title: Radiation-induced impacts on the degradation of 2,4-D and the microbial population in soil microcosms.
abstract: In a soil microcosm experiment, the influence of low-level (137)Cs and (90)Sr contamination on the degradation of (14)C-ring-labeled 2,4-dichlorophenoxyacetic acid (2,4-D) was studied. Two differently treated soils (one native soil and one soil sterilized and reinoculated with a biotic soil aliquot) were artificially contaminated with various concentrations of (137)Cs and (90)Sr as nitrate salts. The cumulative doses increased up to 4 Gy for 30 days of incubation in soil microcosms. Changes in microbial community structure were observed with help of the denaturing gradient gel electrophoresis (DGGE). A radiation-induced impact appeared only in the microcosms treated with 30 times the maximum contamination appearing in the exclusion zone around reactor 4 in Chernobyl. In contrast to the less contaminated soils, the mineralization of 2,4-D was delayed for 4 days before it recovered. Slight shifts in the microbial communities could be traced to radiation effects. However, other parameters had a major impact on mineralization and community structure. Thus the sterilization and reinoculation and, of course, application of the 2,4-D were predominantly reflected in the (14)CO(2) emissions and the DGGE gel patterns.
authors.affiliation: Agrosphere Institute, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. b.niedree@fz-juelich.de
authors.forename: Bastian
authors.initials: B
authors.lastname: Niedrée
authors.forename: Harry
authors.initials: H
authors.lastname: Vereecken
authors.forename: Peter
authors.initials: P
authors.lastname: Burauel
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002588:Cesium Radioisotopes / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005658:Fungi / Q000378:metabolism*; D006540:Herbicides / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism* / Q000494:pharmacology; D013326:Strontium Radioisotopes / Q000494:pharmacology*
chemical_list: D002588:Cesium Radioisotopes; D004269:DNA, Bacterial; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D006540:Herbicides; D012989:Soil Pollutants; D013326:Strontium Radioisotopes; D015084:2,4-Dichlorophenoxyacetic Acid