TY - JOUR
T1 - Spectroscopic (XANES/XRF) characterization of contaminant manganese cycling in a temperate watershed
AU - Herndon, Elizabeth M.
AU - Martínez, Carmen E.
AU - Brantley, Susan L.
N1 - Funding Information:
Acknowledgments This study was supported by National Science Foundation grant EAR #1052614 to SLB, the NSF
Funding Information:
Susquehanna Shale Hills Critical Zone Observatory grant EAR #0725019 to C. Duffy (Penn State), and NSF grant CHE #0431328 to SLB. The authors particularly acknowledge the help of Matthew Newville (GSECARS) and Dale Brewe (PNC/ XSD) at APS and Timothy Fischer for scientific support at the beamlines, and Katie Gaines, Jim Savage, and Jane Wubbels for leaf collection at SSHCZO. Portions of this work (µXRF and µXANES) were performed at GeoSoilEnviroCARS (Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the NSF—Earth Sciences (EAR-1128799) and DOE—Geosciences (DE-FG02-94ER14466). Use of the APS was supported by the U. S. Department of Energy Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Other portions of this work (bulk XANES) were performed at PNC/XSD facilities. PNC/XSD facilities at the APS, and research at these facilities, are supported by the US DOE—Basic Energy Sciences, a Major Resources Support grant from NSERC, the University of Washington, Simon Fraser University and the Advanced Photon Source. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. DOE Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.
Publisher Copyright:
© 2014, Springer International Publishing Switzerland.
PY - 2014/11/19
Y1 - 2014/11/19
N2 - Many soils around the globe are contaminated with metals due to inputs from anthropogenic activities; however, the long-term processes that retain these metals in soils or flush them into river systems remain unclear. Soils at the Susquehanna/Shale Hills Critical Zone Observatory, a headwater catchment in central Pennsylvania, USA, are enriched in manganese due to past atmospheric deposition from industrial sources. To investigate how Mn is retained in the catchment, we evaluated the spatial distribution and speciation of Mn in the soil–plant system using X-ray fluorescence and X-ray Absorption Near Edge Structure spectroscopies. Weathered soils near the land surface were enriched in both amorphous and crystalline Mn(III/IV)-oxides, presumably derived from biogenic precipitation and atmospheric deposition, respectively. In contrast, mineral soils near the soil–bedrock interface contained Mn(II) in clays and crystalline Mn(III/IV)-oxides that formed as Mn(II) was leached from the parent shale and oxidized. Roots, stems, and foliar tissue were dominated by organic-bound and aqueous Mn(II); however, a small portion of foliar Mn was concentrated as organic-bound Mn(III) in dark spots that denote Mn toxicity. During decomposition of leaves and roots, soluble Mn(II) stored in vegetation was rapidly oxidized and immobilized as mixed-valence Mn-oxides. We propose that considerable uptake of Mn by certain plant species combined with rapid oxidation of Mn during organic matter decomposition contributes to long-term retention in soils and may slow removal of Mn contamination from watersheds.
AB - Many soils around the globe are contaminated with metals due to inputs from anthropogenic activities; however, the long-term processes that retain these metals in soils or flush them into river systems remain unclear. Soils at the Susquehanna/Shale Hills Critical Zone Observatory, a headwater catchment in central Pennsylvania, USA, are enriched in manganese due to past atmospheric deposition from industrial sources. To investigate how Mn is retained in the catchment, we evaluated the spatial distribution and speciation of Mn in the soil–plant system using X-ray fluorescence and X-ray Absorption Near Edge Structure spectroscopies. Weathered soils near the land surface were enriched in both amorphous and crystalline Mn(III/IV)-oxides, presumably derived from biogenic precipitation and atmospheric deposition, respectively. In contrast, mineral soils near the soil–bedrock interface contained Mn(II) in clays and crystalline Mn(III/IV)-oxides that formed as Mn(II) was leached from the parent shale and oxidized. Roots, stems, and foliar tissue were dominated by organic-bound and aqueous Mn(II); however, a small portion of foliar Mn was concentrated as organic-bound Mn(III) in dark spots that denote Mn toxicity. During decomposition of leaves and roots, soluble Mn(II) stored in vegetation was rapidly oxidized and immobilized as mixed-valence Mn-oxides. We propose that considerable uptake of Mn by certain plant species combined with rapid oxidation of Mn during organic matter decomposition contributes to long-term retention in soils and may slow removal of Mn contamination from watersheds.
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U2 - 10.1007/s10533-014-0018-7
DO - 10.1007/s10533-014-0018-7
M3 - Article
AN - SCOPUS:84911806544
VL - 121
SP - 505
EP - 517
JO - Biogeochemistry
JF - Biogeochemistry
SN - 0168-2563
IS - 3
ER -