基于GIS和PMF模型的石嘴山市土壤多环芳烃空间分布及来源解析

随着城市化和工业化进程加速，城市土壤多环芳烃（PAHs）含量及污染状况受到广泛关注.以石嘴山市为例，分析8个城市功能区156个表层土壤（0~20 cm）样品PAHs含量的空间分布特征，运用单因子指数、内梅罗综合指数和终生癌症风险增量模型评价土壤PAHs污染状况，利用正定矩阵因子分解模型（PMF）对PAHs来源进行解析.结果表明，石嘴山市表层土壤PAHs总含量均值为489.82 ng·g^-1，除芘（Pyr）外的15种PAH单体变异系数均大于100%，属强变异；不同功能区土壤PAHs含量呈现出：交通区（1217.61 ng·g^-1） > 工业区（809.58 ng·g^-1） > 公园（273.66 ng·g^-1） > 文教区（268.18 ng·g^-1） > 商业区（240.05 ng·g^-1） > 农业区（226.81 ng·g^-1） > 医疗区（211.90 ng·g^-1） > 居民区（183.49 ng·g^-1）；内梅罗综合指数显示82.58%的样点不存在污染，轻微、轻度和中度污染占比分别为6.45%、4.52%和0.65%，5.8%的样点存在重度污染；健康风险评价结果表明，皮肤接触和误食是最主要的土壤PAHs暴露途径，其健康风险处于可接受水平；源解析表明石嘴山市土壤PAHs的主要来源为交通排放源、煤炭燃烧源、生物质/重油燃烧的混合源以及石油源，其贡献率分别为10.5%、36.6%、50.3%和2.6%，且高值大多分布在工业或煤炭生产区域.研究结果可为工业城市土壤污染研究提供参考，并对预防土壤污染、保障土壤环境质量及人体健康安全有积极作用.

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

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.