Carbon sources in the North Sea evaluated by means of radium and stable carbon isotope tracers
Burt, W.J.; Thomas, H.; Hagens, M.; Pätsch, J.; Clargo, N.; Salt, L.A.; Winde, V.; Böttcher, M.E. (2016). Carbon sources in the North Sea evaluated by means of radium and stable carbon isotope tracers. Limnol. Oceanogr. 61: 666-683. dx.doi.org/10.1002/lno.10243
In: Limnology and Oceanography. American Society of Limnology and Oceanography: Waco, Tex., etc. ISSN 0024-3590; e-ISSN 1939-5590, more
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| Authors | | Top |
- Burt, W.J.
- Thomas, H., more
- Hagens, M.
- Pätsch, J.
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- Clargo, N., more
- Salt, L.A., more
- Winde, V.
- Böttcher, M.E.
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| Abstract |
A multitracer approach is applied to assess the impact of boundary fluxes (e.g., benthic input from sedimentsor lateral inputs from the coastline) on the acid-base buffering capacity, and overall biogeochemistry,of the North Sea. Analyses of both basin-wide observations in the North Sea and transects through tidalbasins at the North-Frisian coastline, reveal that surface distributions of the d13C signature of dissolved inorganiccarbon (DIC) are predominantly controlled by a balance between biological production and respiration.In particular, variability in metabolic DIC throughout stations in the well-mixed southern North Sea indicatesthe presence of an external carbon source, which is traced to the European continental coastline usingnaturally occurring radium isotopes (224Ra and 228Ra). 228Ra is also shown to be a highly effective tracer ofNorth Sea total alkalinity (AT) compared to the more conventional use of salinity. Coastal inputs of metabolicDIC and AT are calculated on a basin-wide scale, and ratios of these inputs suggest denitrification as aprimary metabolic pathway for their formation. The AT input paralleling the metabolic DIC release preventsa significant decline in pH as compared to aerobic (i.e., unbuffered) release of metabolic DIC. Finally, longtermpH trends mimic those of riverine nitrate loading, highlighting the importance of coastal AT productionvia denitrification in regulating pH in the southern North Sea. |
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