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• Clay minerals and carbonate cementation are associated with U mineralization. • δD and δ18O values of clay minerals suggesting meteoric origin of the ore fluid. • Hydrocarbons may have played an important role in U mineralization. • H-O-C isotopes suggest a transient interface between oxidizing/reducing fluids. The Meso-Cenozoic Yili Basin in northwestern China hosts important uranium and coal resources. The uranium deposits are mainly hosted by sandstones and are characterized by clay and carbonate alterations within and surrounding the orebodies. H-O-C isotopes of clay minerals and carbonate cement in the different alteration zones of the uranium deposits in the southern margin of the Yili Basin are summarized to examine the mechanisms of uranium mineralization. The alteration zones associated with the uranium mineralization include an intensely oxidized zone, a weakly oxidized zone, a transitional (mineralization) zone, and a reduced zone. The δD and δ18O values of the parent fluids calculated from clay minerals from the different alteration zones show a linear trend that intersects the global meteoric line at a point with a δ18O V-SMOW of ca. −5‰ and a δD V-SMOW of ca. −30‰, which coincide with the upper end of the δD – δ18O trend (along the meteoric line) of formation waters in the basin, suggesting that the uranium mineralizing fluid was of meteoric origin. The general trends of decreasing δD and δ13C and increasing δ18O from the intensely oxidized zone to the reduced zone, together with the fact that calculated δD V-SMOW values of the mineralizing fluids are lower than the original meteoric fluid, and that the δ13C values of the calcite cement overlap with those of organic matter in sedimentary rocks, suggest that hydrocarbons were involved in uranium mineralization. The hydrocarbons may have been important reducing agents causing precipitation of uranium minerals. The hydrogen ion released from oxidation of the hydrocarbons may have been buffered by the formation of clay minerals, which favors co-development of clay alteration and calcite cement. Deviation of H-O-C isotopes from the general variation trends as expected from the above redox mechanism likely resulted from the dynamic nature of the redox front, which changed its position in response to hydrodynamic balance between a downward flow of uranium-bearing, oxidizing fluid and an upward flow of reductants-bearing, reducing fluid from the lower part of the basin. [ABSTRACT FROM AUTHOR]

The Maoniuping rare earth elements deposit is the second largest rare earth elements deposit in China, and the third largest in the world. A sediment core was collected from the river floodplain downstream from the Maoniuping rare earth elements mining area (Sichuan Province, China) to reconstruct the cadmium contamination history and trace its contamination source. Based on lead-210 (210Pb) dating by gamma ray spectrometry and elements determination with inductively coupled plasma mass spectrometry of the sediment core, it was found that the cadmium accumulation rate of the flood plain increased from 0.16 to 2.22 µg cm−2yr−1over the past 100 years. Combining aspects of time, space, and element composition information, it is proved that the exploitation of Maoniuping rare earth elements deposit was the main reason for the increase. Moreover, to evaluate the mobility and availability of cadmium in the sediment core, the modified European Communities Bureau of Reference sequential extraction procedure in combination with inductively coupled plasma mass spectrometry was applied. Risk assessment code was used to further assess the environmental risk of cadmium in the sediment. It was found that the environmental risk from cadmium was high in the surface of the sediments. The results from gamma ray spectrometric and mass spectrometric methods may provide important information for the control and remedy of cadmium-related pollution areas. [ABSTRACT FROM PUBLISHER]

