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| Titel |
Benthic remineralisation rates in southern North Sea - from point measurements to areal estimates |
| VerfasserIn |
Andreas Neumann, Jana Friedrich, Justus van Beusekom, Celine Naderipour |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112790
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| Publikation (Nr.) |
 EGU/EGU2015-12967.pdf |
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| Zusammenfassung |
| The southern North Sea is enclosed by densely populated hinterland with intensive
use by agriculture and industry and thus substantially affected by anthropogenic
influences. As a coastal subsystem, this applies especially to the German Wadden Sea, a
system of back-barrier tidal flats along the whole German Bight. Ongoing efforts to
implement environmental protection policies during the last decades changed the
significance of various pollutants such as reactive nitrogen or phosphate, which raises the
desire for constant monitoring of the coastal ecosystem to assess the efficiency of
the employed environmental protection measures. Environmental monitoring is
limited to point measurements which thus have to be interpolated with appropriate
models. However, existing models to estimate various sediment characteristics for
the interpolation of point measurements appear insufficient when compared with
actual field measurements in the southern North Sea. We therefore seek to improve
these models by identifying and quantifying key variables of benthic solute fluxes
by comprehensive measurements which cover the complete spatial and seasonal
variability.
We employ in-situ measurements with the eddy-correlation technique and flux chambers
in combination with ex-situ incubations of sediment cores to establish benthic fluxes of
oxygen and nutrients. Additional ex-situ measurements determine basic sediment
characteristics such as permeability, volumetric reaction rates, and substrate concentration.
With our first results we mapped the distribution of measured sediment permeability,
which suggest that areas with water depth greater than 30 m are impervious whereas
sediment in shallower water at the Dogger Bank and along the coast is substantially
permeable with permeability between 10-12 m2 and 10-10 m2. This implies that
benthic fluxes can be estimated with simple diffusion-type models for water depths
>30 m, whereas estimates especially for coastal sediments require percolation
modelling. We are further able to estimate sediment permeability and volumetric oxygen
consumption rate on the basis of grain size distribution. Since grain size distribution
is already mapped with high spatial resolution, we now have the prerequisites to
interpolate two key variables for benthic consumption and influx of oxygen. With
our next step we intend to assess model-based estimates of benthic oxygen and
nutrient fluxes with our in-situ measurements as references to refine the underlying
models.
Our field measurements contribute to the NOAH project (North Sea; Observation and
Assessment of Habitats), the established methods for routine monitoring contribute to the
WiMO project (Wissenschaftliches Monitoring / Scientific Monitoring). |
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