Global variability and controls on the accumulation of fallout radionuclides in cryoconite

Caroline C. Clason; Giovanni Baccolo; Edyta Łokas; Philip N. Owens; Przemyslaw Wachniew; Geoff E. Millward; Alex Taylor; Will H. Blake; Dylan B. Beard; Ewa Poniecka; Nick Selmes; Elizabeth A. Bagshaw; Joseph Cook; Ralph Fyfe; Melanie Hay; Deborah Land; Nozomu Takeuchi; Massimiliano Nastasi; Monica Sisti; Francesca Pittino; Andrea Franzetti; Roberto Ambrosini; Biagio Di Mauro

doi:10.1016/j.scitotenv.2023.164902

Global variability and controls on the accumulation of fallout radionuclides in cryoconite

Caroline C. Clason^*, Giovanni Baccolo, Edyta Łokas, Philip N. Owens, Przemyslaw Wachniew, Geoff E. Millward, Alex Taylor, Will H. Blake, Dylan B. Beard, Ewa Poniecka, Nick Selmes, Elizabeth A. Bagshaw, Joseph Cook, Ralph Fyfe, Melanie Hay, Deborah Land, Nozomu Takeuchi, Massimiliano Nastasi, Monica Sisti, Francesca PittinoAndrea Franzetti, Roberto Ambrosini, Biagio Di Mauro

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

13 Citations (Scopus)

Abstract

The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically ¹³⁷Cs, ²⁴¹Am and ²¹⁰Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg⁻¹. These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability.

Original language	English
Article number	164902
Journal	Science of The Total Environment
Volume	894
Early online date	19 Jun 2023
DOIs	https://doi.org/10.1016/j.scitotenv.2023.164902
Publication status	Published - 10 Oct 2023

Bibliographical note

Funding Information:
Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia . Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057 .

Funding Information:
Analysis of FRNs, supported by analytical quality assurance, was carried out by gamma spectrometry in three laboratories in Europe (University Milano-Bicocca, Italy; Institute of Nuclear Physics PAS, Poland; University of Plymouth, UK) and one in Canada (University of Manitoba, Canada). Table A3 provides further information on the analytical capabilities and quality assurance for these facilities. Gamma analysis using a well detector requires the dried cryoconite samples to be packed and sealed in 4 ml plastic/polypropylene vials, and the quantity of material for each of our samples varied between 0.5 g and 22 g. The sealed samples were incubated for a minimum of 24 days to allow establishment of radioactive equilibrium with 222Rn and its progenies, prior to counting. Activity concentrations were determined using different detectors with a counting time of at least 24 h (up to 72 h for samples with lower weights). The isotopes 210Pb (t½ = 22.3 years), 241Am (t½ = 432 years), and 137Cs (t½ = 30.1 years) were determined by their gamma emissions at 46.52, 59.54, and 661.6 keV, respectively, for the majority of samples, with 241Am in some samples from Svalbard, the Caucasus, and Ecology Glacier, Antarctica analysed by alpha spectrometry (Łokas et al., 2018). The data were verified by inter-laboratory comparisons with soil/sediment and reference materials (IAEA, Vienna, Austria; see Table A4 for exemplar quality assurance data). All values given here are correct to the date of sampling where sampling was conducted between 2015 and the present day, with other values decay-corrected to 2020 to optimise comparison between sites. We acknowledge that use of different detectors and run times introduces uncertainty when making direct comparisons, however the nature of this study and inclusion of previously published data precluded the use of a single, standardised approach. We also acknowledge that there is uncertainty around the extent to which cryoconite will adsorb/absorb and leach radionuclides, but decay-correcting values from prior to 2015 allows us to represent where radioactivity is likely to have decreased over longer timescales. We report 210Pb-ex unless otherwise stated, which is estimated by subtracting 214Pb from total 210Pb (Zaborska et al., 2007).Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia. Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057.

