Concentrations of Metals in Fishes from the Athabasca and Slave Rivers of Northern Canada.

There is growing concern about possible effects of exploitation of the Alberta Oil Sands on the ambient environment, including possible effects on populations of fishes in the Athabasca River and farther downstream in Lake Athabasca and the Slave River. In the present study, concentrations of metals in dorsal muscle tissue of 5 fish species-goldeye, northern pike, walleye, whitefish, and burbot-from the Slave, Peace, and Athabasca Rivers were quantified. A suite of 25 metals including As, Hg, Se, Tl, and V was analyzed. Most metals exhibited no significant variations in concentration among locations. Concentrations of 5 metals, As, Hg, Se, Tl, and V, revealed significant variations among locations and were of sufficient magnitude to be of interest. Concentrations of Hg did not vary significantly among locations; however, because it was detected at concentrations of concern and the use of the selected fishes was a local source of food for humans and pets, it was of interest. Concentrations of As, Se, Tl, and V in dorsal muscle of certain fishes in the farthest downstream sites on the Slave River were greater than those in the same tissues and species in the farther upstream sites on the Peace and Athabasca Rivers. This phenomenon was most prevalent with Tl and to a lesser extent with As and Se. Nevertheless, concentrations were not of concern for the health of human consumers. Although metals did not appear to be increased in fish in the Alberta Oil Sands region in the present study, further research is needed to understand the potential impacts. Environ Toxicol Chem 2020;39:2180-2195. © 2020 SETAC.

Potential health risks posed by polycyclic aromatic hydrocarbons in muscle tissues of fishes from the Athabasca and Slave Rivers, Canada.

Polycyclic aromatic hydrocarbons (PAHs) are released to the environment from oil sands operations and from natural sources in Alberta, Canada. Concentrations of 16 USEPA priority PAHs were measured in tissues of fishes collected from three locations on the Athabasca River in Alberta and two downstream locations on the Slave River in the Northwest Territories, Canada. A total of 425 individual fish were collected including 89 goldeye (Hiodon alosoides), 93 whitefish (Coregonus clupeaformis), 104 northern pike/jackfish (Esox lucius), 96 walleye (Sander vitreus) and 43 burbot/loche mariah/mariah (Lota lota). Fish were sampled during the summer and fall of 2011 and spring of 2012. Dorsal muscle of fishes from upstream reaches of the Athabasca River, close to oil sands extraction and upgrading activities, contained greater concentrations of individual PAHs than concentrations in muscle of fishes from further downstream in the Slave River. Concentrations of the sum of USEPA indicator PAHs (∑PAHs) in fishes collected in the vicinity of Fort McKay, closest to oil sands activities, varied among seasons with average concentrations ranging from 11 (burbot, summer) to 1.2 × 102 ng/g, wm (burbot, spring) with a mean of 48 ng/g, wm. Concentrations of ∑PAHs in fishes collected in the vicinity of Fort Resolution, the location most distant from oil sands activities, also varied among species and seasons, with average concentrations ranging from 4.3 (whitefish, summer) to 33 ng/g, wm (goldeye, summer) with a mean of 13 ng/g, wm. Significant differences in concentrations of ∑PAHs in muscle were observed within goldeye, jackfish, walleye and whitefish among sites. Health risks posed by PAHs to humans were assessed probabilistically using a B[a]P equivalents approach (B[a]Peq). The average lifetime risk of additional cancers for humans who consumed fish was deemed to be within an 'acceptable' range of risk (i.e., less than 10-6).

Products of biotransformation of polycyclic aromatic hydrocarbons in fishes of the Athabasca/Slave river system, Canada.

Concentrations of products of biotransformation of polycyclic aromatic hydrocarbons (PBPAH) were measured in bile of five fishes of nutritional, cultural and ecological relevance from the Athabasca/Slave river system. Samples were collected in Alberta and the Northwest Territories, Canada, during three seasons. As a measure of concentrations of PBPAHs to which fishes are exposed and to gain information on the nature and extent of potential exposures of people or piscivorous wildlife, concentrations of biotransformation products of two- and three-ringed, four-ringed and five-ringed PAHs were measured using synchronous fluorescence spectroscopy. Spatial and seasonal differences were observed with greater concentrations of PBPAHs in samples of bile of fish collected from Fort McKay as well as greater concentrations of PBPAHs in bile of fish collected during summer compared to those collected in other seasons. Overall, PBPAHs were greater in fishes of lower trophic levels and fishes more closely associated with sediments. In particular, goldeye (Hiodon alosoides), consistently contained greater concentrations of all the PBPAHs studied.

Simultaneous extraction and clean-up of polybrominated diphenyl ethers and polychlorinated biphenyls from sheep liver tissue by selective pressurized liquid extraction and analysis by gas chromatography-mass spectrometry.

We describe a selective pressurized liquid extraction (SPLE) method, followed by gas chromatography-mass spectrometry (GC-MS), for the simultaneous extraction and clean-up of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in sheep liver tissue samples. The on-line clean-up of liver tissue by SPLE was tested using differing amount of acid-modified silica (sulphuric acid:silica gel, 1:2, w/w), the most effective amount being 20 g. Different extraction solvents (iso-hexane and dichloromethane), either alone or in various combinations, were used to extract these target compounds from spiked liver samples. Variables affecting the SPLE extraction efficiency, including temperature, pressure, number of extraction cycles and static extraction time were studied; the optimum parameters were 80 °C, 10.3 MPa, 2 cycles and 5 min, respectively. The SPLE based method was compared with more traditional Soxhlet, off-line PLE, ultrasonic and heating extraction methods. Overall the mean percentage recoveries for all target chemicals using SPLE were 86-103% (n=3, SD < 9%), and compared favourably with the Soxhlet (63-109%, n=3, SD < 8%), off-line PLE (82-104%, n=3, SD < 18%), ultrasonic (86-99%, n=3, SD < 11%) and heating (72-102%, n=3, SD < 21%) extraction methods. The limits of detection of the proposed method were 5-96 pg g⁻¹ and 2-29 pg g⁻¹ for the different PBDE and PCB chemicals studied, respectively. The outputs of the proposed method were linear over the range from 0.02 to 30 ng g⁻¹, for all PCB and PBDE congeners except for PBDE 100 and 153 (0.05-30 ng g⁻¹) and PBDE 183 (0.1-30 ng g⁻¹). The method was successfully applied to sheep liver samples for the determination of the target PBDE and PCB compounds.