Persistence and sorption of imazapyr in three Argentinean soils

Abstract

Imazapyr is a herbicide widely used for weed control in imidazolinone-tolerant sunflower. Imazapyr has a high potential for leaching into groundwater because it is highly water-soluble, persistent in soil, and only weakly sorbed by soils. There is a lack of information available in Argentina concerning groundwater leaching of imazapyr. Therefore, the objective of the present study was to determine the persistence and sorption of imazapyr in 3 Argentinean soils (Tandil, Anguil, and Cerro Azul sites). The presence and concentration of imazapyr were determined and quantified by ultra-performance liquid chromatography and tandem mass spectrometry. The persistence in soils followed the order: Cerro Azul > Tandil > Anguil, with half-life values of 121 d, 75 d, and 37 d, respectively. The half-life of imazapyr was negatively associated with soil pH and iron and aluminum content, and was positively related to clay content. Imazapyr sorption was found to be well described by the Freundlich isotherm. Soil pH and clay, iron, and aluminum contents were the main factors affecting the sorption of imazapyr. The sorption had a limiting effect on the degradation rate. Under certain conditions, the weak sorption and high persistence may increase the movement of imazapyr in the soil profile and the risk of groundwater pollution.

Herbicide detection in groundwater in Córrego Rico-SP watershed

“…Hexazinone and imazapyr have the highest solubility values among products evaluated (Garcia et al, 2012;Gianelli et al, 2014), while sulfentrazone is extremely persistent in soil and has a low adsorption coefficient (Passos et al, 2013). Jointly, according to Gustafson (1989) and Laskowski et al (1982), these features help to classify these products as the most probably detected in groundwater (Table 5).…”

Riesgo De Lixiviación De Imazapir en Tres Suelos De Argentina

“…La persistencia del herbicida se determinó bajo condiciones controladas de laboratorio, obteniéndose la vida media (T 1/2 ) para cada suelo, mientras que la adsorción del herbicida se caracterizó a través de isotermas de adsorción, de las cuales se calculó el coeficiente de partición en adsorción (K d ) para cada sitio de estudio (Gianelli et al, 2014). Las determinaciones del herbicida se llevaron a cabo mediante Cromatografía Líquida de Ultra Performance y Espectrometría de masas (UPLC-MS/MS) acorde a la metodología descripta en Gianelli et al (2013).…”

“…Mulder y Schmidt (2011) realizaron un estudio de monitoreo en el estado de Montana, con el objeto de determinar el impacto potencial de los compuestos químicos en el agua superficial y subterránea, encontrando presencia de imazapir en 42 y 75% de las muestras de agua superficial y subterránea, respectivamente, a concentraciones inferiores al valor máximo permitido por la Unión Europea en el agua para consumo humano de 0,1 μg L -1 (Hamilton et al, 2003). En Argentina se han realizado diversos estudios en laboratorio, a campo y mediante bioensayos con el objeto de determinar la persistencia de imazapir en el suelo y sus efectos fitotóxicos sobre cultivos de invierno y de verano (Porfiri y Montoya, 2008;Gianelli et al, 2011;Gianelli et al, 2014). No obstante, es escasa la información relacionada con el riesgo de lixiviación de esta molécula hacia el agua subterránea (Gianelli et al, 2010;Porfiri et al, 2015).…”

Optimization Method for Simultaneous Extraction and Detection of Imazapic and Imazapyr Herbicides in Soil and Water Using HPLC-UV with Verification of LC-MS

“…The physico-chemical properties of imazapic and imazapyr are shown in Table 1. Extraction processes were conducted using 0.5 M sodium hydroxide (Ramezani et al 2009), 10 μM ammonium acetate (Moser 2010) and 0.1 M potassium chloride (Gianelli et al 2014), that were prepared with ultra-pure water.…”

“…The method proposed by Gianelli et al (2014) for extraction of imidazolinone herbicides was conducted using 0.1 M potassium chloride. 5 g soil and water samples were placed in 50 mL centrifuged tube and added with 1 mL of imazapic and imazapyr standard solution.…”