Publisher Copyright:
© 2023 The Authors

Keywords

Contamination
Cryoconite
Environmental quality
Fallout radionuclides
Glaciers
Radiocaesium

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Clason, C. C., Baccolo, G., Łokas, E., Owens, P. N., Wachniew, P., Millward, G. E., Taylor, A., Blake, W. H., Beard, D. B., Poniecka, E., Selmes, N., Bagshaw, E. A., Cook, J., Fyfe, R., Hay, M., Land, D., Takeuchi, N., Nastasi, M., Sisti, M., ... Di Mauro, B. (2023). Global variability and controls on the accumulation of fallout radionuclides in cryoconite. Science of The Total Environment, 894, Article 164902. https://doi.org/10.1016/j.scitotenv.2023.164902

@article{c013c09b1fe6441295ccefb6fb6d7ce1,

title = "Global variability and controls on the accumulation of fallout radionuclides in cryoconite",

abstract = "The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically 137Cs, 241Am and 210Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg−1. These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability.",

keywords = "Contamination, Cryoconite, Environmental quality, Fallout radionuclides, Glaciers, Radiocaesium",

author = "Clason, {Caroline C.} and Giovanni Baccolo and Edyta {\L}okas and Owens, {Philip N.} and Przemyslaw Wachniew and Millward, {Geoff E.} and Alex Taylor and Blake, {Will H.} and Beard, {Dylan B.} and Ewa Poniecka and Nick Selmes and Bagshaw, {Elizabeth A.} and Joseph Cook and Ralph Fyfe and Melanie Hay and Deborah Land and Nozomu Takeuchi and Massimiliano Nastasi and Monica Sisti and Francesca Pittino and Andrea Franzetti and Roberto Ambrosini and {Di Mauro}, Biagio",

note = "Funding Information: Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia . Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057 . Funding Information: Analysis of FRNs, supported by analytical quality assurance, was carried out by gamma spectrometry in three laboratories in Europe (University Milano-Bicocca, Italy; Institute of Nuclear Physics PAS, Poland; University of Plymouth, UK) and one in Canada (University of Manitoba, Canada). Table A3 provides further information on the analytical capabilities and quality assurance for these facilities. Gamma analysis using a well detector requires the dried cryoconite samples to be packed and sealed in 4 ml plastic/polypropylene vials, and the quantity of material for each of our samples varied between 0.5 g and 22 g. The sealed samples were incubated for a minimum of 24 days to allow establishment of radioactive equilibrium with 222Rn and its progenies, prior to counting. Activity concentrations were determined using different detectors with a counting time of at least 24 h (up to 72 h for samples with lower weights). The isotopes 210Pb (t½ = 22.3 years), 241Am (t½ = 432 years), and 137Cs (t½ = 30.1 years) were determined by their gamma emissions at 46.52, 59.54, and 661.6 keV, respectively, for the majority of samples, with 241Am in some samples from Svalbard, the Caucasus, and Ecology Glacier, Antarctica analysed by alpha spectrometry ({\L}okas et al., 2018). The data were verified by inter-laboratory comparisons with soil/sediment and reference materials (IAEA, Vienna, Austria; see Table A4 for exemplar quality assurance data). All values given here are correct to the date of sampling where sampling was conducted between 2015 and the present day, with other values decay-corrected to 2020 to optimise comparison between sites. We acknowledge that use of different detectors and run times introduces uncertainty when making direct comparisons, however the nature of this study and inclusion of previously published data precluded the use of a single, standardised approach. We also acknowledge that there is uncertainty around the extent to which cryoconite will adsorb/absorb and leach radionuclides, but decay-correcting values from prior to 2015 allows us to represent where radioactivity is likely to have decreased over longer timescales. We report 210Pb-ex unless otherwise stated, which is estimated by subtracting 214Pb from total 210Pb (Zaborska et al., 2007).Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia. Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057. Publisher Copyright: {\textcopyright} 2023 The Authors",

year = "2023",

month = oct,

day = "10",

doi = "10.1016/j.scitotenv.2023.164902",

language = "English",

volume = "894",

journal = "Science of The Total Environment",

issn = "0048-9697",

publisher = "Elsevier",

}

Clason, CC, Baccolo, G, Łokas, E, Owens, PN, Wachniew, P, Millward, GE, Taylor, A, Blake, WH, Beard, DB, Poniecka, E, Selmes, N, Bagshaw, EA, Cook, J, Fyfe, R, Hay, M, Land, D, Takeuchi, N, Nastasi, M, Sisti, M, Pittino, F, Franzetti, A, Ambrosini, R & Di Mauro, B 2023, 'Global variability and controls on the accumulation of fallout radionuclides in cryoconite', Science of The Total Environment, vol. 894, 164902. https://doi.org/10.1016/j.scitotenv.2023.164902

TY - JOUR

T1 - Global variability and controls on the accumulation of fallout radionuclides in cryoconite

AU - Clason, Caroline C.

AU - Baccolo, Giovanni

AU - Łokas, Edyta

AU - Owens, Philip N.

