Exploring GEOTRACES: Advancements in Marine Biogeochemistry

1. Sunil Kumar Singh Document prepared by:GEOTRACES IPO

2. 1. GEOTRACES International Programme • Co-chairs: Reiner Schlitzer (AWI, Germany)Ed Boyle (Massachusetts Institute of Technology, USA) • GEOTRACES is an international programme which aims to improve the understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes in the marine environment • Scientists from approximately 35 nations have been involved in the programme, which is designed to study all major ocean basins over the next decade • GEOTRACES Science Plan (2006) • First Intermediate Data Product (IDP2014) released in February 2014 (Ocean Sciences Meeting, Honolulu, Hawaii)

3. 2. Status of GEOTRACES Field Programme 59 cruises (29 GEOTRACES Section cruises) completed Overall (including IPY cruises) 70 cruisescompleted GEOTRACES Sections In red: Planned Sections In yellow: Completed Sections In black: Sections completed as GEOTRACES contribution to the IPY

4. 2… GEOTRACES Process Studies (Completed) They investigate a particular process relevant to the cycling of trace metal and isotopes.

5. 2… GEOTRACES International Arctic Programme Main field effort in the past year: Cruisescompleted in 2015 (in yellow) GN02 – Canada (ArcticNet 15022) 10 July 2015 – 20 August 2015 GN01 – USA (HLY1501) 7 August 2015 – 10 Oct 2015 GN04 –Germany (TRANSARC II) 16 August 2915 – 15 Oct 2015 GN03 – Canada (ArcticNet 1503) 5 September 2015 – 01 October 2015 Forthcoming in 2016 (in red) GN05 – Germany (GRIFF, PS100) 19 July 2016 – 9 Sept. 2016

6. 2… Forthcoming cruises (scheduled)

7. 3. GEOTRACES Intermediate Data Product 2014 DOI: Mawji, E., et al., The GEOTRACES Intermediate Data Product 2014, Mar. Chem. (2015), http://dx.doi.org/10.1016/j.marchem.2015.04.005 Version 2 now available Total number of downloads = 641 Total number of IDP2014 version 1 downloads = 437 Total number of IDP2014 version 2 downloads = 204

8. 3… GEOTRACES Intermediate Data Product 2014 2 parts: Digital Data Package(available at www.bodc.ac.uk/geotraces/data/idp2014/) eGEOTRACES Electronic Atlas (available at www.egeotraces.org) It includes hydrographic and marine geochemical data acquired during the first 3 years of the programme

9. 3… Next GEOTRACES Intermediate Data Product Next Intermediate Data Product planned for 2017(Goldschmidt 2017, 13-18 August, Paris, France) Check GEOTRACES website for data submission timelines

10. 4. GEOTRACES Publications Resing, J. et al. (2015). Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean. Nature, 523(7559), 200–203. doi:10.1038/nature14577. GEOTRACES findings cover of Nature To date: 576 Papers 7 papers published in Nature in the past year (a selection of highlights follows)

11. 4. GEOTRACES Science Highlights: Examples • Field Data Constrain Ocean Mercury Budget Estimates of the total amount and spatial distribution of anthropogenic mercury in the global ocean were substantially improved Global budgets of total mercury suggest a tripling of the surface water mercury content and a ~150% increase in the amount of mercury in thermocline waters above preindustrial levels Lamborg, C. H., Hammerschmidt, C. R., Bowman, K. L., Swarr, G. J., Munson, K. M., Ohnemus, D. C., Lam P.J., Heimbürger L-E., Rijkenberg M., Saito, M. A. (2014). A global ocean inventory of anthropogenic mercury based on water column measurements. Nature, 512(7512), 65–68. doi:10.1038/nature13563

12. 4… GEOTRACES Science Highlights: Examples • Seasonal Iron Supply in the Southern Ocean is Dominated by Winter Mixing Amount of iron supplied to the surface waters of the Southern Ocean is quantified Seasonal iron supply is dominated by winter mixing with little iron input afterwards Biological observations suggest that following the depletion of this wintertime iron pulse, intense iron recycling sustains productivity over the subsequent spring and summer This places important constraints on how climate models represent the iron distribution and how changes in ocean physics impact iron limitation Tagliabue, A., Sallée, J.-B., Bowie, A. R., Lévy, M., Swart, S., & Boyd, P. W. (2014). Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing. Nature Geoscience, 7(4), 314–320. doi:10.1038/ngeo2101

