Deep Weathering of Calcareous Sedimentary Rock and the Redistribution of Iron and Manganese in Soil and Saprolite

Phillips, Debra; Ammons, J. T.; Lee, S.Y.; Lietzke, D. A.

doi:10.1097/00010694-199801000-00010

Cited by 12 publications

(8 citation statements)

References 5 publications

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“…The presence of gibbsite is indicative of intense weathering, and gibbsite followed by kaolinite in brittle/soft concretions indicates that weathering reached an extreme stage. This agrees with the findings of Phillips et al (1998) and Islam et al (2002).…”

Section: Micromorphology Of Fe/mn and Their Associated Mineralssupporting

confidence: 93%

Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Arachchi

Tokashiki

Baba

2004

Clays and clay miner.

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Manganese minerals are not common and the distinction of poorly crystalline Mn minerals from other associated minerals is important. For many years, the crystal structures of poorly crystalline Mn minerals in Fe/Mn concretions have been the subject of considerable conjecture and controversy. This study reports the micromorphological and mineralogical characteristics, and the chemical composition of Fe/Mn minerals in soft Fe/Mn concretions formed in Shimajiri Mahji soils (Typic Hapludalfs) that developed from Ryukyu limestone on Okinawa Island, Japan. The Fe/Mn minerals in brittle/soft Fe/Mn concretions were characterized using a sequential selective dissolution procedure (SSDP) by treatments with NaOH, hydroxylamine hydrochloride (HAHC) at 25ºC and 60ºC, and dithionite-citrate-bicarbonate (DCB) in combination with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The HAHC treatment at 25ºC dissolved birnessite, but not lithiophorite and goethite. A subsequent extraction with HAHC at 60ºC dissolved lithiophorite but not goethite. Finally, the DCB treatment was able to dissolve goethite. The SEM images show that birnessite crystals, with a blade-or plate-like habit, form globular aggregates inside veins and cavities. Pseudo-hexagonal crystals of lithiophorite have produced thread-ball structures with crystal shape similar to birnessite and birnessite crystals are closely associated with lithiophorite. Well developed hexagonal plates of gibbsite crystals are clustered in different directions to make foliated vermiform structures. Aggregates of goethite crystals are acicular and are arranged into stars. The supplementary SSDP, in combination with XRD and SEM techniques, provides methods to distinguish and partly quantify birnessite and lithiophorite in the presence of layer silicate and Fe oxide minerals and confirm their own morphological features.

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Section: Micromorphology Of Fe/mn and Their Associated Mineralssupporting

confidence: 93%

Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Arachchi

Tokashiki

Baba

2004

Clays and clay miner.

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“…The ground water at the S‐3 site contained both high Ca 2+ and bicarbonate concentrations because of the presence of CaCO 3 –rich Nolichucky shale bedrock (Phillips et al, 1998) and strong nitric acid leachate from the S‐3 ponds, and from the neutralization of the acid by limestone. Calcium concentrations have remained relatively consistent for the last 15 mo of operation (Gu et al, 2002a).…”

Section: Resultsmentioning

confidence: 99%

Mineralogical Characteristics and Transformations during Long‐Term Operation of a Zerovalent Iron Reactive Barrier

et al. 2003

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Design and operation of Fe0 permeable reactive barriers (PRBs) can be improved by understanding the long-term mineralogical transformations that occur within PRBs. Changes in mineral precipitates, cementation, and corrosion of Fe0 filings within an in situ pilot-scale PRB were examined after the first 30 months of operation and compared with results of a previous study of the PRB conducted 15 months earlier using X-ray diffraction and scanning electron microscopy employing energy dispersive X-ray and backscatter electron analyses. Iron (oxy)hydroxides, aragonite, and maghemite and/or magnetite occurred throughout the cores collected 30 mo after installation. Goethite, lepidocrocite, mackinawite, aragonite, calcite, and siderite were associated with oxidized and cemented areas, while green rusts were detected in more reduced zones. Basic differences from our last detailed investigation include (i) mackinawite crystallized from amorphous FeS, (ii) aragonite transformed into calcite, (iii) akaganeite transformed to goethite and lepidocrocite, (iv) iron (oxy)hydroxides and calcium and iron carbonate minerals increased, (v) cementation was greater in the more recent study, and (vi) oxidation, corrosion, and disintegration of Fe0 filings were greater, especially in cemented areas, in the more recent study. If the degree of corrosion and cementation that was observed from 15 to 30 mo after installation continues, certain portions of the PRB (i.e., up-gradient entrance of the ground water to the Fe0 section of the PRB) may last less than five more years, thus reducing the effectiveness of the PRB to mitigate contaminants.

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“…Soils and saprolite from the Oak Ridge site in eastern Tennessee (where the FRC composite sediment was obtained) are known to contain abundant Mn(III/IV) oxides resulting from the weathering of micas, carbonates, and shale. These phases are disseminated in many circumstances and have defied mineralogic identification by X-ray diffraction and other such techniques, implying amorphous or microcrystalline character (Lee et al, 1990;Phillips et al, 1998;Phillips et al, 1997).…”

Section: Abiotic Tco 4 Reduction Is Facilitated By Biogenic Fe(ii)mentioning

confidence: 99%

Reduction of TcO4− by sediment-associated biogenic Fe(II)

Fredrickson

Zachara

Kennedy

et al. 2004

Geochimica et Cosmochimica Acta

189

205

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The potential for reduction of 99 TcO 4 Ϫ (aq) to poorly soluble 99 TcO 2 · nH 2 O (s) by biogenic sediment-associated Fe(II) was investigated with three Fe(III)-oxide containing subsurface materials and the dissimilatory metal-reducing subsurface bacterium Shewanella putrefaciens CN32. Two of the subsurface materials from the U.S. Department of Energy's Hanford and Oak Ridge sites contained significant amounts of Mn(III,IV) oxides and net bioreduction of Fe(III) to Fe(II) was not observed until essentially all of the hydroxylamine HCl-extractable Mn was reduced. In anoxic, unreduced sediment or where Mn oxide bioreduction was incomplete, exogenous biogenic TcO 2 · nH 2 O (s) was slowly oxidized over a period of weeks. Subsurface materials that were bioreduced to varying degrees and then pasteurized to eliminate biological activity, reduced TcO 4 Ϫ (aq) at rates that generally increased with increasing concentrations of 0.5 N HClextractable Fe(II). Two of the sediments showed a common relationship between extractable Fe(II) concentration (in mM) and the first-order reduction rate (in h Ϫ1 ), whereas the third demonstrated a markedly different trend. A combination of chemical extractions and 57 Fe Mössbauer spectroscopy were used to characterize the Fe(III) and Fe(II) phases. There was little evidence of the formation of secondary Fe(II) biominerals as a result of bioreduction, suggesting that the reactive forms of Fe(II) were predominantly surface complexes of different forms. The reduction rates of Tc(VII)O 4Ϫ were slowest in the sediment that contained plentiful layer silicates (illite, vermiculite, and smectite), suggesting that Fe(II) sorption complexes on these phases were least reactive toward pertechnetate. These results suggest that the in situ microbial reduction of sedimentassociated Fe(III), either naturally or via redox manipulation, may be effective at immobilizing TcO 4 Ϫ (aq) associated with groundwater contaminant plumes.

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Deep Weathering of Calcareous Sedimentary Rock and the Redistribution of Iron and Manganese in Soil and Saprolite

Cited by 12 publications

References 5 publications

Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Mineralogical Characteristics and Transformations during Long‐Term Operation of a Zerovalent Iron Reactive Barrier

Reduction of TcO4− by sediment-associated biogenic Fe(II)

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