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close this bookCentral Eurasian Water Crisis: Caspian, Aral, and Dead Seas (UNU, 1998, 203 pages)
close this folderPart I: introduction
close this folder3. Major environmental problems in world lakes
View the document(introduction...)
View the documentDeclining water levels
View the documentRapid siltation
View the documentAcidification
View the documentThe progress of eutrophication
View the documentContamination with man-made toxics
View the documentThe collapse of aquatic ecosystems
View the documentAcknowledgements
View the documentReferences


Acidification of lake water is caused by the input of acid air pollutants such as acid rain and dry fallout, either directly on the lake surface or indirectly via inflowing rivers.

Tens of thousands of small lakes in northern and central Europe and in North America have already become too acid to allow fish to breed there and, in extreme cases, almost any kinds of animals to survive. At present, the acidification of lake water is largely confined to rather limited regions such as Scandinavia, parts of central Europe, the north-eastern United States, and neighbouring parts of Canada, most probably owing to particular geological conditions, though acid precipitation itself occurs more widely over the northern hemisphere.

Fig. 3.3 The relation between the concentration of suspended solids in lake water and the area of farmland in corresponding catchment areas (Note: closed and open circles refer, respectively, to lakes and reservoirs in humid/subhumid regions and those in arid regions)

However, soil scientists have recently tried to predict how long it will take for the buffer capacity of the soil to be exhausted by continued acid precipitation. The predicted value of course depends on soil type, but may range, e.g. in Japanese soils, from several years to several decades. This is an alarming prediction, which suggests that the acidification of lake water may sooner or later become a global issue.