BINDING OF PENTACHLOROPHENOL TO HUMIC SUBSTANCES IN SOIL BY THE ACTION OF WHITE-ROT FUNGI

The fate of C-14-pentachlorophenol (C-14-PCP) in soil inoculated with each of four wood degrading fungi was studied. After 9 wk of incubatio n with the fungi, the majority of the C-14 (between 34 and 65%) was fo und bound to humic (HA), fulvic acid (FA) and humin, with lesser amoun ts found. in the organic-extractable fraction or mineralized. The high est amounts of PCP were bound to HA (20-36%, compared to 7.5-8.3% in t he uninoculated controls). Binding to FA and to humin was lower, rangi ng between 8.7 and 17.5% and 4.8 and 11.1%, respectively, in the funga l cultures. In control experiments around 5% of the radioactivity was found associated to FA and between 2 and 4% to the humin. The highest binding of PCP to the humic materials was obtained with Pleurotus ostr eatus, followed by Irpex lacteus, Trametes versicolor and Bjerkandera adusta. Mineralization of PCP from soil cultures by the fungi was low. The fungus that mineralized the most PCP was T. versicolor, convertin g 8.8% of C-14-PCP into (CO2)-C-14, compared to 0.6% mineralized in th e uninoculated controls. Methylation of PCP to pentachloroanisole by t he fungi was low, ranging between 0 and 6.8% after 9 wk. (C) 1997 Else vier Science Ltd.