4.3 Oxygen Depletion
FROM WATER:
http://www.unep.org/geo/geo4/report/04_Water.pdf
OXYGEN DEPLETION:
A harmful algal bloom of the dinoflagellates Noctiluca scintillans, known as a red tide
Organic materials, from such sources as algal blooms and discharges from domestic wastewater treatment plants and food-processing operations, are decomposed by oxygen-consuming microbes in waterbodies. This pollution is typically measured as the biochemical oxygen demand (BOD). High BOD levels can cause oxygen depletion, jeopardizing fish and other aquatic species. Lake Erie’s oxygen- depleted bottom zone, for example, has expanded since 1998, with negative environmental impacts. Some coastal areas also undergo oxygen depletion, including the eastern and southern coasts of North America, southern coasts of China and Japan, and large areas around Europe (WWAP 2006). Oxygen depletion in the Gulf of Mexico has created a huge “dead zone,” with major negative impacts on biodiversity and fisheries (MA 2005) (see Chapter 6).