Gao Yanzheng, Xiong Wei, Ling Wanting, Xu Jianming
College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
Chemosphere. 2006 Nov;65(8):1355-61. doi: 10.1016/j.chemosphere.2006.04.030. Epub 2006 Jun 2.
The fate of polycyclic aromatic hydrocarbons (PAHs) in soils with co-contaminants of heavy metals has yet to be elucidated. This study examined sorption of phenanthrene as a representative of PAHs by three soils contaminated with Pb, Zn or Cu. Phenanthrene sorption was clearly higher after the addition of heavy metals. The distribution coefficient (K(d)) and the organic carbon-normalized distribution coefficient (K(oc)) for phenanthrene sorption by soils spiked with Pb, Zn or Cu (0-1000 mg kg(-1)) were approximately 24% larger than those by unspiked ones, and the higher contents of heavy metals added into soils resulted in the larger K(d) and K(oc) values. The enhanced sorption of phenanthrene in the case of heavy metal-contaminated soils could be ascribed to the decreased dissolved organic matter (DOM) in solution and increased soil organic matter (SOM) as a consequence of DOM sorption onto soil solids. Concentrations of DOM in equilibrium solution for phenanthrene sorption were lower in the case of the heavy metal-spiked than unspiked soils. However, the decreased DOM in solution contributed little to the enhanced sorption of phenanthrene in the presence of metals. On the other hand, the sorbed DOM on soil solids after the addition of heavy metals in soils was found to be much more reactive and have far stronger capacity of phenanthrene uptake than the inherent SOM. The distribution coefficients of phenanthrene between water and the sorbed DOM on soil solids (K(ph/soc)) were about 2-3 magnitude larger than K(d) between water and inherent SOM, which may be the dominant mechanism of the enhanced sorption of phenanthrene by soils with the addition of heavy metals.
多环芳烃（PAHs）在受重金属共同污染的土壤中的命运尚未阐明。本研究考察了作为PAHs代表的菲在三种被铅、锌或铜污染的土壤中的吸附情况。添加重金属后，菲的吸附明显增强。添加铅、锌或铜（0 - 1000 mg kg⁻¹）的土壤对菲吸附的分配系数（K(d)）和有机碳归一化分配系数（K(oc)）比未添加的土壤大约高24%，并且土壤中添加的重金属含量越高，K(d)和K(oc)值越大。在重金属污染土壤中菲吸附增强的原因可能是溶液中溶解有机物（DOM）减少以及由于DOM吸附到土壤固体上导致土壤有机质（SOM）增加。在菲吸附的平衡溶液中，添加重金属的土壤中DOM的浓度低于未添加的土壤。然而，溶液中DOM的减少对金属存在下菲吸附增强的贡献不大。另一方面，发现土壤中添加重金属后吸附在土壤固体上的DOM比固有SOM更具反应性且对菲的吸附能力更强。水与吸附在土壤固体上的DOM之间的菲分配系数（K(ph/soc)）比水与固有SOM之间的K(d)大约大2 - 3个数量级，这可能是添加重金属后土壤对菲吸附增强的主要机制。
