Andrew McDonnell, a joint program student in marine chemistry and geochemistry, holds a jar full of sinking particles collected at 150 meters depth during a cruise along the West Antarctic Peninsula. These particles—mostly krill fecal pellets and diatom aggregates—are an important component of the ocean's natural carbon cycle. As they sink through the water column, they transport carbon away from the atmosphere and surface ocean and deliver it to the deep waters and sediments. This special sample jar is full of a viscous polyacrylamide gel that keeps particles separated and intact upon collection, allowing for the enumeration, measurement, and identification of particles that are important to the sinking flux.
(Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)