The Occurrence of Lepidocrocite in Two Well-Drained Ontario Soils

Tarzi, J. G.; Protz, R.

doi:10.1346/ccmn.1978.0260609

Cited by 16 publications

(7 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…soil. However, in the < 4 µm size fraction of the albic horizon, the LCF results indicate the presence of lepidocrocite, which may be trapped by phyllosilicates as previously observed by Peacock (1942) and Tarzi and Protz (1978). The XANES analysis performed on the < 4 µm fraction can therefore be used to identify lepidocrocite in response to the strong phyllosilicate contribution.…”

Section: Accepted Manuscriptsupporting

confidence: 78%

“…No peak at 6.23 Å corresponding to lepidocrocite (e.g. Tarzi and Protz, 1978;Ross et al, 1979) is observed. However, in this studied wetland, Guénet et al (2016) demonstrated that Fe is present as nano-lepidocrocite, small Fe clusters and Fe monomers bound to OM in response to a slow oxidation kinetic and to the presence of a large amount of OM.…”

Section: Accepted Manuscriptmentioning

confidence: 95%

See 1 more Smart Citation

Iron speciation at the riverbank surface in wetland and potential impact on the mobility of trace metals

Ratié

Vantelon

Lotfi-Kalahroodi

et al. 2019

Science of The Total Environment

View full text Add to dashboard Cite

Fe oxyhydroxides in riverbanks and their high binding capacity can be used to hypothesize that riverbanks may act as a "biogeochemical filter" between wetlands and rivers and may constitute a major mechanism in the trapping and flux regulation of chemical elements. Until now, the properties of Fe minerals have been very poorly described in riverbanks. The goals of the present work are to identify Fe speciation in riverbanks where ferric deposits are observed and to determine their impact on the metal behavior (As, Co, Cu, Ni, Pb, Zn, etc.). At the surface, Fe speciation is mainly composed of small poorly crystalline Fe phases, i.e. ferrihydrite (~30%), Fe-OM associations (~40%) as well as crystalline Fe phases, i.e. goethite (~35%). At the subsurface, the Fe distribution is dominated by goethite (~35%) and Fe-mica (~35%), the proportion of which increases at the expense of ferrihydrite and the Fe-OM associations. At the riverbank surface, ferrihydrite and the Fe-OM associations are therefore the main Fe hosting phases in response to (i) the fast Fe(II) oxidation induced by the presence of O and (ii) the high amount of OM favoring the formation of nano-phases bound to OM (Fe monomers, polymers and nanoparticles) and preventing mineralogical transformation (ferrihydrite into goethite). During the high-water level period (high flow), a strong erosion of the riverbank transfers these ferric deposits into the river. However, the physicochemical parameters of the river (pH 6.6-7.6 and continuous oxic conditions) do not promote the dissolution of Fe oxyhydroxides and OM. Ferric deposits and the associated trace metals are therefore maintained as colloids/particles and are exported to the outlet. All of the results presented here demonstrate that the ferric deposits trap metals on a seasonal basis and are therefore a key factor in the mobilization of metals during riverbank erosion by river flow.

show abstract

Section: Accepted Manuscriptsupporting

confidence: 78%

Section: Accepted Manuscriptmentioning

confidence: 95%

Iron speciation at the riverbank surface in wetland and potential impact on the mobility of trace metals

Ratié

Vantelon

Lotfi-Kalahroodi

et al. 2019

Science of The Total Environment

View full text Add to dashboard Cite

show abstract

“…Either "relict" weathering profiles experience rapid mineralogical adjustments to changes in climatic conditions, or the mineral assemblages have formed under modern conditions. The former is unlikely; witness the widely documented persistence of relict weathering mineral assemblages that are clearly not related to modern climatic conditions (for example, Tarzi and Protz, 1978;Thiry and Schmitt, 1983;Guendon and Parron, 1983). Whether the 100,000-yr time-scale is an "age" for the profile or a "response time" is largely irrelevant; what is significant is that the saprolites of the southern Blue Ridge need not be relict deep weathering profiles of Tertiary age.…”

Section: Rate Of Saprolite Formationmentioning

confidence: 99%

Geochemical mass balances and weathering rates in forested watersheds of the southern Blue Ridge; III, Cation budgets and the weathering rate of amphibole

