Mineralisation of atrazine, metolachlor and their respective metabolites in vegetated filter strip and cultivated soil

Abstract

In vegetated filter strips (VFS) the presence of perennial vegetation, rhizodeposition of labile organic substrates and the accumulation of an organic residue thatch layer may enhance microbial numbers and activity, thereby increasing the potential for mineralisation of herbicides and herbicide metabolites retained during run-off events. The objective of this laboratory experiment was to compare the mineralisation of atrazine and metolachlor with that of their respective metabolites in VFS and cultivated soil. With the exception of total bacteria, propagule density of the microbial groups, endogenous soil enzymes and microbial diversity were higher in the VFS soil. This correlated with increased mineralisation of metolachlor and its metabolites in the VFS soil and indicates potential for VFS to curtail the subsequent transport of these compounds. In contrast, the mineralisation of atrazine and the majority of its metabolites was substantially reduced in VFS soil relative to cultivated soil. Consequently, the potential for subsequent transport of atrazine and many of its metabolites may be greater in VFS soil than in cultivated soil if reduced mineralisation is not offset by increased sorption in the VFS.

Trends and Transformation of Nutrients and Pesticides in a Coastal Plain Aquifer System, United States

“…8, Table 2). Metolachlor OA has been hypothesized to degrade at a faster rate in the soil zone than metolachlor ESA (Phillips et al, 1999; Krutz et al, 2006; Steele et al, 2008), which may explain the differences in detection rates in this study. Once in groundwater, these degradates appeared to persist at low levels over decadal time scales.…”

Hot Spots and Hot Moments in Riparian Zones: Potential for Improved Water Quality Management1

“…Most degradation and adsorption/desorption studies have been carried out in agricultural soils or wetlands (Benoît et al. , 1999; Krutz et al. , 2006) and new research is necessary to understand processes that regulate pesticide transport to and removal from riparian zones and streams.…”

“…The accumulation of labile OM and organic residues near the root zone may increase microbial biomass and activity. In riparian zones with high surface area contact between roots and pesticides as well as those with sufficient contact time, pesticides and pesticide metabolites may be mineralized and adsorbed (Krutz et al. , 2006).…”

Analysis of metolachlor ethane sulfonic acid (MESA) chirality in groundwater: A tool for dating groundwater movement in agricultural settings

“…After application, metolachlor is readily transported into the soil where it is transformed into several compounds, the most abundant being, metolachlor ethane sulfonic acid (2-[(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxoethanesulfonic acid, MESA) (Baran and Gourcy, 2013;Bayless et al, 2008;White et al, 2010). MESA can be found in groundwater wherever metolachlor has been used and it appears to be quite stable in groundwater (Baran et al, 2004;Barbash et al, 1999;Bayless et al, 2008;Denver et al, 2010;Domagalski et al, 2008;Huntscha et al, 2008;Kalkhoff et al, 2012;Krutz et al, 2006;Rebich et al, 2004;Hancock et al, 2008).…”