Radium isotopes as a tracer of sediment-water column exchange in the North Sea

W. J. Burt*, H. Thomas, J. Paetsch, A. M. Omar, C. Schrum, U. Daewel, H. Brenner, H. J. W. de Baar

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

17 Citaten (Scopus)
279 Downloads (Pure)

Samenvatting

Sediment-water column exchange plays an important role in coastal biogeochemistry. We utilize short-lived radium isotopes (Ra-224 and Ra-223) to understand and quantify the dominant processes governing sediment-water column exchange throughout the North Sea. Our comprehensive survey, conducted in September 2011, represents the first of its kind conducted in the North Sea. We find that two main sources regulate surface Ra distributions: minor coastal input from rivers and shallow mudflats and North Sea sediments as the dominant source. Pore waters show 100-fold larger activities than the water column. North Sea sediment characteristics such as porosity and mean grain size, as well as turbulence at the sediment-water interface, are the dominant factors contributing to variability of Ra efflux. Ra inventory and mass balance approaches consistently yield high benthic Ra effluxes in the southern North Sea, driven by strong tidal and wind mixing, which in turn cause high sediment irrigation rates. These results exceed incubation-based Ra flux estimates and the majority of previously reported Ra flux estimates for other regions. Ra-based estimates of benthic alkalinity fluxes compare well to observed values, and the high rates of Ra efflux imply a potentially significant exchange of other products of sedimentary reactions, including carbon and nutrient species. Passive tracer simulations lend strong support to the Ra source attribution and imply seasonal variation in the surface water Ra distribution depending on stratification conditions.

Originele taal-2English
Pagina's (van-tot)786-804
Aantal pagina's19
TijdschriftGlobal Biogeochemical Cycles
Volume28
Nummer van het tijdschrift8
DOI's
StatusPublished - aug.-2014

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