Archive for November, 2007

Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II)

The influence of seawater CO2 concentration on the size distribution of suspended particles (2–60 μm) and on phytoplankton abundance was investigated during a mesocosm experiment at the large scale facility (LFS) in Bergen, Norway, in the frame of the Pelagic Ecosystem CO2 Enrichment study (PeECE II). In nine outdoor enclosures the partial pressure of CO2 in seawater was modified by an aeration system to simulate past (~190 parts per million by volume (ppmV) CO2), present day (~370 ppmV CO2) and future (~700 ppmV CO2) CO2 conditions in triplicates.
Continue reading ‘Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II)’

Global warming: Oceans could absorb far more CO2, says study

PARIS (AFP) — The ocean’s plankton can suck up far more airborne carbon dioxide (CO2) than previously realised, although the marine ecoystem may suffer damage if this happens, a new study into global warming says.

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Scientists discover biological mechanism for enhanced carbon consumption in the ocean

Microscopically tiny marine organisms known as plankton increase their carbon uptake in response to increased concentrations of dissolved CO2 and thereby contribute to a dampening of the greenhouse effect on a global scale. An international group of scientists led by the Leibniz Institute of Marine Sciences in Kiel, Germany documented this biological mechanism in a natural plankton community for the first time. In simulations of the future ocean, they measured an increased CO2 uptake of up to 39%. The unexpected positive effect for the global climate system harbours at the same time considerable risks for the oceans and their ecosystems. The study points to three major areas of concern: increased CO2 uptake by plankton will accelerate the rate of ocean acidification in deeper layers, lead to a decrease in oxygen concentrations in the deeper ocean, and will negatively influence the nutritional quality of plankton. The latter development can have consequences for entire food webs in the ocean. The results of the study will appear in the international science journal “Nature” on November 11, 2007*.

Continue reading ‘Scientists discover biological mechanism for enhanced carbon consumption in the ocean’

Scientists enhance Mother Nature’s carbon handling mechanism

Taking a page from Nature herself, a team of researchers developed a method to enhance removal of carbon dioxide from the atmosphere and place it in the Earth’s oceans for storage.

Unlike other proposed ocean sequestration processes, the new technology does not make the oceans more acid and may be beneficial to coral reefs. The process is a manipulation of the natural weathering of volcanic silicate rocks. Reporting in today’s (Nov. 7) issue of Environmental Science and Technology, the Harvard and Penn State team explained their method.

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Electrochemical acceleration of chemical weathering as an energetically feasible approach to mitigating anthropogenic climate change

House et al.

We describe an approach to CO2 capture and storage from the atmosphere that involves enhancing the solubility of CO2 in the ocean by a process equivalent to the natural silicate weathering reaction. HCl is electrochemically removed from the ocean and neutralized through reaction with silicate rocks. The increase in ocean alkalinity resulting from the removal of HCl causes atmospheric CO2 to dissolve into the ocean where it will be stored primarily as HCO3 without further acidifying the ocean. On timescales of hundreds of years or longer, some of the additional alkalinity will likely lead to precipitation or enhanced preservation of CaCO3, resulting in the permanent storage of the associated carbon, and the return of an equal amount of carbon to the atmosphere. Whereas the natural silicate weathering process is effected primarily by carbonic acid, the engineered process accelerates the weathering kinetics to industrial rates by replacing this weak acid with HCl. In the thermodynamic limit—and with the appropriate silicate rocks—the overall reaction is spontaneous. A range of efficiency scenarios indicates that the process should require 100–400 kJ of work per mol of CO2 captured and stored for relevant timescales. The process can be powered from stranded energy sources too remote to be useful for the direct needs of population centers. It may also be useful on a regional scale for protection of coral reefs from further ocean acidification. Application of this technology may involve neutralizing the alkaline solution that is coproduced with HCl with CO2 from a point source or from the atmosphere prior to being returned to the ocean.

Continue reading ‘Electrochemical acceleration of chemical weathering as an energetically feasible approach to mitigating anthropogenic climate change’

More Acidic Seas Can Change Behavior of Anxious Sea Snails

Climate change may get the most publicity, but it’s not the only global phenomenon linked to rising levels of carbon dioxide in the atmosphere. Another is the gradual acidification of the oceans, as more of CO2 dissolves in seawater, creating carbonic acid and lowering the pH.

Continue reading ‘More Acidic Seas Can Change Behavior of Anxious Sea Snails’

Mussels face extinction as oceans turn acidic

Prized as a luxury treat in the best restaurants and a staple food in the human diet for thousands of years, oysters and mussels are now being threatened by rising levels of carbon dioxide.

Mussels face extinction as oceans turn acidic
By 2100 some waters are expected to be corrosive enough to cause the shells of mussels to dissolve

By the end of the century many popular seafood dishes will disappear from our tables as shellfish become increasingly scarce, scientists warn.

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Rising acid levels in oceans threaten shellfish

Rising acidity levels in the ocean, due mainly to increased levels of carbon dioxide from fossil fuels, could pose a major threat to New Jersey’s shellfish industry by the end of the century.

That view comes from scientists with the National Oceanic and Atmospheric Administration, or NOAA, and has drawn serious attention from U.S. Sen. Frank Lautenberg, D-N.J.

Lautenberg said the problem could harm the state’s $121 million-per-year shellfish industry. A NOAA scientist said the problem could affect 500 million people worldwide who rely on the ocean for food. In the U.S. alone, the fish and shellfish industry is worth $4 billion per year. Lautenberg has sponsored a bill to study the problem.

The immediate concern is that certain marine creatures, especially in their juvenile stages, may not be able to form calcium carbonate skeletons and shells if the ocean is too acidic. This includes plankton, shellfish, coral, sea urchins and starfish.

“Ocean acidification is a threat to our marine ecosystem and our economy. The change in ocean chemistry caused by greenhouse gases is corrosive and affects our marine life, food supply and overall ocean health,” Lautenberg said.

The Federal Ocean Acidification Research and Monitoring Act of 2007, or FOARAM, co-sponsored by Lautenberg and Sen. Barbara Boxer, D-Ca., would include $30 million to study the problem. The bill would lead to the formation of a committee and a national plan to address the issue.

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Ocean Acidification: The Biggest Threat

When it comes to the oceans and carbon dioxide, there’s good news and bad news. To date, the world’s oceans have absorbed nearly a third of the excess carbon dioxide emitted as a result of anthropogenic activities. That may be good news for the atmosphere, but scientists and policymakers are increasingly concerned about the side effect of carbon dioxide absorption: ocean acidification.

Continue reading ‘Ocean Acidification: The Biggest Threat’

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Ocean acidification in the IPCC AR5 WG II

OUP book