13. 4… GEOTRACES Science Highlights: Examples What Controls the Copper Isotopic Composition in Oceanic Waters? The isotopic composition of dissolved copper (δ65Cu) in surface seawater is mainly controlled by supply from rivers, the atmosphere and deep seawater The finding contradicts previous interpretations suggesting a strong role of the biological activity in δ65Cu fractionation At depth, δ65Cu  values are becoming heavier with the age of deep seawater The authors built a box-model to quantify the oceanic budgets of both Cu concentrations and δ65Cu. Imbalance in this model suggests that Cu fluxes from continental shelf sediment might affect Cu distribution in the open ocean Takano, S., Tanimizu, M., Hirata, T., & Sohrin, Y. (2014). Isotopic constraints on biogeochemical cycling of copper in the ocean. Nature Communications, 5, 5663. doi:10.1038/ncomms6663 

14. 4… GEOTRACES Science Highlights: Examples • Coupling Rare Earth Elements Concentrations, Neodymium And Radium Isotopes: A Powerful Tool to Decode Environmental Processes For the first time, neodymium (Nd) isotopic compositions have been measured together with dissolved and colloidal Rare Earth Elements (REE) concentrations in the Amazon estuary salinity gradient Sharp drop of REE concentrations in the low-salinity area is driven by the coagulation of colloidal material Nd isotopic ratios allow tracing that REE are released by the lithogenic material, weathered and transported by the river to the Atlantic Ocean The original coupling with the radium (Ra) isotopes demonstrates that these dissolution processes are occurring within three weeks in the Amazon plume Rousseau, T. C. C., Sonke, J. E., Chmeleff, J., Beek, P. van, Souhaut, M., Boaventura, G., Seyler, P., Jeandel, C. (2015). Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary. Nature Communications, 6, 7592. doi:10.1038/ncomms8592.

15. 4… GEOTRACES Science Highlights: Examples • Unexpected Magnitude of the Hydrothermal Iron Inputs in the Deep Pacific GEOTRACES data demonstrate that lateral transport of hydrothermal iron, manganese and aluminium extends up to 4000 km west of the southern East Pacific Rise, therefore crossing a significant part of the deep Pacific Ocean The dissolved iron behaves more conservatively than expected, and the resulting flux is more than four times what was assumed before Results from a coupled ocean circulation/biogeochemical model demonstrate that this hydrothermal iron input may sustain a large fraction of the Southern Ocean export production Resing, J. A., Sedwick, P. N., German, C. R., Jenkins, W. J., Moffett, J. W., Sohst, B. M., & Tagliabue, A. (2015). Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean. Nature, 523(7559), 200–203. doi:10.1038/nature14577

16. Published: 4…GEOTRACES Special Issues 3 more in preparation New!! Marine Chemistry (Volume 177, Part 1, Pages 1-202, 20 December 2015) Biogeochemistry of trace elements and their isotopes New!! Deep Sea Research Part II: Topical Studies in Oceanography (Volume 116, Pages 1-342, June 2015)  GEOTRACES GA-03 - The U.S. GEOTRACES North Atlantic Transect New!! Progress in Oceanography(Vol. 133, Pages 1-78, April 2015)
GEOTRACES Synthesis and Modeling: The role of particles in the marine biogeochemical cycles of trace elements and their isotopes Limnology and Oceanography: Methods (2012) “Intercalibration in Chemical Oceanography”devoted to GEOTRACES Intercalibrationhttp://www.aslo.org/lomethods/si/intercal2012.html Deep-Sea Research Part II (Vol. 58/25-26, pages 2497-2784, 2011) “Physics, Carbon Dioxide, Trace Elements and Isotopes in the Southern Ocean: The Polastern Expeditions ANT XXIV-3 (2008) and ANT XXIII/3 (2006)” Deep Sea Research Part II(Volume 58, Issues 21-22, Pages 2051-2316, November 2011) Biogeochemistry of the Australian Sector of the Southern Ocean

17. 5. GEOTRACES Synthesis Strategy 3-pronged synthesis covering main scientific goals of GEOTRACES

18. 5… GEOTRACES Synthesis Workshops in 2015 Royal Society scientific meetings, December 7-10, 2015: “Biological and climatic impacts of ocean trace element chemistry”December 7-8, 2015, London, UKhttps://royalsociety.org/events/2015/12/ocean-chemistry/ “Quantifying fluxes and processes in trace-metal cycling at ocean boundaries”, December 9-10, Chicheley Hall, Buckinghamshirehttps://royalsociety.org/events/2015/12/trace-metal-cycling/

19. 6. GEOTRACES Meetings in 2015

20. 7. Outreach and educational Resources Available on a dedicatedOutreach website Cruise blogs videos podcasts PressReleasescartoons eNewsletter Teacher at sea educational initiatives Posters Brochures Webinars ….

21. Thank you very much! International Coordination: GEOTRACES International Project Office (LEGOS-OMP, Toulouse, France) Catherine Jeandel (Scientific Director) Elena Masferrer Dodas (Executive Officer) Data Management: GEOTRACES Data Assembly Centre (BODC, Liverpool) Abby Bull (GEOTRACES Data Manager) www.geotraces.org