Search

Firefighters can be exposed to complex mixtures of airborne substances, including hazardous substances released during structural fires. This study employed silicone wristbands (SWBs) as passive samplers to investigate potential exposure to polycyclic aromatic hydrocarbons (PAHs) and flame retardants (FRs). SWBs were deployed at different areas of four fire stations, in four truck cabins, and at an office control location; they were also donned outside the jackets of 18 firefighters who responded to fire calls. Overall, office areas had significantly lower PAHs than fire station areas. Vehicle bays and truck cabins had significantly higher concentrations of low molecular weight (LMW) PAHs than sleeping and living room areas. For organophosphate ester flame retardants (OPFRs), tri-n-butyl phosphate (TnBP) and tris(1-chloro-2-propyl) phosphate (TCPP) were detected in all the samples; 2-ethylhexyl diphenyl phosphate (EHDPP) was more frequently detected in the fire station areas. Triphenyl phosphate (TPP) concentrations were highest in the truck cabin and office areas, and tris(1,3-dichloro-2-propyl)phosphate (TDCPP) was highest in truck cabins. Thirteen of 16 PAHs and nine of 36 OPFRs were detected in all the SWBs worn by firefighters, and tris (2-butoxyethyl) phosphate (TBEP) was the predominant OPFR. Levels of LMW PAHs were significantly lower when firefighters did not enter the fire. LMW PAHs, HMW (high molecular weight) PAHs, and EHDPP were significantly elevated when heavy smoke was reported. This work highlights the potential for occupational exposure to PAHs and flame retardants in some fire station areas; moreover, factors that may influence exposure during fire suppression. Whilst firefighters' occupational exposure to PAHs is likely related to fire suppression and exposure to contaminated gear and trucks, exposure to OPFRs may be more related to their presence in truck interiors and electronics. [ABSTRACT FROM AUTHOR]

Archaeological studies of pre-historic Arctic cultures are often limited to artefacts and architecture; such records may be incomplete and often do not provide a continuous record of past occupation. Here, we used lake sediment archives to supplement archaeological evidence to explore the history of Thule and Dorset populations on Somerset Island, Nunavut (Canada). We examined biomarkers in dated sediment cores from two ponds adjacent to abandoned Thule settlements (PaJs-3 and PaJs-13) and compared these to sediment cores from two ponds without past human occupation. Coprostanol and epicoprostanol, δ15N measurements, sedimentary chlorophyll a and the ratio of diatom valves to chrysophyte cysts were elevated in the dated sediment profiles at both sites during Thule and Dorset occupations. Periods of pronounced human impact during the Thule occupation of the site were corroborated by 14C-dated caribou bones found at both sites that identified intense caribou hunting between ca 1185 and 1510 CE. Notably, these sediment core data show evidence of the Dorset occupation from ca 200 to 500 CE at sites where archaeological evidence was heretofore lacking. We highlight the utility of lake sediments in assisting archaeological studies to better establish the timings, peak occupations and even lifestyle practices of the Dorset and Thule Arctic peoples. [ABSTRACT FROM AUTHOR]

Heavy crude oil transportation over land is increasing, yet the ecological impacts of spills, particularly of diluted bitumen, in freshwater environments remain poorly understood. We simulated spills of diluted bitumen in 1400 L land-based mesocosms containing water and sediments from a boreal, oligotrophic lake and monitored the response of natural planktonic communities over 11 days. Most species of phytoplankton (chrysophytes and dinoflagellates) and zooplankton (copepods and cladocerans) were sensitive to oil, exhibiting >70% overall abundance reductions in response to the spills. Declines in nano- and microphytoplankton were short-lived and began to recover after the oil sank, whereas picophytoplankton and zooplankton populations remained depressed at the end of the experiment. In contrast, oil spills stimulated bacteria known to degrade hydrocarbons, especially Alphaproteobacteria, whereas Gammaprotobacteria(a common marine oil spill bacterial class) increased less. This is the first experiment to examine the effects of diluted bitumen in a multitrophic freshwater community. Si le transport terrestre de petrole brut lourd est a la hausse, la comprehension des impacts ecologiques de deversements, particulierement de bitume dilue, dans les milieux d'eau douce demeure limitee. Nous avons simule des deversements de bitume dilue dans des mesocosmes terrestres de 1400 L contenant de l'eau et des sediments d'un lac oligotrophe boreal et surveille les reactions de communautes de plancton naturelles sur une periode de 11 jours. La plupart des especes de phytoplancton (chrysophytes et dinoflagelles) et de zooplancton (copepodes et cladoceres) etaient sensibles a la presence de petrole, presentant des baisses d'abondance globale de >70 % en reaction aux deversements. Les baisses etaient de courte duree en ce qui concerne le nanophytoplancton et le microphytoplancton, et ils commencaient a se remettre une fois le petrole coule au fond, alors que les populations de picophytoplancton et de zooplancton demeuraient reduites a la fin de l'experience. En comparaison, les deversements de petrole stimulaient les bacteries connues pour degrader les hydrocarbures, particulierement les alphaproteobacteries, alors que l'abondance de gammaprotobacteries (une classe repandue de bacteries associees aux deversements de petrole en mer) n'augmentait pas autant. Il s'agit de la premiere experience a examiner les effets du bitume dilue dans une communaute d'eau douce multitrophique. [Traduit par la Redaction], Introduction Heavy crude oils are complex mixtures of organic components and carry additional contaminants, including sulfur, and metals (vanadium, nickel, iron) (Martinez-Palou et al. 2011; ECCC 2013; Lee et al. [...]

