Award: OCE-0926092

During the past 25 years, the oceanography community has learned that certain trace elements such as iron play a major role in determining where living things can grow in the ocean. We have also seen how anthropogenic pollutants such as lead and mercury have been globally dispersed and injected into the ocean. From studies of other trace elements and natural radioisotopes, we have also learned that major changes in ocean circulation have taken place during past climate changes, so we expect that ocean circulation will also vary as the climate changes in the future. But, these inferences have been made from a very limited number of observations because the measurements have been difficult due to low concentrations (parts per trillion and lower) and contamination (e.g., Fe from rusty ships). In order to model and predict how the life and circulation of the ocean, and the environmental consequences of global pollution, will respond to the human perturbations to the planetÆs surface and atmosphere, we need to have global scale data defining processes that govern trace elements and radioisotopes in the ocean (see processes in Figure 1). During the first decade of this century, chemical oceanographers from all of the nations of the world that study the ocean have come together to create an international scientific program called GEOTRACES. The mission of this program is to identify processes and quantify the rates of transfer that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Specifically, we aim to determine global ocean distributions of selected trace elements and isotopes – including their concentrations, and chemical and physical forms – and to evaluate the sources, sinks, and internal cycling of these elements to characterize more completely the physical, chemical and biological processes regulating their distributions. As part of the international planning, United States oceanographers aimed to contribute 5 major "sections" (top to bottom measurements at ~20 "stations" along a ~4000 mile long shipÆs track) during the 2010-2020 decade. Based on readiness, we chose to first undertake a transect in the North Atlantic Ocean that defined the major biogeochemical provinces and processes (see chart in Figure 2). 33 scientists set up shipboard sampling systems (Figure 3) and chemical laboratories, and then they and 25 crew members departed from Lisbon Portugal on October 11, 2010 on the R/V Knorr operated by the Woods Hole Oceanographic Institution. We began working a half day later, continuing southwards along the coast of northwest Africa. During this work many interesting events occurred including a fire in one of the shipboard laboratories, a desert dust storm and a plague of windblown insects that covered the deck of the ship. Despite these events, shipboard work was going well, but on October 27, half of the shipÆs propulsion system failed. While the shipÆs officers, crew, and the home port pondered what to do, we were left with uncertainty over whether we could complete any more of our work. Eventually, it was decided that we would work on our stations from the African continental margin to the Cape Verde Islands. We limped into the Cape Verde port of Mindelo and most of us left the ship for it to proceed to a repair yard in Charleston South Carolina. A skeleton science crew stayed on board to measure surface water properties while underway, and then we met the ship in Charleston, dismantled our shipboard laboratories and sampling gear, and shipped everything back to our home institutions. The R/V Knorr was repaired, and then a year later, on November 6, 2011, we reassembled our shipboard sampling gear and laboratories and departed from Woods Hole Massachusetts to complete our section. Despite difficulties (a hurricane to the south of us sent rough s...