Fragments of asthenosphere incorporated in the lithospheric mantle underneath the Subei Basin, eastern China: Constraints from geothermobarometric results and water contents of peridotite xenoliths in Cenozoic basalts

Anhydrous, medium/coarse-grained spinel bearing mantle xenoliths from the Subei Basin, Eastern China have mineral arrangements that reflect low energy geometry. Because of clinopyroxene modal contents, they are grouped into cpx-rich lherzolites (cpx ≥ 14percentage), lherzolites (8 5My, based on modelled H2O solid-solid diffusion rate) the occurrence of the last melting episode. Keywords: Water contents, Fertile mantle, Melting models, Water diffusion, Asthenosphere/lithospher

Cr6+ adsorption by modified vermiculite

This work aimed at investigating the adsorption of Cr6+ in water by exfoliated vermiculite. The adsorbant tested in this experiment was a vermiculite (from China) which has been subjected to heating at 1000 °C for 1 minute, resulting in an exfoliated vermiculite. Three effects were studied: 1) contact time; 2) initial concentracion of Cr6+; 3) adsorbent mass. Samples were analysed by X Ray Fluorescence (XRF), X Ray Diffraction (XRD) and the solutions with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to quantify the adsorbed Cr6+ by the vermiculite. Results from XRD diffraction showed a conversion of vermiculite into flogopite after heating at 1000°C for 1 minute because of: 1) high content of potassium, 2) dehydration and 3) structural re-ordering; after the contact of vermiculite with Cr6+, the mineral structure did not change. The adsorption of Cr6+ was studied by Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. DKR model, indicative of a cooperative process, described adsorption equilibrium better than the other two models and the maximum adsorption capacity obtained was of 2.81 mol/g. Kinetic was studied using pseudo-first and pseudo-second order kinetic models, with a better description of the process by pseudo-second order model with correlation coefficient almost unitary (R2=0.9984; other kinetic parameters were k2=0.0015 and the absorption initial rate of 0.2x10-8 mg g-1 h-1). The present study demonstrates the effectiveness of modified vermiculite adsorbents for the treatment of hexavalent chromium-contaminated waters and that its adsorption depends on the experimental conditions (such as contact time, initial concentracion of Cr6+ and adsorbent mass)

Reduction of Nitrogen Load in a Zootechnical Wastewater Using a Natural Chabazite Zeolite: An Investigation on Sorption Mechanisms

The use of zeolite-rich tuffs is a valid method for recovering nitrogen from wastewaters. This paper aims at describing the NH4+ adsorption processes of an Italian chabazite zeolite tuff used for the treatment of raw liquid swine manure. The effects of temperature, grain size and contact time were investigated. The isothermal analysis showed a multilayer adsorption behavior, well explained by the Harkins–Jura model, while kinetics was explained by pseudo-second-order, Elovich and intraparticle diffusion models. This study highlighted the complexity of the adsorption process from raw liquid manure, as well as the significant differences between tested particle sizes of the same zeolite tuff

Ammonium adsorption by chabazite zeolite-tuff from swine manure for soil amendment

T he use of natural sorbent geomaterials, like zeolitites (rocks containing > 50% of zeolites) is recognized as a valid method to recover N in the form of ammonium ions (NH4 +) from Zootechnical Wastewaters (ZoWs). Using zeolite-rich tuff as N sorbent from ZoWs lead to varius advantages like the decrease in environmental impact of ZoWs (decreased N content) and the subsequent creation of a high-value soil amendment employable also in organic agriculture (NH4-charged zeolite-tuff). In order to understand the characteristics of NH4-charged zeolites (CZ) as sorbent, it is mandatory a deep investigation on their sorption dynamics when they react with ZoWs. Scientific literature is rich of studies about sorption in sintetic solutions (especially NH4CL) while it lacks studies about sorption in real ZoWs. The aim of this work was therefore to characterize the NH4 sorption dynamics of a chabazite zeolite tuff from swine manure. In particular, two grain sizes were selected, a micronized (< 125 μm, CHAμ) and a granular one (0.7-2.0 mm, CHAg). A series of batch experiments were performed to investigate the effects of temperature, contact time and grain size on sorption of NH4. Equilibrium data were fitted with appropriate isothermal models; kinetic models were also investigated to characterize the kinetik sorption reactions and the thermodinamic parameters like change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS). Results have shown a significant grain size effect with respect to the equilibrium loading (qe), with better performances for CHAμ in all the temperatures investigated; the isothermal data showed that the influence of temperature is less for CHAμ with respect to CHAg. The kinetic data differs from the two grain size investigated, in particular CHAg showed an initial external surface adsorption and macropore diffusion during the first 60 minutes of contact, then the diffusion occurs also inside the micropores. The Intraparticle Diffusion model (ID) for CHAμ showed that the diffusion in the macropores are much more fast than CHAg and the intercept indicates the formation of a boundary layer thicker than CHAg. Pseudo-second-order kinetic model well explained CHAg behavior but not that of CHAμ. Both grain sizes were well explained by Elovich equation wich is a model used to explain the sorption kinetics for energetically heterogeneous solids surfaces (as likely the surface of the zeolite-tuff employed). Thermodinamic data showed that the energy in the liquid-solid adsorption surfaces increased during adsorption (ΔH ˃ 0), thus the cation exchange reaction needs energy from the liquid phase. The free standard entropy change (ΔS) is also positive, indicating that the NH4 sorption is a directional process with no significant differences with respect to the tested temperatures and that the randomness at the solid-solution interface increased during adsorption. The negative values of Gibbs free energy (ΔG) indicates that the NH4 sorption is an exergonic process (spontaneous reaction)

