TY - JOUR

T1 - Recovery of groundwater N2spiinf;o at the soil surface and its contribution to total N2spiinf;o emissions

AU - Weymann, Daniel

AU - Well, Reinhard

AU - von der Heide, Carolin

AU - Böttcher, Jürgen

AU - Flessa, Heiner

AU - Duijnisveld, Wilhelmus H.M.

N1 - Funding information: Acknowledgments We thank the German Research Foundation for funding this research project. Modification of the gas probes, the instrumentation of the measuring field and sampling would not have been possible without the help of G. Benseler, G. Klump, and F. Trienen. We thank I. Ostermeyer, K. Schmidt and L. Szwec as well as R. Langel (Centre for Stable Isotope Research and Analysis at the University of Göttingen) for always reliable assistance during the laboratory efforts.

PY - 2009/10

Y1 - 2009/10

N2 - 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 15N tracer study conducted in the Fuhrberger Feld aquifer in northern Germany. A K15NO3 tracer solution (60 atom%) was applied to the surface groundwater on an 8 m2 measuring plot using 45 injection points in order to stimulate production of 15N2O 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 μg N2O-N m-2 h-1. 15N enrichment of N2O decreased considerably upwards in the profile. In the surface groundwater, we found a 15N enrichment of N2O between 13 and 42 atom%. In contrast, 15N enrichment of N2O in flux chambers at the soil surface was very low, but a detectable 15N enrichment was found at all sampling events. Fluxes of groundwater-derived 15N-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 15N 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.

AB - 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 15N tracer study conducted in the Fuhrberger Feld aquifer in northern Germany. A K15NO3 tracer solution (60 atom%) was applied to the surface groundwater on an 8 m2 measuring plot using 45 injection points in order to stimulate production of 15N2O 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 μg N2O-N m-2 h-1. 15N enrichment of N2O decreased considerably upwards in the profile. In the surface groundwater, we found a 15N enrichment of N2O between 13 and 42 atom%. In contrast, 15N enrichment of N2O in flux chambers at the soil surface was very low, but a detectable 15N enrichment was found at all sampling events. Fluxes of groundwater-derived 15N-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 15N 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.

KW - N-Labeling

KW - Denitrification

KW - Nitrate

KW - Nitrous oxide fluxes

KW - Stable isotopes

KW - Surface groundwater

UR - http://www.scopus.com/inward/record.url?scp=70350379597&partnerID=8YFLogxK

U2 - 10.1007/s10705-009-9269-4

DO - 10.1007/s10705-009-9269-4

M3 - Article

AN - SCOPUS:70350379597

VL - 85

SP - 299

EP - 312

JO - Nutrient cycling in agroecosystems

JF - Nutrient cycling in agroecosystems

SN - 1385-1314

IS - 3

ER -