Geochemical fingerprints in topsoils of the volcanic Brava Island, Cape Verde

Marques, Rosa; Prudêncio, M.I.; Waerenborgh, J.C.; Rocha, Fernando; Silva, Eduardo Ferreira da; Dias, María Isabel; Madeira, José; Vieira, Bruno; Marques, José Gonçalo

doi:10.1016/j.catena.2016.08.008

Cited by 12 publications

(17 citation statements)

References 32 publications

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“…In the case of PT-Cum samples the doublets with IS~0.45mm/s, QS~0.90mm/s and IS~1.23-1.29mm/s, QS~2.95 mm/s may be assigned to Fe 3+ and Fe 2+ , respectively, in the silicate phases. The magnetic splitting with IS ~ 1.27 mm/s and magnetic hyperfine field Bhf ~10.2 T is consistent with pyroxenes containing significant amounts of Fe 2+ that become magnetically ordered below 20-25 K [10,11] Finally the sextet with IS ~0.49mm/s, Bhf ~50.1 T and quadrupole shift ~-0.24 mm/s is attributed to Fe 3+ in goethite which is nano-sized since at room temperature no sextets are observed. In the case of PT-Cov spectra taken at 4 K in addition to the subspectra observed for PT-Cum samples a third doublet with IS~1.42 mm/s and QS~3.66 mm/s (significantly higher than IS and QS of Fe 2+ in silicates) is detected.…”

Section: Resultssupporting

confidence: 63%

“…The doublets and magnetic splittings observed in the Mössbauer spectra at 4 K (spectra of selected sample in Fig. 2) correspond to contributions from Fe 2+ and Fe 3+ in several Fe-bearing phases, as explained in detail [10]. Doublets are defined by their IS and quadrupole splitting, QS.…”

Section: Resultsmentioning

confidence: 74%

“…It is assigned to hematite, also nano-sized since the room temperature spectrum of PT-Cum samples show no sextets. The poor crystallinity (small crystal size, unspecific particle shape, structural disorder) and possible Fe 3+ isomorphous substitution by impurity cations such as Al 3+ explain why these hematite nano-particles did not undergo the Morin transition [10,11]. The results deduced from the Mössbauer spectra are summarized in Table 2.…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of REE potential in Portuguese legacy mines

et al. 2019

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REE have unique properties that are mostly used to manufacture high tech devices. Most REE have geochemical properties that cause them to be typically dispersed and not often found in concentrated and economically exploitable forms, and difficult to separate. The ENVIREE project aims to develop environmentally friendly and efficient methods for their extraction from secondary sources. REE contents of tailings from four legacy mining sites have been obtained by INAA and analysed by 57Fe Mössbauer spectroscopy. REE concentrations in the tailings of Covas and Cumieira are more dependent on the REE contents of the primary ores and the treatment to extract the target metals than on the nano-sized oxides present. The tailings’ size, REE contents and Mössbauer results support the selection of the Covas tailing as the one to be submitted for further steps of REE extraction on the framework of the project.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

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Evaluation of REE potential in Portuguese legacy mines

et al. 2019

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“…Therefore, NaOH-treatment was an effective tool for concentrating iron oxide in the studied pedomaterials, revealing an important strategy on volcanic soil sample preparation for mineralogical analysis. These observations were complemented with the results on the corresponding sets of X-ray patterns, presented at Verde (Marques et al, 2016). The authors found more crystalline strongly oxidized iron oxides (such as hematite, oxidized magnetite and maghemite), located at the oldest and most weathered fractions of the studied pedons.…”

Section: Chemically Treated Silt and Clay Fractionsmentioning

confidence: 69%

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Mineralogical characterisation supported by Mössbauer spectroscopy

Pizarro¹,

Escudey²,

Gacitúa³

et al. 2017

J. Soil Sci. Plant Nutr.

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On this work, the iron oxide mineralogy of Chilean volcanic ashes derived soils have been reviewed, emphasizing on new finding linked to the application of Mössbauer spectroscopy. It has been established that free iron oxide layer contributes with positive variable surface charge to the clay-size soil particle, at soil pH. However, the importance of such contribution seems to depend on the evolutionary stage of the different volcanic soil orders, which defines the crystalline degree of their iron oxide contents. Mössbauer spectroscopy complemented with different physical, chemical and instrumental techniques revealed key aspects of iron oxide mineralogy on these Chilean volcanic soils. For instance, results for Ultisol revealed that the evolution of the soil particle could be followed just analysing the main component of their iron oxide mineralogy; thus, the iron oxide mineralogy change when passing from the volcanic ashes (magnetite), to sand-size magnetic separates (partially-oxidized magnetite), to silt-size (strongly-oxidized magnetite), and finally to clay-size (maghemite) soil samples. Therefore, it would seem that physical weathering of the Ultisol produces smaller and more oxidized particles. On the other hand, the Andisol samples, a young volcanic soil compared to Ultisol, seems to have a constant iron oxide mineralogy among all its different particle size fractions: paramagnetic Fe 2+ and Fe 3+ species with low crystalline degree, the last one possibly assignable to a ferrihydrite-like mineral. Therefore, on the case of Andisols, it seems that the high contents of organic matter somehow prevent mineral evolution towards higher oxidation and more crystalline levels, in agreement with past studies.

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“…During fieldwork, 43 representative topsoil samples were taken from the source areas (geomorphological/lithological units) as the ‘sediment sources’ and deposition areas (sand dunes) as the ‘sink sources’. Geological or geomorphological/lithological sources were delineated as spatial sources 51 , 77 – 80 . Certain factors during sampling, such as topography and erosional processes, were also considered to combine the spatial source and the erosional processes 81 , 82 .…”

Section: Methodsmentioning

confidence: 99%

Sediment Source Fingerprinting of the Lake Urmia Sand Dunes

Ahmady‐Birgani

Agahi

Ahmadi

et al. 2018

Sci Rep

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Aeolian sand dunes are continuously being discovered in inner dry lands and coastal areas, most of which have been formed over the Last Glacial Maximum. Presently, due to some natural and anthropogenic implications on earth, newly-born sand dunes are quickly emerging. Lake Urmia, the world’s second largest permanent hypersaline lake, has started shrinking, vast lands comprising sand dunes over the western shore of the lake have appeared and one question has been playing on the minds of nearby dwellers: where are these sand dunes coming from, What there was not 15 years ago!! In the present study, the determination of the source of the Lake Urmia sand dunes in terms of the quantifying relative contribution of each upstream geomorphological/lithological unit has been performed using geochemical fingerprinting techniques. The findings demonstrate that the alluvial and the fluvial sediments of the western upstream catchment have been transported by water erosion and they accumulated in the lower reaches of the Kahriz River. Wind erosion, as a secondary agent, have carried the aeolian sand-sized sediments to the sand dune area. Hence, the Lake Urmia sand dunes have been originating from simultaneous and joint actions of alluvial, fluvial and aeolian processes.

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Geochemical fingerprints in topsoils of the volcanic Brava Island, Cape Verde

Cited by 12 publications

References 32 publications

Evaluation of REE potential in Portuguese legacy mines

Evaluation of REE potential in Portuguese legacy mines

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Mineralogical characterisation supported by Mössbauer spectroscopy

Sediment Source Fingerprinting of the Lake Urmia Sand Dunes

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