Bioaccumulation of radiocaesium in Arctic seals from Northeast Greenland

摘要

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. In 1999 and 2000 seals were captured from the northeast coast of Greenland (75— 80°N) in order to document the levels and bioaccumulation potential of radiocaesium in the high latitude seal species: harp, ringed, and hooded seals. The results are compared with previous studies in order to assess geographic differences in bioaccumulation for Arctic seals. Concentrations of ~(137)Cs were determined in muscle, liver and kidney samples from a total of 25 juvenile and 3 adult seals. The mean concentration in muscle and liver samples for all animals was 0.36 ± 0.14 Bq/kg f.w. and 0.26 ± 0.08 Bq/kg f.w. The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of ~(137)Cs in the Greenland Sea region. Comparing levels in muscle tissue among the different seal species, the ~(137)Cs activity concentration of harp (0.36 ± 0.14 Bq/kg f.w.) and hooded seals (0.37 ± 0.14 Bq/kg f.w.) are similar within uncertainty limits while average concentrations in ringed seals are slightly lower (≤ 0.2 Bq/kg f.w.). Bioconcentration factors (BCFs) for the seals (30-110) correspond well with the variety of prey consumed by seals in this region indicating that diet selection is a dominant factor controlling bioaccumulation of radiocaesium in these Arctic seals.