Ocean Biogeochemical Processes Group

EO Lawrence Berkeley National Laboratory

Overview of OBP Group by Jim Bishop

Our main area of interest is the ocean's carbon cycle. As geochemists, we're interested in how carbon cycle processes influence 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 living systems respond to climate induced change in the ocean? How does the ocean naturally sequester carbon and how will this change in the future?

The research is multidisciplinary and requires knowledge of mathematics, chemistry, physics, biology, computer science, and engineering.

Experimental approaches to the problem of ocean carbon dynamics include:

(1) Multiple Unit Large Volume in-situ Filtration System. MULVFS permits collection of particulate matter samples from the upper 1000 m of the ocean and was designed and developed by our group. The collected samples representing material present in 1000's of liters of seawater are analyzed by gravimetry, Inductively-Coupled Plasma - Mass Spectroscopy (ICP-MS), and other wet chemical techniques, as well as using various microscopic approaches. Resulting data are related to the physical, biological and chemical environments encountered at the time of sampling. MULVFS provides 'process' insight into carbon cycle mechanisms and results lead to better parameterizations of biogeochemical processes within ocean circulation models.

MULVFS has been used to sample the subarctic NE Pacific as part of Canadian JGOFS (Joint Global Ocean Flux Study) in 1996 and 1997. In that study we got the first profiles ever obtained in winter conditions. We deployed MULVFS in the California Current 2001 as a shake down for deployment in frigid Antarctic waters of the Southern Ocean in 2002 as part of the Southern Ocean Iron Experiment (SOFeX). There we sampled waters at 66S which were -1.7C --- exactly --- the freezing temperature of sea water. Most recently we sampled warm tropical waters near Hawaii (2004) and biologically productive waters of the Oyashio current near Japan (2005). This general samping strategy of observing differences in chemistry and behaviour of particulate matter in widely varying ocean environments is useful for gaining a first order insight into the 'now' of the carbon cycle processes at the time they are happening.

(2) Robotic Carbon Explorers. Ships can't sustain high-frequency observations. Satellites 'see' the surface only when clouds are absent. We know that marine plant biomass is consumed on average once every week and the most biologically dynamic areas of the ocean are also in many cases perpetually cloud covered. 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 that can bridge the space-time gap in ocean observations. 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 first resut of this effort was the development of the Carbon Explorer.

In 2001 our first Carbon Explorers operating 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 (Bishop et al. 2002, Science). Four more Explorers were deployed during the 2002 Southern Ocean Iron Experiment (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 (Bishop et al. 2004, Science). The SOFeX Explorers went on for over one year to observe biological processes in one of the most remote and extreme ocean environments in the world. One Explorer survived 18 months and 2 successive Antartic Winters in the seasonal ice edge zone. In 2003 we deployed 2 Explorers near station PAPA and three more in the North Atlantic.

We're now busy developing the Carbon Flux Explorer. Our group is developing skills in free vehicle ocean observing. Everything we build from hardware to firmware to software finds special challenges in the ocean.

Research to develop new in-situ sensors for carbon cycle processes is also a high priority. For example, in 2003 and 2005 our group operationally deployed a new optical sensor for calcium carbonate particles in the Atlantic Ocean during NOAA's Repeat Hydrography program expeditions. The result is a pole to pole - surface to bottom view of calcium carbon dynamics in the Atlantic Ocean.

(3) Advanced analytical methods Inductively-Coupled Plasma Mass Spectrometry is one of the tools we use for multi-element analysis of ocean particulate matter samples. 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. Recently, we used the synchrotron Advanced Light Source at LBNL to trace the origins of particulate iron found in abundance >1000 km from shore in the subarctic North Pacific 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.

4 Computation of surface solar irradiance on a global basis. Simply stated, no light => no ocean biology => boring marine geochemistry. We calculated surface solar irradiance fields (temporally resolved on a 3 hr basis (1983-1992) using combined satellite data from the International Satellite Cloud Climatology Project. More on SeaWiFS project.

Research opportunities exist in applying SeaWiFS and other remotely sensed data to marine geochemical problems on both global and regional scales.

(5) Network-Distributed Object-Oriented Data Systems. Our group co-developed a network distributed object-oriented data system for JGOFS. This system is operational.

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.

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Last updated: Nov 21 2005