Anisothermal dissolution method was employed to investigate thephase equilibrium at 308 K of the mixed aqueous system containinglithium, magnesium, sulfate, and borate. The solid phases of the invariantpoints were confirmed with the X-ray diffraction method. The stablephase diagram, the water content diagram, and the diagrams of thephysicochemical properties versus the composition of the solutionhave been constructed. The system contained two invariant points (notedas E1and E2), five univariant curves, and fourcrystallization fields corresponding to single salts epsomite (MgSO4·7H2O), hungchaoite (MgB4O7·9H2O), lithium sulfate monohydrate (Li2SO4·H2O), and lithium borate trihydrate(Li2B4O7·3H2O). Invariantpoints E1and E2are of commensurate invariantpoints. The crystallization fields decrease in the sequence MgB4O7·9H2O, Li2B4O7·3H2O, Li2SO4·H2O, and MgSO4·7H2O, which was contrarywith the solubility of the salts. Compared with the temperature at298 K, the crystallization area of salts MgB4O7·9H2O and Li2SO4·H2O enlarged, whereas that of salts Li2B4O7·3H2O and MgSO4·7H2O decreased at 308 K, which lead the change for property ofinvariant point, one invariant point change from incommensurate tocommensurate. The solubility of salt MgSO4increases withtemperature strongly; thus, its crystallization field decreases obviously,whereas the solubility of salt Li2SO4decreaseswith temperature and its crystallization field is enlarged. [ABSTRACT FROM AUTHOR]

Abstract: In China, soil pollution is very serious, which has jeopardized the ecology, food safety, the people''s health, and even the sustainable development of agriculture. In order to investigate the soil pollution situation, a total of 874 agricultural and non-agricultural topsoil samples were collected from Dexing area, northeast of Jiangxi Province, China. The total elemental concentrations of 17 elements (As, Hg, Mo, Cd, Cr, Zn, Cu, Mn, Ti, Pb, Fe, Ca, K, Si, Al, Mg, and Na) were determined. The geochemical background and threshold was predicted with the method of the median±median absolute deviation (MAD). The agricultural soil median concentration of trace elements was similar to that of the non-agricultural soil. In contrast to Jiangxi soil background of trace elements, the geochemical background of the study area was obviously higher. The maps of the pollution indices for As, Cd, Cr, Cu, Hg, Mn, Mo, Pb, Ti and Zn of non-agricultural soil and agricultural soils in the study area, showed that the highest level of pollution is distributed near and along the Lean River, especially in the neighboring and surrounding Dexing and Leping mining area. [Copyright &y& Elsevier]

Vanadium is a trace element widely distributed in the Earth’s crust. Naturally high levels of vanadium are recognized mainly in basic rocks and minerals, particularly in titaniferous magnetite. And the anthropogenic sources of vanadium include fossil fuel combustion and wastes including steel-industry slags. In the last few years, the authors have made investigations and assessments on the environmental geochemistry and ecological risk of vanadium in the Panzhihua mining and smelting area. In the study area, anthropogenic vanadium resulted from mining, extracting and smelting of V-Ti magnetite; vanadium pollution of topsoil and sediments occurs mainly in the mining and extracting area, smelting area, slag dumping area, tailing dam and coal mining area. In the soil, the chemical speciation of vanadium shows: insoluble residue > organically bound > Fe (amorphous) oxide-bound > Mn oxide-bound > soluble component. Vanadium pollution can cause potential harmful effects on ecological systems, and lead to animal poisoning and human disease. So vanadiam pollution should be monitored on a regular basis in the Panzhihua area. [ABSTRACT FROM AUTHOR]

An eco-environmental geochemical investigation was carried out in and around the Dexing mining area to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective of this study is to assess the environmental situation and evaluate the transferring of heavy metals from mining activities into the food chain. Some samples of water, sediment, topsoil and plant were collected along the Lean River in the Dexing mining area. The total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS, and Hg was analyzed by cold-vapor AAS. Some indices such as 'contamination degree', 'geo-accumulation index', and 'biological absorption coefficient' were used to assess eco-environmental quality. The investigation indicated a highly localized distribution pattern closely associated with the two pollution sources along the Le'an River bank: one is strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and the other is the high concentrations of Pb and Zn in the effluents released from many smelters and mining, processing and extracting activities in the riparian zone. Results from the investigated localities indicated, at least in part, that some problems associated with environmental quality deterioration should be solved in the future. [ABSTRACT FROM AUTHOR]

Presents a study on the kinetic modeling of diagenesis of Eogene Lacustrine sandstone reservoirs in the Jianghan Basin, Southeastern China. Diagenetic features identified in the sandstones; Simulation of the kinetics of fluid-mineral reactions and the concentrations of aqueous species; Result of the weak pore fluid during the early diagenetic stage; Cause of the precipitation of quartz, kaolinite and illite.

