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Description
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We here present a detailed dataset of automated greenhouse gas (GHG) net soil and ditch fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from a drained fen in Denmark covering a full year. The dataset resolves small scale spatial and hourly-daily-seasonal dynamics of GHG soil fluxes. The GHG flux dataset is accompanied by simultaneous time series of soil temperature and moisture, as well as groundwater table depth and covers spatiotemporal gradients in soil hydrological and climatic variability. The GHG fluxes of CO2, CH4 and N2O were measured simultaneously by a high-precision cavity ring down laser spectrometer connected with a novel automated GHG system platform called SkyLine2D (Earthbound Scientific Ltd., UK) that allowed up to 27 individual chamber measurement points along a 24 meter transect. In total 47.483 chamber measurements were completed and after quality control 44.631 CO2 fluxes, 44.099 N2O and 42.515 CH4 fluxes remained. The average net soil CO2 efflux observed at the site (2.55 μmol CO2 m-2 s-1 or 35 tCO2 ha-1 y-1) aligns with findings from similar drained fens in northern Europe. However, this transect average masks substantial spatial variability and highlights the role of episodic emission bursts related to hydrological variability. N2O fluxes measured at this site were similarly variable in space, but displayed a more dynamic flux behaviour than CO2, where increasing groundwater table depth in response to precipitation during warmer seasons lead to emission bursts of N2O that dominated the annual budget and decreased to near-zero fluxes in drier periods. Soil CH4 fluxes were near-zero and the site overall acted as a small net source, although net uptake was observed as well especially in drier conditions. Diurnal and seasonal patterns of net soil CO2 and N2O fluxes align with expectations of soil temperature driven processes, but no clear patterns were observed for CH4. Compared to soil GHG fluxes, ditch CO2 and N2O fluxes were 4-fold and 27-fold lower, respectively, while CH4 fluxes were more than two orders of magnitude larger, confirming earlier findings that ditches can be CH4 hotspots, where the CH4 is emitted in bursts with little seasonal variability, including emissions as ebullitions. The data set is well suited for testing and developing biogeochemical models, with emphasis on the soil thermal-hydrology interactions with the peat C and N cycles. (2025-03-03)
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Notes
| This dataset has been submitted to Earth System Science Data and is currently under peer review. Note that the final version of this dataset will be updated. |
