An introduction to the program Bob Anderson Co-chair International GEOTRACES SSC

Mission GEOTRACES An international study of the marine biogeochemistry of trace elements and their isotopes (TEIs) GEOTRACES guiding mission “To identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions”

Motivation MOTIVATION Three decades of research by individual PIs provided relatively little progress in understanding marine biogeochemical cycles of TEIs. A coordinated international strategy is needed to accelerate progress. Marine organic geochemistry community may be in a similar situation.

Key TEIs What are the “key” elements? They include: Essential micronutrients that influence ocean productivity: e.g., Fe, Zn, Cu, Co, Ni, Cd. Diagnostic tracers of sources and sinks in the modern ocean: e.g., Al, 3 He, Mn, Ra isotopes, 15 N, Nd isotopes; 234 Th, 230 Th, 231 Pa. Chemical species used as proxies to reconstruct past ocean circulation and productivity: e.g., 231 Pa, 230 Th,  15 N of NO 3,  13 C of DIC, Cd/PO 4 3-, Nd isotopes, Ba. Contaminants in the present and future ocean: e.g., Pb, Hg.

Need to understand fluxes at four interfaces and four types of internal cycling. Coupled to study of the capture of information as proxies Global Strategy and Overarching Goals

GEOTRACES: Program Elements Enabling Activities Standards and intercalibration Data protocols, management, archiving Modeling Capacity Building International Polar Year Ocean Sections Core activity - requires international cooperation Covering regions dominated by major processes National cruises with international collaboration Process Studies Targeted at processes known to be important Targeted at “anomalies” detected in ocean sections Some will focus on ocean boundaries (e.g., coastal regions) Some will exploit time-series stations

GEOTRACES: Capacity Building Trace metal - clean sampling technology and methods Many nations lack infrastructure and expertise for clean sampling Principal barrier is sampling at sea, not analyses GEOTRACES offers international assistance in design, construction and use of clean sampling systems

Metals as Essential Micronutients Nitrogen CycleUptake of C, N and P Morel et al., 2003

DataLimited for Fe Existing deep ocean Fe data Stations with Fe concentrations at depths > 2000 m in 2003 (taken from GEOTRACES Science Plan 2006) Fe data is scarce, particularly in the deep ocean, limited understanding of the Fe cycle

DataLimited for Fe Existing deep ocean Zn data Stations with Zn concentrations at depths > 2000 m As of compiled by Maeve Lohan Distribution and cycling of other micronutrients poorly known

Section 3 POLARSTERN July-October 2007 Greenland Siberia Polarstern ARK XXII-2 Cruise (Rutgers van der Loeff, de Baar) An IPY Highlight

Data from Klunder, Laan, Middag, de Baar et al. Significant Fe and Mn supply from Gakkel Ridge

Strategy for Global Ocean Coverage International workshops define priorities for each basin National committees select research targets based on: National priorities Anticipated benefits Resources Interests and expertise Coordination via international SSC

Strategy for Global Ocean Coverage International workshops define priorities for each basin National committees select elements based on: National priorities Anticipated benefits Resources Interests and expertise Coordination via international SSC

Global Ocean Coverage In red: Planned Sections. In yellow: Completed Sections. In black: Sections completed as GEOTRACES contribution to the IPY.

Global Ocean Coverage Completed GA02: Netherlands (2010/11) GA03: USA (2010/11) GA06: UK (2011) GA10: UK (2010/11) GA11: Germany (2010) GA04: Netherlands and Spain (2013) Future plans GA01: France ( )

Global Ocean Coverage Completed GI04: Japan (2010) GI02: India (2012) GI03: India (2013) Future Plans GI01: India (2013) GI05: Australia/France (2015/2016)

Global Ocean Coverage Completed GP03: Japan (2010) GP13: Aus/NZ (2011) GP18: Japan (2011) GP12: France (2012) GP02: Japan (2012) Firm Plans GP16: USA (2013) GP07: China-Taipei (2014) Future plans GP04: Canada GP06: China-Japan GP08 and GP09: China GP10: Japan (2014) GP11: Australia GP15 and GP17: USA GP19: Japan

GEOTRACES Arctic Workshop (May 2-4, Vancouver, Canada) 2015 GEOTRACES International Arctic Programme Proposed tentative cruise tracks: Red (US, UK, Russia) Magenta (Canada) Yellow (Sweden) Black (Germany) Yellow dots denote cross- over stations to be occupied by more than one national program for calibration. Report available on the GEOTRACES site:

Timeline Development of GEOTRACES 2000Group discussions at international meetings 2001Fall AGU special session and open meeting 2003International Planning Workshop - Toulouse (Funded by NSF) SCOR sponsorship and establishment of Planning Group 2004National planning meetings Science Plan writing starts 2006Science Plan published; SSC forms First cruises - IPY and intercalibration 2007Basin planning workshops (Hawaii; Oxford; Goa) First Model-Data Workshop (Delmenhorst) Data assembly centre starts; COST Action starts 2009Arctic Basin workshop (Delmenhorst) Second Model-Data Workshop (Paris) 2010First full GEOTRACES Sections International Project Office (IPO) set up (Toulouse)

Timeliness Substantial interdisciplinary benefits of disciplinary study of ocean geochemistry Now 30 years since last global program in marine geochemistry (GEOSECS) Improved ability to sample the ocean without contamination Increased sensitivity of analytical instrumentation Advances in modeling permit rates and fluxes to be derived

Overriding Goal: Characterize TEI distributions Combine distributions with knowledge of basic processes Infer: Sources, sinks, internal cycling Multi TEI strategy reveals additional information Initial emphasis on sections to characterize distributions

Contamination free sampling systems: Principal GEOTRACES Capacity-Building Effort Japan Netherlands U.S.A. New Zealand (2000m) France (under construction) Germany (funded) Canada (expanding) India (funded) Australia (under construction) Taiwan (3000m) UK (awaiting winch) China (seeking funding with new ship)