Presents a study that determined geochemical baseline models and assessed the contributions of trace elements from natural and anthropogenic sources in the Panzhihua mining area in China. Background on Panzhihua; Adoption of a normalization procedure to establish geochemical baselines; Analytical results and relevant parameters for trace metals in topsoil samples from the area.

The ophiolites along the North Qilian Orogenic Belt are considered to be fragments of ancient oceanic crusts and lithospheric mantle of the Palaeozoic North Qilian Ocean (a branch of the Proto‐Tethys). Compared with other ophiolites in this belt, the genesis of the Xiejiayao ophiolite has been poorly studied so far, making it difficult to understand the tectonic evolution of the ocean. In this study, we present new compositional and Sr‐Nd isotopic analyses of basaltic rocks from the Xiejiayao ophiolite to shed light on its petrogenesis and geodynamic background. These oceanic basalts are characterized by flat REE patterns, low elemental ratios of high‐field‐strength elements (e.g., La/Sm, Sm/Yb, La/Yb, Gd/Yb, [Th/Yb]PM) and abundant spinels, implying that they were generated via partial melting in the spinel stability field of the mantle. Their positive εNd(t) values (6.1–8.4), high Zr/Nb (43.65–79.40) as well as low Nb/Ta (10.91–15.09), Zr/Hf (34.64–39.28), and Nb/Yb (0.41–0.59) ratios further reflect that the ancient mantle had already become depleted to some extent before the onset of the Palaeozoic ocean. Additionally, basalts share many geochemical similarities (e.g., Zr, Y, Ti, and V) with both mid‐ocean ridge and island arc basalts. This supports the strong likelihood of origin in a back‐arc basin close to the suprasubduction zone for the ophiolite. Therefore, accompanied by the northward subduction of the oceanic lithosphere during the early Palaeozoic, a large‐scale back‐arc basin developed progressively in response to the back‐arc expansion. The Xiejiayao basaltic magmas were generated in the back‐arc basin via partial melting of the depleted mantle and their source was probably mixed with subducted melts/fluids from the dehydration and melting of oceanic slabs and sediments. [ABSTRACT FROM AUTHOR]

The article discusses the research study conducted to examine the geologic history of the iron oxide copper gold (IOCG) deposits in Southwestern China that was associated with polymetallic mineralization. It reveals the age of magmatic rocks and metallogenic epoch and the coupling relationship between polymetallic elements. It also reveals the ore-forming process including the volcanic sedimentation, grenville orogenic event, and superimposed mineralization.

This work aims to understand the distribution and migration mechanisms of U and Mo between surface sediment and water in acid mine drainage (AMD) regions near a molybdenum mining region. A series of river sediment and water samples near the Jinduicheng mining area, one of the largest deposits of molybdenite ore in Asia, were collected and analyzed. Our results indicate that: (1) The pH value of river water samples increases with distance from upstream to downstream, while the pH has poor correlation with Mo and U; (2) The content of Mo and U in the sediment are significantly higher than the background value, which suggests potential pollution; (3) The content of Mo and U in the water and sediments in the lower reaches of the Wenyu river is significantly linearly related with the distance from the mining area, suggesting that AMD is a potential source; (4) BCR analysis shows that Mo in river sediments mainly existed as the residual, while U mainly existed as the non-residual; (5) The distribution coefficient Kd(Mo) exceeds Kd(U), indicating that Mo is enriched in sediments while U is more prone to porewater. [ABSTRACT FROM AUTHOR]

The nanoakaganeite (β-FeOOH) was synthesized by the hydrothermal method in the study. The structural characterization and adsorption investigation of the produced materials were performed with powder X-ray diffractometer (XRD), scanning electron microscope (SEM), and inductively coupled plasma optical emission spectrometer (ICP-OES). Moreover, the influences of hydrothermal time, Fe3+ concentration, and hydrothermal temperature on the product structure and chromium adsorption were investigated. In addition, the influence of initial Cr(VI) concentration on chromium adsorption was investigated. The investigation results confirmed the optimal synthesis conditions of β-FeOOH as follows: 72 h hydrothermal reaction, 0.20 M Fe3+, and hydrothermal temperature at 70 °C. The as-synthesized β-FeOOH was spindle-shaped akaganeite. When the initial Cr(VI) concentration increased from 9.91 mg/L to 99.47 mg/L, the adsorption capacity increased and Cr(VI) removal rate decreased. Cr(VI) adsorption on β-FeOOH was a single-molecule layer chemical adsorption, conforming to the Langmuir adsorption model. The maximum saturation adsorption was 16.35 mg/g. [ABSTRACT FROM AUTHOR]

