Increased retention of polycyclic aromatic hydrocarbons in soils induced by soil treatment with humic substances

The analytical recovery of a mixture of polycyclic aromatic hydrocarbons (P AHs) was determined from a soil before and after oxidation with hydrogen pe roxide, and subsequently treated with increasing amounts of an exogenous hu mic acid and subjected to different incubation periods. The release of PAHs from soil depended on the specific structure and physico-chemical properti es of each PAH, and increased with additions of exogenous humic materials f or both the oxidized and non-oxidized soil as well as with time of PAH perm anence in soil. PAH recoveries were lower in the non-oxidized soil, thereby revealing the importance of native organic matter in increasing PAH retent ion in soils. This study shows that mobility of PAHs in soils can be contro lled by soil conditioning with humic substances. (C) 2001 Elsevier Science Ltd. All rights reserved.