长江口滩涂沉积物及稻田土壤 PAHs 和Oxy-PAHs 的污染特征及来源解析

Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated polycyclic aromatic hydrocarbons (Oxy-PAHs) enriched in soil and sediment can affect human health through the food chain. The reduction of parent PAHs during soil remediation can lead to an increase in the concentration of Oxy-PAHs, which are more toxic, migratory, and bioavailable, resulting in an underestimation of ecological health risk assessment results. The pollution characteristics and influencing factors of PAHs and Oxy-PAHs in tidal flat sediment and paddy field soil from the Yangtze Estuary were analyzed in this study. The ratio method and principal component analysis were used to identify the main sources of pollutants. The results showed that the total concentration of 16 PAHs in sediments ranged from 124.9 ng/g to 259.9 ng/g, with a mean value of 194.8 ng/g, while the total concentration was 43.5-229.8 ng/g, with the mean value of 113.2 ng/g in soils. The total concentration of 11 Oxy-PAHs was 97.7-231.4 ng/g and 87.9-137.2 ng/g in sediments and soils, respectively. The total concentration of PAHs and Oxy-PAHs in sediments and soils were ranked as: natural beaches> long-term paddy fields> reclamation areas> short-term paddy fields. The differences in vertical leaching, microbial degradation, vegetation absorption and transformation, and exogenous input caused by the duration of human development were the most important reasons for the deviations in the spatial distribution of PAHs and Oxy-PAHs concentrations in the Yangtze Estuary sediments and rice field soil. Correlation analysis showed that particle size composition, organic carbon content, and pH were not the main influencing factors for the concentrations of PAHs and Oxy-PAHs in the sediments. The concentration of PAHs in soil was significantly affected by the water content, TOC and the proportion of fine mucous powder particles, and redox potential (Eh). The results showed that PAHs in sediments and soils were mainly from the combustion of fossil fuels and biomass, and the sources of PAHs in soil were more complex and diverse, and the contribution of industrial emissions such as automobile exhaust and coking production could not be ignored.