High‐precision measurement of X‐ray spectra is affected by the statistical fluctuation of the X‐ray beam under low‐counting‐rate conditions. It is also limited by counting loss resulting from the dead‐time of the system and pile‐up pulse effects, especially in a high‐counting‐rate environment. In this paper a detection system based on a FAST‐SDD detector and a new kind of unit impulse pulse‐shaping method is presented, for counting‐loss correction in X‐ray spectroscopy. The unit impulse pulse‐shaping method is evolved by inverse deviation of the pulse from a reset‐type preamplifier and a C‐R shaper. It is applied to obtain the true incoming rate of the system based on a general fast–slow channel processing model. The pulses in the fast channel are shaped to unit impulse pulse shape which possesses small width and no undershoot. The counting rate in the fast channel is corrected by evaluating the dead‐time of the fast channel before it is used to correct the counting loss in the slow channel. [ABSTRACT FROM AUTHOR]

To explore geochemical factors affecting the chronological reconstruction of a historical arsenic pollution accident in Lake Qionghai at southwest of China, heavy metals and radionuclides (210Pbexand137Cs) in two sediment cores were sampled and analyzed. Our study revealed that (1) industrialization and urbanization of Xichang since the mid-20thCentury, aggravated soil erosion in the catchment and resulted in a significant and lasting increase in the sedimentation rate of Lake Qionghai; (2) sharp arsenic peaks in two sediment cores recorded an arsenic pollution accident in 2006 in which a large amount of arsenic was discharged into the lake from a chemical plant. Arsenic peaks in sediment cores A and B were dated to 1988 ± 3.5, 2006 ± 3.1, respectively. Only the arsenic peak time in core B: 2006 ± 3.1, agreed with the real pollution accident time of 2006. Linear correlation analysis suggested that arsenic sorption by Fe/Mn minerals and organic materials in sediment core A probably changed the depth distribution of the peak and affected the accuracy of chronological reconstruction. This case study suggested that sorption of heavy metals by Fe/Mn minerals and organic materials should be assessed before the chronological reconstruction of the metal pollution accident in the lake. [ABSTRACT FROM AUTHOR]

Abstract: Results of molecular dynamics (MD) and Monte Carlo (MC) simulations on transport process of small molecules in poly (chloro-p-xylylene) membranes are discussed. Diffusion coefficients have been obtained by MD combined with Einstein fluid equation. Solubility coefficients have also been calculated by the transition state Great Canonical ensemble Monte Carlo (GCMC) method. Then permeability has been derived by diffusion coefficient and solubility. The agreement between calculated and experimental data for diffusion coefficient, solubility factors and permeability can be considered acceptable. Therefore, atomistic simulations techniques have proven to be a useful tool for the understanding of structure–property relationships of materials and in particular MD can be used for detailed descriptions of the complex morphologies and transport mechanisms associated with rigid glassy structures. [Copyright &y& Elsevier]

