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For any form of publication, please include the link to this page and give the cartographer/designer credit (in this case Philippe Rekacewicz, UNEP/GRID-Arendal)
Global Environment Monitoring System (GEMS), Freshwater Quality Programme, UNEP, 2001.
Uploaded on Saturday 25 Feb 2012
Regional trends in biochemical oxygen demand (BOD)
Philippe Rekacewicz, UNEP/GRID-Arendal
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 time periods.