Our main area of interest is the ocean's carbon cycle. As geochemists, we're interested on it's impact on the geochemical cycles of the 50 or so elements which exhibit nonconservative behavior in sea water (they don't follow variations of sodium). Most of these elements are transported vertically in the ocean associated with particles of biogenic and terrestrial origin.
As earth scientists, we're concerned with the consequences of rising levels of CO2 in the atmosphere. How will the ocean's carbon cycle change in response to increased CO2 in the atmosphere? How does the ocean naturally sequester carbon and how will this change in the future? How would we evaluate the feasibility, effectiveness and environmental consequences of purposeful ocean carbon sequestration as a strategy for managing levels of atmospheric CO2. Would such actions be 'safe'?
The research is multidisciplinary and requires knowledge of mathematics, chemistry, physics, biology, computer science, and engineering. Funded activities are listed separately.
Experimental approaches to the problem include:
(1) Multiple Unit Large Volume in-situ Filtration System. Collection of oceanic particulate matter sample from the upper 1000 m of the ocean using the Multiple Unit Large Volume in-situ Filtration System (MULVFS; designed and developed by our group) and their subsequent analysis by gravimetry, Inductively-Coupled Plasma - Mass Spectroscopy (ICP-MS), and other wet chemical techniques, as well as using various microscopic approaches. Sea going data are related to the physical, biological and chemical environments encountered at the time of sampling. Eventually this will lead to parameterizations of biogeochemical processes within ocean circulation models. Work in the equatorial Pacific as part of the US Joint Global Ocean Flux Study in 1992 (100 days at sea) was aimed at understanding the effects of El Nino on the carbon cycle of the equatorial Pacific. MULVFS has been deployed in the subarctic NE Pacific as part of Canadian JGOFS cruises in 1996 and 1997; the California Current 2001; and in the SOuthern Ocean as Part of the Southern Ocean Iron Experiment (SOFeX) in 2002.
(2) Computation of surface solar irradiance on a global basis. Simply stated, no light => no ocean biology => boring marine geochemistry. We are charged with producing surface solar irradiance fields (temporally resolved on a 3 hr basis beginning 1983 -> forever) using combined satellite data from the International Satellite Cloud Climatology Project. The data will be used by the SeaWiFS (next generation of ocean colour imaging system) science team to model ocean productivity. As contributors to and members of the SeaWiFS effort, we will have access to data from the SeaWiFS project.
Research opportunities exist in areas of improving the radiative transfer scheme used in the algorithm and in applying SeaWiFS data to marine geochemical problems on both global and regional scales.
(3) Robotic Carbon Explorers. The satellite 'sees' the surface only when clouds are absent. Then it sees at most several 10's of meters into the water in the best of conditions. The need to ground truth satellite observations coupled with limitations of ship-board sampling abilities dictate the development of autonomously operating vehicles deployed in the oceanic water column. We are working with colleagues at Scripps to develop an inexpensive vehicle that is capable of profiling the water column twice a day and returning information on biological productivity, carbon concentrations and fluxes, and upper ocean temperature and salinity via a communications link. The resut of this effort was the development of the Carbon Explorer.
Carbon Explorers during their maiden deployment near station PAPA (50N 145W) in the subarctic North Pacific Ocean observed the enhancement of phytoplankton biomass following an intense storm carrying Gobi Desert Dust. Four more Explorers were deployed during SOFeX and recorded trends in carbon biomass and carbon sedimentation at 55S in response to the addition of iron to nutrient rich waters of the SOuthern Ocean. In 2003 we deployed 2 Explorers near station PAPA and three more in the North Atlantic.
Research to develop new in-situ sensors for carbon cycle processes is a high priority.
(4) Advanced analytical methods We use Inductively-Coupled Plasma Mass Spectrometry for analysis of ocean particulate matter samples. The LBNL Center for Isotope Geochemistry has a VG Plasma Quad 3 and a magnetic sector multi collector instrument. Our group has a Finnigan Element II magnetic sector single collector instrument and we are applying this instrument to problems of trace metal dynamics in the ocean.
Research opportunities exist on a whole range of geochemical and environmental applications of the technique. Examples span the open ocean work described in (1) to problems of coastal and riverine contamination.
(5) Network-Distributed Object-Oriented Data Systems. Our group co-developed a network distributed object-oriented data system for JGOFS. This system is operational but some system tools need development. Research opportunities exist in the area of system level applications development as well in the area of tools needed for inexperienced users to interact with the system. Platforms supported include Unix, Mac and PCs.