Spatial and temporal variability of N₂O in the surface groundwater

A detailed analysis from a sandy aquifer in northern Germany

authored by

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

Abstract

The knowledge of the spatial and temporal variability of N₂O concentrations in surface groundwater is the first step towards upscaling of potential indirect N₂O emissions from the scale of localized samples to aquifers. This study aimed to investigate the spatial and the temporal variability of N₂O concentrations at different scales in the surface groundwater of a denitrifying aquifer in northern Germany. The spatial variability of N₂O concentrations in the surface groundwater was analysed at the plot (200 × 200 m) and at the transect scale (12 m). Twenty plots that were distributed across an area of 11 km² and 6 transects were sampled. Sixty per cent of the spatial variance of N₂O was located at the plot scale and 68-79% was located at the transect scale. This indicates that small-scale processes governed the spatial variability of N₂O in the surface groundwater. A spatial upscaling of N₂O from the transect to the aquifer scale might be possible with an adequate number of samples that represent important boundary conditions for N₂O accumulation in the catchment (topography, groundwater level, land use). For the investigation of the temporal variability, 4 multilevel wells were sampled monthly over a period of 13 months. In two periods, a multilevel well was additionally sampled in 2-day intervals over 8 days. At the annual scale, N₂O concentrations in the surface groundwater were higher during the vegetation period (median 87 μg N₂O-N l^-1) and could change rapidly on the day scale whereas the concentrations were smaller in winter (median 21 μg N₂O-N l^-1). Groundwater recharge events seemed to be crucial for the day scale variability. Capture of the temporal variations for upscaling might be achieved with a process-based sampling strategy with weekly sampling intervals during the vegetation period, the additional sampling after groundwater recharge events and monthly sampling intervals in winter.

Organisation(s)

Institute of Soil Science
Section Soil Biophysics

External Organisation(s)

New Zealand Institute for Plant & Food Research Limited (Plant & Food Research)
Federal Institute for Geosciences and Natural Resources (BGR)
University of Göttingen
Johann Heinrich von Thünen Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries

Type

Article

Journal

Nutrient cycling in agroecosystems

Volume

87

Pages

33-47

No. of pages

15

ISSN

1385-1314

Publication date

05.2010

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Agronomy and Crop Science, Soil Science

Sustainable Development Goals

SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1007/s10705-009-9310-7 (Access: Open)