Publications (3)4.86 Total impact
Article: Degradation of the (R)- and (S)-enantiomers of the herbicides MCPP and dichlorprop in a continuous field-injection experiment.[show abstract] [hide abstract]
ABSTRACT: An aerobic field-injection experiment was performed to study the degradation and migration of different herbicides at trace levels in an aerobic aquifer at Vejen, Denmark. Mecoprop (MCPP) and dichlorprop monitored in a dense network of multilevel samplers were both degraded within a distance of 1 m after a period of 120 days. The study showed that no preferential degradation of the (R)- and (S)-enantiomers of MCPP and of dichlorprop took place as the enantiomeric forms of the phenoxy acids were degraded simultaneously in the aquifer.Water Research 10/2002; 36(16):4160-4. · 4.86 Impact Factor
Article: Characterization of Predominant Reductants in an Anaerobic Leachate-Contaminated Aquifer by Nitroaromatic Probe Compounds[show abstract] [hide abstract]
ABSTRACT: The biogeochemical processes controlling the reductive transformation of contaminants in an anaerobic aquifer were inferred from the relative reactivity patterns of redox-sensitive probe compounds. The fate of five nitroaromatic compounds (NACs) was monitored under different redox conditions in a landfill leachate plume of a sandy aquifer. Results of field experiments (continuous injection and in situ microcosms) were compared to the findings of laboratory batch and column experiments (using aquifer matrix and model systems for sulfate- and iron-reducing conditions). NACs were transformed within 2−70 days in the leachate plume as well as in microbially active and in microbially deactivated experiments. Generally, aromatic amines were the predominant reduction products, and these compounds were stable within the time frame and under the conditions of our experiments. Despite the presence of various potential reductants (e.g., H2S/HS-, Fe(II)aq, reduced organic matter, microorganisms), the patterns of relative reactivity of the probe compounds indicated that ferrous iron associated with iron(III) (hydr)oxide surfaces was the dominant reductant throughout the anaerobic region of the plume. Our results suggest that Fe(II) associated with ferric iron minerals is a highly reactive reductant in anaerobic aquifers, which may also determine the fate of other classes of reducible contaminants such as halogenated solvents, azo compounds, sulfoxides, chromate, or arsenate.12/1997;
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ABSTRACT: The fate of the two pesticides MCPP (mecoprop) and atrazine was investigated in an anaerobic aquifer downgradient from the Grindsted Landfill, Denmark, by means of a field injection experiment, in situ microcosms and laboratory batch experiments. The redox conditions in the experiments were dominated by iron reduction, but also methanogenesis and sulfate reduction occurred closest to the landfill. No degradation nor sorption was observed for the two pesticides in any of the biologically active experiments. In microbially inhibited laboratory experiments, supplied with sodium azide as a sterilizing agent, a chemical degradation of atrazine occurred.Water Research.