Document Detail


Fate of the herbicides 2,4,5-T, atrazine, and DNOC in a shallow, anaerobic aquifer investigated by in situ passive diffusive emitters and laboratory batch experiments.
MedLine Citation:
PMID:  11708448     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The fate of the three herbicides 2,4,5-T (2,4,5-trichlorophenoxyacetic acid), atrazine (6-chloro-N-ethyl-N'-[1-methyl-ethyl]-1,3,5-triazine-2,4-diamine), and DNOC (4,6-dinitro-2-methylphenol) in an anaerobic sandy aquifer was investigated. In the field, each of the herbicides was released simultaneously with tritiated water (HTO) as tracer in the depth interval 3 to 4 mbs (meters below surface) by use of passive diffusive emitters. Atrazine and 2,4,5-T were persistent during the approximately 18 days residence time in the aquifer. In contrast, DNOC was rapidly removed from the water phase following first-order kinetics. The removal mechanism was likely an abiotic reduction. At day 25, the first-order rate constant was 1.47 d(-1), but it decreased with time and seemed to stabilize at 0.35 d(-1) after 150 to 200 days. In the laboratory, batch experiments were conducted with sediments from 3 to 4 mbs and from 8 to 9 mbs. In these incubations, formation of Fe2+ and depletion of sulfate showed iron and sulfate reduction in sediment from 3 to 3.5 mbs and sulfate reduction in 3.5 to 4 mbs sediment. In sediment from 8 to 9 mbs, the dominant redox process was methane formation. In sediment from 3 to 3.5 mbs, only 27% to 52% of the 2,4,5-T remained after 196 days. 2,4,5-trichlorophenol was identified as the major metabolite. A lag period of at least 50 days was observed, and no degradation occurred in HgCl2 amended controls, verifying that the process was microbially mediated. In the other 2,4,5-T incubations and all the atrazine incubations, concentrations decreased linearly, but less than 25% was removed within 200 to 250 days. No degradation products could be detected, and slow sorption was the likely explanation. In all the laboratory incubations DNOC was degraded, following first-order kinetics, and when normalized to the sediment/water-ratio, the field and laboratory derived rate constants compared well. The DNOC degradation in the methanogenic incubations (8 to 9 mbs) was up to 50 times faster than in the sediments from 3 to 4 mbs, likely due to the low redox potential.
Authors:
N P Arildskov; P G Pedersen; H J Albrechtsen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ground water     Volume:  39     ISSN:  0017-467X     ISO Abbreviation:  Ground Water     Publication Date:    2001 Nov-Dec
Date Detail:
Created Date:  2001-11-15     Completed Date:  2002-02-20     Revised Date:  2013-01-28    
Medline Journal Info:
Nlm Unique ID:  9882886     Medline TA:  Ground Water     Country:  United States    
Other Details:
Languages:  eng     Pagination:  819-30     Citation Subset:  IM    
Affiliation:
Environment & Resources DTU and Groundwater Research Center, Technical University of Denmark, Lyngby.
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MeSH Terms
Descriptor/Qualifier:
2,4,5-Trichlorophenoxyacetic Acid / analysis*,  chemistry,  metabolism
Atrazine / analysis*,  chemistry,  metabolism
Dinitrocresols / analysis*,  chemistry,  metabolism
Environmental Monitoring
Euryarchaeota / physiology
Geologic Sediments / chemistry
Herbicides / analysis*,  chemistry,  metabolism
Kinetics
Oxidation-Reduction
Soil Microbiology
Soil Pollutants / analysis*,  metabolism
Water Pollutants, Chemical / analysis*,  metabolism
Chemical
Reg. No./Substance:
0/Dinitrocresols; 0/Herbicides; 0/Soil Pollutants; 0/Water Pollutants, Chemical; 1604ZJR09T/4,6-dinitro-o-cresol; 1912-24-9/Atrazine; 93-76-5/2,4,5-Trichlorophenoxyacetic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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