Rock weathering controls the potential for soil carbon storage at a continental scale

As rock-derived primary minerals weather to form soil, they create reactive, poorly crystalline minerals that bind and store organic carbon. By implication, the abundance of primary minerals in soil might influence the abundance of poorly crystalline minerals, and hence soil organic carbon storage. However, the link between primary mineral weathering, poorly crystalline minerals, and soil carbon has not been fully tested, particularly at large spatial scales. To close this knowledge gap, we designed a model that links primary mineral weathering rates to the geographic distribution of poorly crystalline minerals across the USA, and then used this model to evaluate the effect of rock weathering on soil organic carbon. We found that poorly crystalline minerals are most abundant and most strongly correlated with organic carbon in geographically limited zones that sustain enhanced weathering rates, where humid climate and abundant primary minerals co-occur. This finding confirms that rock weathering alters soil mineralogy to enhance soil organic carbon storage at continental scales, but also indicates that the influence of active weathering on soil carbon storage is limited by low weathering rates across vast areas.

Implication of Mineralogy and Isotope Data on the Origin of the Permian Basic Volcanic Rocks of the Hronicum (Slovakia, Western Carpathians)

The paper presents new geochemical data of the basic to intermediate volcanic rocks from the Hronic unit. The studied rocks are strongly altered and the primary mineral composition (clinopyroxenes, amphiboles, spinels, biotites, and plagioclases) is preserved only in some localities. The clinopyroxene corresponds to augite and primary amphiboles to pargasites. Spinels have a chemical composition similar to spinels from volcanic rocks. According to chemical composition, the studied basalts correspond to rift-related continental tholeiites. 143Nd/144Nd vs. 87Sr/86Sr isotopic ratios of the basalts are scattered around the value of 143Nd/144Nd for CHUR, where 143Nd/144Nd ratios are relatively stable and 87Sr/86Sr values are relatively varied. According to isotopic ratio of 207Pb/204Pb vs. 206Pb/204Pb, the basalt analyses lie in the field of EMII (mantle source enriched with crustal materials). The new results of U-Pb LA-ICP-MS dating of apatite point to an age 254 ± 23 Ma (Lopingian).

A review of indium recycling methods from LCD screen wastes

Indium, one of the important rare metals, has drawn more and more attention due to its semiconductor and optoelectronic performance. The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. Indium contents of these products usually vary in a range of 100÷200 g/t. However, as a main secondary source of indium, LCDs waste contains much higher contents of indium than that in mineral ores. LCDs waste may contain up to 1,400 g/t In (equivalent to 0.7 g/m2). The indium recovery process from LCD screen wastes undergoes three stages: dismantling LCD screens; separation of indium-containing ITO glass, and recovery of indium metal. This paper presents the characteristics of the indium recovery process from LCD screen wastes and the main techniques used in each stage of technology. From there, a few suitable specific indium recycling processes are proposed for the conditions in Vietnam.

Rippite, K2(Nb,Ti)2(Si4O12)O(O,F), a New K-Nb-Cyclosilicate from Chuktukon Carbonatite Massif, Chadobets Upland, Krasnoyarsk Territory, Russia

Rippite K2(Nb,Ti)2(Si4O12)(O,F)2, a new K-Nb-cyclosilicate, has been discovered in calciocarbonatites from the Chuktukon massif (Chadobets upland, SW Siberian Platform, Krasnoyarsk Territory, Russia). It was found in a primary mineral assemblage, which also includes calcite, fluorcalciopyrochlore, tainiolite, fluorapatite, fluorite, Nb-rich rutile, olekminskite, K-feldspar, Fe-Mn–dolomite and quartz. Goethite, francolite (Sr-rich carbonate–fluorapatite) and psilomelane (romanèchite ± hollandite) aggregates as well as barite, monazite-(Ce), parisite-(Ce), synchysite-(Ce) and Sr-Ba-Pb-rich keno-/hydropyrochlore are related to a stage of metasomatic (hydrothermal) alteration of carbonatites. The calcite–dolomite coexistence assumes crystallization temperature near 837 °C for the primary carbonatite paragenesis. Rippite is tetragonal: P4bm, a = 8.73885(16), c = 8.1277(2) Å, V = 620.69(2) Å3, Z = 2. It is closely identical in the structure and cell parameters to synthetic K2Nb2(Si4O12)O2 (or KNbSi2O7). Similar to synthetic phase, the mineral has nonlinear properties. Some optical and physical properties for rippite are: colorless; Mohs’ hardness—4–5; cleavage—(001) very perfect, (100) perfect to distinct; density (meas.)—3.17(2) g/cm3; density (calc.)—3.198 g/cm3; optically uniaxial (+); ω = 1.737-1.739; ε = 1.747 (589 nm). The empirical formula of the holotype rippite (mean of 120 analyses) is K2(Nb1.90Ti0.09Zr0.01)[Si4O12](O1.78OH0.12F0.10). Majority of rippite prismatic crystals are weakly zoned and show Ti-poor composition K2(Nb1.93Ti0.05Zr0.02)[Si4O12](O1.93F0.07). Raman and IR spectroscopy, and SIMS data indicate very low H2O content (0.09–0.23 wt %). Some grains may contain an outermost zone, which is enriched in Ti (+Zr) and F, up to K2(Nb1.67Ti0.32Zr0.01)[Si4O12](O1.67F0.33). It strongly suggests the incorporation of (Ti,Zr) and F in the structure of rippite via the isomorphism Nb5+ + O2− → (Ti,Zr)4+ + F1−. The content of a hypothetical end-member K2Ti2[Si4O12]F2 may be up to 17 mol. %. Rippite represents a new structural type among [Si4O12]-cyclosilicates because of specific type of connection of the octahedral chains and [Si4O12]8− rings. In structural and chemical aspects it seems to be in close with the labuntsovite-supergroup minerals, namely with vuoriyarvite-(K), K2(Nb,Ti)2(Si4O12)(O,OH)2∙4H2O.

