Tuesday, December 20, 2011

Where Have All of the Oysters Gone?

Just where Have All of the Oysters Gone? An excellent question indeed.  Check out the NOAA "Habitat of the Month" article on oyster reefs to find out more.  Once a dominant species in Chesapeake Bay and all of Long Island's coastal waters, their numbers now are a fraction of what they once were.

Click the link and read on to learn more.  NOAA Habitat of the Month Article
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Wednesday, December 14, 2011

More Radiation Leaks in Japan

The contamination issues from the Fukushima nuclear complex in Japan continue.


Scientists Assess Radioactivity in the Ocean from Japan Nuclear Power Facility

ScienceDaily (Dec. 9, 2011) — With current news of additional radioactive leaks from the Fukushima nuclear power plants, the impact on the ocean of releases of radioactivity from the plants remains unclear.
But a new study by U.S. and Japanese researchers analyzes the levels of radioactivity discharged in the first four months after the accident.
It draws some basic conclusions about the history of contaminant releases to the ocean.
The study was conducted by Woods Hole Oceanographic Institution chemist Ken Buesseler and two colleagues based in Japan, Michio Aoyama of the Meteorological Research Institute and Masao Fukasawa of the Japan Agency for Marine-Earth Science and Technology.
They report that discharges from the Fukushima Dai-Ichi nuclear power plants peaked one month after the March 11 earthquake and tsunami that precipitated the nuclear accident, and continued through at least July.
Their study finds that the levels of radioactivity, while high, are not a direct threat to humans or marine life, but cautions that the effect of accumulated radionuclides in marine sediments is poorly known.
The release of radioactivity from Fukushima--both as atmospheric fallout and direct discharges to the ocean--represents the largest accidental release of radiation to the ocean in history.
Concentrations of cesium-137, a radioactive isotope with a 30-year half-life, at the plants' discharge points to the ocean peaked at more than 50 million times normal/previous levels.
Concentrations 18 miles offshore were higher than those measured in the ocean after the Chernobyl accident 25 years ago.
This is largely related to the fact, says Buesseler, that the Fukushima nuclear power plants are located along the coast, whereas Chernobyl was several hundred miles from the nearest salt water basins, the Baltic and Black Seas.
However, due to ocean mixing processes, the levels are rapidly diluted off the northwest coast of Japan.
The study used data on the concentrations of cesium-137, cesium-134 and iodine-131 as a basis to compare the levels of radionuclides released into the ocean with known levels in the sea surrounding Japan prior to the accident.
The resulting paper, Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity, is published in the current issue of the journal Environmental Science & Technology.
Buesseler was awarded a rapid-response grant from the National Science Foundation's (NSF) Division of Ocean Sciences to establish baseline concentrations of radionuclides in the Atlantic and Pacific Oceans.
"Understanding and management of the long-term geochemical fate and ecological consequences of radiochemical contamination of the sea is dependent on our knowledge of the initial conditions," says Don Rice, director of NSF's Chemical Oceanography Program. "Acquiring that knowledge depends on our ability to deploy experts to the scene with minimal delay."
The investigators compiled and analyzed data on concentrations of cesium and iodine in ocean water near the plants' discharge points.
The data were made public by TEPCO, the electric utility that owns the plants, and the Japanese Ministry of Culture, Sports, Science and Technology.
The team found that releases to the ocean peaked in April, a fact they attribute to "the complicated pattern of discharge of seawater and freshwater used to cool the reactors and spent fuel rods, interactions with groundwater, and intentional and unintentional releases of mixed radioactive material from the reactor facility."
The scientists also found that the releases decreased in May by a factor of 1,000, "a consequence of ocean mixing and a primary radionuclide source that had dramatically abated," they report.
While concentrations of some radionuclides continued to decrease, by July they were still 10,000 times higher than levels measured in 2010 off the coast of Japan.
This indicates that the plants "remain a significant source of contamination to the coastal waters off Japan," the researchers report.
"There is currently no data that allow us to distinguish between several possible sources of continued releases," says Buesseler.
"These most likely include some combination of direct releases from the reactors, or storage tanks or indirect releases from groundwater beneath the reactors or coastal sediments, both of which are likely contaminated from the period of maximum releases."
Buesseler says that at levels indicated by these data, the releases are not likely to be a direct threat to humans or marine biota in the surrounding ocean waters.
There could be an issue, however, if the source remains high and radiation accumulates in marine sediments.
"We don't know how this might affect benthic marine life, and with a half-life of 30 years, any cesium-137 accumulating in sediments or groundwater could be a concern for decades to come," he says.
While international collaborations for comprehensive field measurements to determine the full range of radioactive isotopes released are underway, says Buesseler, it will take some time before results are available to fully evaluate the impacts of this accident on the ocean.
The Gordon and Betty Moore Foundation also funded the research.
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Journal Reference:
  1. Ken Buesseler, Michio Aoyama, Masao Fukasawa.Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity. Environmental Science & Technology, 2011; 45 (23): 9931 DOI: 10.1021/es202816c
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National Science Foundation (2011, December 9). Scientists assess radioactivity in the ocean from Japan nuclear power facility. ScienceDaily. Retrieved December 14, 2011, from http://www.sciencedaily.com­/releases/2011/12/111209171940.htm
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Tuesday, December 6, 2011

