| dc.description.abstract | Loons in Kejimkujik National Park (KNP), southwestern Nova Scotia, have the highest levels of mercury (Hg) concentration in blood of any loon population in North America. For the past several years, a multi-disciplinary team of research scientists has been attempting to identify the potential Hg source(s) and process(es) responsible for the anomalous Hg levels. This thesis is a geochemical component of this research involving the collection and geochemical analysis of till and bedrock samples to quantify the geogenic contribution of Hg from glacial sediments and bedrock sources of the Meguma Supergroup. Health Canada provided funding for the project through the Toxic Substance Research Initiative (TSRI).
A total of 32 C horizon till samples were collected at 100 to 200 m intervals from three NW-SE transects that cross the inferred contact between the Halifax and Goldenville Groups immediately south of the KNP boundary. Samples were collected at depths ranging from 70 to 120 cm. Geochemical results for the <63 microns size fraction were determined by Cetac CV-AA and indicate Hg ranges from 6.6 ppb to 151.5 ppb (mean = 37.7 ppb). Nine slate and greywacke bedrock samples were collected along the same transects. Geochemical results for the <105 microns size fraction of the bedrock samples, also determined by Cetac CV-AA, had Hg values ranging from 0.2 ppb to 3.4 ppb (mean = 2.37 ppb). Strict QA/QC protocols were followed in the collection, preparation, and analysis of all samples.
Results show that the Hg concentrations of slate till (mean = 40.8 ppb) and greywacke till (mean = 32.4 ppb) are quite comparable. Till Hg values are similar to reported values within the Park. Log-probability plots indicate there is only one geologic control affecting Hg values such as lithology or mineralogy. Mercury values in the bedrock samples are low but comparable to other values in KNP. There is no apparent correlation between Hg and the Goldenville - Halifax Transition Zone (GHT). Field mapping, clast identification and counts and total field magnetic survey indicate that the geologic boundary is 500m to 1000m further north and the areal extent of the Halifax Group is smaller than reported on recent geologic maps.
Pages: 123
Supervisor: Don Fox and Marcos Zentilli | en_US |
