Flessa, Heiner

[["dc.bibliographiccitation.firstpage","299"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Nutrient Cycling in Agroecosystems"],["dc.bibliographiccitation.lastpage","312"],["dc.bibliographiccitation.volume","85"],["dc.contributor.author","Weymann, Daniel"],["dc.contributor.author","Well, Reinhard"],["dc.contributor.author","von der Heide, Carolin"],["dc.contributor.author","Boettcher, Juergen"],["dc.contributor.author","Flessa, Heiner"],["dc.contributor.author","Duijnisveld, Wilhelmus H. M."],["dc.date.accessioned","2018-11-07T11:23:03Z"],["dc.date.available","2018-11-07T11:23:03Z"],["dc.date.issued","2009"],["dc.description.abstract","Production and accumulation of the major greenhouse gas nitrous oxide (N2O) in surface groundwater might contribute to N2O emissions to the atmosphere. We report on a N-15 tracer study conducted in the Fuhrberger Feld aquifer in northern Germany. A (KNO3)-N-15 tracer solution (60 atom%) was applied to the surface groundwater on an 8 m(2) measuring plot using 45 injection points in order to stimulate production of (N2O)-N-15 by denitrification and to detect its contribution to emissions at the soil surface. Samples from the surface groundwater, from the unsaturated zone and at the soil surface were collected in regular intervals over a 72-days period. Total N2O fluxes at the soil surface were low and in a range between -7.6 and 29.1 mu g N2O-N m(-2) h(-1). N-15 enrichment of N2O decreased considerably upwards in the profile. In the surface groundwater, we found a N-15 enrichment of N2O between 13 and 42 atom%. In contrast, N-15 enrichment of N2O in flux chambers at the soil surface was very low, but a detectable N-15 enrichment was found at all sampling events. Fluxes of groundwater-derived N-15-N2O were very low and ranged between 0.0002 and 0.0018 kg N2O-N ha(-1) year(-1), indicating that indirect N2O emissions from the surface groundwater of the Fuhrberger Feld aquifer occurring via upward diffusion are hardly significant. Due to these observations we concluded that N2O dynamics at the soil-atmosphere interface is predominantly governed by topsoil parameters. However, highest N-15 enrichments of N2O throughout the profile were obtained in the course of a rapid drawdown of the groundwater table. We assume that such fluctuations may enhance diffusive N2O fluxes from the surface groundwater to the atmosphere for a short time."],["dc.description.sponsorship","German Research Foundation"],["dc.identifier.doi","10.1007/s10705-009-9269-4"],["dc.identifier.isi","000270649300008"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/6796"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/56106"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","1385-1314"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Recovery of groundwater N2O at the soil surface and its contribution to total N2O emissions"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1953"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","BIOGEOSCIENCES"],["dc.bibliographiccitation.lastpage","1972"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Weymann, Daniel"],["dc.contributor.author","Geistlinger, H."],["dc.contributor.author","Well, Reinhard"],["dc.contributor.author","von der Heide, Carolin"],["dc.contributor.author","Flessa, H."],["dc.date.accessioned","2018-11-07T08:47:08Z"],["dc.date.available","2018-11-07T08:47:08Z"],["dc.date.issued","2010"],["dc.description.abstract","Knowledge of the kinetics of N2O production and reduction in groundwater is essential for the assessment of potential indirect emissions of the greenhouse gas. In the present study, we investigated this kinetics using a laboratory approach. The results were compared to field measurements in order to examine their transferability to the in situ conditions. The study site was the unconfined, predominantly sandy Fuhrberger Feld aquifer in northern Germany. A special characteristic of the aquifer is the occurrence of the vertically separated process zones of heterotrophic denitrification in the near-surface groundwater and of autotrophic denitrification in depths beyond 2-3 m below the groundwater table, respectively. The kinetics of N2O production and reduction in both process zones was studied during long-term anaerobic laboratory incubations of aquifer slurries using the N-15 tracer technique. We measured N2O, N-2, NO3-, NO2-, and SO42- concentrations as well as parameters of the aquifer material that were related to the relevant electron donors, i.e. organic carbon and pyrite. The laboratory incubations showed a low denitrification activity of heterotrophic denitrification with initial rates between 0.2 and 13 mu g N kg(-1) d(-1). The process was carbon limited due to the poor availability of its electron donor. In the autotrophic denitrification zone, initial denitrification rates were considerably higher, ranging between 30 and 148 mu g N kg(-1) d(-1), and NO3- as well as N2O were completely removed within 60 to 198 days. N2O accumulated during heterotrophic and autotrophic denitrification, but maximum concentrations were substantially higher during the autotrophic process. The results revealed a satisfactory transferability of the laboratory incubations to the field scale for autotrophic denitrification, whereas the heterotrophic process less reflected the field conditions due to considerably lower N2O accumulation during laboratory incubation. Finally, we applied a conventional model using first-order-kinetics to determine the reaction rate constants k(1) for N2O production and k(2) for N2O reduction, respectively. The goodness of fit to the experimental data was partly limited, indicating that a more sophisticated approach is essential to describe the investigated reaction kinetics satisfactorily."],["dc.description.sponsorship","German Research Foundation (DFG)"],["dc.identifier.doi","10.5194/bg-7-1953-2010"],["dc.identifier.isi","000279390700009"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5734"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20872"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Copernicus Gesellschaft Mbh"],["dc.relation.issn","1726-4170"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Kinetics of N2O production and reduction in a nitrate-contaminated aquifer inferred from laboratory incubation experiments"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","216"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","European Journal of Soil Science"],["dc.bibliographiccitation.lastpage","225"],["dc.bibliographiccitation.volume","62"],["dc.contributor.author","Boettcher, Juergen"],["dc.contributor.author","Weymann, Daniel"],["dc.contributor.author","Well, Reinhard"],["dc.contributor.author","von der Heide, Carolin"],["dc.contributor.author","Schwen, A."],["dc.contributor.author","Flessa, H."],["dc.contributor.author","Duijnisveld, Wilhelmus H. M."],["dc.date.accessioned","2018-11-07T08:57:48Z"],["dc.date.available","2018-11-07T08:57:48Z"],["dc.date.issued","2011"],["dc.description.abstract","Indirect emissions of the major greenhouse gas nitrous oxide (N2O) occurring from aquatic ecosystems are considered to be a highly uncertain component in the global N2O budget. In this study, we investigated the fate of N2O produced by denitrification in a sandy shallow aquifer in northern Germany. The experimental data from a previous 15N field study and site-specific diffusion coefficients were used to simulate upward fluxes of groundwater-derived (15N-)N2O in the soil as well as its ultimate emission into the atmosphere. The one-dimensional simulation model considered gas diffusion and gas retardation by dissolution in the water phase. The modelled concentration gradients and emissions were in good agreement with the experimental data, indicating that diffusion was the dominant transport process in the soil, and that our model approach was thus suitable for simulating N2O fluxes from the unsaturated zone to the atmosphere. Furthermore, the results revealed that there was no evidence for consumption of 15N-N2O during upward diffusion from the surface groundwater to the atmosphere. Simulated concentrations and emissions of groundwater-derived N2O were found to be very small and a negligible component of total N2O."],["dc.identifier.doi","10.1111/j.1365-2389.2010.01311.x"],["dc.identifier.isi","000288503100004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/23486"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell"],["dc.relation.issn","1351-0754"],["dc.title","Emission of groundwater-derived nitrous oxide into the atmosphere: model simulations based on a 15N field experiment"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]