title: Stimulation of aerobic degradation of bentazone, mecoprop and dichlorprop by oxygen addition to aquifer sediment.
abstract: In order to investigate aerobic degradation potential for the herbicides bentazone, mecoprop and dichlorprop, anaerobic groundwater samples from two monitoring and three drinking water wells near a drinking water abstraction field in Nybølle, Denmark, were screened for their degradation potential for the herbicides. In the presence of oxygen (14)C-labelled bentazone and mecoprop were removed significantly from the two monitoring wells' groundwater samples. Oxygen was added to microcosms in order to investigate whether different oxygen concentrations stimulate the biodegradation of the three herbicides in microcosms using groundwater and sandy aquifer materials. To maintain a certain oxygen concentration this level was measured from the outside of the bottles with a fibre oxygen meter using oxygen-sensitive luminescent sensor foil mounted inside the microcosm, to which supplementary oxygen was added. The highest oxygen concentrations (corresponding to 4-11 mg L(-1)) stimulated degradation (a 14-27% increase for mecoprop, 3-9% for dichlorprop and 15-20% for bentazone) over an experimental period of 200 days. Oxygen was required to biodegrade the herbicides, since no degradation was observed under anaerobic conditions. This is the first time bentazone degradation has been observed in aquifer material at low oxygen concentrations (2 mg L(-1)). The sediment had substantial oxygen consumption (0.92-1.45O2 g(-1)dw over 200 days) and oxygen was depleted rapidly in most incubations soon after its addition, which might be due to the oxidation of organic matter and other reduced species such as Fe(2+), S(2-) and Mn in sediment before the biodegradation of herbicides takes place. This study suggests that oxygen enhancement around a drinking water abstraction field could stimulate the bioremediation of diffuse source contamination.
authors.affiliation: Technical University of Denmark, DTU Environment, Department of Environmental Engineering, Miljoevej 113, 2800 Kongens Lyngby, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Levi
authors.affiliation: Technical University of Denmark, DTU Environment, Department of Environmental Engineering, Miljoevej 113, 2800 Kongens Lyngby, Denmark.
authors.forename: A-M
authors.initials: AM
authors.lastname: Hybel
authors.affiliation: Technical University of Denmark, DTU Environment, Department of Environmental Engineering, Miljoevej 113, 2800 Kongens Lyngby, Denmark.
authors.forename: P L
authors.initials: PL
authors.lastname: Bjerg
authors.affiliation: Technical University of Denmark, DTU Environment, Department of Environmental Engineering, Miljoevej 113, 2800 Kongens Lyngby, Denmark. Electronic address: hana@env.dtu.dk.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Albrechtsen
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D000332:Aerobiosis; D001581:Benzothiadiazines / Q000378:metabolism; D001673:Biodegradation, Environmental; D003718:Denmark; D052918:Environmental Restoration and Remediation / Q000379:methods; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology; D060587:Groundwater / Q000737:chemistry* / Q000382:microbiology; D006540:Herbicides / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D001581:Benzothiadiazines; D006540:Herbicides; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; C008340:mecoprop; D008456:2-Methyl-4-chlorophenoxyacetic Acid; C010571:dichlorprop; C002003:bentazone; D010100:Oxygen
keywords: Anaerobic aquifer; Dichlorprop and bentazone; Enhanced aerobic degradation; Groundwater; Herbicides mecoprop; Oxygen addition