Atrazine and Metribuzin Sorption in Soils of the Argentinean Humid Pampas

Abstract

Laboratory studies were conducted to determine the influence of surface and subsurface properties of three representative soils of the humid pampas of Argentina on atrazine and metribuzin sorption. Atrazine and metribuzin sorption isotherms were constructed for each soil at four depths. Sorption affinity of herbicides was approximated by the Freundlich constant (K(f)), distribution coefficient (Kd), and the normalized Kd based on organic carbon content (K(oc)). Multiple regression of the sorption constants against selected soil properties indicated that organic carbon content (OC) and silt were related positively and negatively, respectively, to atrazine K(f) coefficient (r2 = 0.93), while Kd coefficient of atrazine was related positively to organic carbon content and negatively to both silt and cation exchange capacity (CEC) (r2 = 0.96). For metribuzin, only organic matter content was related positively to Kr coefficient (r2 = 0.51). Lower K(f) values for atrazine were obtained for all soils with increasing depth, indicating lesser sorption at greater depths. Metribuzin sorption was quite similar across all depths. Sorption constant K(f) of atrazine ranged from 2.06 to 7.82, while metribuzin K(f) values ranged from 1.8 to 3.52 and were lower than atrazine for all soils and depths, indicating a greater leaching potential across the soil profile.

Pesticide adsorption in relation to soil properties and soil type distribution in regional scale

“…Metribuzin sorption was examined by Garcia-Valcarcel et al [17], Daniel et al [18], and Kah and Brown [7]. Metribuzin adsorption in 18 soil of Central Spain did not show any correlation with studied soil properties [17].…”

“…Metribuzin adsorption in 18 soil of Central Spain did not show any correlation with studied soil properties [17]. The K F was related positively to OM [18]. Adsorption was negatively correlated with soil pH and positively correlated with OC [7].…”

Distribution of atrazine into three chemical fractions: Impact of sediment depth and organic carbon content

“…Many laboratory studies have examined the effects of sediment depth and sediment organic matter on the recovery and degradation of atrazine using traditional methanol-water extractions [1,2,4,5]. More specifically, we measured the partitioning of 14 C activity over time into aqueous, organic solvent, and basic fractions.…”

Helping farmers to reduce herbicide environmental impacts

“…Apart from 2,4-D and glyphosate, the other active ingredients had the lowest mean and minimum I-PHY values. In addition, the same herbicides are regularly incriminated in water pollution in many tropical or temperate countries (Daniel et al, 2002;Haarstad and Ludvigsen, 2007;Ghosh and Singh, 2013). Indeed, 2,4-D and glyphosate alone account for over 2/3 of pesticide sales in Reunion (Maillary, 2012).…”