text: Trace elements serve as regulators of biological processes in the ocean, influencing marine ecosystem dynamics and the carbon cycle.  Despite this significance, knowledge of the marine biogeochemical cycles of these essential micronutrients is surprisingly incomplete. GEOTRACES is quantifying the supply, removal, internal cycling, chemical form and distribution of essential micronutrients and other trace elements. Understanding the sensitivity of these biogeochemical cycles to changing environmental conditions will improve projections of the ocean’s response to global change.
  The cycles of many trace elements and isotopes have been impacted significantly by human activity, which has increased the discharge of harmful elements into the ocean. GEOTRACES’ emphasis on understanding the processes regulating the marine biogeochemical cycles of trace elements will improve prediction of the transport and fate of contaminants in the ocean and thereby help to protect the ocean environment.
  Much of what is known about ocean conditions in the past and, therefore, about the ocean’s role in climate variability is derived from trace element and isotope patterns recorded in marine archives (sediments, corals, etc.). Greater knowledge of the processes governing these tracers in the modern ocean will improve interpretation of ocean conditions in the past, from which more reliable prediction of future changes can be made.