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Environ Toxicol Chem

Title:		Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review
Author(s):		Paszko T; Muszynski P; Materska M; Bojanowska M; Kostecka M; Jackowska I;
Address:		"Department of Chemistry, University of Life Sciences, Lublin, Poland"
Journal Title:		Environ Toxicol Chem
Year:		2016
Volume:		20160108
Issue:		2
Page Number:		271 - 286
DOI:		10.1002/etc.3212
ISSN/ISBN:		1552-8618 (Electronic) 0730-7268 (Linking)
Abstract:		"The primary aim of the present review on phenoxyalkanoic acid herbicides-2-(2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), (2R)-2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop-P), (2R)-2-(4-chloro-2-methylphenoxy) propanoic acid (mecoprop-P), 4-(2,4-dichlorophenoxy) butanoic acid (2,4-DB), and 4-(4-chloro-2-methylphenoxy) butanoic acid (MCPB)-was to compare the extent of their adsorption in soils and degradation rates to assess their potential for groundwater contamination. The authors found that adsorption decreased in the sequence of 2,4-DB > 2,4-D > MCPA > dichlorprop-P > mecoprop-P. Herbicides are predominantly adsorbed as anions-on organic matter and through a water-bridging mechanism with adsorbed Fe cations-and their neutral forms are adsorbed mainly on organic matter. Adsorption of anions of 2,4-D, MCPA, dichlorprop-P, and mecoprop-P is inversely correlated with their lipophilicity values, and modeling of adsorption of the compounds based on this relationship is possible. The predominant dissipation mechanism of herbicides in soils is bacterial degradation. The contribution of other mechanisms, such as degradation by fungi, photodegradation, or volatilization from soils, is much smaller. The rate of bacterial degradation decreased in the following order: 2,4-D > MCPA > mecoprop-P > dichlorprop-P. It was found that 2,4-D and MCPA have the lowest potential for leaching into groundwater and that mecoprop-P and dichlorprop-P have slightly higher potential. Because of limited data on adsorption and degradation of 2,4-DB and MCPB, estimation of their leaching potential was not possible"
Keywords:		"Adsorption Animals *Biodegradation, Environmental Herbicides/analysis/*chemistry Humans Soil Pollutants/analysis/*chemistry Degradation Desorption GUS index Modeling;"
Notes:		"MedlinePaszko, Tadeusz Muszynski, Pawel Materska, Malgorzata Bojanowska, Monika Kostecka, Malgorzata Jackowska, Izabella eng Research Support, Non-U.S. Gov't Review 2015/08/21 Environ Toxicol Chem. 2016 Feb; 35(2):271-86. doi: 10.1002/etc.3212. Epub 2016 Jan 8"