Reducing Nitrogen Fertilization in Olive Growing by the Use of Natural Chabazite-Zeolitite as Soil Improver

In order to improve the sustainability and productivity of modern agriculture, it is manda tory to enhance the efficiency of Nitrogen (N) fertilizers with low-impact and natural strategies, without impairing crop yield and plant health. To achieve these goals, the ZeOliva project conducted an experiment using a zeolite-rich tuff as a soil amendment to improve the efficiency of the N fertiliz ers and allow a reduction of their inputs. The results of three years of experimentation performed in three different fields in the Emilia-Romagna region (Italy) are presented. In each field, young olive trees grown on zeolite-amended soil (−50% of N-input) were compared to trees grown on unamended soil (100% N-input). Soils and leaves were collected three times every year in each area and analyzed to monitor the efficiency of the zeolite treatment compared to the control. Vegetative measurements were performed along with analysis of pH, Soil Organic Matter and soluble anions in soil samples, whereas total C and N, C discrimination factor and N isotopic signature were investigated for both soils and leaves. Besides some fluctuations of nitrogen species due to the sampling time (Pre-Fert, Post-Fertilization and Harvest), the Total Nitrogen of leaves did not highlight any difference between treatments, which suggest that plant N uptake was not affected by lower N input in the zeolite treatment. Results, including vegetative measurements, showed no significant differences between the two treatments in all the observed variables, although the control received twice the N-input from fertilization. Based on these results, it is proposed that zeolite minerals increased the N retention time in the soil, allowing a better exploitation by plants which led to the same N uptake of the control notwithstanding the reduction in the N inputs. The use of zeolite-rich tuff in olive growing thus allows a reduction in the amount of fertilizer by up to 50% and improves the N use efficiency with many environmental and economic benefits

The alkaline lamprophyres of the Dolomitic Area (Southern Alps, Italy): markers of the Late Triassic change from orogenic-like to anorogenic magmatism

We present the first complete petrological, geochemical and geochronological characterization of the oldest lamprophyric rocks in Italy, which crop out around Predazzo (Dolomitic Area), with the aim of deciphering their relationship with Triassic magmatic events across the whole of the Southern Alps. Their Mg# of between 37 and 70, together with their trace element contents, suggests that fractional crystallization was the main process responsible for their differentiation, together with small-scale mixing, as evidenced by some complex amphibole textures. Moreover, the occurrence of primary carbonate ocelli suggests an intimate association between the alkaline lamprophyric magmas and a carbonatitic melt. 40Ar/39Ar data show that the lamprophyres were emplaced at 219·22 ± 0·73 Ma (2σ; full systematic uncertainties), around 20 Myr after the high-K calc-alkaline to shoshonitic, short-lived, Ladinian (237–238 Ma) magmatic event of the Dolomitic Area. Their trace element and Sr–Nd isotopic signatures (87Sr/86Sri = 0·7033–0·7040; 143Nd/144Ndi = 0·51260–0·51265) are probably related to a garnet–amphibole-bearing lithosphere interacting with an asthenospheric component, significantly more depleted than the mantle source of the high-K calc-alkaline to shoshonitic magmas. These features suggest that the Predazzo lamprophyres belong to the same alkaline–carbonatitic magmatic event that intruded the mantle beneath the Southern Alps (e.g. Finero peridotite) between 190 and 225 Ma. In this scenario, the Predazzo lamprophyres cannot be considered as a late-stage pulse of the orogenic-like Ladinian magmatism of the Dolomitic Area, but most probably represent a petrological bridge to the opening of the Alpine Tethys