Influence of Fenton oxidation on soil organic matter and its sorption and desorption of pyrene

The influences of Fenton oxidation on the content and composition of soil organic matter (SOM) and the consequent change of its sorption and desorption of pyrene were investigated using three soil samples. The results showed that both the content and the composition of the SOM changed, with total SOM content decreasing. The content of humic acid (HA) was reduced, while the content of humin did not change significantly, however the content of fulvic acid (FA) had a tendency to increase. Correlation analysis of soil-water distribution coefficient (Kd) and different parts of the SOM reveals that humin and HA are the key factors controlling the sorption of pyrene. Organic carbon normalized Kd (KOC) varied to different extents after Fenton oxidation due to the change of SOM composition. The reduction of KOC is significant in Soils 1 and 2 where large part of HA was reduced to FA, whose sorption ability is low. The change of KOC by oxidation in Soil 3 is not so significant due to that the percentage of humin and HA in Soil 3 did not change greatly after oxidation. Desorption was hysteretic in all cases, and humin percentage was found to be the key factor on the extent of desorption hystersis. Oxidation made desorption more hysteretic due to the elevated proportion of humin.