ABSTRACT

The Division of Ocean Sciences at NSF provides base support for the operation and maintenance of the National Ocean Sciences Accelerator Mass Spectrometer (NOSAMS) facility. The facility will provide natural level radiocarbon dating services to the oceanographic community. Radiocarbon is an important tool in climate, carbon cycle, and biogeochemical science. It is useful as a chronometer covering the past ~50,000 years, it is a diagnostic of past changes in the carbon cycle, it serves as a tracer of ocean circulation, and it is a probe for carbon flow in the environment. Thus radiocarbon measurements are used in many sectors of ocean science research ranging from paleoceanography, physical oceanography, biogeochemistry, and climate change science. Current environmental level radiocarbon measurements require careful sample processing that minimizes contamination risk and other experimental artifacts, and the use of Accelerator Mass Spectrometry (AMS) systems. Consequently, it is advantageous to have and maintain a central facility that serves the broader ocean sciences community by making such measurements and acting as a center of expertise, as well as sustaining and advancing the state-of-the-art in such measurements.

Over the past decade and more, there has been a steady growth in sample submissions to NOSAMS. Presently the facility analyzes about 7,900 samples per year, 1,000 for the Climate Variability and Predictability (CLIVAR) program and 6,900 for other clients (550-600 batch submissions annually from ~270 different investigators). Sample submission information is entered through a web portal, samples are tracked through all stages of processing and analysis using a robust, scalable, and secure database management system, and clients have secure and convenient access to sample processing status and analytical results through the web. The PI?s propose to continue operations for another five years, while gradually increasing the numbers of samples analyzed each year, improving the accuracy and precision of measurements, and expanding the methodology in new directions.

The PI?s propose to continue to improve and develop new radiocarbon measurement capabilities and propose to expand the portfolio of services offered to the community. Recent advances include high precision radiocarbon measurements on carbonates, and the development of a unique gas-accepting ion source for continuous flow AMS (GIS-CFAMS) which can be coupled to a variety of different interfaces, leading to new measurement capabilities. Proposed research includes new inroads into compound specific and compound class radiocarbon analysis, as well as extending analyses to smaller samples.

Broader Impacts: The research enabled by the NOSAMS measurements addresses questions that are important to society: among them issues of past and future global climate change, local and regional environmental impacts, and the development of natural resources. In addition to supporting socially relevant research, NOSAMS will play an important role in training and mentorship of graduate students and postdoctoral researchers. NOSAMS promotes general public understanding of radiocarbon and related scientific issues through web sites and in hosting tours for the visiting public.

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