Growth of Fathead Minnows in Oilsand-Processed Wastewater in Laboratory and Field

Abstract

Abstract-Two waste products of Syncrude Canada Ltd. (SCL) oilsands mine are mature fine tailings (MFT), a toxic aqueous suspension of particles, organic acids, bitumen, and metals, and tailings pond water (TPW), a saline solution containing organic and inorganic contaminants. The chemical profiles of MFT interstitial water and TPW are very similar. Syncrude Canada has proposed disposing of MFT in constructed lakes, which would be lined with MFT and capped with clean water. As the MFT consolidates, MFT-associated water would be released into the overlying watercap. Prototype ponds support fathead minnows (Pimephales promelas), but the long-term viability of these populations is unknown. This study attempts to determine if exposure to MFT and TPW, a related waste product, affected growth of fathead minnow larvae in the laboratory and field. Laboratory larval growth bioassays (7 and 56 d) on whole effluent from numerous prototype ponds yielded no significant differences in dry weight, but one 7-d bioassay showed reduced survival in two SCL sites. A 56-d growth bioassay showed significant increases in length of fish exposed to SCL wastewater at 7 d but not at 28 or 56 d. Larvae exposed as embryos and then introduced into field mesocosms did display significant differences in dry weight. In this instance, fish exposed to wastewater were significantly larger during the laboratory portion of the test (initial), but after 21 d in a field mesocosm (final), they were similar in size or smaller than fish growing in nonprocessed water.

Toxicity of oil sands to early life stages of fathead minnows (Pimephales promelas)

“…The toxicity of weathered crude oils to marine organisms has also been correlated with polar, low‐molecular‐weight hydrocarbon degradation products [34]. Naphthenic acids are a family of carboxylic acids that are abundant oil sands wastes [6] and are acutely toxic to aquatic organisms [1]. In addition, C 1 ‐ through C 4 ‐DBTs are sulfur‐containing compounds that are typically found at high levels in natural oil sands and tailings extracts [4,31].…”

“…A recent study of adult yellow perch ( Perca flavescens ) showed that exposure to tailings waters was associated with altered mixed‐function oxygenase activity and bile PAH equivalent concentrations [5]. In field mesocosms, native fathead minnows ( Pimephales promelas ) reared in oil sands wastewater exhibited reduced growth compared to fish growing in nonprocessed water [6]. Tributaries that flow through the Athabasca Oil Sands region have eroded bitumen deposits, thereby distributing naturally derived hydrocarbons throughout the watershed.…”

Overview of Existing Science to Inform Oil Sands Process Water Release: A Technical Workshop Summary

“…Classes of constituents include suspended solids (e.g., clay, silt), bitumen, dissolved organic compounds (e.g., organic acids and bases, polar organics, nonpolar organics), and dissolved inorganic materials (e.g., salts, trace elements, ammonia). Some components of OSPW are well understood: trace elements including metals, semimetals, and metalloids (Nix and Martin ; Siwik et al ; Bicalho et al ; Donner et al ), salts and ammonia (COSIA ), and suspended solids (El‐Din et al ; COSIA ; McQueen, Hendrikse et al ). However, the complexity of the organics in OSPW creates a practical challenge for determining treatment methods (Headley et al ; Pereira et al 2013; Goff et al ; Brown and Ulrich ; Quinlan and Tam ; Wilde et al ; Ajaero et al ), in addition to estimating potential risks (West et al ; Huang et al ).…”

Environmental Challenges of Heavy Crude Oils: Management of Liquid Wastes

“…Syncrude Canada currently is including heavy oil production wastes in reclamation projects for the mined areas (35). Lakes are being built in the mine pits and filled with MFT and clean water.…”

“…Lakes are being built in the mine pits and filled with MFT and clean water. These constructed ponds seem to support normal aquatic communities with little or no serious biological effects (35).…”