Distribution and speciation of trace elements in iron and manganese oxide cave deposits

Journal Article · Wed Oct 24 04:00:00 EDT 2012 · Geochim. Cosmochim. Acta

DOI:https://doi.org/10.1016/j.gca.2012.05.032· OSTI ID:1046850

Frierdich, Andrew J; Catalano, Jeffrey G ^[1]

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1. WU

Fe and Mn oxide minerals control the distribution and speciation of heavy metals and trace elements in soils and aquatic systems through chemical mechanisms involving adsorption, incorporation, and electron transfer. The Pautler Cave System in Southwest Illinois, an analog to other temperate carbonate-hosted karst systems, contains Fe and Mn oxide minerals that form in multiple depositional environments and have high concentrations of associated trace elements. Synchrotron-based micro-scanning X-ray fluorescence ({mu}-SXRF) shows unique spatial distributions of Fe, Mn, and trace elements in mineral samples. Profile maps of Mn oxide cave stream pebble coatings show Fe- and As-rich laminations, indicating dynamic redox conditions in the cave stream. {mu}-SXRF maps demonstrate that Ni, Cu, and Zn correlate primarily with Mn whereas As correlates with both Mn and Fe; As is more enriched in the Fe phase. Zn is concentrated in the periphery of Mn oxide stream pebble coatings, and may be an indication of recent anthropogenic surface activity. X-ray absorption fine structure spectroscopy measurements reveal that As(V) occurs as surface complexes on Mn and Fe oxides whereas Zn(II) associated with Mn oxides is adsorbed to the basal planes of phyllomanganates in a tetrahedral coordination. Co(III) and Se(IV) are also observed to be associated with Mn oxides. The observation of Fe, Mn, and trace element banding in Mn oxide cave stream pebble coatings suggests that these materials are sensitive to and document aqueous redox conditions, similar to ferromanganese nodules in soils and in marine and freshwater sediments. Furthermore, speciation and distribution measurements indicate that these minerals scavenge trace elements and limit the transport of micronutrients and contaminants in karst aquifer systems while also potentially recording changes in anthropogenic surface activity and land-use.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: OTHERNSF
• OSTI ID: 1046850
• Journal Information: Geochim. Cosmochim. Acta, Journal Name: Geochim. Cosmochim. Acta Journal Issue: 08, 2012 Vol. 91; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABSORPTION
ADSORPTION
AQUIFERS
COATINGS
DISTRIBUTION
ELECTRON TRANSFER
ELEMENTS
FINE STRUCTURE
FLUORESCENCE
HEAVY METALS
IRON
LAND USE
MANGANESE OXIDES
OXIDE MINERALS
OXIDES
SEDIMENTS
SOILS
SPATIAL DISTRIBUTION
SPECTROSCOPY
TRACE AMOUNTS