Organic pollution produces changes in the aquatic environment. Effluent reduces the dissolved-oxygen concentration as a result of decomposition of organic material and increases the levels of ammonia and phosphate, and both the biochemical oxygen demand (BOD) and chemical oxygen demand (COD). These affect the stream fauna so that different communities often show a zonation that characterizes distinct sections downstream of the discharge (Kolkwitz, 1950; Hynes, 1960; Liebmann, 1962; Hawkes, 1962; Chandler, 1970). This biotic zonation led to the traditional classification of water quality: a heavily polluted (polysaprobic) zone, a moderate (mesosaprobic) polluted zone (divided into two subzones, alpha and beta), and a slightly (oligo-saprobic) polluted zone, also known as the recovery zone, which indicates an advanced stage of self-purification of the river.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Ostracodes as Indicators of River Pollution in Northern Israel
- Springer US
- Chapter 7