Evidence for the presence of strong Mn(III)-binding ligands in the water column of the Chesapeake Bay

Véronique E. Oldham; Shannon M. Owings; Matthew R. Jones; Bradley M. Tebo; George W. Luther

doi:10.1016/j.marchem.2015.02.008

Evidence for the presence of strong Mn(III)-binding ligands in the water column of the Chesapeake Bay

Véronique E. Oldham, Shannon M. Owings, Matthew R. Jones, Bradley M. Tebo, George W. Luther

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

73 Scopus citations

Abstract

Soluble manganese speciation was determined in suboxic and anoxic waters of the Chesapeake Bay using a water soluble porphyrin ligand as spectrophotometric reagent. Initial addition of the reagent detected only Mn(II); on addition of 100μM H₂S (excess of the expected total dissolved Mn concentration) an increase in Mn occurred, indicating a reduction of Mn(III). Mn(III) comprised up to 54.21±2.71% of the total dissolved Mn pool. Samples with low H₂S (4.82±0.80μM) had high Mn(III) (6.98±0.63μM) whereas those with high H₂S (38.37±1.70μM) had low Mn(III) (1.12±0.17μM) indicating that Mn(III) is kinetically stabilized in situ by strong ligands so reduction to Mn(II) is not complete. Assays for MnO_x particles showed that these were negligible or not detected except near the oxic-anoxic interface, and Mn(III) depth profiles showed peaks below the oxic-anoxic interface. Sulfidic sediments were not a source of Mn(III) to overlying waters as no Mn(III) was detected in overlying waters. These Mn(III) profiles likely result from the one electron reductive dissolution of solid MnO₂ particles formed at the oxic-anoxic interface, which then fall into the anoxic hydrogen sulfide rich zone. Laboratory experiments with known ligands bound to Mn(III) confirm that Mn(III)-L complexes do not completely react with H₂S as these are concentration dependent reactions under kinetic control.

Original language	English (US)
Pages (from-to)	58-66
Number of pages	9
Journal	Marine Chemistry
Volume	171
DOIs	https://doi.org/10.1016/j.marchem.2015.02.008
State	Published - Apr 1 2015
Externally published	Yes

Keywords

Absorption spectroscopy
Anoxic
Chesapeake Bay
Kinetics
Metal-ligand complexes
MnOx
Soluble manganese(III)
Speciation

ASJC Scopus subject areas

Oceanography
Chemistry(all)
Environmental Chemistry
Water Science and Technology

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10.1016/j.marchem.2015.02.008

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@article{a43fb9cbaabe492e8342bc8ba88464d2,

title = "Evidence for the presence of strong Mn(III)-binding ligands in the water column of the Chesapeake Bay",

abstract = "Soluble manganese speciation was determined in suboxic and anoxic waters of the Chesapeake Bay using a water soluble porphyrin ligand as spectrophotometric reagent. Initial addition of the reagent detected only Mn(II); on addition of 100μM H2S (excess of the expected total dissolved Mn concentration) an increase in Mn occurred, indicating a reduction of Mn(III). Mn(III) comprised up to 54.21±2.71% of the total dissolved Mn pool. Samples with low H2S (4.82±0.80μM) had high Mn(III) (6.98±0.63μM) whereas those with high H2S (38.37±1.70μM) had low Mn(III) (1.12±0.17μM) indicating that Mn(III) is kinetically stabilized in situ by strong ligands so reduction to Mn(II) is not complete. Assays for MnOx particles showed that these were negligible or not detected except near the oxic-anoxic interface, and Mn(III) depth profiles showed peaks below the oxic-anoxic interface. Sulfidic sediments were not a source of Mn(III) to overlying waters as no Mn(III) was detected in overlying waters. These Mn(III) profiles likely result from the one electron reductive dissolution of solid MnO2 particles formed at the oxic-anoxic interface, which then fall into the anoxic hydrogen sulfide rich zone. Laboratory experiments with known ligands bound to Mn(III) confirm that Mn(III)-L complexes do not completely react with H2S as these are concentration dependent reactions under kinetic control.",

keywords = "Absorption spectroscopy, Anoxic, Chesapeake Bay, Kinetics, Metal-ligand complexes, MnOx, Soluble manganese(III), Speciation",

author = "Oldham, {V{\'e}ronique E.} and Owings, {Shannon M.} and Jones, {Matthew R.} and Tebo, {Bradley M.} and Luther, {George W.}",

note = "Funding Information: This work was supported primarily by research grants from the Chemical Oceanography Program of the National Science Foundation ( OCE-1155385 to GWL and OCE-1154357 to BMT) and with partial support from the U.S. National Oceanic and Atmospheric Administration Sea Grant program ( NA14OAR4170087 ). Veronique Oldham thanks the University of Delaware for receipt of a Marian R. Okie Fellowship. Thanks to Alyssa Findlay and Dan MacDonald for the Fe and sulfide analyses. Thanks also to Gabriel Browning, for his technical assistance with UV/Vis analyses, and the crew and staff of the R/V Sharp, who made the sampling for this research possible. Publisher Copyright: {\textcopyright} 2015 Elsevier B.V.",

year = "2015",

month = apr,

day = "1",

doi = "10.1016/j.marchem.2015.02.008",

language = "English (US)",

volume = "171",

pages = "58--66",

journal = "Marine Chemistry",

issn = "0304-4203",

publisher = "Elsevier",

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TY - JOUR

T1 - Evidence for the presence of strong Mn(III)-binding ligands in the water column of the Chesapeake Bay

AU - Oldham, Véronique E.

