ENHANCED MINERALIZATION OF [C-14]ATRAZINE IN KOCHIA-SCOPARIA RHIZOSPHERIC SOIL FROM A PESTICIDE-CONTAMINATED SITE

Mineralization of atrazine -2-ethyl-N-4-isoproppl-1,3,5-triazine-2,4-d iamine) in soil treated with a mixture of atrazine and metolachlor -et hyl-N-(2-methoxy-1-methylethyl)acet-o-toluidide at concentrations typi cal of point-source contamination (50 mu g g(-1) each) was significant ly greater (P < 0.001) in rhizospheric soil from Kochia scoparia (L.) Roth., a herbicide-resistant plant, than in non-vegetated and control soils. Soils were collected from an agrochemical dealership contaminat ed with several herbicides, including atrazine, metolachlor, triflural in pha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine and pendimethali n (N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidene at concentrations well e xceeding the field application rates. Mineralization rates of ring-lab eled atrazine in both rhizospheric and non-vegetated soils were quite high (>47% of the initial C-14 applied after 36 days) compared to lite rature values. These results suggest that plants such as Kochia might be managed at pesticide-contaminated sites to help facilitate microbia l degradation of wastes such as atrazine in soil.