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

Pollution Characteristics and Source Analysis of PAHs and Oxy-PAHs in Yangtze Estuary and Paddy Fields

富集在土壤和沉积物中的多环芳烃(PAHs)及其氧化多环芳烃(Oxy-PAHs)会通过食物链影响人体健康。土壤修复过程中母体PAHs的减少会造成更具毒性、迁移性和生物有效性的Oxy-PAHs浓度增加,从而造成生态健康风险评价结果的低估。通过采集长江口滩涂沉积物和稻田土壤,分析PAHs和Oxy-PAHs的污染特征及其影响因素,利用比值法和主成分分析法来判别污染物的主要来源。结果表明,长江口沉积物中16种PAHs的浓度范围为124.9~259.9 ng/g,均值为194.8 ng/g,而稻田土壤中PAHs的浓度范围为43.5~229.8 ng/g,平均值为113.2 ng/g。沉积物和稻田土壤中11种Oxy-PAHs的浓度范围分别为97.7~231.4 ng/g和87.9~137.2 ng/g。表层沉积物和土壤中PAHs与Oxy-PAHs的浓度分布具体表现为:自然滩地>长期稻田>围垦区>短期稻田。人类开发时间的长短所导致的垂向淋洗、微生物降解、植被吸收转化和外源输入的不同是造成长江口沉积物及稻田土壤中PAHs及Oxy-PAHs浓度空间分布差异的重要原因。相关性分析表明,粒径组成、有机碳含量、pH等不是沉积物中PAHs与Oxy-PAHs浓度的主要影响因子。土壤中PAHs浓度受含水率、TOC和颗粒较细的黏粉粒占比以及氧化还原电位(Eh)影响显著。判源结果表明,沉积物和土壤中PAHs主要来源于化石燃料及生物质的燃烧,土壤中PAHs的来源更加复杂多样,汽车尾气排放和焦化等工业排放对土壤PAHs污染的贡献不容忽视。

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.