William J. Jenkins, (Director of NOSAMS) is a tracer geochemist whose research activities include the study of ocean circulation and ventilation, carbon and nutrient cycles, and the impact of climate change on them. He developed the use of tritium-3He dating to characterize water mass formation and ventilation, as well as oxygen utilization rates to determine biological production rates in the ocean. Jenkins has also used the efflux of tritiugenic 3He to estimate subtropical ocean biological new productivity. He has also worked with noble gases in the shallow ocean as tools to determine air-sea gas exchange rates, as well as upper-ocean net community production. He has applied helium isotope measurements to submarine volcanic systems to study the long-term role of sea-floor spreading processes in affecting the chemistry of ocean waters, and to constrain abyssal ocean circulation. More recently, Bill has been working on the influence of global climate change on the carbon cycle. He recently demonstrated substantial changes in biological production in a major marginal sea (the Japan/East Sea) during the latter half of the 20th century. With Jess Adkins (CalTech), he is exploring the possibility of “shotgun dating” of abyssal coral collections as tool for highlight periods of major ocean circulation reorganization. Bill is also developing a novel medium-complexity carbon cycle model (with Konrad Hughen, WHOI) to simulate atmospheric radiocarbon levels over the past 50,000 years that may improve the construction of the radiocarbon “calibration curve”. In addition to illuminating broad-brush changes in ocean circulation and carbon cycle since the Last Glacial Maximum, these improvements may have significant benefits to archeology.