A Study Of Water And Sediment Quality As - TO THE TAR SANDS .ca

Total Mercury
Total mercury was 0.00139 µg/L at the Rochers River, 0.00161 µg/L at the Lake
Athabasca water intake, 0.00325 µg/L at the Fletcher Channel, and 0.00083 µg/L for
treated tap water (Table 7). The total mercury level in the Fletcher Channel approaches
the chronic exposure guideline for protection of aquatic life (0.005 µg/L, Table 3).
Other data place the preceding mercury concentrations in context. Many observed
mercury concentrations exceed aquatic life protection guidelines (Table 5).
For the Athabasca River above Embarras Portage the 90 th percentile mercury
concentration was 0.02 µg/L with a maximum of 0.05 µg/L; for the Peace River at Peace
Point, the 90 th percentile mercury concentration was 0.03 µg/L with a maximum of 0.13
µg/L (Table 5; Donald et al. 2004).
A lower Athabasca River maximum of the median background concentration of
0.036 µg/L was reported by Golder (2007). Maximum mercury concentrations for the
Athabasca River between Fort Creek and Embarras were: 1.3, 0.05, 0.11, and 0.4 µg/L
for winter, spring, summer, and fall (Table 5). Modelled median mercury concentrations
for the Athabasca River reaches “downstream of Steepbank River” and “upstream of
Embarras River” were 0.027 and 0.030 µg/L, respectively (ranges: