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| Titel |
Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers |
| VerfasserIn |
Deborah Wood, Kirsty Crocket, Tim Brand, Marc Stutter, Clare Wilson, Christian Schröder |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122050
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| Publikation (Nr.) |
 EGU/EGU2016-976.pdf |
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| Zusammenfassung |
| Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers
Wood, D.A¹, Crocket, K², Brand, T², Stutter, M³, Wilson, C¹ & Schröder, C¹
¹Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA
²Scottish Association for Marine Science, University of the Highlands and Islands, Dunbeg, Oban, PA37 1QA
³James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH
The biogeochemical iron cycle exerts significant control on the carbon cycle¹. Iron is a limiting nutrient in large areas of the world’s oceans and its bioavailability controls CO2 uptake by marine photosynthesizing microorganisms. While atmospheric iron inputs to the open ocean have been extensively measured, global river inputs have likely been underestimated because most major world rivers exhibit extensive iron removal by flocculation and sedimentation during seawater mixing. Iron minerals and organic matter mutually stabilise each other², which results in a ‘rusty carbon sink’ in sediments³ on the one hand but may also enhance transport beyond the salinity gradient on the other. Humic-rich, high latitude rivers have a higher iron-carrying capacity⁴⁻⁶ but are underrepresented in iron flux calculations.
The West Coast sea lochs in Scotland are fed by predominantly peatland drainage catchments, and the rivers entering the sea lochs carry a high load of organic matter. The short distance between many of these catchments and the coastal ocean facilitates source-to-sea research investigating transport, fate and mineralogy of iron-bearing colloids providing a good analogue for similar high latitude fjordic systems.
We use SeaFAST+ICP-MS and Mössbauer spectroscopy to survey trace metal concentrations, with emphasis on iron concentrations, speciation and mineralogy, across salinity gradients. In combination with ultra-filtration techniques, this allows determination of the concentrations and chemical composition of different size fractions of iron-organic matter particles and colloids. We are developing new filtering and enrichment protocols to enable the use of Mössbauer spectroscopy in order to close a gap in the understanding of iron mineralogy in sub-micron particles. Here we will present results from a first sampling campaign in Loch Sunart and its tributaries.
Acknowledgements: This is a MASTS-funded PhD project (GSS30). Preliminary work was supported by a SAGES PECRE grant to C.S., and a MASTS Visiting Fellowship award (VF41) to
K.C.
References:
1. Raiswell and Canfield (2012). The Iron Biogeochemical Cycle Past and Present. Geochemical Perspectives 1(1), 1-220.
2. Schröder et al. The biogeochemical iron cycle and astrobiology. Hyperfine Interactions in press.
3. Lalonde et al. (2012). Preservation of organic matter in sediments promoted by iron. Nature 483, 198–200.
4. Batchelli et al. (2010). Evidence for strong but dynamic iron-humic colloidal associations in humic-rich coastal waters. Environ. Sci. Technol., 44, 8485-8490.
5. Krachler et al. (2010). Relevance of peat-draining rivers for the riverine input of dissolved iron into the ocean. Sci. Total Environ., 408, 2402-2408.
6. Pokrovsky et al. (2014). Fate of colloids during estuarine mixing in the Arctic. Ocean Sci., 10, 107-125. |
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