Life-history traits of two Salvelinus species and mercury concentrations in fish and prey in ten Canadian lakes (2006-2008)

Mercury concentrations ([Hg]) in Arctic food fish often exceed guidelines for human subsistence consumption. Previous research on two food fish species, Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush), indicates that anadromous fish have lower [Hg] than nonanadromous fish, but there have been no intraregional comparisons. Also, no comparisons of [Hg] among anadromous (sea-run), resident (marine access but do not migrate), and landlocked (no marine access) life history types of Arctic char and lake trout have been published. Using intraregional data from 10 lakes in the West Kitikmeot area of Nunavut, Canada, we found that [Hg] varied significantly among species and life history types. Differences among species-life history types were best explained by age-at-size and C:N ratios (indicator of lipid); [Hg] was significantly and negatively related to both. At a standardized fork length of 500 mm, lake trout had significantly higher [Hg] (mean 0.17 µg/g wet wt) than Arctic char (0.09 µg/g). Anadromous and resident Arctic char had significantly lower [Hg] (each 0.04 µg/g) than landlocked Arctic char (0.19 µg/g). Anadromous lake trout had significantly lower [Hg] (0.12 µg/g) than resident lake trout (0.18 µg/g), but no significant difference in [Hg] was seen between landlocked lake trout (0.21 µg/g) and other life history types. Our results are relevant to human health assessments and consumption guidance and will inform models of Hg accumulation in Arctic fish

Assessing 134Cs & 137Cs levels in abiotic and biotic samples in British Columbia following the Fukushima Nuclear Accident

The Fukushima nuclear power plant accident on March 11, 2011 raised global concerns due to the uncontrolled release of radioisotopes into the atmosphere and Pacific Ocean. With the aim to investigate potential Fukushima-associated radioactive contamination in British Columbia, detailed analysis of 134Cs and 137Cs activity levels in abiotic (soil and clay) and biotic (wild Pacific salmon including, Chinook, Oncorhynchus tshawytscha; chum, O. keta; and sockeye, O. nerka, as well as roof plant-material) samples collected in British Columbia was performed using gamma-ray spectroscopy. The extended source shape of each sample was modeled using the GEANT4 software package, previously developed to model the Germanium Detector for Elemental Analysis and Radioactivity Studies (GEARS), in order to measure the larger environmental samples. 134Cs and 137Cs activity levels were compared relative to 40K, a (Naturally Occuring Radioactive Material (NORM), to examine the impact of anthropogenic radiation relative to existing natural background radiation. In abiotic samples, the maximum 134Cs and 137Cs activity concentrations measured were 1.33(17) and 155.6(19) Bq/kg respectively while in the salmon biotic samples, the maximum 137Cs activity concentrations measured was 2.8(4) Bq/kg. 134Cs was not detected in any of the salmon samples. In the single plant biotic sample, the activiy concentrations for 134Cs and 137Cs were measured to be 13.1(2) and 54.4(8) Bq/kg. The Minimum Detection Limit (MDL) was calculated for samples where neither 134Cs and 137Cs were detected to provide an upper limit for the amount of each radioisotope present. The maximum ratio of anthropogenic activity to naturally occurring activity in all of the samples measured was 0.0336(9) and 0.68(2) for 134Cs/40K and 137Cs/40K respectively, though the required ratios to give equal dose contributions from man-made and naturally occurring radioactivity would be 3.17 and 2.67. It was observed that in the samples where 134Cs was positively identified, 7Be was also detected suggesting the contribution of 134Cs into these samples may have been through the atmospheric deposition rather then through ocean currents. For all samples, the measured activity concentration of 134Cs and 137Cs were below 1000 Bq/kg, the 134Cs and 137Cs action level for commercial food and beverages established by the Canadian Guidelines for the Restriction of Radioactively Contaminated Food and Water Following a Nuclear Emergenc

Fukushima-derived radioactivity measurements in Pacific salmon and soil samples collected in British Columbia, Canada

Despite the many studies which have shown minimal health risks to individuals living outside of Japan following the Fukushima Nuclear Accident, there are persisting concerns regarding the consumption of Pacific seafood which may be contaminated with radioactive species from Fukushima. To address these concerns, the activity concentrations of anthropogenicThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Isotopic signatures and mercury content of arctic char and their prey, and water chemistry of 18 arctic Canadian lakes

Concentrations of mercury (Hg) have increased slowly in landlocked Arctic char over a 10- to 15-year period in the Arctic. Fluxes of Hg to sediments also show increases in most Arctic lakes. Correlation of Hg with trophic level (TL) was used to investigate and compare biomagnification of Hg in food webs from lakes in the Canadian Arctic sampled from 2002 to 2007. Concentrations of Hg (total Hg and methylmercury [MeHg]) in food webs were compared across longitudinal and latitudinal gradients in relation to d13C and d15N in periphyton, zooplankton, benthic invertebrates, and Arctic char of varying size-classes. Trophic magnification factors (TMFs) were calculated for the food web in each lake and related to available physical and chemical characteristics of the lakes. The relative content of MeHg increased with trophic level from 4.3 to 12.2% in periphyton, 41 to 79% in zooplankton, 59 to 72% in insects, and 74 to 100% in juvenile and adult char. The d13C signatures of adult char indicated coupling with benthic invertebrates. Cannibalism among char lengthened the food chain. Biomagnification was confirmed in all 18 lakes, with TMFs ranging from 3.5 ± 1.1 to 64.3 ± 0.8. Results indicate that TMFs and food chain length (FCL) are key factors in explaining interlake variability in biomagnification of [Hg] among different lakes