title: Atrazine degradation by bioaugmented sediment from constructed wetlands.
abstract: The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis 97331-3804, USA.
authors.forename: H B
authors.initials: HB
authors.lastname: Runes
authors.forename: J J
authors.initials: JJ
authors.lastname: Jenkins
authors.forename: P J
authors.initials: PJ
authors.lastname: Bottomley
mesh_terms: D001280:Atrazine / Q000378:metabolism*; D019015:Geologic Sediments / Q000382:microbiology*; D006540:Herbicides / Q000378:metabolism*; D009922:Oregon; D010944:Plants; D012988:Soil Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D001280:Atrazine