Spatial variability of N₂O concentrations and of denitrification-related factors in the surficial groundwater of a catchment in Northern Germany

verfasst von

C. von der Heide, J. Böttcher, M. Deurer, D. Weymann, R. Well, W. H.M. Duijnisveld

Abstract

N₂O concentrations and denitrification-related factors (NO₃, SO₄, dissolved organic carbon (DOC) and CO₂) were investigated in the surface groundwater of a catchment in northern Germany, the Fuhrberger Feld Aquifer (FFA). We sampled 79 plots that were selected according to the three criteria of land use, historical land use conversion (1954-1995) and groundwater level. We sampled three sites within each plot. The sampling depth was 0.5 m below the groundwater surface. We found no indication for the occurrence of autotrophic denitrification in the surface groundwater. Heterotrophic denitrification was identified as the main process for N₂O accumulation. The variability of N₂O concentrations on the plot-scale was extremely high and was poorly explained by the three sampling criteria. Other denitrification-related variables such as NO₃, SO₄ and DOC were less variable. The selection criteria land use and groundwater level clearly influenced the order of magnitude of N₂O concentrations in the surface groundwater. Under arable land, high NO₃ concentrations resulted in high N₂O concentrations. The surface groundwater under forest and pasture was almost NO₃-free and had also very small N₂O concentrations. Plots where the distance from the soil surface to the groundwater surface was large (>1 m up to 3.4 m) showed higher N₂O concentrations in the surface groundwater than plots where the distance was small (<1 m). A larger distance from the soil surface to the groundwater leads to a longer residence time and more decomposition of DOC in the soil. Consequently the less bioavailable DOC could inhibit the efficiency of the heterotrophic denitrification in the groundwater, yielding more N₂O. Elevated organic carbon levels in plots with historic land use conversion (pasture to arable) were very stable and did not influence N₂O concentrations. The high within plot variability showed that an upscaling of N₂O from the plot-scale to the catchment-scale is possible as long as the groundwater level regime and the land use do not change.

Organisationseinheit(en)

Institut für Bodenkunde
AG Bodenbiophysik

Externe Organisation(en)

Plant & Food Research New Zealand
Georg-August-Universität Göttingen
Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)

Typ

Artikel

Journal

Journal of hydrology

Band

360

Seiten

230-241

Anzahl der Seiten

12

ISSN

0022-1694

Publikationsdatum

15.10.2008

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Gewässerkunde und -technologie

Ziele für nachhaltige Entwicklung

SDG 15 – Lebensraum Land

Elektronische Version(en)

https://doi.org/10.1016/j.jhydrol.2008.07.034 (Zugang: Unbekannt)