Search results for "MINERALS"
showing 10 items of 247 documents
Chemical weathering of volcanic rocks at the island of Pantelleria, Italy: Information from soil profile and soil solution investigations
2007
Abstract Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state …
Over-estimation of efficiency of weathering in tropical “Red Soils”: its importance for geoecological problems
2000
Abstract Weathering and soil formation rates are regarded as the main criteria of a tolerable soil loss. The efficiency of weathering in the seasonal semiarid tropics has often been greatly over-estimated especially in the geomorphologic literature in which weathering is assumed to be as fast or even faster than surface erosion. Six selected “Red Soils” in two intramontane basins of hyperthermic SW Nepal near the border with India, with 1500–1750 mm annual rainfall (5 humid months), and a “Black Soil” near Baroda, Gujarat, India (3–4 humid months) were studied mineralogically. Two of the “Red Soils” have TL ages between 10 and 30 ka, the “Black Soil” has one of about 10 ka. The yellowish si…
Clay minerals, oxyhydroxide formation, element leaching and humus development in volcanic soils
2008
Aweathering sequence with soils developing on volcanic, trachy-basaltic parent materials with ages ranging from 100–115,000 years in the Etna region served as the basis to analyse and calculate the accumulation and stabilisation mechanisms of soil organic matter (SOM), the transformation of pedogenic Fe and Al, the formation and transformation of clay minerals, the weathering indices and, by means of mass-balance calculations, net losses of the main elements. Although the soils were influenced by ash depositions during their development and the soil on the oldest lava flow developed to a great extent under a different climate, leaching of elements and mineral formation and transformation co…
Dielectric response of disordered BaBi2Nb2O9perovskite ceramics
2007
Studies of dielectric properties of BaBi2Nb2O9 ceramics are reported. Considerable dispersion of ?* at low- and infra-low frequencies has been revealed in the region of the diffused phase transition. Dispersion of ?* is divided into ''low-temperature'' dispersion related to relaxation of polar formations and their boundaries and ''high-temperature'' dispersion (at T ? Tm) the main contribution to which comes from Maxwell-Wagner relaxation.
The Mineral Contents of Some Boletaceae Species from Sicily (Southern Italy)
2014
Abstract Data on the accumulation of metals in wild edible and inedible macrofungi of the Boletaceae family are discussed here and compared with data reported in literature from northern Italy and other European countries, as well as from China, Brazil, and Africa. The results show a significant difference in the values detected in Sicilian fungi compared to those reported in the literature.
Calcium, iron and zinc uptakes by Caco-2 cells from white beans and effect of cooking
2006
White beans (Phaseolus vulgaris L.) have an interesting content of essential elements, calcium, iron and zinc, but they content also phytates, oxalates, proteins, polyyphenols and complex polysaccharides that are known to interact with minerals and to affect their bioavailability. The bioavailability of calcium, iron and zinc from raw and cooked white beans was estimated using their uptake by Caco-2 cells as the criteria. Previously, the mineral fraction (soluble or dialysable) to be added to the Caco-2 cell monolayer was selected. The results obtained show that cooking increases the Caco-2 cells' uptake percentages (calcium, 18.8 versus 3.6; iron, 33.7 versus 1.7; and zinc, 17.2 versus 2.1…
Distribution of rare earth elements in marine sediments from the Strait of Sicily (western Mediterranean Sea): Evidence of phosphogypsum waste contam…
2010
Concentrations of rare earth elements (REE), Y, Th and Sc were recently determined in marine sediments collected using a box corer along two onshore–offshore transects located in the Strait of Sicily (Mediterranean Sea). The REE + Y were enriched in offshore fine-grained sediments where clay minerals are abundant, whereas the REE + Y contents were lower in onshore coarse-grained sediments with high carbonate fractions. Considering this distribution trend, the onshore sediments in front of the southwestern Sicilian coast represent an anomaly with high REE + Y concentrations (mean value 163.4 lg g 1) associated to high Th concentrations (mean value 7.9 lg g 1). Plot of shale-normalized REE + …
Role of clays in protecting adsorbed DNA against X-ray radiation
2004
The X-ray emission of the young Sun was much harder and intense than today and might have played a significant role in the evolution of complex organics in protoplanetary environments. We investigate the effects of soft X-rays on tryptophan molecules in aqueous solutions at room temperature. As results of the irradiation experiments we detect several light species indicative of fragmentation, together with large molecular structures such as tryptophan dipeptide and tripeptide. Complexification is more evident in H2O solution than in D2O, probably due to isotopic effects. The abundances of peptides depend on the irradiation dose and decrease with increasing energy deposition. Radicals such a…
A Unique Collection of Palaeolithic Painted Portable Art: Characterization of Red and Yellow Pigments from the Parpalló Cave (Spain).
2016
In this work we analyze the pigments used in the decoration of red and yellow motifs present in the portable art of the Parpallo Cave (Gandia, Spain), one of the most important Palaeolithic sites in the Spanish Mediterranean region. Energy dispersive X-ray fluorescence spectrometry (EDXRF) and spectrophotometry in the visible region (CIEL*a*b*color coordinates and spectral reflectance curves) were used to perform in situ fast analyses of the red and yellow motifs with portable equipment and to characterize their elemental composition and their colorimetric perception, respectively. According to the elemental composition, the intensity of the fluorescence iron signals in red and yellow motif…
Mines and quarries production: A driver analysis of withdrawals in Italy
2020
Abstract The growing demand for non-energy mineral resources has determined relevant withdrawals as well as import-export flows. This paper aims to disentangle the drivers of raw non-energy mineral resources extraction in Italy. Using a new dataset of raw resources extracted from mines and quarries in the 21 Italian regions (19 regions and 2 autonomous provinces of Trento and Bolzano) for the period 2013–2016, our empirical analysis confirms the relevance of mining and quarrying producer price index as well as the manufacturing and construction sectors as main drivers. In line with the Hotelling (1931)'s theory, a positive relationship between m&q mineral resources extraction intensity and …