--FOR IMMEDIATE RELEASE--
November 17, 2010
Contact: Tatiana Brailovskaya, Director of Communications, Bigelow Laboratory for Ocean Sciences, (207) 633-9633; firstname.lastname@example.org
A Paradigm Shift: Shedding Light on the Ocean’s Biological Pump
WEST BOOTHBAY HARBOR, ME -- Researchers from Bigelow Laboratory for Ocean Sciences in Maine and the National Oceanography Centre in the United Kingdom have published a paper in the November 20, 2010 issue of Geophysical Research Letters (Balch, W. M., B. C. Bowler, D. T. Drapeau, A. J. Poulton, and P. M. Holligan (2010), Biominerals and the vertical flux of particulate organic carbon from the surface ocean, Geophys. Res. Lett., VOL. 37, L22605, doi:10.1029/2010GL044640) demonstrating for the first time that particulate inorganic carbon (PIC, aka calcium carbonate) is responsible for a major fraction of the backscattering of light in vast subtropical gyres of the Atlantic Ocean.
Since chlorophyll has always been thought to be the primary determinant of the ocean’s bio-optical properties, these findings represent a paradigm shift in remote sensing. PIC is also a major driver of the ocean’s biological carbon pump, providing a significant portion of ballast for sinking aggregates of particulate matter in the ocean.
Balch and his co-authors address the influence of biogenic silica (BSi) and inorganic calcium carbonate (PIC), on particle optical properties in the ocean and the resulting efficiency of the biological carbon pump. They demonstrate a highly significant, robust relationship between the ratio of calcium carbonate and biogenic silica (PIC:BSi), versus the concentration of particulate organic carbon (POC). This relationship applies over most of the Atlantic, and provides a basis for predicting the rate of the ocean’s biological pump.
Using data from three trans-Atlantic cruises, the researchers measured particle optical properties and POC, PIC, and BSi concentrations. Differences in the way light is scattered by PIC and POC made it possible to quantify surface PIC:POC ratios and determine that PIC contributed up to a quarter of particle backscattering in oligotrophic subtropical gyres and temperate waters.
PIC, BSi, and POC are the major components of the aggregate matter that sinks through the water column as part of the biological pump. The ratio of the two minerals (PIC:BSi) was strongly – and inversely -- correlated to POC concentration. Results of aggregate density models showed greater PIC:POC ratios and sinking rates in oligotrophic gyres than eutrophic regions, due to the greater relative abundance of PIC in the gyres. The authors have combined these observations into a model that makes it possible to predict carbon flux from the surface ocean by estimating PIC, POC, and BSi concentrations using satellite remote sensing images.
An internationally known global ocean research center since 1974, research at Bigelow Laboratory for Ocean Sciences ranges from microbial oceanography to large-scale biogeochemical processes that drive interactions between ocean ecosystems and global environmental conditions. This research was funded by NASA (National Aeronautics and Space Administration; Ocean Biology and Biogeochemistry research program) and NERC (Natural Environment Research Council of the UK). ####