Velbel¹

1992

American Journal of Science

View full text Add to dashboard Cite

Weathering rates of rock-forming silicate minerals in natural forested watersheds can be calculated using a system of geochemical mass balance equations constructed and constrained by petrologic, mineralogic, hydrologic, botanical, and aqueous geochemical data. Solving the systems of equations for the weathering rates of biotite mica, almandine garnet, and oligoclase-andesine plagioclase feldspar in deeply weathered (saprolitized) schists and gneisses of a study area (the USDAFS Coweeta Hydrologic Laboratory, near Otto, N.C.) suggests that: (1) The rate at which the weathering front penetrates into the fresh rock (3.8 cm/1000 yrs) agrees well with the "average" denudation rate for the southern Appalachians (4 cm/1000 yrs) determined by a variety of different methods. (2) When normalized to the estimated mineral surface area in the watersheds, rates of garnet and plagioclase weathering are approximately one to two orders of magnitude slower than rates determined in laboratory experiments under similar hydrogeochemical conditions. Two possible sources of this discrepancy are (A) the character of artificially-treated mineral surfaces, which renders them more reactive than their natural counterparts, and/or (B) difficulties in estimating reactive mineral surface area in natural systems. (3) Present rates of primary mineral weathering and secondary mineral neof ormation at Coweeta appear to be sufficient to neutralize present levels of atmospheric hydrogen ion input. The relatively good accord between field and laboratory geochemical and geomorphologic results suggests that present sources of error may not be large, that mass-balance models provide quantitative estimates of rates of important environmental processes, and that refinement of laboratory kinetic data and field surface area determinations should rank high among future research priorities.

show abstract

“…Laboratory studies have also shown that the crystallinity of lepidocrocite is sensitive to oxidation rate, [Si], [Cl] and pH (Schwertmann & Thalmann, 1976;Schwertmann & Taylor, 1979;Taylor, 1984). Lepidocrocite has rarely been reported in well drained or calcareous soils (Tarzi & Protz, 1978;Ross & Wang, 1982) but has commonly been observed in acid, hydromorphic soils where, in some instances, it may be a weathering product of pyrite (FeS 2 ) (Pawluk, 1971).…”

mentioning

confidence: 99%

Spatial distribution of lepidocrocite in a soil hydrosequence

et al. 2002

View full text Add to dashboard Cite

Three terrace soils comprising a hydrosequence were examined to determine how the spatial distribution of lepidocrocite was related to depth and duration of saturation. Vertical relief was 1.0 m with well drained, moderately well drained, and somewhat poorly drained pedons spaced ∼60 m apart. All soils contained brittle, slowly-permeable subsoil horizons and were acidic with <35% base saturation throughout the upper sola. The well drained soil (Fragic Hapludult) had no morphological indicators of wetness within a depth of 180 cm, and water was perched above a brittle horizon at 82 cm for a total of only 41 days during the 3.4 year observation period. Nevertheless, trace amounts of lepidocrocite were detected in the subsoil. The moderately well drained soil (Typic Fragiudult) was saturated at a depth of 180 cm for 6% of the time, and water was perched on top of a fragipan at 74 cm for 13% of the time. Lepidocrocite was most abundant in this pedon and reached maximum concentrations below the fragipan in the capillary fringe of the regional water table (150–183 cm). The somewhat poorly drained member of the hydrosequence (Aeric Fragiaquult) was saturated at a depth of 180 cm for 96% of the observation period and also contained perched water above a fragipan for >90% of the time. Lepidocrocite occurred throughout this pedon but was most concentrated in fragipan horizons (86–135 cm) between the perched and regional zones of saturation. These horizons were saturated from 22 to 48% of the observation period. The results of this study suggest that lepidocrocite formation was favoured in horizons that were saturated for 5–50% of the time when soil temperatures exceeded 5°C.

show abstract

The Occurrence of Lepidocrocite in Two Well-Drained Ontario Soils

Cited by 16 publications

References 12 publications

Iron speciation at the riverbank surface in wetland and potential impact on the mobility of trace metals

Iron speciation at the riverbank surface in wetland and potential impact on the mobility of trace metals

Geochemical mass balances and weathering rates in forested watersheds of the southern Blue Ridge; III, Cation budgets and the weathering rate of amphibole

Spatial distribution of lepidocrocite in a soil hydrosequence

Contact Info

Product

Resources

About