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

dc.contributor.author

Richardson, JB

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Aguirre, AA

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Buss, HL

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Toby O'Geen, A

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Gu, X

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Rempe, DM

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Richter, DDB

dc.date.accessioned

2020-08-01T15:49:13Z

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2020-08-01T15:49:13Z

dc.date.issued

2018-10-01

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2020-08-01T15:49:11Z

dc.description.abstract

©2018. American Geophysical Union. All Rights Reserved. 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.

dc.identifier.issn

0886-6236

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1944-9224

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https://hdl.handle.net/10161/21236

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en

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American Geophysical Union (AGU)

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Global Biogeochemical Cycles

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10.1029/2018GB005974

dc.subject

Science & Technology

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Life Sciences & Biomedicine

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Physical Sciences

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Environmental Sciences

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Geosciences, Multidisciplinary

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Meteorology & Atmospheric Sciences

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Environmental Sciences & Ecology

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Geology

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soil

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regolith

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mercury cycling

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excess mercury

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mercury inventories

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critical zone

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NORTHERN NEW-ENGLAND

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FOREST SOILS

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LUQUILLO MOUNTAINS

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CHEMICAL FORM

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PUERTO-RICO

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LONG-TERM

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METHYLMERCURY

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DEPOSITION

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WATER

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GEOCHEMISTRY

dc.title

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

dc.type

Journal article

pubs.begin-page

1542

pubs.end-page

1555

pubs.issue

10

pubs.organisational-group

Nicholas School of the Environment

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Environmental Sciences and Policy

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Duke

pubs.publication-status

Published

pubs.volume

32

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