About the ExpeditionThe ocean is a key part of the global environment. It is also a complex chemical and biological system. Its chemistry is key to supporting life as we know it. It is controlled both by in situ biological activity, physical circulation, and geologic and atmospheric processes. Trace metals such as iron (Fe), cobalt (Co) and molybdenum (Mo) exist in extremely tiny concentrations in the ocean, but play a crucial role in formation of life-supporting enzymes and proteins in marine organisms.
Unfortunately, our knowledge of trace elements in the marine environment is limited. This is partly because they are difficult to measure. Imagine trying to detect a billionth of a gram of iron on board a ship containing many tons of it. However, modern instrumentation coupled with very careful chemistry now allows us to make these measurements and to begin to reveal the distributions and detailed behavior of these important trace elements in the ocean.
GEOTRACES is a newly created international program aimed at making a large-scale survey of these trace elements throughout the global ocean. In addition to trace metals, GEOTRACES includes measurements of isotopes, which allow us to probe the mechanisms and rates of the biological, physical, chemical, and geological processes that control trace element distributions in the ocean.
It is a big task. The GEOTRACES program involves scientists from Asia, Europe, and North America and is expected to extend over decades. This cruise is the first U.S. contribution to the GEOTRACES program. We will be conducting a trans-Atlantic section that takes us from just north of the Straits of Gibraltar, south to the coast of Africa, west across the Atlantic to a submarine hydrothermal site (TAG), to Bermuda, and back to the northeast coast of the U.S. over the course of two months.
The First Installment
The ship (R/V KNORR) arrived in Lisbon on October 10, 2010 from a journey via Iceland. Over the course of 4 days, a team of scientists consisting of the actual cruise participants along with 5 other scientists and Eric Benway worked hard loading gear on board, securing equipment, setting up the laboratory vans (including connecting electric, water, and compressed air supplies), and assembling the trace metal clean areas (bubbles)* using plastic sheeting and HEPA filters. Liquid nitrogen tanks were topped up. Gas tank regulators were installed and tubing connected to equipment. The CTD rosettes were assembled and connected to the conducting wires, and various sampling and sample processing systems were set up.
After spending more than two days testing and sampling at this first site, we continued our south-westward transect with alternating “demi” and full stations (see Cruise Map). A demi-station typically involved single shallow GTC and Niskin cast (the one exception to this was station 4, where we only completed a Niskin cast so that the GTC sampling team could catch up). Station 5 found us at the beginning of our 22°W meridional section, where we turned due southward, alternating full- and demi-stations. Station 7, a full station, coincided with the recently sampled German GEOTRACES occupation (Meteor Cruise M81/1, GEOTRACES section A11 by Martin Frank and others). We attempted to replicate most of the depths sampled during the German cruise to allow maximum opportunity for inter-comparison. Unfortunately, stringent limitations in water availability (heavy subscription by participating U.S. analysts) prevented us taking any “library samples” for distribution to non-U.S. laboratories. Following this station we continued on to Station 8, a demi-station.
Read All About It!Public Interest Articles
An article about GEOTRACES appeared in Chemical and Engineering News in September, 2008. Please check out
This work has been funded by the National Science Foundation through numerous research grants. The planning, logistics, and coordination of the cruise, along with ship-board hydrographic measurements, have been supported by NSF grant OCE-0926423.
We are grateful to the Captain and crew of the Research Vessel R/V KNORR for their support and hard work during the cruise. The Woods Hole Oceanographic Institution Port Office, in particular Eric Benway were very helpful in coordination and staging.
Leadership and Inspiration
This would not have happened without the vision, planning, and hard work of the GEOTRACES committees (both U.S. and International). These groups of scientists worked tirelessly over many years to design and assemble an ambitious global research program. We are particularly indebted to two individuals: Dr. Robert Anderson (Lamont-Doherty Earth Observatory) and Dr. Gideon Henderson (Oxford University), who led the way.