Spatial trends of perfluoroalkyl compounds in ringed seals (Phoca hispida) from the Canadian Arctic

The present study examined spatial trends of perfluoroalkyl compounds (PFCs) in liver samples from 11 populations of ringed seals (Phoca hispida) in the Canadian Arctic from 2002 to 2005. Trophic position and relative carbon sources were compared by analyzing stable nitrogen and carbon isotopes in muscle samples. Geometric mean concentrations of total C9-C15 perfluorinated carboxylates (PFCAs) ranged from 8.8 to 84 ng/g wet weight, and C9-C11 PFCAs predominated. Perfluorooctane sulfonate was the dominant PFC measured, with concentrations ranging from 6.5 to 89 ng/g wet weight, contributing between 29 and 56% of the total PFC concentration. Overall, mean PFC concentrations were similar between populations, and differences were attributed largely to elevated levels in the Gjoa Haven (Rae Strait, central Canadian Arctic archipelago) and Inukjuak populations (eastern Hudson Bay) and to lower concentrations at Pangnirtung (Cumberland Sound, Baffin Island). Mean stable nitrogen isotope ratios (+/-95% confidence intervals) ranged from 14.7 per thousand (+/-0.3 per thousand) at Nain (Labrador) to 17.9 per thousand (+/-0.7 per thousand) at Gjoa Haven, suggesting that all populations were within the same trophic level. Stable carbon isotope ratios varied widely between the seal populations, ranging from -22.9 per thousand (+/-0.2 per thousand) at Gjoa Haven to -17.7 per thousand (+/-0.4 per thousand) at Nain. The delta13C ratios from Gjoa Haven were significantly more depleted than those for other populations and may suggest a terrestrially based carbon source. The depleted stable carbon isotope ratio may explain the elevated PFC concentrations in the Gjoa Haven population. Analysis of covariance indicated that delta13C was a significant covariable for seven of nine seal populations for which delta13C values were available. After adjusting for delta13C values, concentrations of most PFCs generally were statistically greater in the Grise Fiord, Qikiqtarjuaq, Arviat, and Nain populations.