| This research evaluated the impacts of discharging diamond drilling wastes into lakes, at the scale of first stage mineral exploration drilling. Three field programs monitored impacts to water quality, sediment quality, and benthic biota. (1) The Great Slave Lake drilling program involved release of small quantities of rock fines, and affected benthos within 15m of the discharge point. Volumes of solids were too small to effect measurable changes to particle size structure and sediment chemistry, with the exception of increased calcium concentrations. (2) The Baton Lake drilling program dealt with greater quantities of drilling effluent. Water chemistry changes were observed after drilling, but these did not persist beyond the first year, with the exception of manganese in the bottom waters above the discharge site. Total suspended solids concentrations during drilling remained low. The layer of drill fines overlying the sediments had a maximum depth of 7 mm; this was sufficient to measurably increase levels of aluminum, magnesium, potassium and sodium in the sediments and decrease organic carbon and nitrogen. One year after effluent release there were no detectable differences in the benthic invertebrate population when compared to pre-release. (3) The Lac de Gras drilling program involved release of kimberlite effluent containing polyacrylamide additives. Water quality monitoring identified elevations in some metal parameters in the lower water column during drilling only.* (Abstract shortened by UMI.); *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Adobe Acrobat; Microsoft Office. |
