title: Degradation of herbicides in two sandy aquifers under different redox conditions.
abstract: We examined the potential for complete degradation (mineralisation) of the four [ring-U-14C]herbicides mecoprop, isoproturon, atrazine, and metsulphuron-methyl in two sandy aquifers representing aerobic, denitrifying, sulphate-reducing, and methanogenic conditions. Slurries with sediment and groundwater were set-up aerobically or anaerobically in the presence of the electron-acceptor prevailing at the sampling site, amended with 25 microg l(-1) herbicide, and incubated at 10 degrees C. Considerable mineralisation was only observed in sediment from the plough layer incubated aerobically. Here, 30% of 14C-mecoprop was recovered as 14CO2 after 15 days and 15% of isoproturon was recovered as 14CO2 after 267 days. Only 7% of mecoprop was recovered as 14CO2 after 313 days in sediment from the aquifer below sampled at 1.95-3.00 mbs (m below the surface). In denitrifying and methanogenic slurries, 3% of 14C added as mecoprop was recovered as 14CO2. Isoproturon was not mineralised except in the aerobic plough layer, and atrazine and metsulphuron-methyl were not mineralised under any of the conditions applied.
authors.affiliation: Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Larsen
authors.forename: J
authors.initials: J
authors.lastname: Aamand
mesh_terms: D001673:Biodegradation, Environmental; D002244:Carbon / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000032:analysis; D006540:Herbicides / Q000378:metabolism*; D010084:Oxidation-Reduction; D012822:Silicon Dioxide; D012988:Soil Microbiology; D014872:Water Movements
chemical_list: D002250:Carbon Radioisotopes; D006540:Herbicides; D002244:Carbon; D012822:Silicon Dioxide