Development of aquatic communities in high-altitude mine pit lake systems of west-central Alberta.

摘要

Reclamation on the Cardinal River and Gregg River coal mines includes the construction of mine pit lakes connected to stream environments. Key physical, chemical and biological parameters of these "truck and shovel" lakes and the r streams were investigated, and hypotheses regarding ecosystems and populations were tested. Findings include: (1) Sphinx Lake and Pit Lake CD exhibit meromictic (partial-mixing) tendencies, but still function in a similar fashion to shallower, natural sub-alpine lakes. (2) Elevated selenium concentrations as high as 16 ug/g (dry weight) were recorded in Rainbow trout (Oncorhynchus mykiss) eggs taken from gravid Sphinx Lake and Pit Lake CD fish. Potential detrimental effects associated with the bioaccumulation of selenium on fish reproduction were not observed. (3) Stream water temperatures downstream of Sphinx Lake and Pit Lake CD were significantly wanner than in inlet streams and streams without pit lakes. (4) Streambed concretions caused by calcite precipitation were documented and found to affect portions of the upper Gregg River basin. Remediation of this concretion is important for sustainability of trout populations. (5) Aquatic communities including fish, invertebrates, zooplankton and aquatic plants are present in these pit lake systems. Athabasca Rainbow trout populations are self-propagating (spawning at the outlets) with higher densities downstream than there were prior to lake reclamation.;The development of sub-alpine mine pit lakes connected to the stream environment appears to be an appropriate and beneficial reclamation technique in this area.