title: Mineralisation and degradation of 2,4-dichlorophenoxyacetic acid dimethylamine salt in a biobed matrix and in topsoil.
abstract: BACKGROUND
  Biobeds are used for on-farm bioremediation of pesticides in sprayer rinsate and from spills during sprayer filling. Using locally sourced materials from Saskatchewan, Canada, a biobed matrix was evaluated for its effectiveness for mineralising and degrading 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D DMA) compared with the topsoil used in the biobed matrix.
  
  
  RESULTS
  Applying 2,4-D DMA to the biobed matrix caused a 2-3 day lag in CO2 production not observed when the herbicide was applied to topsoil. Despite the initial lag, less residual 2,4-D was measured in the biobed (0%) matrix than in the topsoil (57%) after a 28 day incubation. When the herbicide was applied 5 times to the biobed matrix, net CO2 increased immediately after each 2,4-D DMA application. Mineralisation of 2,4-D DMA was 61.9% and residual 2,4-D in the biobed matrix was 0.3% after 60 days, compared with corresponding values of 32.9 and 70.9% in topsoil.
  
  
  CONCLUSIONS
  The biobed matrix enhanced the mineralisation and degradation of 2,4-D DMA, indicating the potential for successful implementation of biobeds under Canadian conditions. The biobed matrix was more effective for mineralising and degrading the herbicide compared with the topsoil used in the biobed matrix. By correcting for biobed matrix and formulation blank, CO2 evolution was a reliable indicator of 2,4-D DMA mineralisation. © 2016 Society of Chemical Industry.
authors.affiliation: Department of Soil Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: J Diane
authors.initials: JD
authors.lastname: Knight
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Cessna
authors.affiliation: Integrated Crop Management Services, Saskatoon, Saskatchewan, Canada.
authors.forename: Dean
authors.initials: D
authors.lastname: Ngombe
authors.affiliation: Agrimetrix Research and Training, Saskatoon, Saskatchewan, Canada.
authors.forename: Tom M
authors.initials: TM
authors.lastname: Wolfe
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000737:chemistry; D004123:Dimethylamines / Q000378:metabolism*; D004787:Environmental Pollution / Q000517:prevention & control; D006540:Herbicides / Q000378:metabolism*; D012525:Saskatchewan; D012987:Soil / Q000737:chemistry*
chemical_list: D004123:Dimethylamines; D006540:Herbicides; D012987:Soil; D002245:Carbon Dioxide; C037991:2,4-D amine; D015084:2,4-Dichlorophenoxyacetic Acid
keywords: 2,4-dichlorophenoxyacetic acid; biobed; carbon dioxide production; degradation; formulation blank; mineralisation