The oxidation/weathering of molybdenite (MoS2) is too slow to be monitored, even under pure oxygen and high temperatures, while it proceeds rapidly through humid air. The adsorption of water molecules on molybdenite is necessary for the wet oxidation/weathering of molybdenite. Therefore, we employ kinetic Monte Carlo modeling to clarify the adsorption isotherm, site preferences and kinetics of water on different surfaces of molybdenite. Our results indicate that (1) the adsorption capacity and adsorption rate coefficient of H2O on the (110) surface are significantly larger than those on the (001) surface at a temperature of 0~100 °C and a relative humidity of 0~100%, suggesting that the (110) surface is the predominant surface controlling the reactivity and solubility of molybdenite in its interaction with water; (2) the kinetic Monte Carlo modeling considering the adsorption/desorption rate of H2O, dissociation/formation rate of H2O and adsorption/desorption of dissociated H indicates that the adsorption and dissociation of H2O on the (110) surface can be completed in one microsecond (ms) at 298 K and in wet conditions; (3) the adsorption and dissociation of H2O on molybdenite are not the rate-limiting steps in the wet oxidation/weathering of molybdenite; and (4) kinetic Monte Carlo modeling explains the experimental SIMS observation that H2O and OH (rather than H+/H− or H2O) occupy the surface of MoS2 in a short time. This study provides new molecular-scale insights to aid in our understanding of the oxidation/weathering mechanism of molybdenite as the predominant mineral containing molybdenum in the Earth's crust. [ABSTRACT FROM AUTHOR]

Metal contamination in sediment of the Mianyuan River (one of the major upper reaches of the Yangtze River) in Longmenshan Region (China) was investigated in 2012. Means of metal concentrations in sediment (<74μm) were Cr: 59.93 ± 19.8% mg/kg; As: 7.21 ± 50.2% mg/kg; Se: 0.45 ± 66.3% mg/kg; Pb: 19.89 ± 29.3% mg/kg; Zn: 78.98 ± 31.9% mg/kg; Cd: 0.69 ± 28.3% mg/kg; Ba: 0.71 ± 34.0% g/kg; Mn: 0.55 ± 62.2% g/kg. This study suggested: (1) concentrations of Cd, As, Cr, and Pb in Mianyuan River sediment were lower than those of the middle and lower reaches of the Yangtze River; (2) the increase of metals during the period from 2006 to 2009 was probably related to the destruction of tailings piles by the Wen Chun earthquake in 2008; (3) organic materials decided the distribution of Cd, Se, As, Ba, and Mn in the upstream sediment, while the iron and manganese minerals controlled the distribution of Ba, Cr, and Zn in the downstream sediment; (4) sources of Cd, Se, and As were geogenic, while sources of Cr, Zn, Ba, and Mn were anthropogenic; (5) the source of Pb in the upstream sediment was probably automobile exhaust, but that of Pb in the downstream sediment was geogenic. [ABSTRACT FROM AUTHOR]

The carbonaceous-siliceous-argillitic rock type uranium deposit in the Zoige area is located in the northeastern margin of the Tibetan Plateau, and has gained much attention of many geologists and ore deposit experts due to its scale, high grade and abundant associated ores. Because of the insufficient reliable dating of intrusive rocks, the relationship between mineralization and the magmatic activities is still unknown. In order to study this key scientific issue and the ore-forming processes of the Zoige uranium ore field, the LA-ICP-MS zircon U-Pb dating of magmatic rocks was obtained: 64.08±0.59 Ma for the granite-prophyry and ∼200 Ma for the dolerite. U-Pb dating results of uraninite from the Zoige uranium ore field are mainly concentrated on ∼90 Ma and ∼60 Ma. According to LA-ICP-MS U-Pb zircon dating, the ages for the dolerite, porphyry granite and granodiorite are 200 Ma, 64.08 Ma approximately and 226.5-200.88 Ma, respectively. This indicates that the mineralization has close relationship with activities of the intermediate-acidic magma. The ages of the granite porphyry are consistent with those uraninite U-Pb dating results achieved by previous studies, which reflects the magmatic and ore-forming event during the later Yanshanian. Based on the data from previous researches, the ore bodies in the Zoige uranium ore field can be divided into two categories: the single uranium type and the uranium with polymetal mineralization type. The former formed at late Cretaceous (about 90 Ma), while the latter, closely related to the granite porphyry, formed at early Paleogene (about 60 Ma). And apart from ore forming elemental uranium, the latter is often associated with polymetallic elements, such as molybdenum, nickel, zinc, etc. [ABSTRACT FROM AUTHOR]

