Environmental and health effects of the herbicide glyphosate.

https://hal-univ-rennes1.archives-ouvertes.fr/hal-01516026/document

AminoMethylPhosphonic acid (AMPA) in natural waters: Its sources, behavior and environmental fate.

The global environmental hazard of glyphosate use

Controversies over human health and ecological impacts of glyphosate: Is it to be banned in modern agriculture?

https://digital.csic.es/bitstream/10261/148442/3/Behaviour_glyphosate_Esmeralda_Postprint.pdf

Behaviour of glyphosate in a reservoir and the surrounding agricultural soils.

Adsorption of the herbicide glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) was investigated on 17 different agricultural soils. Batch equilibration adsorption data are shown by Freundlich adsorption isotherms. Glyphosate adsorption is clearly affected by equilibration concentrations, but the nonlinear AMPA adsorption isotherms indicate saturation of the adsorption sites with increasing equilibrium concentrations. pHCaCl2 (i.e. experimental pH) is the major parameter governing glyphosate and AMPA adsorption in soils. However, considering pHCaCl2 values, available phosphate amount, and amorphous iron and aluminium oxide contents by using a nonlinear multiple regression equation, obtains the most accurate and powerful pedotransfer rule for predicting the adsorption constants for these two molecules. As amorphous iron and aluminium oxide contents in soil are not systematically determined, we also propose a pedotransfer rule with two variables-pHCaCl2 values and available phosphate amount-that remains acceptable for both molecules. Moreover, the use of the commonly measured pHwater or pHKCl values gives less accurate results compared to pHCaCl2 measurements. To our knowledge, this study is the first AMPA adsorption characterization for a significant number of temperate climate soils.

Glyphosate and AMPA adsorption in soils: laboratory experiments and pedotransfer rules

Experimental and modeling of the unsaturated transports of S-metolachlor and its metabolites in glaciofluvial vadose zone solids.

The vulnerability of groundwater to pesticides is governed in part by sorption mechanisms in the vadose zone, commonly studied in soil but less well-known in the geological solids. To alleviate this lack of knowledge, adsorption of the herbicide S-metolachlor (SMOC) and of two of its metabolites—metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA)—was studied with batch equilibrium method on seventeen surface soils and three geological solids of the vadose zone overlying a glaciofluvial aquifer. In grainsize terms, the latter three were sand for the first two samples and gravel for the third. Adsorption is ordered as follows: SMOC > > MESA > MOXA, except for one of the geological solids for which MESA adsorption was slightly higher than that of SMOC (Kd = 0.73 vs. 0.44 L kg−1). The low MOXA adsorption could only be quantified for the gravel sample (Kd = 0.74 L kg−1), which was also more reactive than all the other samples to MESA and SMOC (Kd = 2.08 and 28.8 L kg−1, respectively). Statistical multivariate tests related the highest Kd values for SMOC with the soils and geological solids with the highest organic-carbon and clay-fraction contents. The highest Kd values for MESA were found in the samples containing high oxide concentrations. Our results shed a new light on the adsorption of SMOC, MESA and MOXA suggesting that during their transfer to groundwater, pesticides and metabolites can be adsorbed in the vadose zone on both soils and geological solids.

Pauline Sidoli

Papers

Glyphosate and AMPA adsorption in soils: laboratory experiments and pedotransfer rules

Experimental and modeling of the unsaturated transports of S-metolachlor and its metabolites in glaciofluvial vadose zone solids.

Reactivity of vadose-zone solids to S-metolachlor and its two main metabolites: case of a glaciofluvial aquifer