EXECUTIVE SUMMARY
Mines exist in geologically anomalous areas where elevated metals are a common feature of the surrounding area. Surfïcial mineralized zones cause elevated metal concentrations in the terrestrial and aquatic environments, and the natural biota, via acclimatization, tend to reflect these highly mineralized environments. The study is to provide realistic information on the environmental effects of mining activities and the application of laboratory sublethal toxicity tests to highly mineralized waters (HMVs).
This study tested the following hypothesis. natural waters in mineralized areas which have been mined, or are likely to be mined, have no potential for chronic toxicity. The study involved submitting samples with a battery of tests, including growth inhibition with Selenastrum capricornutum and Lemna minor, reproduction and survival of Ceriodaphnia dubia, growth and survival of the fathead minnow, and viability of the rainbow trout embryo. If a HMW is toxic, Ceriodaphnia and fathead minnow are acclimated to the sample and retested.
Criteria for selecting a HMW sample were developed following discussions with specialists in geochemistry and CANMET representatives. The criteria propose that if concentrations of metals and of sulphates in a receiving water surpass the limits listed in the British Columbia working/approved criteria for aquatic life, the receiving water would be considered as a HMW.
Only a single site, Discovery Pond, from Voisey’s Bay, Labrador (Voisey’s Bay Nickel Co. Ltd.) was tested and the sample was toxic to all of the test organisms. Acclimation of Ceriodaphnia dubia and fathead minnows was also not successful. Due to the toxicity of the sample, no tests could be performed with acclimated animals.
Representatives of the mining industry recommended additional sites for future HMW samples. These included B.C. sites on the Windy Craggy Deposit, Red Mountain, Bruceside Project/Sulphurets Property and Mount Mclntosh/Pemberton Hills.
A method of identifying the input of HMWs in a stream or river is needed (such as conductivity) which can be simply used in the field. The water quality of HMWs can vary substantially. A large number of samples should be tested to identify the scale of problem, the degree of variation and the typical background conditions for different types of mines.
AETE
