Clifton Buck, shown here on a cruise in the North Pacific, studies the cycling of trace elements in the ocean. Trace elements, aptly named for their minute concentrations in seawater, can control the distribution of life in the surface ocean and help regulate the planet’s climate. In addition to sunlight and macronutrients like nitrate and silicate, phytoplankton require trace elements such as iron, zinc, manganese and copper for proper metabolic function. The program aims to better understand how trace elements move through the ocean and influence marine chemical cycles. Sheridan collected atmospheric samples for 56 days from the South Pacific Ocean to the Southern Ocean and finally to Chile.