The fate of imazapyr in a Swedish railway embankment

Abstract

The long-term fate of the herbicide imazapyr [2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid] applied to a Swedish railway embankment was studied. Imazapyr was applied at 750 and 1500 g ha(-1) by a spraying train used for full-scale herbicide treatment operations. Soil and groundwater were sampled twice a year for 8 years after application of the herbicide, and the dissipation of imazapyr was studied by HPLC analysis of the residues in soil and groundwater. A clean-up procedure including solid-phase extraction was performed prior to detection by HPLC. Recoveries of imazapyr from soil and water samples were 76-98% and 61-90%, respectively, and detection levels were 0.003 mg kg(-1) and 0.05 microg litre(-1), respectively. Sorption, desorption and microbial amount and activity were also measured at the two locations. The organic matter content correlated positively and the pH negatively to the adsorption of imazapyr on soil, and increasing organic matter contents decreased desorption. Apart from the 0-10-cm top layers of both sites, the microbial amount and activity were small. The main proportion of imazapyr was found in the upper 30 cm of the soil, and degraded with a half-life in the range 67-144 days. Small amounts were transported to lower soil layers and to the groundwater in proportion to the amounts applied. Traces of imazapyr were detected in the groundwater even 8years after application. It was concluded that environmental risks from the use of herbicides on railway embankments could be reduced by including adsorption layers in the embankment during their construction and by reducing the dose of the herbicide used.

Metabolic and cometabolic degradation of herbicides in the fine material of railway ballast

“…Due to the coarse texture and low organic matter content of railway embankments, there is much concern that application of herbicides to railways may lead to groundwater contamination. Several studies have investigated the leaching of pesticides from railway tracks and, with some exceptions, most of them indicate that the leaching potential is considerable and that concentrations in the groundwater beneath the track may significantly exceed the EU limit for drinking water of 0.1 µg l -1 if the application rate is too high (Torstensson, 1983;1985;Lode and Meyer, 1999;Schmidt et al, 1999;Börjesson et al, 2004;Ramwell et al, 2004;Torstensson and Börjesson, 2004;Torstensson et al, 2005).…”

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

“…Separate studies on the detection of imazapic and imazapyr in water samples with good recovery rates were also reported by Börjesson et al (2004) and Martini et al (2013). These developments encouraged the creation of new methodology and the improvement of existing methods used for the determination of pesticide residues in food and environmental matrices.…”

Riesgo De Lixiviación De Imazapir en Tres Suelos De Argentina

“…Estas aproximaciones sugeridas mediante los estimadores de riesgo han sido confirmadas por estudios de monitoreo, en los cuales se ha detectado la presencia de imazapir en el agua subterránea en diversas regiones del mundo (Michael y Neary, 1993;Bush et al, 1995;Börjesson et al, 2004;Mulder y Schmidt, 2011). Por lo tanto, los índices empleados en este trabajo permitirían establecer tendencias generales del riesgo potencial de lixiviación de este herbicida hacia el agua subterránea, constituyendo una herramienta eficaz para uso racional de los herbicidas, tendientes a minimizar su impacto negativo en el ambiente.…”

“…Michael y Neary (1993) y Bush et al (1995), encontraron residuos de imazapir en agua subterránea en el suroeste de Estados Unidos. En la misma línea, Börjesson et al (2004), encontraron residuos del herbicida en el agua subterránea, después de 8 años de la aplicación, presentando niveles de contaminación entre 0,16 y 0,89 μg L -1 . Por su parte, Battaglin et al (1998), en un estudio en ríos y arroyos de EE.UU., detectaron concentraciones de imazapir superiores a los límites permitidos en más del 5% de las muestras analizadas.…”