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Distribution of coldwater and tropical coral reefs Distribution of coldwater and tropical coral reefs
Coral reefs are marine ridges or mounds, which have formed over millennia as a result of the deposition of calcium carbonate by living organisms, predominantly corals, but also a rich diversity of other organisms such as coralline algae and shellfish. The coldwater reefs are highly susceptible to deep-sea trawling and ocean acidification from climate change, which has its greatest impacts at high latitudes, while tropical reefs will become severe...
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Regional trends in biochemical oxygen demand (BOD) Regional trends in biochemical oxygen demand (BOD)
Biochemical oxygen demand is an indicator of the organic pollution of freshwater. Alkalinity (concentration of calcium carbonate or CaCO3) is another indicator of freshwater quality. These graphics compare the concentrations of these two factors, in milligrams per litre, in the major regions of the world for the periods 1976 to 1990 and 1991 to 2000. The accompanying text explains the implications of the changes in BOD and alkalinity during these...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Calcium levels in major rivers Calcium levels in major rivers
This graphic shows the average calcium levels, in milligrams per litre, at major river mouths for the time periods 1976 to 1990 and 1991 to 2000. The graphic also shows the changes in average calcium levels between these two time periods.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Coldwater coral reefs, distribution Coldwater coral reefs, distribution
Scientists are just beginning to learn about the many species in the remote, deep waters of the polar oceans. Corals, for example, are not limited to the warm, shallow waters of the tropics. They also exist in many cold, deep waters all over the world, including Arctic and sub-Antarctic waters. Coral reefs are marine ridges or mounds, which have formed over millennia as a result of the deposition of calcium carbonate by living organisms, predomin...
31 Jul 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Coldwater coral reefs, distribution Coldwater coral reefs, distribution
Scientists are just beginning to learn about the many species in the remote, deep waters of the polar oceans. Corals, for example, are not limited to the warm, shallow waters of the tropics. They also exist in many cold, deep waters all over the world, including Arctic and sub-Antarctic waters. Coral reefs are marine ridges or mounds, which have formed over millennia as a result of the deposition of calcium carbonate by living organisms, predomin...
21 May 2010 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Freshwater alkalinity: 1976-2008 Freshwater alkalinity: 1976-2008
Alkalinity is commonly used to indicate a water body’s capacity to buffer against acidity; that is, the ability to resist, or dampen, changes in pH. Thus, alkaline compounds in water, such as bicarbonates, carbonates, and hydroxides, lower the acidity of the water and increase the pH. Alkalinity (as CaCO3) was analysed for all sampling stations available at the continental level. Concentrations remained reasonably steady between the two decades ...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), February 2006
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