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Tag: Oxygen

Water Discharges measured by Biological Oxygen Demand
Illustration in a set of graphics prepared for a pilot assessment report on the Black Sea drainage basin, for the UNEP Global Impact on Waters Assessment (GIWA). All data and information were prepared in close collaborat...
10 Mar 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Regional trends in biological oxygen demand
The graphic is a global comparison of the biological oxygen demand measured in milligrams per litre. It covers the years from 1976 - 2000. The biological oxygen demand refers to the amount of oxygen required by aerobic m...
28 Sep 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Sites with dead zones (oxygen depletion on the sea bottom)
Dead zones (hypoxic i.e. oxygen deficient water) in the coastal zones are increasing, typically surrounding major industrial and agricultural centers. This is commonly occuring due to nutrient pollution, in the form of n...
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
Industrial areas and seasonal zones of oxygen-depleted waters
This graphic illustrates that there is a strong correlation between the world's industrial areas and the areas in which seasonally oxygen-depleted waters occur. The accompanying text explains some of the effects of land-...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Nitrate in major rivers
Considering the data for all the rivers at the continental level, there has been little change in nitrate (NO3-N) concentrations between the two decades under comparison. Changes in the median value were not statisticall...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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 concentrat...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Discharge of selected pollutants
Nitrogen and phosphorous represents nutrients that can be seen as pollutants, as large concentations of those increase eutrophication. Nutrients are present in primarily commercial fertilisers and in sewage. A measure of...
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Biological oxygen demand - BOD: 1976-2008
The availability of oxygen is one of the most important indicators of the condition of a water body, because dissolved oxygen, or DO, (the amount of oxygen dissolved in water) is necessary for most aquatic organisms, inc...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
When the city harms its own water resources
In areas where surface water is not readily available (located far from areas of need), groundwater is the primary water source. Groundwater aquifers supply an estimated 20% of the global population living in arid and se...
01 Oct 2009 - by Philippe Rekacewicz
Industrial areas and seasonal zones of oxygen depleted waters
This graphic illustrates the strong link between areas with high densities of industrial activity and zones of seasonally oxygen-depleted waters. There is a strong link between areas with high densities of industrial ac...
26 Jan 2009 - by Phillipe Rekacewicz, (Le Monde diplomatique) February 2008