title: Factors influencing 2,4-D sorption and mineralization in soil.
abstract: This study quantified 2,4-D [(2,4-dichlorophenoxy)acetic acid] sorption and mineralization rates in five soils as influenced by soil characteristics and nutrient contents. Results indicated that 2.4-D was weakly sorbed by soil, with Freundlich distribution coefficients ranging from 0.81 to 2.89 microg(1 - 1/n) g(-1) mL(1/n). First-order mineralization rate constants varied from 0.03 to 0.26, corresponding to calculated mineralization half-lives of 3 and 22 days, respectively. Herbicide sorption generally increased with increasing soil organic carbon content, but the extent of 2,4-D sorption per unit organic carbon varied among the soils due to differences in soil pH, clay content and/or organic matter quality. Herbicide mineralization rates were greater in soils that sorbed more 2,4-D per unit organic carbon, and that had greater soil nitrogen contents. We conclude that the effect of sorption on herbicide degradation cannot be generalized without a better understanding of the effects of soil characteristics and nutrient content on herbicide behavior in soil.
authors.affiliation: Department of Soil Science, University of Manitoba, Winnipeg, Canada.
authors.forename: Paula
authors.initials: P
authors.lastname: Picton
authors.forename: Annemieke
authors.initials: A
authors.lastname: Farenhorst
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry*; D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry; D000818:Animals; D002170:Canada; D002244:Carbon / Q000032:analysis; D000077215:Clay; D006207:Half-Life; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D009747:Nutritional Physiological Phenomena / Q000502:physiology; D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D000538:Aluminum Silicates; D006540:Herbicides; D008903:Minerals; D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants; D015084:2,4-Dichlorophenoxyacetic Acid; D002244:Carbon; D009584:Nitrogen; D000077215:Clay