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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 (T_1/2 = 5.75 yr), which is continuously supplied to the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf ²²⁸Ra fluxes are combined with TEI/ ²²⁸Ra 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.

Item Type:	Refereed Article
Keywords:	iron biogeochemistry, cross shelf transport, GEOTRACES, trace elements, isotopes, radium, continental shelf
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Chemical oceanography
Objective Division:	Environmental Management
Objective Group:	Marine systems and management
Objective Field:	Oceanic processes (excl. in the Antarctic and Southern Ocean)
UTAS Author:	Boyd, PW (Professor Philip Boyd)
ID Code:	114114
Year Published:	2016
Web of Science® Times Cited:	53
Deposited By:	Ecology and Biodiversity
Deposited On:	2017-02-07
Last Modified:	2018-04-19
Downloads:	90 View Download Statistics