British Columbia Mine Reclamation Symposium

Sulphate toxicity to freshwater organisms and molybdenum toxicity to rainbow trout embryos/alevins Davies, Trevor D.; Pickard, Janet S.; Hall, Ken J.


The guidelines for sulphate and molybdenum used for the protection of aquatic life may be overly protective. The current BC guidelines for sulphate and molybdenum are set at 100 and 1 mg/L, respectively. Key toxicity tests used in the development of the guidelines were replicated to determine whether results of tests reporting extremely low toxicity endpoints were artefacts or indicators that these substances can be more toxic under specific environmental conditions. Tests on sulphate were conducted using the amphipod, Hyalella azteca; the cladoceran, Daphnia magna; striped bass, Morone saxatilus; and the aquatic moss, Fontinalis antipyretica. An early life stage test using rainbow trout, Oncorhynchus mykiss, was conducted to examine molybdenum toxicity. The results of these tests indicated that the key studies used to justify the current conservative guidelines do not accurately assess sulphate or molybdenum toxicity. These findings indicate that the water quality guidelines for the protection of aquatic life for both molybdenum and sulphate need to be re-examined.

Item Media

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International