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Sorption and desorption of glyphosate in Mollisols and Ultisols soils of Argentina
Author(s) -
Gómez Ortiz Ana Maria,
Okada Elena,
Bedmar Francisco,
Costa José Luis
Publication year - 2017
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.3851
Subject(s) - sorption , freundlich equation , desorption , glyphosate , environmental chemistry , soil water , chemistry , ultisol , bioavailability , adsorption , agronomy , soil science , environmental science , biology , organic chemistry , bioinformatics
In Argentina, glyphosate use has increased exponentially in recent years as a result of the widespread adoption of no‐till management combined with genetically modified glyphosate‐resistant crops. This massive use of glyphosate has created concern about its potential environmental impact. Sorption–desorption of glyphosate was studied in 3 Argentinean soils with contrasting characteristics. Glyphosate sorption isotherms were modeled using the Freundlich equation to estimate the sorption coefficient ( K f ). Glyphosate sorption was high, and the K f varied from 115.6 to 1612 mg 1–1/n L 1/n /kg. Cerro Azul soil had the highest glyphosate sorption capacity as a result of a combination of factors such as higher clay content, cation exchange capacity, total iron, and aluminum oxides, and lower available phosphorus and pH. Desorption isotherms were also modeled using the Freundlich equation. In general, desorption was very low (<12%). The low values of hysteresis coefficient confirm that glyphosate strongly sorbs to the soils and that it is almost an irreversible process. Anguil soil had a significantly higher desorption coefficient ( K fd ) than the other soils, associated with its lower clay content and higher pH and phosphorus. Glyphosate high sorption and low desorption to the studied soils may prevent groundwater contamination. However, it may also affect its bioavailability, increasing its persistence and favoring its accumulation in the environment. The results of the present study contribute to the knowledge and characterization of glyphosate retention in different soils. Environ Toxicol Chem 2017;36:2587–2592. © 2017 SETAC