There’s thorium in those tubes

Sediment traps are containers that scientists place in the ocean to collect tiny sediment or larger accumulations called “marine snow” —bits of organic matter, dead sea creatures, shells, dust and minerals— falling toward the sea floor.  Analyzing the samples helps scientists understand how fast nutrients and trace elements move from the ocean surface to the deep ocean. During this April/May 2009 cruise in the Bering Sea, researchers were measuring thorium levels in the water itself and also on the particles that fall into the sediment traps.
(Photo by Chris Linder, Woods Hole Oceanographic Institution)