• There was severe Cd and Cr pollution in the soil of Hutou Village. • The primary source of soil pollution was the use of coal. • Mineralogical and geochemical characteristics revealed the migration direction of the pollution. • The contents of REY and Eu in the soil were significantly higher than those in road dust. • The fractionation of LREY and HREY in the soil was more substantial than that in the road dust. This study aimed to reveal the status and source apportionment of trace element soil pollution in a village with a relatively high incidence of lung cancer in China and determine the element migration characteristics from coal to road dust and soil. To this end, 24 soil samples, 48 road dust samples (from a previous study), and 2 coal samples were collected; major element oxides, V, Cr, Co, Ni, Cu, Zn, Zr, Cd, and rare earth elements were analyzed; minerals were identified by SEM-EDX and XRD; a geoaccumulation index (I geo), Spearman's correlation analysis, provenance index (PI) and positive matrix factorization (PMF) were carried out to assess the status and source apportionment of soil pollution; and mineralogical and geochemical methods were used for provenance discrimination and migration characteristics identification. The results demonstrated that (1) the Cd and Cr pollution of the soil was severe and originated mainly from indigenous zinc smelting, agricultural activities, and the use of coal. (2) The pollution migrated from Yantang coal to the road dust to the soil through mineralogical and geochemical methods. (3) A stronger fractionation of light and heavy rare earth elements was observed in the soil than in the road dust, indicating a single pollution source in the road dust and a complex source in the soil. (4) The primary reason for the lower rare earth element values in the road dust could be physical separation by the wind. [ABSTRACT FROM AUTHOR]

Accumulating heavy metal contamination in soils caused by industrial waste, fertilizer, and wastewater irrigation is a matter of grave concern for the environment and food safety. In recent years, remediation agents with the characteristics of economy, high efficiency, and simple operation have become a popular choice for remediation of heavy metal contaminated soil. By far, there are relatively few studies evaluating the effects on remediation agents for their both heavy metal passivation and soil fertility promotion. This study investigated the effects of a remediation agent on Cd passivation, soil pH, and heavy metal uptake by rice crops. Eight treatments were used to evaluate the effect of Cd immobilization in soil. Changes in soil pH and soil Cd fractions were monitored during incubation for 30 days. The field study was conducted during the whole growth stages of rice crops, samples of rice plants and soil at the tillering, booting, and harvesting stages were collected and tested. Cd fractions were extracted from soil at different stages to investigate the effects of various treatments on Cd uptake and bioaccumulation in rice plants. The results show that composite mineral remediation agents composed of mineral fertilizer and synthetic zeolite could effectively improve the pH of soil in incubation experiments and field experiments. Composite mineral remediation agents were effective in stabilizing Cd and increasing rice yield. Mineral fertilizer and Synthetic zeolite played an important role in the tillering stage and harvesting stage of rice growth in field, respectively. Group A4 (mineral fertilizer: synthetic zeolite at mass ration of 10:6) had the best results. Compared with control experiment (CK), HOAc extractable Cd of A4 group decreased by 6%, oxidizable Cd of A4 group increased by 2%, and the residue Cd of A4 group increased by 4%. [ABSTRACT FROM AUTHOR]

The effects of rhizodeposition on soil C and N availabilities lead to substantial changes of microbial community composition and processes in the rhizosphere of plants. Under heterogeneous light, photosynthates can be translocated or shared between exposed and shaded ramets by clonal integration. Clonal integration may enhance the rhizodeposition of the shaded ramets, which further influences nutrient recycling in their rhizosphere. To test the hypothesis, we conducted a pot experiment by the stoloniferous herb Glechoma longituba subjected to heterogeneous light. Microbial biomass and community composition in the rhizosphere of shaded offspring ramets, assessed by phospholipid fatty acids (PLFAs) analysis, were markedly altered by clonal integration. Clonal integration positively affected C, N availabilities, invertase and urease activities, N mineralization (Nmin) and nitrification rates (Nnitri) in the rhizosphere of shaded offspring ramets. However, an opposite pattern was also observed in phenoloxidase (POXase) and peroxidase (PODase) activities. Our results demonstrated that clonal integration facilitated N assimilation and uptake in the rhizosphere of shaded offspring ramets. The experiment provides insights into the mechanism of nutrient recycling mediated by clonal integration. [ABSTRACT FROM AUTHOR]

