Degradation of glyphosate in the aquatic environment:  An enzymic kinetic model that takes into account microbial degradation of both free and colloidal (or sediment) particle adsorbed glyphosate

Zaranyika, Mark F.; Nyandoro, Munyaradzi G

doi:10.1021/jf00029a030

Cited by 63 publications

(56 citation statements)

References 5 publications

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“…Nevertheless, the knowledge about loss of glyphosate and AMPA through surface run-off, especially following extreme erosive precipitation events very soon after herbicide application before the plants can absorb it is insufficient and the importance of this transport as related to ecological risk assessment has previously been scarcely investigated, (Borggaard and Gimsing, 2008;De Jonge et al, 2000;Donald et al, 2005;Giesy et al, 2000;Peruzzo et al, 2008;Zaranyika and Nyandro, 1993).…”

Section: Introductionmentioning

confidence: 99%

Influence of soil tillage and erosion on the dispersion of glyphosate and aminomethylphosphonic acid in agricultural soils

Todorovic

Rampazzo

Mentler

et al. 2014

International Agrophysics

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A b s t r a c t. Erosion processes can strongly influence the dissipation of glyphosate and aminomethylphosphonic acid applied with Roundup Max® in agricultural soils; in addition, the soil structure state shortly before erosive precipitations fall can be a key parameter for the distribution of glyphosate and its metabolite. Field rain simulation experiments showed that severe erosion processes immediately after application of Roundup Max® can lead to serious unexpected glyphosate loss even in soils with a high presumed adsorption like the Cambisols, if their structure is unfavourable. In one of the no-tillage-plot of the Cambisol, up to 47% of the applied glyphosate amount was dissipated with surface run-off. Moreover, at the Chernozem site with high erosion risk and lower adsorption potential, glyphosate could be found in collected percolation water transported far outside the 2x2 m experimental plots. Traces of glyphosate were found also outside the treated agricultural fields.K e y w o r d s: glyphosate, aminomethylphosphonic acid, erosion, adsorption, soils

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Section: Introductionmentioning

confidence: 99%

Influence of soil tillage and erosion on the dispersion of glyphosate and aminomethylphosphonic acid in agricultural soils

Todorovic

Rampazzo

Mentler

et al. 2014

International Agrophysics

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“…The fact that both the fast and the slower rates of degradation of pirimiphos-methyl, chlorpyrifos and fenamiphos in the water phase, as well as the sediment phase, of the experiment are linear, points to steady state kinetics, and hence microbial degradation, whereby the observed rates correspond to the plateau in the Michelis-Menten curve (Zaranyika and Nyandoro, 1993;Zaranyika et al, 2010). The difference between the fast linear rate and the slow linear rate of degradation in the water phase of the experiment is attributed to adsorption of the pesticide by colloidal particles (Nomura and Hilton, 1977;Zaranyika and Nyandoro, 1993;Zaranyika et al, 2010).…”

Section: Microbial Degradationmentioning

confidence: 94%

“…The difference between the fast linear rate and the slow linear rate of degradation in the water phase of the experiment is attributed to adsorption of the pesticide by colloidal particles (Nomura and Hilton, 1977;Zaranyika and Nyandoro, 1993;Zaranyika et al, 2010).…”

Section: Microbial Degradationmentioning

confidence: 99%

“…The much higher rates of degradation of the free pesticide in the sediment pore water has been attributed to greater microbial populations in the sediment. (Zaranyika and Nyandoro, 1993;Zaranyika et al, 2010).…”

Section: Speciation Trends Of Pirimiphos-methyl Chlorpyrifos and Fenmentioning

confidence: 99%

“…It is apparent therefore that more studies are required to elucidate further the kinetics of the degradation of pesticides in the aquatic environment. Zaranyika and Nyandoro (1993) studied the kinetics of the degradation of glyphosate [N-(phosphonomethyl) glycine] in the aquatic environment and observed two linear rates of degradation. The results were explained in terms of a steady state enzymatic kinetic model, which takes into account microbial degradation of both free and colloidal-particle-adsorbed glyphosate.…”

Section: Introductionmentioning

confidence: 99%

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Degradation of Fenamiphos, Chlorpyrifos and Pirimiphos-Methyl in the Aquatic Environment: A Proposed Enzymatic Kinetic Model That Takes Into Account Adsorption/Desorption of the Pesticide by Colloidal and Sediment Particles

Zaranyika¹,

Mlilo²

2012

Pesticides - Recent Trends in Pesticide Residue Assay

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Role of sediments in modifying the toxicity of two Roundup formulations to six species of larval anurans

Fuentes

Moore

Rodgers

et al. 2014

Enviro Toxic and Chemistry

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The role of sediment in modifying the toxicity of the original formulation of Roundup® and Roundup WeatherMAX® was examined in aqueous laboratory tests. Six species of anurans (Bufo fowleri, Hyla chrysoscelis, Rana catesbeiana, Rana clamitans, Rana sphenocephala, and Rana pipiens) were exposed at Gosner stage 25 to concentrations of the 2 herbicide formulations in 96-h, static, nonrenewal experiments in the presence and absence of sediment. All species tested had lower median lethal concentration values in water-only exposures of both formulations compared with exposures with sediment. Sediment significantly altered the potency slopes in all tests with the exceptions of H. chrysoscelis and R. clamitans when exposed to the original formulation of Roundup and H. chrysoscelis and R. sphenocephala when exposed to Roundup WeatherMAX. Thresholds were significantly different in all tests, including those in which potency slopes did not differ. Based on water-sediment exposures of the original formulation of Roundup, all 6 species tested had a margin of safety when compared with the predicted environmental concentration of the highest label application rate. Of the 6 species, 5 had a margin of safety when exposed to Roundup WeatherMAX. During incidental exposures in the field, sediments and organic matter present in aquatic systems provide significant sources of environmental ligands. If used according to label instructions, both herbicides should pose minimal risk to anuran amphibians in actual field applications. Environ Toxicol Chem 2014;33:2616-2620. © 2014 SETAC.

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Degradation of glyphosate in the aquatic environment: An enzymic kinetic model that takes into account microbial degradation of both free and colloidal (or sediment) particle adsorbed glyphosate

Cited by 63 publications

References 5 publications

Influence of soil tillage and erosion on the dispersion of glyphosate and aminomethylphosphonic acid in agricultural soils

Influence of soil tillage and erosion on the dispersion of glyphosate and aminomethylphosphonic acid in agricultural soils

Degradation of Fenamiphos, Chlorpyrifos and Pirimiphos-Methyl in the Aquatic Environment: A Proposed Enzymatic Kinetic Model That Takes Into Account Adsorption/Desorption of the Pesticide by Colloidal and Sediment Particles

Role of sediments in modifying the toxicity of two Roundup formulations to six species of larval anurans

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