TY - JOUR
T1 - The distribution and migration of sodium from a reclaimed upland to a constructed fen peatland in a post-mined oil sands landscape
AU - Kessel, Eric D.
AU - Ketcheson, Scott J.
AU - Price, Jonathan S.
N1 - Publisher Copyright:
© 2018
PY - 2018/7/15
Y1 - 2018/7/15
N2 - Post-mine landscape reclamation of the Athabasca Oil Sands Region requires the use of tailings sand, an abundant mine-waste material that often contains large amounts of sodium (Na+). Due to the mobility of Na+ in groundwater and its effects on vegetation, water quality is a concern when incorporating mine waste materials, especially when attempting to construct groundwater-fed peatlands. This research is the first published account of Na+ redistribution in groundwater from a constructed tailings sand upland to an adjacent constructed fen peat deposit (Nikanotee Fen). A permeable petroleum coke layer underlying the fen, extending partway into the upland, was important in directing flow and Na+ beneath the peat, as designed. Initially, Na+ concentration was highest in the tailings sand (average of 232 mg L−1) and lowest in fen peat (96 mg L−1). Precipitation-driven recharge to the upland controlled the mass flux of Na from upland to fen, which ranged from 2 to 13 tons Na+ per year. The mass flux was highest in the driest summer, in part from dry-period flowpaths that direct groundwater with higher concentrations of Na+ into the coke layer, and in part because of the high evapotranspiration loss from the fen in dry periods, which induces upward water flow. With the estimated flux rates of 336 mm yr−1, the Na+ arrival time to the fen surface was estimated to be between 4 and 11 years. Over the four-year study, average Na+ concentrations within the fen rooting zone increased from 87 to 200 mg L−1, and in the tailings sand decreased to 196 mg L−1. The planting of more salt-tolerant vegetation in the fen is recommended, given the potential for Na+ accumulation. This study shows reclamation designs can use layered flow system to control the rate, pattern, and timing of solute interactions with surface soil systems.
AB - Post-mine landscape reclamation of the Athabasca Oil Sands Region requires the use of tailings sand, an abundant mine-waste material that often contains large amounts of sodium (Na+). Due to the mobility of Na+ in groundwater and its effects on vegetation, water quality is a concern when incorporating mine waste materials, especially when attempting to construct groundwater-fed peatlands. This research is the first published account of Na+ redistribution in groundwater from a constructed tailings sand upland to an adjacent constructed fen peat deposit (Nikanotee Fen). A permeable petroleum coke layer underlying the fen, extending partway into the upland, was important in directing flow and Na+ beneath the peat, as designed. Initially, Na+ concentration was highest in the tailings sand (average of 232 mg L−1) and lowest in fen peat (96 mg L−1). Precipitation-driven recharge to the upland controlled the mass flux of Na from upland to fen, which ranged from 2 to 13 tons Na+ per year. The mass flux was highest in the driest summer, in part from dry-period flowpaths that direct groundwater with higher concentrations of Na+ into the coke layer, and in part because of the high evapotranspiration loss from the fen in dry periods, which induces upward water flow. With the estimated flux rates of 336 mm yr−1, the Na+ arrival time to the fen surface was estimated to be between 4 and 11 years. Over the four-year study, average Na+ concentrations within the fen rooting zone increased from 87 to 200 mg L−1, and in the tailings sand decreased to 196 mg L−1. The planting of more salt-tolerant vegetation in the fen is recommended, given the potential for Na+ accumulation. This study shows reclamation designs can use layered flow system to control the rate, pattern, and timing of solute interactions with surface soil systems.
KW - Athabasca Oil Sands region
KW - Constructed wetland
KW - Peatland
KW - Reclamation
KW - Sodium transport
KW - Tailings sand
UR - http://www.scopus.com/inward/record.url?scp=85042857542&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2018.02.253
DO - 10.1016/j.scitotenv.2018.02.253
M3 - Journal Article
C2 - 29554772
AN - SCOPUS:85042857542
SN - 0048-9697
VL - 630
SP - 1553
EP - 1564
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -