North Atlantic Transect

The first major ocean section by the U. S. GEOTRACES program was completed in two legs:

Fall 2010 (Lisbon, Portugal to Mindelo, Cape Verde) and Fall 2011 (Woods Hole, MA to Bermuda to Praia, Cape Verde).

Chief Scientists: Ed Boyle (MIT), Bill Jenkins (WHOI) and Greg Cutter (Old Dominion University)

Within the context of this global survey of trace elements and isotopes (TEIs), our group from L-DEO is collaborating with

groups from the Woods Hole Oceanographic Institute, the University of Minnesota, and the University of Rhode Island

to complete analyses and interpretations of dissolved and particulate ²³¹Pa, ²³⁰Th, and ²³²Th. This large data set will serve

many purposes including validating ²³¹Pa/²³⁰Th as a proxy for ocean circulation, calculating rates of removal by

scavenging, important for biogeochemical cycling of many insoluble trace elements, the chemical fractionation of

²³¹Pa/²³⁰Th due to the chemical composition of marine particles, and ²³²Th as a tracer of lithogenic supplies, such as

dust deposition.

Selected abstracts:

Hayes, C. T., R. F. Anderson, M. Q. Fleisher, L. F. Robinson, H. Cheng, R. L. Edwards, S. B. Moran (2012) Pa and Th

distributions along the GEOTRACES North Atlantic Transect. 2012 Ocean Sciences Meeting (Salt Lake City, Utah, February)

Robinson, L., K.-F. Huang, M. E. Auro, R. F. Anderson, C. T. Hayes, M. Q. Fleisher, H. Cheng, R. L. Edwards, S. B. Moran,

M. Saito (2012) Sources, sinks and cycling of seawater ²³²Th in the north and south Atlantic basins. (22^nd V. M. Goldschmidt

Conference, Montreal, Canada, June).

Funding for this project from the National Science Foundation is acknowledged.

Photos: (above) The R/V Knorr departing Bermuda in November 2011 (credit B. Longworth)

Home (Left) Sampling the Niskin Rossette for dissolved TEIs including Pa/Th (credit B. Sohst)

(Right) Lowering McLane pumps to sample particulate TEIs (credit B. Longworth)