The fate of imazapyr in a Swedish railway embankment
Authors: Börjesson E.; Torstensson L.; Stenström J.
Source: Pest Management Science, Volume 60, Number 6, June 2004 , pp. 544-549(6)
Publisher: John Wiley & Sons, Ltd.
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 7698% and 6190%, respectively, and detection levels were 0.003 mg kg-1 and 0.05 µg 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 010-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 67144 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 8 years 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. Copyright © 2004 Society of Chemical Industry
Document Type: Research article
Publication date: 2004-06-01