Continental shelves and shelf seas play a central role in the global carbon cycle. However, their importance with respect to trace element and isotope (TEI) inputs to ocean basins is less well understood. Here, we present major findings on shelf TEI biogeochemistry from the GEOTRACES programme as well as a proof of concept for a new method to estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The proposed shelf flux tracer is 228-radium (T1/2?=?5.75 yr), which is continuously supplied to the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf (228)Ra fluxes are combined with TEI/ (228)Ra ratios to quantify ocean TEI fluxes from the western North Atlantic margin. The results from this new approach agree well with previous estimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmospheric deposition by factors of approximately 3-23. Lastly, recommendations are made for additional GEOTRACES process studies and coastal margin-focused section cruises that will help refine the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes to the ocean.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.
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Cites: Proc Natl Acad Sci U S A. 2015 Mar 31;112(13):3926-3025775554
Cites: Nature. 2009 Jan 29;457(7229):577-8019177128
Cites: Science. 2010 Mar 5;327(5970):1246-5020203047
Cites: Nat Commun. 2015 Jul 09;6:759226158849
Cites: Nature. 2014 Aug 7;512(7512):65-825100482
Cites: Environ Sci Technol. 2007 May 1;41(9):3090-517539509