Control of smelting emissions in the Sudbury (Ontario, Canada) area has dramatically decreased the amount of selenium (Se) deposited onto the surrounding landscape. Historically, Se emissions in Sudbury correlated with lower total mercury (Hg) and methylmercury levels (MeHg) in tissues of zooplankton, amphipods (Hyalella azteca), mayflies (Stenonema femoratum), and young-of-the-year perch (Percaflavescens). In 2017, ten years following emission reductions, we evaluated whether changes in Se deposition affected total Hg and MeHg burden in lake biota. We show that total Se concentrations in the water of the majority of lakes have increased despite decreases in Se depositions, most likely due to the long residence time of Se in the watershed and the water column. As a result, Se in water continues to correlate with lower total Hg and MeHg accumulation in tissues of zooplankton, amphipods, mayflies, and perch. These results suggest that Se continues to exhibit a protective effect on Hg accumulation in biota, even years after emissions have greatly decreased. We expect this work to inform efforts aiming at long-term recovery of aquatic environments affected by smelter emissions and aid in designing remediation strategies involving Se additions. Le controle des emissions de fonderie dans la region de Sudbury (Ontario, Canada) s'est traduit par une reduction drastique de la quantite de selenium (Se) depose dans le paysage environnant. Historiquement, les emissions de Se a Sudbury etaient correlees a des concentrations reduites de mercure total (Hg) et de methylmercure (MeHg) dans les tissus de zooplancton, d'amphipodes (Hyalella azteca), d'heptagenies rousses (Stenonemafemoratum) et des perchaudes (Percaflavescens) de l'annee. En 2017, dix ans apres les reductions des emissions, nous avons examine si les changements de la quantite de Se deposee affectaient la charge de Hg total et de MeHg dans le biote des lacs. Nous montrons que les concentrations de Se total dans l'eau de la plupart des lacs ont augmente, malgre des baisses du depot de Se, vraisemblablement en raison du long temps de sejour du Se dans le bassin versant et la colonne d'eau. Par consequent, le Se dans l'eau continue d'etre correle a une accumulation plus faible de Hg total et de MeHg dans les tissus de zooplancton, d'amphipodes, d'heptagenies et de perchaudes. Ces resultats donnent a penser que le Se continue d'avoir un effet protecteur contre l'accumulation de Hg dans le biote, meme des annees apres des reductions substantielles des emissions. Nous prevoyons que ces travaux soutiendront les efforts visant au retablissement a long terme des milieux aquatiques touches par les emissions de fonderie et aideront a concevoir des strategies de remise en etat comprenant l'ajout de Se. [Traduit par la Redaction], Introduction The metal mining and smelting industry in Sudbury, Ontario, Canada, has been operating for more than 130 years (Saarinen 2013), extracting primarily nickel and copper, but also large quantities [...]

A new sensitive method to determine polonium-210 (210Po) and lead-210 (210Pb) in a diversity of environmental samples was developed. For fresh and marine waters, Po was pre-concentrated using a titanium (III) hydroxide (Ti(OH)3) co-precipitation. Solid environmental samples were digested with nitric acid (HNO3) and hydrogen peroxide (H2O2). The alpha thin layer source was prepared using CuS micro-precipitation and 210Po was measured by alpha spectrometry. Lead-210 was left to decay for up to a year and indirectly measured via its progeny, 210Po. The chemical recoveries for 210Po and 210Pb were high, 90% and 97%, respectively, for a large variety of samples and a very low minimum detectable activity (MDA) was obtained. The method was validated using standardized solutions and certified reference materials. [ABSTRACT FROM AUTHOR]

ABSTRACT. Niven Lake was the first wastewater disposal site for the City of Yellowknife (Northwest Territories, Canada), receiving domestic sewage for more than 30 years. Here, we used a high-resolution [...]