Project: Collaborative Research: Distribution and Cycling of Carboxyl-Rich Alicyclic Molecules (CRAM) in the Ocean

NSF Award Abstract:
Collaborative Research: Distribution and Cycling of Carboxyl-Rich Alicyclic Molecules (CRAM) in the Ocean

Dissolved organic matter is the largest pool of organic carbon in the ocean. Thus, it plays an important role in carbon storage and climate change. The components of dissolved organic matter are the remains of biological products. As a result, the chemical make-up of dissolved organic matter (DOM) can provide important clues about the processes affecting this carbon pool. By learning more about the chemical structures and reactions that produce DOM, connections can be made to biological and biochemical processes and their importance. This project will study the distribution, production, and removal of one important class of molecules called carboxyl-rich alicyclic molecules (CRAM). These molecules are abundant in marine DOM and play an important role in the ocean carbon cycle. They also affect the supply of the micronutrient iron, and thus have an important influence on primary production and ocean food webs. The research includes field and laboratory experiments and takes advantage of ocean locations with long-term data. Together, the lead scientists will provide training and resources for the graduate students, undergraduate research opportunities for underrepresented groups in STEM, and direct outreach to the public through a website, articles in local newspapers, and talks at public venues.

CRAM make-up 8 to 25% of marine dissolved organic carbon (DOC) and represent a carbon reservoir of >65 Pg C that is equivalent to at least 8% of the atmospheric CO2 pool. CRAM play a central role in the functioning of the microbial carbon pump, a conceptual framework for producing refractory carbon by microbial processes in the ocean. Further, CRAM act as an important ligand of Fe(III) in the ocean, thereby playing an important role in regulating marine primary production. The main project objectives are: (1) measure the variable distribution of CRAM in the ocean, and (2) determine the dominant mechanisms of CRAM production and removal. The project will leverage an extensive set of already collected samples across the world’s oceans and new field work within the framework of the Bermuda Atlantic and Hawaii Ocean Time Series. Field measurements will be combined with experimental approaches to specifically address microbial and photochemical reactions leading to CRAM production and removal. This research will fill important gaps in resolving the key questions about organic carbon cycling in the ocean and explore the role of DOM in mediating the cycles of iron and other trace elements.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.