珠江三角洲表层水中多环芳烃的季节分布、来源和原位分配

分别于2011年4月(春季)和2011年9月(夏季)采集珠江广州河段及东江东莞河段表层水体样品,对该区域表层水体中优控多环芳烃(PAHs)的时空分布、固液分配及其来源进行了分析和讨论.结果表明,珠江广州河段及东江东莞河段表层水体中多环芳烃浓度春季高于夏季.藻类有机碳是该水环境有机碳的主要成分.溶解有机碳(DOC)、颗粒态有机碳(POC)以及叶绿素a(Chl a)含量是控制水体PAHs浓度的主要因素,说明水环境的富营养化程度可以通过增长的浮游生物量来影响多环芳烃的生物地球化学过程,继而影响其环境行为和归宿.多环芳烃在水/颗粒物间的有机碳归一化分配系数(log Koc)与辛醇/水分配系数(log Kow)间存在明显的线性关系,其斜率是夏季大于春季,可能与多环芳烃的非平衡吸附有关.多环芳烃同系物比值法和主成分分析(PCA)的结果表明,研究区域水体中PAHs主要来源于石化燃料、煤和生物质的混合燃烧,并且PAHs的来源未体现出明显的季节变化.通过本研究我们能够比较全面的了解该流域多环芳烃的时空分布状况,固液分配及其可能的来源,并且为珠江广州河段及东江东莞河段多环芳烃污染的控制和生态风险评价提供科学依据.

Seasonal distribution, sources, and in-situ partitioning of polycyclic aromatic hydrocarbons in water and suspended particulate matters from the Pearl River Delta

Watet samples were collected from the Pearl River and Dongjing River in April and September 2011. Spatial distribution, partitioning and source of PAHs in this area were examined. Total PAHs concentrations were higher in spring than in summer. Phytoplankton was one of the critical components of organic carbon in the study area. Dissolved organic carbon (DOC), particulate organic matter (POC), and chlorophyll a (Chl a) were critical factors on regulating the distribution of PAHs, suggesting that the eutrophication degree can influence the biogeochemical processes of PAHs by increasing phytoplankton biomass and the environmental behaviors and fate of PAHs. The organic carbon-normalized particle-water partitioning coefficients (logK_oc, mL · g^-1) were significantly correlated to logK_ow for the samples collected in both spring and summer, and their correlation slope was higher in summer than in spring, possibly due to non-equilibrium sorption of PAHs. PAH isomer pair ratios and principal component analysis (PCA) indicated that main sources were petroleum combustion, coal and biomass combustion in the study region. No significant seasonal differences were found in the source of PAHs. This study provided a scientific basis for the control and ecological risk assessment of PAHs in the Pearl River Delta region.