AU - Owings, Shannon M.

AU - Jones, Matthew R.

AU - Tebo, Bradley M.

AU - Luther, George W.

N1 - Funding Information: This work was supported primarily by research grants from the Chemical Oceanography Program of the National Science Foundation ( OCE-1155385 to GWL and OCE-1154357 to BMT) and with partial support from the U.S. National Oceanic and Atmospheric Administration Sea Grant program ( NA14OAR4170087 ). Veronique Oldham thanks the University of Delaware for receipt of a Marian R. Okie Fellowship. Thanks to Alyssa Findlay and Dan MacDonald for the Fe and sulfide analyses. Thanks also to Gabriel Browning, for his technical assistance with UV/Vis analyses, and the crew and staff of the R/V Sharp, who made the sampling for this research possible. Publisher Copyright: © 2015 Elsevier B.V.

PY - 2015/4/1

Y1 - 2015/4/1

N2 - Soluble manganese speciation was determined in suboxic and anoxic waters of the Chesapeake Bay using a water soluble porphyrin ligand as spectrophotometric reagent. Initial addition of the reagent detected only Mn(II); on addition of 100μM H2S (excess of the expected total dissolved Mn concentration) an increase in Mn occurred, indicating a reduction of Mn(III). Mn(III) comprised up to 54.21±2.71% of the total dissolved Mn pool. Samples with low H2S (4.82±0.80μM) had high Mn(III) (6.98±0.63μM) whereas those with high H2S (38.37±1.70μM) had low Mn(III) (1.12±0.17μM) indicating that Mn(III) is kinetically stabilized in situ by strong ligands so reduction to Mn(II) is not complete. Assays for MnOx particles showed that these were negligible or not detected except near the oxic-anoxic interface, and Mn(III) depth profiles showed peaks below the oxic-anoxic interface. Sulfidic sediments were not a source of Mn(III) to overlying waters as no Mn(III) was detected in overlying waters. These Mn(III) profiles likely result from the one electron reductive dissolution of solid MnO2 particles formed at the oxic-anoxic interface, which then fall into the anoxic hydrogen sulfide rich zone. Laboratory experiments with known ligands bound to Mn(III) confirm that Mn(III)-L complexes do not completely react with H2S as these are concentration dependent reactions under kinetic control.

AB - Soluble manganese speciation was determined in suboxic and anoxic waters of the Chesapeake Bay using a water soluble porphyrin ligand as spectrophotometric reagent. Initial addition of the reagent detected only Mn(II); on addition of 100μM H2S (excess of the expected total dissolved Mn concentration) an increase in Mn occurred, indicating a reduction of Mn(III). Mn(III) comprised up to 54.21±2.71% of the total dissolved Mn pool. Samples with low H2S (4.82±0.80μM) had high Mn(III) (6.98±0.63μM) whereas those with high H2S (38.37±1.70μM) had low Mn(III) (1.12±0.17μM) indicating that Mn(III) is kinetically stabilized in situ by strong ligands so reduction to Mn(II) is not complete. Assays for MnOx particles showed that these were negligible or not detected except near the oxic-anoxic interface, and Mn(III) depth profiles showed peaks below the oxic-anoxic interface. Sulfidic sediments were not a source of Mn(III) to overlying waters as no Mn(III) was detected in overlying waters. These Mn(III) profiles likely result from the one electron reductive dissolution of solid MnO2 particles formed at the oxic-anoxic interface, which then fall into the anoxic hydrogen sulfide rich zone. Laboratory experiments with known ligands bound to Mn(III) confirm that Mn(III)-L complexes do not completely react with H2S as these are concentration dependent reactions under kinetic control.

KW - Absorption spectroscopy

KW - Anoxic

KW - Chesapeake Bay

KW - Kinetics

KW - Metal-ligand complexes

KW - MnOx

KW - Soluble manganese(III)

KW - Speciation

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U2 - 10.1016/j.marchem.2015.02.008

DO - 10.1016/j.marchem.2015.02.008

M3 - Article

AN - SCOPUS:84923278624

SN - 0304-4203

VL - 171

SP - 58

EP - 66

JO - Marine Chemistry

JF - Marine Chemistry

ER -

Evidence for the presence of strong Mn(III)-binding ligands in the water column of the Chesapeake Bay

Abstract

Keywords

ASJC Scopus subject areas

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