LAKES AND RESERVOIRS - Water Quality Engineering in Natural Systems - page 278

Figure 7.17. Water fountains. Source : vertex Water Features, Inc. (2005).

7.6.3 Control of Acidity The main water-quality problem of acidified lakes is the

increased concentration of heavy metals in the water.
Extensive research has been conducted to refine and
test methods for neutralizing lake waters using a variety
of neutralizing agents as well as application techniques.
The most common approaches to treating acidic lakes
are described below.

Lake waters may naturally be acidic: for example, in
regions with naturally acidic soils or when a lake is part
of wetland system. Anthropogenic lake acidity is caused
by large inputs of organic acids, acid mine drainage,
or acidic atmospheric deposition. Acid atmospheric
deposition (acid rain) is confined mainly to industrial
regions of the northern hemisphere, such as the north-
eastern United States and adjacent parts of Canada,
Scandinavia, parts of Great Britain and Ireland, and
small areas in central Europe and Asia. The low pH/high
acidity is caused by the low buffering capacity (low
alkalinity) of the lake to neutralize these acidic inputs.

Limestone Addition to the Lake Surface. Small lime-
stone particles, limestone powder, or a limestone
slurry are dispersed via boat, plane, or helicopter
over the lake. During winter, the limestone may
be spread on the ice by truck, entering the lake
in the spring as the ice melts. Direct addition of