Polycyclic aromatic hydrocarbons（PAHs）/heavy metals/fluorine（F） mixed-contaminated sites caused by abandoned metallurgic plants are receiving wide attention. To address the associated environmental problems,this s...Polycyclic aromatic hydrocarbons（PAHs）/heavy metals/fluorine（F） mixed-contaminated sites caused by abandoned metallurgic plants are receiving wide attention. To address the associated environmental problems,this study was initiated to investigate the feasibility of using carboxymethyl-β-cyclodextrin（CMCD） and carboxymethyl chitosan（CMC） solution to enhance ex situ soil washing for extracting mixed contaminants. Further,Tenax extraction method was combined with a first-three-compartment model to evaluate the environmental risk of residual PAHs in washed soil. In addition,the redistribution of heavy metals/F after decontamination was also estimated using a sequential extraction procedure. Three successive washing cycles using50 g/L CMCD and 5 g/L CMC solution were effective to remove 94.3% of total PAHs,93.2% of Pb,85.8% of Cd,93.4% of Cr,83.2% of Ni and 97.3% of F simultaneously. After the 3rd washing,the residual PAHs mainly existed as very slowly desorbing fractions,which were in the form of well-aged,well-sequestered compounds; while the remaining Pb,Cd,Cr,Ni and F mainly existed as Fe–Mn oxide and residual fractions,which were always present in stable mineral forms or bound to non-labile soil fractions. Therefore,this combined cleanup strategy proved to be effective and environmentally friendly.展开更多
基金supported by the National Natural Science Foundation of China (Nos.41030531,41001335G,21377138 and 41271464b)
文摘Polycyclic aromatic hydrocarbons（PAHs）/heavy metals/fluorine（F） mixed-contaminated sites caused by abandoned metallurgic plants are receiving wide attention. To address the associated environmental problems,this study was initiated to investigate the feasibility of using carboxymethyl-β-cyclodextrin（CMCD） and carboxymethyl chitosan（CMC） solution to enhance ex situ soil washing for extracting mixed contaminants. Further,Tenax extraction method was combined with a first-three-compartment model to evaluate the environmental risk of residual PAHs in washed soil. In addition,the redistribution of heavy metals/F after decontamination was also estimated using a sequential extraction procedure. Three successive washing cycles using50 g/L CMCD and 5 g/L CMC solution were effective to remove 94.3% of total PAHs,93.2% of Pb,85.8% of Cd,93.4% of Cr,83.2% of Ni and 97.3% of F simultaneously. After the 3rd washing,the residual PAHs mainly existed as very slowly desorbing fractions,which were in the form of well-aged,well-sequestered compounds; while the remaining Pb,Cd,Cr,Ni and F mainly existed as Fe–Mn oxide and residual fractions,which were always present in stable mineral forms or bound to non-labile soil fractions. Therefore,this combined cleanup strategy proved to be effective and environmentally friendly.
