Fall 2007 – Mak Saito Chief Scientist Carl Lamborg, Phoebe Lam, Gabrielle Rocap, Eric Webb Jack DiTullio, Mike Sieracki, Zehr lab Samples collected for Karen Casciotti, Bob Anderson, Laura Robinson, Oliver Rouxel, Chris Measures, Ben Thomas, Matt Charrette South Atlantic Gyre and Benguela – Phytoplankton and Trace metal interactions 2.5 degree spacing, alternating 800m and full depth,14 hours steam between stations 5000m of non-metallic line, 11 bottle rosette, CTD package Our first attempt at being Geotraces-Compliant

Fall 2007 – Mak Saito Chief Scientist Cobalt analyses by Abigail Noble (WHOI Student)

Hybrid-type trace metals (iron and cobalt: subjected to both micronutrient and scavenging processes) From Noble and Saito et al. 2008 DSR II

In oligotrophic regions: Metal-Nitrogen colimitation - two types in a single water column N-Fe

Montoya/Zehr 2006 Seward Johnson

Top: Cobalt time series at BATS (BTM) in 1999 from ~40m depth collected by MITESS Bottom: Temperature data from 15m and 35m on the same Bermuda Testbed Mooring Saito and Moffett, Geochim. Cosmochim. Acta 2002

Cobalt and Iron are “Hybrid-Type” Metals Nutrient-like: micronutrient role results in surface depletion Scavenged-like: processes result in removal from intermediate depth Oceanic inventories of Fe and Co are very small No accumulation with oceanic circulation Results in Co:P correlations only in surface waters, falls apart with depth. Unlike Zn, Cd, and the major nutrients. (Noble, Saito et al., 2008 DSRII)