Brown lakes - causes, effects and remedial measures

摘要

The color of surface water has increased in several parts of Europe during the past decades. This has created serious problems for a large number of drinking water producers since brown water is difficult or impossible to purify to drinking water. Brown color of the surface water may be due to a content of humic substances and/or various iron compounds. Apart from the difficulties with drinking water treatment, the animals in the brown lakes are suffering because of the low light transparency. One example is water fowl such as Black-throated loon (Gavia arctica) and Common merganser (Mergus merganser). These species have disappeared from a large number of lakes in Sweden due to the increased water color. These birds feed on fish that they catch by diving in the water. In dark water, the birds are unable to detect the fish.