Effects of co-existing Cu(Ⅱ)on the speciation of phenanthrene in aging soils
In order to understand the environmental behaviors of PAHs in heavy metal-PAHs co-contaminated soils,4 representative soils in China were selected to investigate the effects of Cu(Ⅱ)at a high content of 1 000 mg·kg-1 on the aging behaviors of phenanthrene(0-360 d).The results showed that the content of the stable-absorbed fraction of phenanthrene in sterilized soils increased by 0.02 mg·kg-1 to 4.48 mg·kg-1,while the content of the bound-residual fraction of phenanthrene decreased by 0.16 mg·kg-1 to 5.01 mg·kg-1.The phenanthrene-Cu(Ⅱ)interaction could enhance the soil adsorption of phenanthrene,thereby promoting the speciation transformation of phenanthrene from the bioavailable fraction to the stable-absorbed fraction,and inhibiting further transformation from the stable-absorbed fraction to the bound-residual fraction.The half-life of the bioavailable fraction of phenanthrene in non-sterilized soils extended by 5.4 d to 135.0 d due to the toxic effects of the co-existing Cu(Ⅱ)on microorganisms.The aging rate of the bioavailable fraction of phenanthrene was accelerated by 0.000 2 d-1to 0.003 6 d-1 in the presence of Cu(Ⅱ)in sterilized soils,where both the aging rate of the bioavailable fraction of phenanthrene with or without Cu(Ⅱ)were significantly correlated with the content of dissolved organic matter in aging soils(P<0.01).This study indicates that the speciation transformation and aging rate of phenanthrene during aging processes are affected by phenanthrene-Cu(Ⅱ)interaction,the extent of which is related to the content and composition of soil organic matter.
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