title: Athabasca River sediments
description: The Athabasca River stretches 1,231 kilometres from the Athabasca Glacier in west-central Alberta to Lake Athabasca in Northeastern Alberta. Annual mean discharge downstream of Fort McMurray is 619 cubic metres per second with a maximum of 1,010 cubic meters per second (http://www.ec.gc.ca/eau-water/, station 07DA001, accessed October 12, 2011). The direction of the flow near Fort McMurray is from the south to the north. A single large 10kg sample was taken from each of the following sites (17 samples): five sampling sites were chosen on the Athabasca River: a reference site near Fort McMurray, upstream of the oil sands mining activities (AR); near the Northland Sawmill, close to mining activities (NSM); near Suncor mining activities (DSU); near the mouth of the Muskeg River, downstream of the mining activities (MSK); and finally near the mouth of the Ells River, about 25 km downstream of the mining activities (AER). Nine other sampling sites were chosen in three of the Athabasca tributaries: upper (EU), mid (EM) and lower (EL) Ells River (slightly affected by mining activities) upper (FU), mid (FM) and lower (FL) Firebag Creek (not affected by mining activities); upper (SU), mid (SM), and lower (SL): Steepbank Creek (strongly affected by mining activities). Three samples were taken from oil sands tailings ponds: samples SY1A was taken from the Mildred Lake settling basin at about the mid-point adjacent to the east shore, SY1B was taken parallel to the east shore but further south in the basin. These positions are on a line transect that includes sites sampled by Penner and Foght (2010). Suncor 8A sediment was retrieved from a tailings pond adjacent to the Athabasca River which was considered full by 2006 and in the process of being transformed into a fine tailings drying site by 2010. The bottom of the tailings ponds consists of sand/silt/clay fractions along with some bitumen in contact with overlying waters.  Although it is reasonable to consider the geological materials in a tailings pond to be sediment, particularly given that in the region natural stream beds may essentially be bitumen, we will note that the tailings being sampled would often be referred to as Mature Fine Tailings (MFT).    Sampling was carried out between September 22, 2010 and September 24, 2010. At the moment of sampling, water temperature was 6.5°C. Sediment samples from the Athabasca River and its tributaries were obtained using a stainless steel shovel from shore in less than 1 m of water while the sediment samples from the tailings ponds were obtained using a long handled scoop in 1-2 m of water. Sediment samples were collected, transferred to plastic bags, excess water was removed although residual water content was retained, the bags were closed and placed in plastic pails for transport. Samples were transported in coolers to the laboratory within 48 hours, kept at 4°C and subsampled for analyses within 10 days.