Award: OCE-1434886

This project is part of a major initiative to study the chemistry of the world's oceans as a means of understanding how the oceans work. This project focused on the Arctic Ocean and on understanding the processes that affect the concentrations of exceedingly rare forms of the elements thorium and protactinium. The particular forms of these elements have the unique characteristic that they are produced everywhere within the ocean at the same rate (from trace amounts of uranium naturally present throughout the oceans). Therefore, by measuring the concentrations of these elements in ocean waters and the particles contained within ocean water, we are able to ascertain processes within the ocean, which remove elements or redistribute elements within the ocean. In order to understand these processes, we analyzed hundreds of samples of Arctic Ocean water and of particles filtered from Arctic Ocean water. We collected these samples at different sites around the Arctic and at different depths. Indeed, not only did we analyze these many samples, but we developed new techniques to analyze different sized particles filtered from seawater. With this data in hand, we proceeded to assess the processes that resulted in the pattern of concentrations that we observed. We were able to assess processes such as the removal of trace metals near submarine hot springs and near the portions of the ocean close to the continents. The former is important as it relates to the cycling of iron in the oceans and the latter is important as it relates to the cycling of carbon in the oceans. Both are ultimately related to carbon dioxide in the atmosphere and to the climate of the earth. Last Modified: 05/01/2019 Submitted by: R. Lawrence Edwards