Mercury deposition and redox transformation processes in peatland constrained by mercury stable isotopes

Chuxian Li; Martin Jiskra; Mats B.  Nilsson; Stefan  Osterwalder; Wei Zhu; Dimitri Mauquoy; Ulf  Skyllberg; Maxime Enrico; Haijun  Pen; Yu Song; Erik  Björn; Kevin H. Bishop

doi:10.1038/s41467-023-43164-8

Mercury deposition and redox transformation processes in peatland constrained by mercury stable isotopes

Chuxian Li^* (Corresponding Author), Martin Jiskra, Mats B. Nilsson, Stefan Osterwalder, Wei Zhu, Dimitri Mauquoy^* (Corresponding Author), Ulf Skyllberg, Maxime Enrico, Haijun Pen, Yu Song, Erik Björn, Kevin H. Bishop

^*Corresponding author for this work

Geography & Environment

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

Peatland vegetation takes up mercury (Hg) from the atmosphere, typically contributing to net production and export of neurotoxic methyl-Hg to downstream ecosystems. Chemical reduction processes can slow down methyl-Hg production by releasing Hg from peat back to the atmosphere. The extent of these processes remains, however, unclear. Here we present results from a comprehensive study covering concentrations and isotopic signatures of Hg in an open boreal peatland system to identify post-depositional Hg redox transformation processes. Isotope mass balances suggest photoreduction of HgII is the predominant process by which 30% of annually deposited Hg is emitted back to the atmosphere. Isotopic analyses indicate that above the water table, dark abiotic oxidation decreases peat soil gaseous Hg0 concentrations. Below the water table, supersaturation of gaseous Hg is likely created more by direct photoreduction of rainfall rather than by reduction and release of Hg from the peat soil. Identification and quantification of these light-driven and dark redox processes advance our understanding of the fate of Hg in peatlands, including the potential for mobilization and methylation of HgII.

Original language	English
Article number	7389
Number of pages	12
Journal	Nature Communications
Volume	14
Early online date	15 Nov 2023
DOIs	https://doi.org/10.1038/s41467-023-43164-8
Publication status	Published - 23 Nov 2023

Bibliographical note

Acknowledgements
This study is supported by a Swedish Science Foundation grant to K.B. (Dnr2018-04695) and a Swiss National Science Foundation Ambizione grant to M.J. (No. PZ00P2_174101). We acknowledge ICOS Sweden and SITES for the provisioning of facilities, experimental support, and data. ICOS Sweden and SITES are funded by the Swedish Research Council as a national research infrastructure. We are grateful to Richard Bindler for his support with field equipment. We would like to thank Pernilla Löfvenius, Jacob Smeds, Xiangwen Zhang, Per Marklund, Rowan Messmer, Johan Westin, Paul Smith, Jutta Holst, Lamia Atouil, Matéo Wodiczko, Myriam Bupto, and Matthias Peichl for assistance in the field and/or data collection. A special thanks to Julie Brochet and Eloi Mathis for their great help with > 2000L peat water collection during the summer of 2021. We thank Manuela Fehr for her support with Hg stable isotope measurements at ETH Zurich, Switzerland. We are grateful to Chenyan Ma and the staff at Beamline 4B7A, BSRF for their assistance with the sulfur K-edge XANES spectroscopy measurements.

Funding
Open access funding provided by Swedish University of Agricultural Sciences.

Data Availability Statement

Data availability
Data generated in this study are provided in both the Source Data files and the Supplementary Information. Source data are provided in this paper.

Supplementary information
The online version contains supplementary material available at https://doi.org/10.1038/s41467-023-43164-8.

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Cite this

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title = "Mercury deposition and redox transformation processes in peatland constrained by mercury stable isotopes",

abstract = "Peatland vegetation takes up mercury (Hg) from the atmosphere, typically contributing to net production and export of neurotoxic methyl-Hg to downstream ecosystems. Chemical reduction processes can slow down methyl-Hg production by releasing Hg from peat back to the atmosphere. The extent of these processes remains, however, unclear. Here we present results from a comprehensive study covering concentrations and isotopic signatures of Hg in an open boreal peatland system to identify post-depositional Hg redox transformation processes. Isotope mass balances suggest photoreduction of HgII is the predominant process by which 30% of annually deposited Hg is emitted back to the atmosphere. Isotopic analyses indicate that above the water table, dark abiotic oxidation decreases peat soil gaseous Hg0 concentrations. Below the water table, supersaturation of gaseous Hg is likely created more by direct photoreduction of rainfall rather than by reduction and release of Hg from the peat soil. Identification and quantification of these light-driven and dark redox processes advance our understanding of the fate of Hg in peatlands, including the potential for mobilization and methylation of HgII.",

author = "Chuxian Li and Martin Jiskra and Nilsson, {Mats B.} and Stefan Osterwalder and Wei Zhu and Dimitri Mauquoy and Ulf Skyllberg and Maxime Enrico and Haijun Pen and Yu Song and Erik Bj{\"o}rn and Bishop, {Kevin H.}",

