Environmental effects monitoring, which includes monitoring of biological populations or
communities, is becoming increasingly important in assessing the impacts of operating mines,
including impacts associated- with acid rock drainage (ARD). However, in many cases, the
interpretation of biological data is severely limited by lack of adequate baseline studies against
which to compare post-mining changes. Therefore, the B.C. Acid Mine Drainage Task Force
contracted Norecol Environmental Consultants Ltd. to investigate the potential for using
paleolimnologîcal techniques to provide “baseline” data.
Large scale studies in North America and Europe have successfully used paleolimnological
indicators to show that acid precipitation has affected lakes on both continents. Norecol reviewed
these studies to evaluate whether similar techniques could be applied to ARD monitoring.
The acid rain studies have used diatoms, chrysophytes, chironomids, various zooplankton, plant
macrofossils, pollen, plant pigments and sediment chemistry as indicators of past environmental
conditions. Of these, the diatoms have been most intensively studied, and they have proven
useful indicators of changes which occurred over periods of five years or less. Calibration
equations have been developed to allow prediction of past pH conditions based on “fossil” diatom
assemblages. There is also considerable information on chrysophytes and chironomids, which
have some potential as indicator taxa. Zooplankton, plant macrofossils, and plant pigments have
not proven particularly useful, while pollen and sediment chemistry cari provide evidence to
support the dating of environmental change.
It should be possible to apply the paleolimnological techniques developed for acid rain studies
to monitoring ARD in British Columbia lakes. However, it first Will be necessary to develop a
calibration data set which relates species assemblages of the chosen indicator taxon to levels of
ARD-related parameters (pH, iron, aluminum, copper, zinc, and/or other metals) in British
Columbia lakes.
Diatoms are recommended as the indicator taxon. A preliminary study to calibrate diatom
distributions in lake sediments with water chemistry should be undertaken in a limited
geographical area which contains some ARD-impacted lakes. The Smithers/Houston is suggested,
as it contains several lakes which have received acidic and other mine drainage.
The report recommends a methodology for carrying out the calibration study. The suggestions
include statistical tests for data analysis, coring techniques to obtain an undisturbed sediment
record, laboratory analytical techniques, and quality assurance/quality control procedures.
