuishan City was 489.82 ng·g-1 and the coefficient of variation of 15 PAHs except for Pyr were more than 100%, indicating strong variation. The PAH contents of urban surface soils in different functional areas showed the following:traffic area (1217.61 ng·g-1) > industrial area (809.58 ng·g-1) > park (273.66 ng·g-1) > cultural and educational area (268.18 ng·g-1) > commercial area (240.05 ng·g-1) > agricultural area (226.81 ng·g-1) > medical area (211.90 ng·g-1) > residential area (183.49 ng·g-1). The Nemero composite index showed that 82.58% of the samples had no pollution, and the proportion of slight, mild, and moderate pollution were 6.45%, 4.52%, and 0.65%, respectively. Only 5.8% of the samples had serious pollution. The results of health risk assessment showed that skin contact and ingestion were the main routes of PAH exposure in soil, and the health risk was acceptable. Source analysis showed that the main sources of PAHs in Shizuishan City were traffic emissions, coal combustion, mixed biomass/heavy oil combustion, and oil sources, with contribution rates of 10.5%, 36.6%, 50.3%, and 2.6% respectively, and most of the high values were distributed in industrial or coal production areas. These results could provide reference for the study of soil pollution in industrial cities, and play an important role in preventing soil pollution, ensuring the environmental quality of the soil and human health and safety.