Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition
Widespread declines in mercury (Hg) in fish in pristine lakes in Fennoscandia since the 1970s are unexplained. Interactions between climate, atmospheric deposition, and elemental cycling of carbon (C), sulphur (S) and Hg are complex and affect Hg bioaccumulation. A parallel significant decline in me...
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ftnorskinstvf:oai:niva.brage.unit.no:11250/2673997 2023-05-15T16:11:38+02:00 Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition Braaten, Hans Fredrik Veiteberg Lindholm, Markus de Wit, Heleen 2020 application/pdf https://hdl.handle.net/11250/2673997 https://doi.org/10.1016/j.scitotenv.2020.136774 eng eng Elsevier Norges forskningsråd: 243644 Science of the Total Environment. 2020, 714, 136774. urn:issn:0048-9697 https://hdl.handle.net/11250/2673997 https://doi.org/10.1016/j.scitotenv.2020.136774 cristin:1819529 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no CC-BY 10 714 Science of the Total Environment Peer reviewed Journal article 2020 ftnorskinstvf https://doi.org/10.1016/j.scitotenv.2020.136774 2023-02-21T08:46:10Z Widespread declines in mercury (Hg) in fish in pristine lakes in Fennoscandia since the 1970s are unexplained. Interactions between climate, atmospheric deposition, and elemental cycling of carbon (C), sulphur (S) and Hg are complex and affect Hg bioaccumulation. A parallel significant decline in methyl-Hg (MeHg) concentrations in aquatic macroinvertebrates (Chironomidae) was found between 1976–78 and 2004–15 in an intensely studied, pristine boreal lake (Langtjern, boreal Fennoscandia). Monitoring at Langtjern demonstrated a four-fold decrease in aqueous sulphate concentrations (SO4, 50-year record), significant lake browning (30-year records), increasing sediment Hg concentrations (50-year record), warming (45-year record) and increased runoff (40-year record). Contrasting Hg trends in biota (downward) and sediment (upward) indicated a disconnect between lake Hg loading and foodweb Hg bioaccumulation. We suggest that reduced SO4-deposition has 1) constrained substrate availability for SO4-reducing methylating bacteria (causing reduced foodweb MeHg exposure despite increased Hg loading to the lake), and 2), increased the binding affinity between aqueous organic matter and Hg species (leading to reduced MeHg bioavailability). The downward MeHg trend at the base of the foodweb at Langtjern is mirrored at higher trophic levels by strong declines in perch (Perca fluviatilis) and pike (Esox lucius) Hg concentrations in boreal Fennoscandia. A plausible explanation is that declining SO4-deposition, rather than climate change or reduced atmospheric Hg, is currently driving reduced MeHg contamination in northern freshwater foodwebs. publishedVersion Article in Journal/Newspaper Fennoscandia Norwegian Institute for Water research: NIVA Open Access Archive (Brage) Boreal Lake ENVELOPE(-127.670,-127.670,58.802,58.802) Browning ENVELOPE(164.050,164.050,-74.617,-74.617) Langtjern ENVELOPE(18.282,18.282,69.396,69.396) Science of The Total Environment 714 136774 |
institution |
Open Polar |
collection |
Norwegian Institute for Water research: NIVA Open Access Archive (Brage) |
op_collection_id |
ftnorskinstvf |
language |
English |
description |
Widespread declines in mercury (Hg) in fish in pristine lakes in Fennoscandia since the 1970s are unexplained. Interactions between climate, atmospheric deposition, and elemental cycling of carbon (C), sulphur (S) and Hg are complex and affect Hg bioaccumulation. A parallel significant decline in methyl-Hg (MeHg) concentrations in aquatic macroinvertebrates (Chironomidae) was found between 1976–78 and 2004–15 in an intensely studied, pristine boreal lake (Langtjern, boreal Fennoscandia). Monitoring at Langtjern demonstrated a four-fold decrease in aqueous sulphate concentrations (SO4, 50-year record), significant lake browning (30-year records), increasing sediment Hg concentrations (50-year record), warming (45-year record) and increased runoff (40-year record). Contrasting Hg trends in biota (downward) and sediment (upward) indicated a disconnect between lake Hg loading and foodweb Hg bioaccumulation. We suggest that reduced SO4-deposition has 1) constrained substrate availability for SO4-reducing methylating bacteria (causing reduced foodweb MeHg exposure despite increased Hg loading to the lake), and 2), increased the binding affinity between aqueous organic matter and Hg species (leading to reduced MeHg bioavailability). The downward MeHg trend at the base of the foodweb at Langtjern is mirrored at higher trophic levels by strong declines in perch (Perca fluviatilis) and pike (Esox lucius) Hg concentrations in boreal Fennoscandia. A plausible explanation is that declining SO4-deposition, rather than climate change or reduced atmospheric Hg, is currently driving reduced MeHg contamination in northern freshwater foodwebs. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Braaten, Hans Fredrik Veiteberg Lindholm, Markus de Wit, Heleen |
spellingShingle |
Braaten, Hans Fredrik Veiteberg Lindholm, Markus de Wit, Heleen Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
author_facet |
Braaten, Hans Fredrik Veiteberg Lindholm, Markus de Wit, Heleen |
author_sort |
Braaten, Hans Fredrik Veiteberg |
title |
Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
title_short |
Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
title_full |
Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
title_fullStr |
Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
title_full_unstemmed |
Five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
title_sort |
five decades of declining methylmercury concentrations in boreal foodwebs suggest pivotal role for sulphate deposition |
publisher |
Elsevier |
publishDate |
2020 |
url |
https://hdl.handle.net/11250/2673997 https://doi.org/10.1016/j.scitotenv.2020.136774 |
long_lat |
ENVELOPE(-127.670,-127.670,58.802,58.802) ENVELOPE(164.050,164.050,-74.617,-74.617) ENVELOPE(18.282,18.282,69.396,69.396) |
geographic |
Boreal Lake Browning Langtjern |
geographic_facet |
Boreal Lake Browning Langtjern |
genre |
Fennoscandia |
genre_facet |
Fennoscandia |
op_source |
10 714 Science of the Total Environment |
op_relation |
Norges forskningsråd: 243644 Science of the Total Environment. 2020, 714, 136774. urn:issn:0048-9697 https://hdl.handle.net/11250/2673997 https://doi.org/10.1016/j.scitotenv.2020.136774 cristin:1819529 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/j.scitotenv.2020.136774 |
container_title |
Science of The Total Environment |
container_volume |
714 |
container_start_page |
136774 |
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1765996787773997056 |