Changes in the chemistry of Lake Hovvatn, Norway, following liming and reacidification

Abstract

Hovvatn, a 1 km², chronically-acidified lake in southernmost Norway, was treated with 200 metric tons of powdered limestone in March 1981. An additional 40 metric tons were spread uniformly on the ice of a 0.045 km² pond (Pollen) draining into Hovvatn. At ice- out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5 (Pollen), Ca and alkalinity increased, and total aluminium decreased by about 120 myg/l. After 2 years 40 % of the limestone in Hovvatn and 20 % in Pollen had dissolved. Hovvatn and Pollen reacidified to about pH 5.0 during the 2 years following liming. The reacidification of Pollen has proceeded by simple flushing. In Hovvatn, however, dissolution of additional limestone during the 2 years since liming has considerably slowed reacidification