title: Sorption and dissipation of aged metolachlor residues in eroded and rehabilitated soils.
abstract: BACKGROUND
  Sorption and dissipation of aged metolachlor were characterized in rehabilitated and eroded prairie soils using sequential batch slurry (conventional) and accelerated solvent extraction (ASE).
  
  
  RESULTS
  In spite of an almost twofold difference in soil organic carbon (OC) content, S-metolachlor sorption coefficients (K(d)) and dissipation rates (DT(50)) were the same in soils from different landscape positions within an eroded landform. Soil was moved within the landform to increase productivity. In areas receiving topsoil addition, S-metolachlor K(d) was higher and DT(50) was longer than in eroded areas. The efficiency of extraction was higher for ASE than for conventional extractions. No consistent aging effect on K(d) was observed. Mineralization in 8 weeks accounted for < 10% of the applied metolachlor.
  
  
  CONCLUSIONS
  The results of this laboratory study support a field dissipation study. Both showed that S-metolachlor has the same retention and dissipation rate throughout an eroded landform, which was not expected owing to the large variability in soil properties, including OC concentrations. Altering soil properties by adding topsoil increased metolachlor sorption and persistence. The method of extraction (conventional versus ASE) affected calculated sorption coefficients and dissipation rates. In all cases, groundwater ubiquity scores (GUSs) categorized metolachlor as having intermediate mobility.
authors.affiliation: Department of Soil, Water and Climate, University of Minnesota, St Paul, MN, USA.
authors.forename: Alegría
authors.initials: A
authors.lastname: Cabrera
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Papiernik
authors.forename: William C
authors.initials: WC
authors.lastname: Koskinen
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Rice
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D000327:Adsorption; D004350:Drug Residues / Q000737:chemistry; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D000081:Acetamides; D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; C051786:metolachlor