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Adsorption of 2,4-Dichlorophenoxyacetic Acid by an Andosol
- Source :
- Journal of Environmental Quality. 36:101-109
- Publication Year :
- 2007
- Publisher :
- Wiley, 2007.
-
Abstract
- To identify the important soil components involved in 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption on Andosols, 2,4-D adsorption on a surface horizon of an Andosol was compared with that on hydrogen peroxide (H2O2)-treated (soil organic matter [SOM] was removed), acid-oxalate (OX)-treated (active metal hydroxides and SOM were removed), and dithionite-citrate-bicarbonate (DCB)-treated (free and active metal [hydr]oxides and SOM were removed) soil samples at equilibrium pHs ranging from 4 to 8. Although the untreated soil contained a large amount of organic C (71.9 g kg-1), removal of SOM had little effect on 2,4-D adsorption. Active surface hydroxyls, which were attached to the active and free metal (hydr)oxides and metal SOM complexes, were identified as the most important soil functional group for 2,4-D adsorption. The dominant mechanism of the 2,4-D adsorption was a ligand exchange reaction in which the carboxylic group of 2,4-D displaced the active surface hydroxyl associated with metals and formed a strong coordination bond between the 2,4-D molecule and soil solid phase. The ligand exchange reaction reasonably accounted for the selective adsorption of 2,4-D over Cl-, competitive adsorption of phosphate over 2,4-D, reduction in plant-growth-inhibitory activity of soil-adsorbed 2,4-D, and the high 2,4-D adsorption ability of Andosols. Although a humic acid purified from the soil did not adsorb 2,4-D, the presence of the humic acid increased 2,4-D adsorption on Al and Fe, probably by inhibiting the hydrolysis and polymerization of Al and Fe resulting in the preservation of available adsorption sites on these metals. The adsorption behavior of 2,4-D on soils could be a good index for predicting the adsorption behavior of other organic acids in soils.
- Subjects :
- chemistry.chemical_classification
Environmental Engineering
Herbicides
Chemistry
Soil organic matter
Inorganic chemistry
Hydrogen-Ion Concentration
Management, Monitoring, Policy and Law
Pollution
Andosol
Metal
Hydrolysis
Adsorption
Selective adsorption
visual_art
Soil water
visual_art.visual_art_medium
Humic acid
2,4-Dichlorophenoxyacetic Acid
Waste Management and Disposal
Humic Substances
Water Science and Technology
Subjects
Details
- ISSN :
- 00472425
- Volume :
- 36
- Database :
- OpenAIRE
- Journal :
- Journal of Environmental Quality
- Accession number :
- edsair.doi.dedup.....41d602adea05f41acb68a6cbbd3e01d5