title: Toxicity of naphthenic acid fraction components extracted from fresh and aged oil sands process-affected waters, and commercial naphthenic acid mixtures, to fathead minnow (Pimephales promelas) embryos.
abstract: Naphthenic acids (NAs) are constituents of oil sands process-affected water (OSPW). These compounds can be both toxic and persistent and thus are a primary concern for the ultimate remediation of tailings ponds in northern Alberta's oil sands regions. Recent research has focused on the toxicity of NAs to the highly vulnerable early life-stages of fish. Here we examined fathead minnow embryonic survival, growth and deformities after exposure to extracted NA fraction components (NAFCs), from fresh and aged oil sands process-affected water (OSPW), as well as commercially available NA mixtures. Commercial NA mixtures were dominated by acyclic O2 species, while NAFCs from OSPW were dominated by bi- and tricyclic O2 species. Fathead minnow embryos less than 24h old were reared in tissue culture plates terminating at hatch. Both NAFC and commercial NA mixtures reduced hatch success, although NAFCs from OSPW were less toxic (EC50=5-12mg/L, nominal concentrations) than commercial NAs (2mg/L, nominal concentrations). The toxicities of NAFCs from aged and fresh OSPW were similar. Embryonic heart rates at 2 days post-fertilization (dpf) declined with increasing NAFC exposure, paralleling patterns of hatch success and rates of cardiovascular abnormalities (e.g., pericardial edemas) at hatch. Finfold deformities increased in exposures to commercial NA mixtures, not NAFCs. Thus, commercial NA mixtures are not appropriate surrogates for NAFC toxicity. Further work clarifying the mechanisms of action of NAFCs in OSPW, as well as comparisons with additional aged sources of OSPW, is merited.
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada.
authors.forename: Julie R
authors.initials: JR
authors.lastname: Marentette
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Frank
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada.
authors.forename: Adrienne J
authors.initials: AJ
authors.lastname: Bartlett
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada.
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Gillis
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada.
authors.forename: L Mark
authors.initials: LM
authors.lastname: Hewitt
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Saskatoon, SK, Canada.
authors.forename: Kerry M
authors.initials: KM
authors.lastname: Peru
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Saskatoon, SK, Canada.
authors.forename: John V
authors.initials: JV
authors.lastname: Headley
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Vancouver, BC, Canada.
authors.forename: Pamela
authors.initials: P
authors.lastname: Brunswick
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Vancouver, BC, Canada.
authors.forename: Dayue
authors.initials: D
authors.lastname: Shang
authors.affiliation: Water Science and Technology Directorate, Environment Canada, Burlington, ON, Canada. Electronic address: Joanne.Parrott@ec.gc.ca.
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Parrott
mesh_terms: D000416:Alberta; D000818:Animals; D002264:Carboxylic Acids / Q000633:toxicity*; D018376:Cardiovascular Abnormalities / Q000139:chemically induced; D003530:Cyprinidae / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D061329:Oil and Gas Fields / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D002264:Carboxylic Acids; D014874:Water Pollutants, Chemical; C046170:naphthenic acid
keywords: Acid-extractable organics (AEO); Deformities; Fish; Hatch success; Larval survival; NAFC; Naphthenic acid; OSPW; Oil sands; Time to hatch