Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2000
Publication Date: November 9, 2000
Citation: Papiernik, S.K., Gan, J., Dungan, R.S., Yates, S.R. 2000. Products of propargyl bromide degradation in soil. Proceedings of International Research Conference on Methyl Bromide Alternatives. Orlando, FL. Nov. 6-9, 2000. Paper No. 27. pp. 27-1 to 27-3. Technical Abstract: Propargyl bromide (PrBr) is being investigated for its potential to partially replace methyl bromide (MeBr) as a soil fumigant. Information on its environmental fate, including mechanisms of degradation, is required to evaluate PrBr's capacity for sustained usage. We have conducted several studies on the degradation on PrBr in soil, and monitored the formation of some of the products of PrBr degradation in soil and water. Results indicated that hydrolysis of PrBr formed PrOH and Br in equimolar amounts: for each mole of PrBr degraded, one mole of PrOH and one mole of Br were formed. Similar results were observed for MeBr. The pattern of product formation indicated that degradation of PrBr in soil was not primarily due to hydrolysis. Degradation of one mole of PrBr formed one mole of Br, but much less than one mole of PrOH. No other degradation products were identified. Similar results were observed for MeBr. The rate of PrBr and MeBr degradation increased with increasing soil organic matter content, consistent with a nucleophilic substitution reaction mechanism. Degradation of 14C-labeled MeBr in soil resulted in the formation of bound (unextractable) residues of the carbon-containing portion of the molecule, with concurrent release of Br. Soil-bound 14C residues increased as the extractable 14C decreased and increased with time, suggesting that degradation of 14C-MeBr was via alkylation of soil organic matter. A similar mechanism is proposed for PrBr degradation in soil.