城市不同功能区PAHs多介质累积规律研究

以上海市为例,分析了城市地表灰尘、土壤和行道树叶片累积PAHs的水平差异,探讨了形成这种累积规律的原因与机制.结果发现,同一功能区内,地表灰尘和土壤中PAHs含量较高,分别为8 992～141 723 ng·g-1(均值为54 964 ng·g-1)、9 306～146 689 ng·g-1(均值为56 883 ng·g-1);而悬铃木叶片和小叶黄杨叶片内含量较低,且悬铃木叶片中的含量普遍高于小叶黄杨叶片,含量分别为2 423～32 883 ng·g-1(均值为12 983 ng·g-1)、1 498～19 418 ng·g-1(均值为7 612 ng·g-1).不同功能区之间,地表灰尘和土壤中PAHs总量存在显著差异,而悬铃木叶片和小叶黄杨叶片对PAHs的累积水平相似.灰尘和土壤中PAHs组分构成具有明显的功能区差异,且高环PAHs含量占主导地位.植物叶片中PAHs组分构成在不同功能区具有相似性,且低环组分占绝对优势,高环组分含量很少.这种累积规律与PAHs的理化性质,以及各介质累积PAHs的主要途径和方式密切相关.

Accumulation Characteristics of PAHs in Multimedia from Various Urban Functional Areas

Taking Shanghai city as an example, the study analyzed the difference of concentration levels in road dust, soil and leaves besides roads. The reasons and mechanisms of the accumulation characteristics were also been discussed. The result shows that, in a same functional area, road dusts and soils accumulated more PAHs while leaves did less, and the concentrations of PAHs in P. orientalis L.leaves were higher than those in Buxus sinica leaves. Total PAHs concentrations in road dust and soil ranged from 8 992 ng·g^-1 to 141 723ng·g^-1, averaged in 54 964 ng·g^-1, and from 9 306 ng·g^-1 to 146 689ng·g^-1, averaged in 56 883 ng·g^-1, respectively. Total PAHs concentrations in P. orientalis L. leaves and Buxus sinica leaves varied from 2 423 ng·g^-1 to 32 883 ng·g^-1, with a mean value of 12 983 ng·g^-1, from 1 498 ng·g^-1 to 19 418 ng·g^-1, with a mean value of 7 612 ng·g^-1. Among various functional areas, there were significant differences in PAHs concentrations in road dusts and soils while those in leaves were similarly. PAH homologue concentrations in road dusts and soils had significant difference in various functional areas with the priority of high molecular homologues. However, PAH homologue concentrations in leaves were similarly dominated by low molecular homologues. The accumulation characteristics were closely corresponding with the physicochemical property of PAHs and the main accumulation ways of PAHs in multimedia.