PARENT SESSION
PW7 - Biotransformation / Metabolisms / Degradation
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P798) Inhibition of lindane mineralization in soil by nitrogenous amendments.
Phillips, Theresa*,1,2, Seech, Alan2, Lee, Hung1, Trevors, Jack1, 1 University of Guelph, Guelph, ON, Canada2 Grace Bioremediation Technologies, Mississauga, ON, Canada
ABSTRACT- Lindane is an organochlorine pesticide and widespread soil pollutant, biodegradable in both aerobic and anaerobic environments. Mineralization of lindane in soil has been demonstrated using Daramend® organic amendments, but only under aerobic conditions (low moisture content (MC)) using an amendment with a low nitrogen (N) content. When the soil was treated under anaerobic conditions (high MC), using a high N Daramend® amendment and zero valent iron, no mineralization was observed. To determine what factors might inhibit lindane mineralization, two aerobic soil microcosm studies were performed, using soil from a former lindane-manufacturing site. In the first study, soil received the low N amendment, with or without iron, at high and low MC. In the second study, soil received either the low or high N amendments, with or without additional N fertilizers (monoammonium phosphate (MAP) or ammonium nitrate). The soil was spiked with 14C-lindane enabling detection of 14CO2 evolving from its mineralization. In the first study, the initial rate of mineralization was reduced at high MC, but the total percent mineralization, on day 100, was the same at low or high MC (23.2% and 20.6%, respectively). Iron enhanced mineralization at either MC. In the second study, total percent mineralization was reduced in soil treated with the high N amendment alone (41.2%), or in combination with the low N amendment (30.5%), compared to the low N amendment alone (48.6%). Mineralization was inhibited slightly by MAP, when applied with either organic amendment. Ammonium nitrate caused a dramatic increase in the lag period prior to lindane mineralization, but much higher total mineralization was achieved after 200 days (63.7% and 51.9% with low and high N amendments, respectively). These results demonstrate that application of nitrogen fertilizers can significantly influence mineralization of lindane and, hence, soil bioremediation.
Key words: soil, bioremediation, lindane, mineralization