A comparison of organic contaminants in two high Arctic lake ecosystems, Bjørnøya (Bear Island), Norway

Abstract

Lake Ellasjøen and Lake Øyangen are two high Arctic lake ecosystem located on the island Bjørnøya (74°30′ N, 19°00′ E) in the Barents Sea. High levels of persistent organic pollutants (POPs), especially PCB and p, p′-DDE, were found in sediment and biota from Lake Ellasjøen while levels were several times lower in Lake Øyangen. Stable isotope signatures (δ 15N) in comparable organisms (e.g. zooplankton, Arctic char) collected from both the lakes were also significantly different. The values of δ 15N were 6–10‰ higher in the organisms from Ellasjøen than from Øyangen. In both Ellasjøen and Øyangen, a statistically significant correlation ( P<0.05) was found between the levels of PCB and DDT, and δ 15N values in organisms indicating enhanced bioaccumulation for higher trophical level lake organisms. As the lakes on Bjørnøya are remote, more than 500 km from any known point source, the presence of POPs is most likely the result of long-range transport of contaminants to the area. The observed higher contaminant concentrations associated with the Ellasjøen ecosystem is attributed to two factors. Ellasjøen is located in the southern, mountainous part of Bjørnøya and it is likely that this area receives more precipitation, and thereby more airborne contaminants, than the flatter areas further north on the island (i.e. the area around Øyangen). In addition, higher δ 15N-levels in organisms from Ellasjøen as compared to Øyangen indicate the input of guano from seabirds using the lake as a resting area as an additional source of POPs to Ellasjøen.