GEOTRACES Intercalibration Intercalibration – The process, procedures, and activities used to ensure that the several laboratories engaged in a monitoring program can produce compatible data. When compatible data outputs are achieved and this situation is maintained, the laboratories can be said to be intercalibrated (Taylor, 1987). Intercalibration therefore is an active process between laboratories that includes all steps from sampling to analyses, with the goal of achieving the same accurate results regardless of the method or lab.

Elemental Coordinators/Leaders for GEOTRACES Intercalibration Dissolved and particulate sampling systems, “core” trace elements – G. Cutter, K. Bruland, and R. Sherrell; Si isotopes - Mark Brzezinski, N (and O) isotopes– Karen Casciotti, P (O isotopes) – Albert Colman, Hg – Carl Lamborg, Metal stable isotopes – Ed Boyle, Nd and Hf – Tina van de Flierdt, Os - Bernhard Peucker-Ehrenbrink, Particulate 234 Th - Ken Buesseler, Ra isotopes – Billy Moore, 210 Pb, 210 Po – Mark Baskaran, Aerosols - Bill Landing, Speciation - Jim Moffett, 230 Th, 231 Pa, 10 Be - Bob Anderson, Pu, 137 Cs - Tim Kenna,

Grant 1: US GEOTRACES Sampling Systems and Intercalibration (PIs: Cutter, Bruland, and Sherrell) (1) Develop and test the US GEOTRACES sampling systems and procedures for dissolved and particulate TEIs. This equipment will be a community resource for use in all future US GEOTRACES cruises; (2) Using these systems, conduct a thorough intercalibration for all the key GEOTRACES TEIs, and as many others as possible, in the dissolved and particulate phases through the participation of the worldwide TEI community; (3) Establish GEOTRACES Baseline Stations in the western North Atlantic (BATS) and eastern North Pacific as part of the Intercalibration Cruises; and (4) Fully document the intercalibration results and create “GEOTRACES User Manuals and Procedures” for future GEOTRACES cruises.

Grant 2: Sampling facility for US GEOTRACES and other trace element biogeochemistry programs (PI: Cutter) (1)Seabird polyurethane powder-coated aluminum rosette with L GO-Flo sampling bottles capable of being triggered 3 at a time while on the up-cast into uncontaminated water. The GO-Flo bottles pivot out slightly to ease mounting and removal (2)Seabird CTD with oxygen probe, fluorometer, and transmissometer; all titanium housings. All pressure housings and nuts/bolts are titanium and isolated from the frame, thus no zinc anodes (3)8000 m Kevlar/polyester conducting cable for deploying the clean CTD/rosette (4)Dynacon traction winch with composite sheaves and line monitoring, plus a composite block/sheave to be hung on the J frame (5)UNOLS-approved trace metal-clean sampling van for processing the clean water and particle samples (6)Shipping flat rack van for the rosette and winch

US GEOTRACES Intercalibration Cruise 1: R/V Knorr, 8 June – 12 July 2008 Western North Atlantic G. Cutter, Chief Scientist K. Bruland and R. Sherrell, Co-Chief Scientists Major Objectives: Test the new Seabird carousel sampling system against known methods, and modify as needed (ship board trace metal analyses). Test particle sampling: small volume GO-Flo filtration vs. in-situ pumps (McLane and MULVFS). Perform intercalibration sampling (2 depths, 1000L) and vertical profiles at BATS and Shelf Break Stations for dissolved and particulate TEIs.

Participants – Leg June (Norfolk-BATS-Bermuda) Cutter’s Group: Cutter, Greg; Barnes, Curtis; Morton, Peter; Gipson, Brandon; Lingle, Carie Bruland’s Group: Bruland, Ken; Brown, Matt; Lippiatt, Sherry; Lohan, Maeve; Smith, Geoffrey; Sohst, Bettina Sherrell’s Group: Sherrell, Rob; Babila, Tali; Theodore, Christine; Severmann, Silke Boyle’s Group: Boyle, Ed; John, Seth Hg Group: Lamborg, Carl; Mason, Rob; Gichuki, Susan CLIVAR Group: Landing, Bill; Gosnell, Kathleen; Grand, Maxime Marcel; Hatta, Mariko Japanese Group: Obata, Hajime; Norisuye, Kazuhiro Wu’s Group: Wu, Jingfeng; Li, Chundi; Rember, Rob; Aguilar-Islas, Ana Shipboard Cd, Pb: Cullen, Jay Spanish Representative: Santos-Echeandía, Juan

Participants – Leg 2 29 June – 12 July (Bermuda-BATS-Shelfbreak-Norfolk) Cutter’s Group: Cutter, Greg; Barnes, Curtis; Morton, Peter; Gipson, Brandon; Lingle, Carie Bruland’s Group: Smith, Geoffrey; Sohst, Bettina Sherrell’s Group: Sherrell, Rob; Field, Paul; Theodore, Christine; Franzese, Allison LDEO Group: Anderson, Bob; Kenna, Tim; Fleisher, Marty; Graham, Dennis; Pahnke, Katharina; van de Flierdt, Tina MULVFS Group: Bishop, Jim; Morales, Alejandro (Alex); Wood, Todd; Lam, Phoebe Th/McLane Pump Group: Maiti, Kanchan; Pal, Sharmila; Pike, Steven Ra Group: Charette, Matt; Dulaiova, Henrieta; Bourquin, Michael Phosphate O isotopes: Colman, Albert N, O isotopes: McIlvin, Matthew

GEOTRACES Intercalibration Time Line Sept Interim GEOTRACES User’s Manuals for IPY Cruises. Dec First Intercalibration workshop (AGU): planning for 1 st cruise June – July st Intercalibration cruise (Sargasso Sea): evaluate sampling apparati and handling methods (diss and part), collect and distribute intercalibration samples, sample storage experiments, establish Baseline Station at BATS Dec Second Intercalibration workshop (AGU): evaluate and interpret intercalibration results, planning for 2 nd cruise Spring nd Intercalibration cruise (eastern North Pacific): final testing of complete sampling system and procedures, intercalibrate with other (non-US) sampling systems, speciation + total TEI intercalibration, determine the time to occupy one GEOTRACES station (for cruise planning purposes) Jan.-Feb Third Intercalibration workshop: finalize complete intercalibration results, begin assembling GEOTRACES User Manuals