The steady rain of settling particles throughout the ocean is the most efficient transport mechanism of many elements from the surface to the deep ocean and the ocean floor. Particles are added to surface waters by inputs from rivers or shelves, or they are produced by plankton in the surface ocean. During their production, particles concentrate many elements and on their way down elements are added by scavenging while others are released by mineralization. The composition of particles reaching the seafloor tells a story of the conditions under which they accumulated in surface waters and of the ocean waters they travelled through, a story that is recorded in the sediments.
In order to be able to read this information, we use several approaches to quantify fluxes and composition of particles in the present ocean.