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Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories

Publication ,  Journal Article
Richardson, JB; Aguirre, AA; Buss, HL; Toby O'Geen, A; Gu, X; Rempe, DM; Richter, DDB
Published in: Global Biogeochemical Cycles
October 1, 2018

Mercury sequestration in regolith (soils + weathered bedrock) is an important ecosystem service of the critical zone. This has largely remained unexplored, due to the difficulty of sample collection and the assumption that Hg is predominantly sequestered within surface soils (here we define as 0–0.3 m). We measured Hg concentrations and inventories in weathering profiles at six Critical Zone Observatories (CZOs): Boulder Creek in the Front Range of Colorado, Calhoun in the South Carolina Piedmont, Eel River in coastal northern California, Luquillo in the tropical montane forest of Puerto Rico, Shale Hills of the valley and ridges of central Pennsylvania, and Southern Sierra in the Sierra Nevada range of California. Surface soils had higher Hg concentrations than the deepest regolith samples, except for Eel River, which had lower Hg concentrations in surface soils compared to regolith. Using Ti normalization, CZOs with <12% rock-derived Hg (Boulder Creek, Calhoun, and Southern Sierra) had Hg peaks between 1.5 and 8.0 m in depth. At CZOs with >50% rock-derived Hg, Eel River Hg concentrations and pools were greatest at >4.0 m in the weathering profile, while Luquillo and Shale Hills had peaks at the surface that diminished within 1.0 m of the surface. Hg and total organic C were only significantly correlated in regolith at Luquillo and Shale Hills CZOs, suggesting that Hg sorption to organic matter may be less dominant than clays or Fe(II) sulfides in deeper regolith. Our results demonstrate the importance of Hg sequestration in deep regolith, below typical soil sampling depths.

Duke Scholars

Published In

Global Biogeochemical Cycles

DOI

EISSN

1944-9224

ISSN

0886-6236

Publication Date

October 1, 2018

Volume

32

Issue

10

Start / End Page

1542 / 1555

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 4101 Climate change impacts and adaptation
  • 3704 Geoinformatics
  • 3703 Geochemistry
  • 0405 Oceanography
  • 0402 Geochemistry
  • 0401 Atmospheric Sciences
 

Citation

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Richardson, J. B., Aguirre, A. A., Buss, H. L., Toby O’Geen, A., Gu, X., Rempe, D. M., & Richter, D. D. B. (2018). Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories. Global Biogeochemical Cycles, 32(10), 1542–1555. https://doi.org/10.1029/2018GB005974
Richardson, J. B., A. A. Aguirre, H. L. Buss, A. Toby O’Geen, X. Gu, D. M. Rempe, and D. D. B. Richter. “Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories.” Global Biogeochemical Cycles 32, no. 10 (October 1, 2018): 1542–55. https://doi.org/10.1029/2018GB005974.
Richardson JB, Aguirre AA, Buss HL, Toby O’Geen A, Gu X, Rempe DM, et al. Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories. Global Biogeochemical Cycles. 2018 Oct 1;32(10):1542–55.
Richardson, J. B., et al. “Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories.” Global Biogeochemical Cycles, vol. 32, no. 10, Oct. 2018, pp. 1542–55. Scopus, doi:10.1029/2018GB005974.
Richardson JB, Aguirre AA, Buss HL, Toby O’Geen A, Gu X, Rempe DM, Richter DDB. Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories. Global Biogeochemical Cycles. 2018 Oct 1;32(10):1542–1555.
Journal cover image

Published In

Global Biogeochemical Cycles

DOI

EISSN

1944-9224

ISSN

0886-6236

Publication Date

October 1, 2018

Volume

32

Issue

10

Start / End Page

1542 / 1555

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 4101 Climate change impacts and adaptation
  • 3704 Geoinformatics
  • 3703 Geochemistry
  • 0405 Oceanography
  • 0402 Geochemistry
  • 0401 Atmospheric Sciences