GEOTRACES 40 o S Cruise Planning Meeting Oxford, 24th March 2009

Published in late 2006 Download PDF from Or hard copies available here (also substantially replicated in Chemie de Erde paper in your workshop folders) Science Plan

Mission GEOTRACES guiding mission To identify processes and quantify fluxes that control the distributions of key trace elements and isotopes (TEIs) in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.

Mission What are “key” elements? They include: -Those acting as micronutrients to control ocean productivity and ecosystems -Those tracing modern processes in the ocean -Contaminants in the present and future ocean -Chemical species used as proxies to reconstruct past climate

Mission Include, but not limited to…

Mission Proposed Atlantic sections

Some GEOTRACES news “Enabling” -Second US-led intercalibration cruise will sail in May/June -Data management is set up at BODC jointly funded by NERC and NSF -The IPO is funded and will be set up in Toulouse -An ESF COST Action is enabling a networking and meetings across Europe The actual science: Successful IPY cruises have occurred in 2008, more in 2009 Germany will sail tropical Atlantic cruise in 2010 USA will sail A03 during 2010 Netherlands will sail some of A01 during 2010 UK will sail A10 during 2010 UK proposal for A06 is under review

The UK 40oS Atlantic Cruise Henderson, Mills, Pancost and Rickaby (Oxford, NOCS, Bristol) Submitted standard NERC proposal to Dec 2007 round Funded 32 day cruise plus calibration work on four paleoproxies: -Pa/Th -Cd -Si isotopes -Organic biomarkers

The two points to this meeting: 1.Fill this cruise with as much good science as possible (with GEOTRACES theme) 2.Plan funding for this research, including a NERC consortium proposal for July 1st 2010

An intro to 40oS in the Atlantic Crosses deep basins (Argentine and Cape) and Mid-Atlantic Ridge

Comparison with WOCE

An intro to 40oS in the Atlantic Productive region with appreciable sedimentation

An intro to 40oS in the Atlantic Samples major deep water masses in Atlantic

Iron as a limiting nutrient in HNLC regions

Input fluxes of bioactive metals

DataLimited for Fe Present ignorance: Existing deep ocean Fe data Stations with Fe concentrations at depths > 2000 m. As of From P. Parekh (MIT) Paucity of information about deep Fe distribution limits understanding of upwelling supply and internal cycling.

Other essential TEIs Iron is not the only trace metal crucial for ocean biology Figure from F. Morel

Deep-water supply to productive regions

Sources of micronutrients to oceans

Dust inputs are uncertain…

Substantial river input

MAR inputs are likely de Baar et al. Zero and Drake cruise

Mission Proposed Atlantic sections

MAR inputs are likely de Baar et al. Zero and Drake cruise

Margin sediments with somewhat varied conditions

Tracing sources of metals E.g. REEs and Al in Equatorial Pacific (Yang et al) Short-lived radioisotopes, Mn, radiogenic isotopes (Nd, Pb)

Sources of micronutrients to oceans

Provide nutrients for richly productive and varied region

DataLimitsModels Constraining fluxes with models (Parekh et al. 2005)

Some things to consider: Cruise co-ordination and logistics Equipment for clean sampling and shipboard analysis Wire time and water budget Funding Will need to make tough choices re. berths, water, budgets

Two possible cruise tracks (approximate!)