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Ocean Research


July 2011 Issue

UK Group Updates Methods For Measuring Cooling-Water Plume
Responding to proposals to build nuclear power stations on the coasts of England and Wales during the next decade, the British Energy Estuarine and Marine Studies (BEEMS) program has published an updated methodology for measuring cooling-water plumes and their associated mixing zones.

The free report, published May 31, is the result of a workshop held by the BEEMS' expert panel. The methods for the treatment of results and the use of the output are covered, particularly with reference to background and zones of influence. Mixing zones are discussed theoretically and from a regulatory point of view.

A cooling-water plume from a direct-cooled power station has several characteristics which makes it unlike the majority of effluent plumes, the report says. Some of these characteristics include: The return is usually of water abstracted from the same water body; the volume is high and can be significant as a proportion of the receiving water; the elevated temperature will render the plume buoyant; the main "contaminant," heat, is a nonconservative property naturally lost to the environment.

The approaches in the report can be used for assessing the outcome of both the thermal and chemical components of the discharge, BEEMS said. For more information, visit www.cefas.defra.gov.uk.

Expedition Measures Radioactive Contaminants in Pacific Ocean
The Woods Hole Oceanographic Institution (WHOI) announced in June it would lead the first international, multidisciplinary assessment of the levels and dispersion of radioactive substances in the Pacific Ocean from Japan's crippled Fukushima nuclear power plant. The 15-day expedition aboard the University of Hawaii's research vessel Kaimikai-O-Kanoloa departed June 4.

The research team, drawing from WHOI and other organizations and universities, collected water and biological samples and took ocean current measurements in a 200-kilometer-area offshore of the plant. Research will also be done further offshore along the Kuroshio Current. Sample analysis will be performed over several months. The team's work will build on efforts by Japanese scientists and lay the foundation for international collaboration and long-term research, WHOI said.

The release of radioactivity from the partial meltdowns, hydrogen explosions and fires that began March 11 at the Fukushima plant, as well as the runoff from the subsequent attempts to cool the reactors, led to an unprecedented release of radiation to the ocean. The total amount of radioactivity that has entered the ocean is not well understood, and until now, only limited assessments of the impacts on the ocean have been undertaken.

Biological samples and measurements in the Kuroshio Current will be gathered using a variety of filters and nets. The research will focus on phytoplankton, zooplankton and key fish species to determine the extent to which radionuclides are accumulated in these organisms. Another group of researchers will deploy drifters to directly track water parcels in the region of the Fukushima power plants, collect profiles of temperature, salinity and oxygen through the water column, and will use shipboard acoustic Doppler current profiler to measure ocean velocity. This will allow scientists to characterize transport and water masses needed for modeling dispersion and removal of radionuclide contaminants. For more information, visit www.whoi.edu.

New Map Reveals Giant Fjords Beneath East Antarctic Ice Sheet
Scientists from the U.S., U.K. and Australia have used ice-penetrating radar to create the first high-resolution topographic map of one of Earth's last uncharted regions, the Aurora Subglacial Basin, an ice-buried lowland in East Antarctica larger than Texas.

The map, published June 1 in Nature, reveals some of the largest fjords on Earth, providing insights into the history of ice in Antarctica. The data will also help computer modelers improve their simulations of the past and future Antarctic ice sheet and its potential impact on global sea level, the scientists said.

"We chose to focus on the Aurora Subglacial Basin because it may represent the weak underbelly of the East Antarctic Ice Sheet, the largest remaining body of ice and potential source of sea level rise on Earth," said Donald Blankenship, principal investigator for the Investigating the Cryospheric Evolution of the Central Antarctic Plate project, a multinational collaboration using airborne geophysical instruments to study the ice sheet.

Because the basin lies kilometers below sea level, seawater could penetrate beneath the ice, causing portions of the ice sheet to collapse and float off to sea. This work also shows the ice sheet has been smaller in the past. For more information, visit www.sciencedaily.com.

Antarctic Icebergs Help the Ocean Take Up CO2, Study Says
The first comprehensive study of the biological effects of Antarctic icebergs shows they fertilize the Southern Ocean, enhancing the growth of algae that take up CO2 from the atmosphere and then, through the food chain, transfer CO2 into the deep sea. This process is detailed in papers published electronically in Deep Sea Research Part II: Topical Studies in Oceanography.

The researchers, led by Monterey Bay Aquarium Research Institute (MBARI) marine biologist Ken Smith, conducted three month-long cruises to the Weddell Sea in 2005, 2008 and 2009 to study icebergs formed from fragments that have broken off Antarctic ice shelves as a result of global climate change.

The new research suggests these icebergs carry iron-rich sediment from land out to sea. As they melt, some of the iron dissolves in the seawater, creating a trail of iron-rich meltwater up to 19 kilometers long. That iron helps fertilize the growth of microscopic algae.

To follow individual icebergs, they used satellites and GPS tracking devices that were dropped on the icebergs using a radio-controlled airplane and used three robotic submersibles to study life underneath the icebergs.

MBARI engineers developed a robotic instrument programmed to sink to 600 meters' depth while an iceberg drifted overhead and then rise back to the surface after the iceberg passed. This instrument was used to collect particles that drifted from the waters around the iceberg, allowing scientists to measure for the first time the amount of organic CO2 sinking into the deep sea beneath a large iceberg. For more information, visit www.mbari.org.


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