note = "Acknowledgements This study is supported by a Swedish Science Foundation grant to K.B. (Dnr2018-04695) and a Swiss National Science Foundation Ambizione grant to M.J. (No. PZ00P2_174101). We acknowledge ICOS Sweden and SITES for the provisioning of facilities, experimental support, and data. ICOS Sweden and SITES are funded by the Swedish Research Council as a national research infrastructure. We are grateful to Richard Bindler for his support with field equipment. We would like to thank Pernilla L{\"o}fvenius, Jacob Smeds, Xiangwen Zhang, Per Marklund, Rowan Messmer, Johan Westin, Paul Smith, Jutta Holst, Lamia Atouil, Mat{\'e}o Wodiczko, Myriam Bupto, and Matthias Peichl for assistance in the field and/or data collection. A special thanks to Julie Brochet and Eloi Mathis for their great help with > 2000L peat water collection during the summer of 2021. We thank Manuela Fehr for her support with Hg stable isotope measurements at ETH Zurich, Switzerland. We are grateful to Chenyan Ma and the staff at Beamline 4B7A, BSRF for their assistance with the sulfur K-edge XANES spectroscopy measurements. Funding Open access funding provided by Swedish University of Agricultural Sciences.",

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doi = "10.1038/s41467-023-43164-8",

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volume = "14",

journal = "Nature Communications",

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T1 - Mercury deposition and redox transformation processes in peatland constrained by mercury stable isotopes

AU - Li, Chuxian

AU - Jiskra, Martin

AU - Nilsson, Mats B.

AU - Osterwalder, Stefan

AU - Zhu, Wei

AU - Mauquoy, Dimitri

AU - Skyllberg, Ulf

AU - Enrico, Maxime

AU - Pen, Haijun

AU - Song, Yu

AU - Björn, Erik

AU - Bishop, Kevin H.

N1 - Acknowledgements This study is supported by a Swedish Science Foundation grant to K.B. (Dnr2018-04695) and a Swiss National Science Foundation Ambizione grant to M.J. (No. PZ00P2_174101). We acknowledge ICOS Sweden and SITES for the provisioning of facilities, experimental support, and data. ICOS Sweden and SITES are funded by the Swedish Research Council as a national research infrastructure. We are grateful to Richard Bindler for his support with field equipment. We would like to thank Pernilla Löfvenius, Jacob Smeds, Xiangwen Zhang, Per Marklund, Rowan Messmer, Johan Westin, Paul Smith, Jutta Holst, Lamia Atouil, Matéo Wodiczko, Myriam Bupto, and Matthias Peichl for assistance in the field and/or data collection. A special thanks to Julie Brochet and Eloi Mathis for their great help with > 2000L peat water collection during the summer of 2021. We thank Manuela Fehr for her support with Hg stable isotope measurements at ETH Zurich, Switzerland. We are grateful to Chenyan Ma and the staff at Beamline 4B7A, BSRF for their assistance with the sulfur K-edge XANES spectroscopy measurements. Funding Open access funding provided by Swedish University of Agricultural Sciences.

PY - 2023/11/23

Y1 - 2023/11/23

N2 - Peatland vegetation takes up mercury (Hg) from the atmosphere, typically contributing to net production and export of neurotoxic methyl-Hg to downstream ecosystems. Chemical reduction processes can slow down methyl-Hg production by releasing Hg from peat back to the atmosphere. The extent of these processes remains, however, unclear. Here we present results from a comprehensive study covering concentrations and isotopic signatures of Hg in an open boreal peatland system to identify post-depositional Hg redox transformation processes. Isotope mass balances suggest photoreduction of HgII is the predominant process by which 30% of annually deposited Hg is emitted back to the atmosphere. Isotopic analyses indicate that above the water table, dark abiotic oxidation decreases peat soil gaseous Hg0 concentrations. Below the water table, supersaturation of gaseous Hg is likely created more by direct photoreduction of rainfall rather than by reduction and release of Hg from the peat soil. Identification and quantification of these light-driven and dark redox processes advance our understanding of the fate of Hg in peatlands, including the potential for mobilization and methylation of HgII.

AB - Peatland vegetation takes up mercury (Hg) from the atmosphere, typically contributing to net production and export of neurotoxic methyl-Hg to downstream ecosystems. Chemical reduction processes can slow down methyl-Hg production by releasing Hg from peat back to the atmosphere. The extent of these processes remains, however, unclear. Here we present results from a comprehensive study covering concentrations and isotopic signatures of Hg in an open boreal peatland system to identify post-depositional Hg redox transformation processes. Isotope mass balances suggest photoreduction of HgII is the predominant process by which 30% of annually deposited Hg is emitted back to the atmosphere. Isotopic analyses indicate that above the water table, dark abiotic oxidation decreases peat soil gaseous Hg0 concentrations. Below the water table, supersaturation of gaseous Hg is likely created more by direct photoreduction of rainfall rather than by reduction and release of Hg from the peat soil. Identification and quantification of these light-driven and dark redox processes advance our understanding of the fate of Hg in peatlands, including the potential for mobilization and methylation of HgII.

U2 - 10.1038/s41467-023-43164-8

DO - 10.1038/s41467-023-43164-8

M3 - Article

SN - 2041-1723

VL - 14

JO - Nature Communications

JF - Nature Communications

M1 - 7389

ER -

Mercury deposition and redox transformation processes in peatland constrained by mercury stable isotopes

Abstract

Bibliographical note

Data Availability Statement

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