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dc.contributor.authorFlatabø, Gudny Øyre
dc.date.accessioned2017-08-30T15:46:33Z
dc.date.available2017-08-30T15:46:33Z
dc.date.issued2017-08-29
dc.date.submitted2017-08-28T22:00:03Z
dc.identifier.urihttps://hdl.handle.net/1956/16430
dc.description.abstractAt Oslo airport, Gardermoen, Norway, large quantities of propylene glycol (PG) are used as de-icing fluid during winter, causing high loads of this chemical to infiltrate in surrounding soil during snow melt and increasing concentrations of soluble manganese (Mn2+) and ferrous iron (Fe2+) in the groundwater. Previous studies have suggested that anaerobic microbial Mn and Fe reduction fuelled by PG in deeper soil layers is the primary reason for the observed increase of Mn2+ and Fe2+ and proposed nitrate (NO3-) fertilization as a mitigation measure. However, laboratory and field experiments with NO3- addition have yielded inconsistent, partly adverse results. To better understand the effect PG has on Mn2+ and Fe2+ release in the Gardermoen soil system, in the presence or absence of moderate NO3- concentrations, a series of batch incubation experiments was carried out with non-contaminated top and subsoil sampled at a research site close to Oslo airport. Microbial activity was measured as O2, CO2, NO, N2O and N2 kinetics, while the release of Fe2+ and Mn2+ was monitored by subsampling the soil solution through microrhizones. After 26 days of incubation, 16S-rDNA was extracted and sequenced to study the effect of PG and N on microbial community composition. Both, top- and subsoil released Mn2+ and Fe2+ in untreated controls but release rates were larger in the presence of PG. Top soil released on average 100 to 1000 times more Mn2+ than subsoil, which was attributed to a larger abundance of Mn(IV) reducing bacteria in the topsoil. Unlike in top soil, moderate NH4NO3 addition to the subsoil triggered additional Mn2+ release, apparently by relieving N limitation of microbial growth. The comparison of 16S rRNA-based taxonomic abundances before and after incubation of subsoil with PG and NO3- revealed that the metabolically versatile families Comamonadaceae, Oxalobacteraceae and Pseudomonadaceae increased in relative abundance, likely dominating PG metabolism and Mn and Fe reduction observed at the end of the incubation. Therefore, NO3- addition, although providing an alternative electron acceptor, cannot be recommended for mitigation of metal release, as it poses the risk to increase microbial Mn and Fe reduction in the subsoil. In contrast, measures that lead to a better aeration of the top layer, particularly during wet periods, appear to be the more promising approach to avoid Mn2+ and Fe2+ release.en_US
dc.language.isoengeng
dc.publisherThe University of Bergenen_US
dc.subject16S rRNAeng
dc.subjectbioremediationeng
dc.subjectpropylene glycoleng
dc.subjectMn reductioneng
dc.subjectde-icing fluidseng
dc.subjectFe reductioneng
dc.subjectmicrobial metal reductioneng
dc.subjectgroundwatereng
dc.subjectsoil contaminationeng
dc.subjectkineticseng
dc.subjectIlluminaeng
dc.subjectAnvendt mikrobiologinob
dc.subjectBioremedieringnob
dc.subjectAvisingsvæskenob
dc.subjectFlyplassernob
dc.subjectGrunnvannsforurensningnob
dc.subjectJordforurensningnob
dc.titleMn/Fe reduction in sandy soil during degradation of de-icing chemical: Respiration kinetics and prokaryotic community compositionen_US
dc.typeMaster thesis
dc.date.updated2017-08-28T22:00:03Z
dc.rights.holderCopyright the Author. All rights reserveden_US
dc.description.degreeMasteroppgåve i biologien_US
dc.description.localcodeBIO399
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c006567
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c004408
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c013313
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c010052
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c006802
dc.subject.realfagstermerhttps://data.ub.uio.no/realfagstermer/c002771
dc.subject.nus751999eng
fs.subjectcodeBIO399
fs.unitcode12-60-00


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