Implication of deoxygenation on trace metal chemistry in the ocean.

Croot, Peter, Heller, Maija and Wuttig, Kathrin (2011) Implication of deoxygenation on trace metal chemistry in the ocean. [Talk] In: EUR-OCEANS Conference - Ocean deoxygenation and implications for marine biogeochemical cycles and ecosystems. , 24.-26.10.2011, Toulouse, France .

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Dissolved oxygen is the most critical parameter controlling redox reactions in the ocean today and is central to understanding the distribution of redox sensitive metals in the ocean. Oxygen is important not only simply from the geological perspective and for systems in apparent thermodynamic equilibrium but crucially over the shorter time scales important to biology (e.g. seconds, hours or seasonal) where kinetic processes dominate and thermodynamically unfavoured species can build up to significant concentrations or undergo rapid cycling and alter the bioavailability of the element considerably. Due to the chemical differences (e.g. organic complexation or particle adsorption) between different metal redox states this can on longer time scales, affect the transport and distribution of this element in the ocean. This is most evident with regard to the limiting nutrient iron, where the reduced form (Fe2+) is significantly more soluble and less particle reactive than the thermodynamically favoured form (Fe3+) under oxygenated conditions. Thus changes in the supply and distribution of oxygen can thus have major effects on the distribution and cycling of many trace metals in the ocean with implications for primary productivity and phytoplankton community composition. In this presentation I will examine the current state of knowledge on trace metal biogeochemical cycles in the ocean with emphasis on recent work in oxygen minimum zones. Using existing data I will estimate the oxygen tipping points at which redox changes in different metals may be first evident, how it can progress (feedbacks) and what changes this implies for metal speciation (including organic complexation), distribution and bioavailability.

Document Type: Conference or Workshop Item (Talk)
Keywords: Marine chemistry
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Date Deposited: 10 Feb 2012 10:35
Last Modified: 23 Feb 2012 05:09

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