- Funded by DOE. February 2005 to January 2008. Bronk, Co-PI. Bronk part $117,039.
- Lead PI John Paul (USF), J. Corredor, J. Morel, and J. Lopez (UPR, Co-PIs), R. Tabita (Ohio State)
The ocean/atmosphere interface is the major conduit for the entry of atmospheric CO2 into oceanic carbon pools that can lead to sequestration or recycled release. The surface layers of the temperate and tropical oceans are often too oligotrophic to result in significant primary production that might lead to carbon sequestration. However, nutrient-rich river plumes can alter the primary production schemes of oligotrophic ocean basins, resulting in increased phytoplankton biomass and carbon fixation. River plumes such as the Amazon are initially supersaturated with dissolved inorganic carbon (DIC) but become rapidly undersaturated because of CO2 efflux combined with dramatic biological drawdown (Koertzinger, 2003). Biological uptake rates of DIC in the Mississippi River Plume (MRP) are amongst the highest reported for estuaries and plumes of the world's largest rivers (Cai, 2003). However, whether this drawdown is the result of diatom-driven, new-production-like processes or picoplanktonic-recycled production is not known. There may be a battle between these two processes in space and time throughout the plume, which ultimately determine if the Mississippi River Plume is a source or sink of CO2 in North America. The ultimate goal of this proposal is to understand these carbon cycling processes in major river plumes from the molecular processes involved in biological DIC uptake to contribution to basin-wide production and potential sequestration. Our research efforts include a field component to determine the DIC questions raised concerning plumes in ocean basins and an intensive genomics/proteomics approach to understanding these processes using genomic fragments obtained from organisms in plumes.
Our specific questions to be answered include:
- Do major river plumes outgas or take up CO2? By accurately measuring all forms of DIC in the plume, CO2 above, and windspeed, an estimate of pCO2 can be made.
- What groups of phytoplankton are ultimately responsible for DIC uptake in plumes?
- What forms of nitrogen are fueling this DIC uptake?
- What are the key elements in the genomic organization of the DIC uptake pathways in plume phytoplankton?