Sediment Quality Mainstem and Tributaries, Oil Sands Region

Sediment Transport

This data set demonstrates some variation in the data parameters, both in time and with distance along the mainstem Athabasca and two tributaries (Ells and Steepbank Rivers). For the mainstem Athabasca (bulk suspended sediment samples collected via continuous flow centrifugation), these variations are not considered unusual for a dynamic mobile bed river. For the Ells and Steepbank Rivers (bulk suspended sediment samples collected via long-term time-integrated Phillips Tube samplers), however, some spatial and temporal trends were evident. Eight polycyclic aromatic hydrocarbon parameters for the Ells River and thirteen for the Steepbank River showed increasing trends as you move downstream (for periods where samples were collected at multiple sites). This is consistent with cumulative exposure time and erosion of surficial channel bitumen as the water/sediment travels down river. Temporally, one sample collection event (August 13 to September 29, 2013) showed a marked increase in numerous polycyclic aromatic hydrocarbon concentrations relative to other sample periods for both the Steepbank River and Ells River sites. The exact reason for this is unclear but may be due to varying flow conditions (different duration of Phillips Tube sampler deployments needs to be considered).

There are no suspended sediment guidelines for the parameters within this data set (polycyclic aromatic hydrocarbons, metals and physicals [% total carbon, % total inorganic carbon, % total organic carbon, % clay, % silt, % sand, % gravel and total suspended solids]). There is very little suspended sediment quality data in the literature for the Athabasca River and its tributaries for comparison. Data from other rivers may prove misleading due to geological and land use differences.