Glyphosate and Aminomethylphosphonic acid (AMPA) contents in the respirable dust emitted by an agricultural soil of the central semiarid region of Argentina

COSTA, JOSÉ L.; DE GERÓNIMO, EDUARDO; RAMIREZ HABERKON, NANCY B.; APARICIO, VIRGINIA C.; MENDEZ, MARIANO J.; COSTA, JOSÉ L.; BUSCHIAZZO, DANIEL E.; RAMIREZ HABERKON, NANCY B.; AIMAR, SILVIA B.; MENDEZ, MARIANO J.; BUSCHIAZZO, DANIEL E.; AIMAR, SILVIA B.; DE GERÓNIMO, EDUARDO; APARICIO, VIRGINIA C.

Aeolian Research

Elsevier B.V.

Año: 2017 vol. 29 p. 23 - 29

1875-9637

Wind erosion, tillage, and driving on agricultural soils generateairborne dust, which affects the environment in a variety of ways. Oneenvironmental issue in the semiarid Pampas of Argentina and elsewhereis the possible accumulation of glyphosate [N-(phosphonomethyl) glycine]in the dust emitted by agricultural soils. This is because thisherbicide is, according to the International Agency for Research onCancer (IARC), classified as ?probably carcinogenic to humans? (IARC,2015) and thousand tons of glyphosate-based herbicides are applied toproduce genetically modified crops in Argentina (Kleffmann Group,2014; Lupi et al., 2015). Glyphosate is a small molecule with three polarfunctional groups (carboxyl, amino and phosphonate groups), that canbe strongly sorbed by soil colloids (Sheals et al., 2002; Gimsing et al.,2007). Studies have shown that the half-life times of glyphosate in thesoil ranges from few days to 1000 (Borggaard and Gimsing, 2008, Bentoet al., 2016). The main metabolic pathway of glyphosate is its microbialdegradation to aminomethylphosphonic acid (AMPA), which is morepersistent in soils than glyphosate (Bento et al., 2016).Glyphosate is accumulated in the soil when it is sorbed by soilcompounds like clays, phosphates, organic matter (OM), aluminumandiron oxides, which reduces its microbial degradation (Gimsinget al., 2004; Vereecken, 2005; Borggaard and Gimsing, 2008). However,the role of some soil compounds like the OM and clay on sorptionis ambiguous. Whereas some studies have shown that it is not related toOM contents (Gimsing et al., 2004; Borggaard and Gimsing, 2008) arecent research showed that glyphosate can easily react with OM,promoting its accumulation in the soil (Gros et al., 2017). According toGimsing et al. (2004) sorption of glyphosate is not related to soil claycontents, but Okada et al. (2016) demonstrated that it is influenced byclay contents in silty clay-loam- and silty-loam soils of different regionsof Argentina. The high variability and uncertainty regarding glyphosatesorption and degradation in the soil make difficult to draw clear andunambiguous decisions about glyphosate behavior in the soil(Borggaard and Gimsing, 2008).Glyphosate and AMPA were already detected in groundwater andwater streams in Argentina (Aparicio et al., 2013), as well as in the dustemitted from wind eroded agricultural soils of Argentina and Belgium(Aparicio et al., 2014; Bento et al., 2017). To our knowledge, there areno glyphosate concentration measurements in the respirable dustemitted by the soils and its different aggregate-size fractions. This fact iscritical because tillage operations destroy the whole soil, being possiblethe emission from all aggregate-size fractions; and in the wind erosionevents aggregates finer than 0.84 mm are mobilized (Mendez et al.,2015). The aim of this study was to determine, for an agricultural soil ofthe central semiarid region of Argentina, the concentrations of glyphosateand AMPA in the respirable dust emitted by the bulk soil and itsaggregate-size fractions. In addition, we explored if the content