The binding of contaminants to humin: A mass balance

A mass balance is presented for the distribution of bound contaminant residues of 3 PAHs and 2 PCBs between the organic matter fractions of 3 different soil types. The PAHs and PCBs show rapid binding to soil with maximum binding happening within the first 30 days of contamination. In all soils and contaminants studied humin contains more than 50% of the bound residue and typically between 70 and 80%. The humin is further fractionated by the methyl isobutyl ketone partitioning method into three additional fractions: 1) lipid, 2) bound-humic acid, and 3) the insoluble residue. This further fractionation shows that the bound-lipidfraction has an extremely high affinity for the contaminants.