Merging Tsunamis

I've been intrigued by tsunamis since I was a kid.  Having researched the Japanese tsunami of 2011 and the Indonesian event of 2004 have been eye openers.  Here's an interesting article regarding the Japanese event earlier this year.


Double Tsunami' Doubled Japan Destruction

ScienceDaily (Dec. 5, 2011) — Researchers have discovered that the destructive tsunami generated by the March 2011 Tōhoku-Oki earthquake was a long-hypothesized "merging tsunami" that doubled in intensity over rugged ocean ridges, amplifying its destructive power before reaching shore.
Satellites captured not just one wave front that day, but at least two, which merged to form a single double-high wave far out at sea -- one capable of traveling long distances without losing its power. Ocean ridges and undersea mountain chains pushed the waves together, but only along certain directions from the tsunami's origin.
The discovery helps explain how tsunamis can cross ocean basins to cause massive destruction at some locations while leaving others unscathed, and raises hope that scientists may be able to improve tsunami forecasts.
At a news conference Dec. 5 at the American Geophysical Union meeting in San Francisco, Y. Tony Song, a research scientist at NASA's Jet Propulsion Laboratory (JPL); and C.K. Shum, professor and Distinguished University Scholar in the Division of Geodetic Science, School of Earth Sciences at Ohio State University, discussed the satellite data and simulations that enabled them to piece the story together.
"It was a one-in-ten-million chance that we were able to observe this double wave with satellites," said Song, the study's principal investigator. "Researchers have suspected for decades that such 'merging tsunamis' might have been responsible for the 1960 Chilean tsunami that killed many in Japan and Hawaii, but nobody had definitively observed a merging tsunami until now."
"It was like looking for a ghost," he continued. "A NASA/French Space Agency satellite altimeter happened to be in the right place at the right time to capture the double wave and verify its existence."
Shum agreed. "We were very lucky, not only in the timing of the satellite, but also to have access to such detailed GPS-observed ground motion data from Japan to initiate Tony's tsunami model, and to validate the model results using the satellite data. Now we can use what we learned to make better forecasts of tsunami danger in specific coastal regions anywhere in the world, depending on the location and the mechanism of an undersea quake."
The NASA/Centre National d'Etudes Spaciales Jason-1 satellite passed over the tsunami on March 11, as did two other satellites: the NASA/European Jason-2 and the European Space Agency's EnviSAT. All three carry a radar altimeter, which measures sea level changes to an accuracy of a few centimeters.
Each satellite crossed the tsunami at a different location. Jason-2 and EnviSAT measured wave heights of 20 cm (8 inches) and 30 cm (12 inches), respectively. But as Jason-1 passed over the undersea Mid-Pacific Mountains to the east, it captured a wave front measuring 70 cm (28 inches).
The researchers conjectured ridges and undersea mountain chains on the ocean floor deflected parts of the initial tsunami wave away from each other to form independent jets shooting off in different directions, each with its own wave front.
The sea floor topography nudges tsunami waves in varying directions and can make a tsunami's destruction appear random. For that reason, hazard maps that try to predict where tsunamis will strike rely on sub-sea topography. Previously, these maps only considered topography near a particular shoreline. This study suggests scientists may be able to create maps that take into account all undersea topography, even sub-sea ridges and mountains far from shore.
Song and his team were able to verify the satellite data through model simulations based on independent data, including the GPS data from Japan and buoy data from the National Oceanic and Atmospheric Administration's Deep-ocean Assessment and Reporting of Tsunamis program.
"Tools based on this research could help officials forecast the potential for tsunami jets to merge," said Song. "This, in turn, could lead to more accurate coastal tsunami hazard maps to protect communities and critical infrastructure."
Song and Shum's collaborators include Ichiro Fukumori, an oceanographer and supervisor in JPL's Ocean Circulation Group; and Yuchan Yi, a research scientist in the Division of Geodetic Science, School of Earth Sciences at Ohio State.
This research was supported by NASA.
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Ohio State University (2011, December 5). 'Double tsunami' doubled Japan destruction.ScienceDaily. Retrieved December 6, 2011, from http://www.sciencedaily.com­/releases/2011/12/111205181924.htm
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