Changes of soil organic matter caused by EDTA soil washing treatment on PTM contaminated soils

摘要

Two soils of contrasting pH and mineralogy(acid and calcareous)strongly polluted by Pb and Zn were remediated by soil washing with EDTA and cultivated after the treatment together with their respective non treated control soils.Humic and fulvic acids were extracted sequentially by NaOH(free fraction)and NaOH+Na2P2O7(bound fraction),before quantitative and spectroscopic characterization.Soil washing caused a significant reduction of the free humic fractions with minor changes in the bound humic fractions.The two cycles of cultivation were not able to restore the original composition of SOM.Structural changes in both FA and HA fractions were observed by UV-vis,FTIR and EEM fluorescence spectroscopies.