Attenuation of the herbicide glyphosate along railroad corridors in Alaska

Abstract

Following the application of glyphosate in the formulation of AquaMaster® at two contrasting sub-arctic zones along the railroad corridor in Alaska, attenuation of the herbicide glyphosate was investigated. Study sites were established in continental and coastal zones. Glyphosate soil attenuation was similar to temperate regions during the growing season but exhibited an extended persistence during the winter months. Although glyphosate microbial degradation likely slowed during winter, both sites showed evidence of slight glyphosate degradation during the winter months. The coastal site attenuated more rapidly than the continental site which is presumably due to increased rainfall relative to the continental site. Glyphosate attenuation at the coastal site was likely driven by dispersion while microbial degradation was responsible for the attenuation of glyphosate at the continental site. Movement to subsurface soils (10-25 cm) at low concentrations was observed at both sites with slightly more transport at the coastal site than the continental site. Glyphosate transport to groundwater along railroad corridors was not conclusive. Vegetation cover reduction was reduced at the continental site but could not be determined at the coastal site.