Glacier mice as a temporary sink for fallout radionuclides and heavy metals on the Norwegian glacier Austerdalsbreen.

Glacier mice are peculiar rolling or stationary moss balls found on the surface of some glaciers. They may harbour an ecological habitat for cold-adapted invertebrates and microorganisms, but little is known about their potential to accumulate and disseminate harmful elements and substances. In this study, we investigate the presence of fallout radionuclides (Cs, Pu, Pu, Pu, Pb) and heavy metals (Pb, As, Hg, Cd) in glacier mice and compare the results to bryophytes from adjacent glacier ecosystems. Samples were collected at Austerdalsbreen, a Norwegian outlet glacier from Jostedalsbreen ice cap. Maximum activity concentrations for bryophytes are 552 ± 12 Bq kg for Cs, 3485 ± 138 Bq kg for Pb, 0.0223 ± 0.065 Bq kg for Pu and 4.34 ± 0.43 Bq kg for Pu while maximum heavy metals concentrations are 70.5 mg kg for Pb, 1.0 mg kg for As, 1.6 mg kg for Hg and 0.13 mg kg for Cd. Maximum activity concentrations in cryconite are 1973.4 ± 5.0 Bq kg for Cs, 3632 ± 593 Bq kg for Pb, 0.51 ± 0.11 Bq kg for Pu and 13.1 ± 1.4 Bq kg for Pu and maximum heavy metal concentrations are 50.4 mg kg for Pb, 3.4 mg kg for As, 1.5 mg kg for Hg and 0.082 mg kg for Cd. We find that glacier mice show lower activity concentrations of radionuclides compared to cryoconite. The major source of plutonium isotopes is related to global fallout, whereas detected radio-cesium may be additionally affected by post-Chernobyl fallout to an unknown extent. Comparison between glacier surface and adjacent glacial habitats shows higher concentrations of heavy metals in glacier mice on the glacier ice surface and medial moraines compared to bryophytes in the glacier forefield. Glacier mice exported from a receding glacier may affect the cycling of radioactive and metal pollutants in developing proglacial ecosystems.