Coastal accretion and sea-level rise in the Cuban Archipelago obtained from sedimentary records

Sea-level rise (SLR) is one of the most pervasive consequences of global warming, and the Cuban Archipelago is threatened by current and future SLR. In order to support adaptation plans, it is essential to have reliable information about sea-level change during the last decades at the local scale, particularly in the most vulnerable regions. Here, we use sedimentary records to evaluate coastal accretion and to estimate the relative sea-level rise (RSLR) in two vulnerable coastal sites in central Cuba: Cayo Santa María (CSM) and Península de Ancón (PA). Both sites showed sediment sections with a continuous record of sediment accretion as a result of relative SLR and tropical storms. The sedimentary process was different between CSM and PA owing to differences in geomorphology and primary mineral composition. Sedimentary records also showed recent impacts of anthropogenic activities, likely increasing the vulnerability of the shoreline to SLR. The estimated RSLR values agreed with tidal gauge records, although they spanned a much longer time period (CSM: 0.5 ± 0.1 mm a−1, span of 38 years; PA: 1.5 ± 0.3 mm a−1, span of 92 years). Our results confirm that this methodology may be used to estimate the RSLR in places where data by instrumental records do not exist.

Mineralogical and Chemical Characteristics of Slags from the Pyrometallurgical Extraction of Zinc and Lead

The slags derived from the fire refining of lead bullion, differ distinctly in the mineral composition, which results from the fact that these slags are end products of a series of chemical reactions (of both reduction and oxidation). The most common phases included in the refining slags are sulphates and hydrated sulphates (anglesite, gypsum, ktenasite and namuvite), oxides and hydroxides (wustite and goethite), nitrates (gerhardtite) and silicates (kirschsteinite and willemite). The other phases are sulphides and hydrated sulphides (sphalerite and tochilinite), metals (metallic Pb) and glass. Among the mineral components of these slags can be distinguished—primary mineral constituents, phase constituents formed in the ISP process and lead refining, secondary mineral constituents, formed in the landfill. The slags contain, in chemical terms, mainly FeO, CuO and SO3, PbO, in smaller contents SiO2, Al2O3 and CaO, TiO2, MnO, MgO, K2O, P2O5. The mineralogical and chemical composition indicate that slags may be a potential source of metals recovery and pyrometallurgical processing of these wastes seems to be highly rational.

Efficiency and mechanism of lead stabilization in soil of lead-acid battery contaminated site with phosphorus-based materials

<p>Lead contaminated soils occurred at lead-acid battery manufacturing and recycling sites are of great concern. Bench-scale batch experiments of stabilization treatment were conducted using twelve materials and three phosphorus-based materials, KH<sub>2</sub>PO<sub>4</sub>(KP), KH<sub>2</sub>PO<sub>4</sub>:oyster shell power = 1:1 (by mass ratio; KSP), and KH2PO4:sintered magnesia = 1:1(by mass ratio; KPM), were screened out for lead contaminated soil in an abandoned lead-acid battery factory site. The three materials had higher remediation efficiencies that led to a 92% reduction in leachable Pb and 12% reduction in bioaccessible Pb with the addition of 5% material, while the acid soluble fraction of lead decreased by 41–46%. The lead activity in the soil solution sharply decreased treated by three materials. Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>Cl was the primary mineral controlling lead solubility in soil treated by KP and KSP and lead activity was related to Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH and Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>Cl in soil amended with KPM.</p>

Anaerobic reduction of europium by a Clostridium strain as a strategy for rare earth biorecovery

The biorecovery of europium (Eu) from primary (mineral deposits) and secondary (mining wastes) resources is of interest due to its remarkable luminescence properties, important for modern technological applications. In this study, we explored the tolerance levels, reduction and intracellular bioaccumulation of Eu by a site-specific bacterium, Clostridium sp. 2611 isolated from Phalaborwa carbonatite complex. Clostridium sp. 2611 was able to grow in minimal medium containing 0.5 mM Eu3+. SEM-EDX analysis confirmed an association between Eu precipitates and the bacterium, while TEM-EDX analysis indicated intracellular accumulation of Eu. According to the HR-XPS analysis, the bacterium was able to reduce Eu3+ to Eu2+ under growth and non-growth conditions. Preliminary protein characterization seems to indicate that a cytoplasmic pyruvate oxidoreductase is responsible for Eu bioreduction. These findings suggest the bioreduction of Eu3+ by Clostridium sp. as a resistance mechanism, can be exploited for the biorecovery of this metal.

Lepageite, Mn32+(Fe73+Fe42+)O3[Sb53+As83+O34], a new arsenite-antimonite mineral from the Szklary pegmatite, Lower Silesia, Poland

Lepageite, a new arsenite-antimonite mineral, was discovered in a granitic pegmatite hosted by serpentinites of the Szklary massif, Lower Silesia, southwest Poland. Lepageite is a primary mineral formed during injection of an evolved LCT-type melt related to anatectic processes within the metasedimentary-metavolcanic complex of the nearby Góry Sowie Block, ~380 Ma, into serpentinite of the Szklary massif and its contamination by fluid-mobile serpentinite-hosted elements, among others As and Sb, transported in the form of H2AsO3− and HSbO2 species at pH ≈ 9–11 and a low redox potential of –0.7 to –0.3 V.