Acid Rain

Fishery biologists especially are interested in liming acidic lakes to create habitat for sportfish. Usually, acidic waters are treated by adding limestone (CaCO₃) or lime (Ca[OH]₂), a process analogous to a whole-lake titration to raise pH. In some parts of Scandinavia liming has been used extensively to mitigate the biological damages of acidification. By 1988 about 5,000 water bodies had been limed in Sweden, mostly with limestone, along with another several hundred lakes in southern Norway. In the early 1980s there was a program to lime 800 acidic lakes in the Adirondack region of New York.

Although liming rapidly decreases the acidity of a lake, the water later re-acidifies at a rate determined by size of the drainage basin, the rate of flushing of the lake, and continued atmospheric inputs. Therefore, small headwater lakes have to be re-limed more frequently. In addition, liming initially stresses the acid-adapted biota of the lake, causing changes in species dominance until a new, steady-state ecosystem is achieved. It is important to recognize that liming is a temporary management strategy, and not a long-term solution to acidification.