AU - Wachniew, Przemyslaw

AU - Millward, Geoff E.

AU - Taylor, Alex

AU - Blake, Will H.

AU - Beard, Dylan B.

AU - Poniecka, Ewa

AU - Selmes, Nick

AU - Bagshaw, Elizabeth A.

AU - Cook, Joseph

AU - Fyfe, Ralph

AU - Hay, Melanie

AU - Land, Deborah

AU - Takeuchi, Nozomu

AU - Nastasi, Massimiliano

AU - Sisti, Monica

AU - Pittino, Francesca

AU - Franzetti, Andrea

AU - Ambrosini, Roberto

AU - Di Mauro, Biagio

N1 - Funding Information: Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia . Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057 . Funding Information: Analysis of FRNs, supported by analytical quality assurance, was carried out by gamma spectrometry in three laboratories in Europe (University Milano-Bicocca, Italy; Institute of Nuclear Physics PAS, Poland; University of Plymouth, UK) and one in Canada (University of Manitoba, Canada). Table A3 provides further information on the analytical capabilities and quality assurance for these facilities. Gamma analysis using a well detector requires the dried cryoconite samples to be packed and sealed in 4 ml plastic/polypropylene vials, and the quantity of material for each of our samples varied between 0.5 g and 22 g. The sealed samples were incubated for a minimum of 24 days to allow establishment of radioactive equilibrium with 222Rn and its progenies, prior to counting. Activity concentrations were determined using different detectors with a counting time of at least 24 h (up to 72 h for samples with lower weights). The isotopes 210Pb (t½ = 22.3 years), 241Am (t½ = 432 years), and 137Cs (t½ = 30.1 years) were determined by their gamma emissions at 46.52, 59.54, and 661.6 keV, respectively, for the majority of samples, with 241Am in some samples from Svalbard, the Caucasus, and Ecology Glacier, Antarctica analysed by alpha spectrometry (Łokas et al., 2018). The data were verified by inter-laboratory comparisons with soil/sediment and reference materials (IAEA, Vienna, Austria; see Table A4 for exemplar quality assurance data). All values given here are correct to the date of sampling where sampling was conducted between 2015 and the present day, with other values decay-corrected to 2020 to optimise comparison between sites. We acknowledge that use of different detectors and run times introduces uncertainty when making direct comparisons, however the nature of this study and inclusion of previously published data precluded the use of a single, standardised approach. We also acknowledge that there is uncertainty around the extent to which cryoconite will adsorb/absorb and leach radionuclides, but decay-correcting values from prior to 2015 allows us to represent where radioactivity is likely to have decreased over longer timescales. We report 210Pb-ex unless otherwise stated, which is estimated by subtracting 214Pb from total 210Pb (Zaborska et al., 2007).Sample collection in Sweden and Iceland was funded by INTERACT Transnational Access and QRA grants awarded to CCC respectively. EP thanks the “Black and Bloom” team who were funded by NERC, and EB thanks the U.S. National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Program at Taylor Valley, Antarctica for field assistance. We thank the British Exploring Society for collecting samples in Ladakh on our behalf, Alexandre Anesio for providing samples from Sweden to EP, and Krzysztof Zawierucha for providing data from Norway and Svalbard. PNO acknowledges financial support from the Natural Sciences and Engineering Research Council of Canada and Forest Renewal British Columbia. Samples from Andean glaciers were collected under permission N. 019/2018 issued by CONAF (Chile), and analyses for Alaska, Norway, and the Chilean Andes were supported by the National Science Centre grant no. 2018/31/B/ST10/03057. Publisher Copyright: © 2023 The Authors

PY - 2023/10/10

Y1 - 2023/10/10

N2 - The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically 137Cs, 241Am and 210Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg−1. These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability.

AB - The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically 137Cs, 241Am and 210Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg−1. These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability.

KW - Contamination

KW - Cryoconite

KW - Environmental quality

KW - Fallout radionuclides

KW - Glaciers

KW - Radiocaesium

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U2 - 10.1016/j.scitotenv.2023.164902

DO - 10.1016/j.scitotenv.2023.164902

M3 - Article (Academic Journal)

C2 - 37343877

AN - SCOPUS:85162199275

SN - 0048-9697

VL - 894

JO - Science of The Total Environment

JF - Science of The Total Environment

M1 - 164902

ER -

Global variability and controls on the accumulation of fallout radionuclides in cryoconite

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