Abstract: The Wenchuan earthquake with magnitude 8.0 hit Longmen Mountain on May 12, 2008. The coseismic deformation changed the slope in an instant and caused massive outbreaks of landslides and debris flows, which altered the river transport system. The seismic landslides, debris flows and subsequent heavy rainfall and flooding increased sediment discharge. Data on sediment discharge, rainfall, landslides, and debris flows were collected in this study for 1980–2010 to describe the effects of the Wenchuan earthquake and post-earthquake heavy rainfall on the increase in sediment discharge in the upper reaches of the Min River. The relationship between precipitation, sediment discharge, landslides, and debris flows before and after the Wenchuan earthquake in the upper reaches of the Min River was analyzed. The variation trends of sediment discharge in the river basin before and after the earthquake were calculated quantitatively. The research results can be summarized as follows: (1) Sediment discharge increased by approximately 30% due to coseismic uplift, coseismic landslides, and debris flows after the Wenchuan earthquake. (2) The sediment discharge caused by heavy rainfall after the earthquake was 1.75 times larger than before the earthquake. The percentage contribution of the sediment yield of debris flows induced by heavy rainfall after the earthquake to the increase in sediment discharge was 34.54%. (3) The heavy rainfall zone basically coincided with the earthquake fault zone and the seismic landslide zone. Therefore, there was a positive-feedback relationship between the increase of sediment discharge and heavy rainfall after the Wenchuan earthquake. (4) The loosening of surface materials and landslides driven by the Wenchuan earthquake resulted in an increase in sediment discharge into the river, bringing about a great disaster which will need to be addressed in the coming decades. [Copyright &y& Elsevier]

The isotopic composition and parameters for deuterium excess of brines, which were sampled in the Sichuan Basin, show obvious regularities of distribution. The brine isotopic composition shows distinct two systems of marine and terrestrial deposits, with the Middle Triassic strata as the boundary. Brine hydrogen isotopic composition of marine deposits is lower while oxygen isotopic composition is higher than that of the SMOW, respectively, indicating that the brines were derived from seawater with different evaporating degrees at different times. From the Sinian strata, up to the Cambrian, Permian Maokou Formation and the Triassic Jialingjiang Formation, the δD values of brines tend to become relatively positive with the strata becoming younger. Brines of terrestrial deposits are considered to have been derived from precipitation and their isotopic composition is close to the globe meteoric water line (GMWL). Brines of transitional deposits between marine and terrestrial ones (the Upper Triassic Xujiahe Formation) have δD and δO values falling between the two end members of marine deposit brines and precipitation, indicating that the brines are a mixture of precipitation and vaporing seawater. Water samples from the brine-bearing strata of different ages show various deuterium excesses ( d) with an evident decreasing trend as the age of strata gets older and older. Brine-bearing strata of the Triassic Leikoupo-Jialingjiang Formation, the Permian Maokou Formation, the Cambrian and Sinian strata are all carbonate rocks which have experienced intensive water/rock reaction and the deuterium excess essentially changes with time. All brine-bearing-strata surrounding the basin or faults, as well as those brine wells exploited for resources, have been obviously influenced by the precipitation supply. Therefore, the deuterium excesses of their brines have increased to different extents, depending on the amount of involvement of meteoric water. The variation and distribution of d values of the brines from different Triassic strata are related to the embedded depth of the strata. The deuterium excesses of brines become lower with increasing burial depth of the strata. [ABSTRACT FROM AUTHOR]

Analyses of fluid inclusion leachates from ore deposits show that Na/Br ratios are within the range of 75 - 358 and Cl/Br 67 - 394, respectively, and this variation trend coincides with the seawater evaporation trajectory on the basis of the Na/Br and Cl/Br ratios. The average Cl/Br and Na/Br ratios of mineralising fluids are 185 and 173 respectively, which are very close to the ratios (120 and 233) of the residual evaporated seawater past the point of halite precipitation. It is suggested that the original mineralizing brine was derived from highly evaporated seawater with a high salinity. However, the inclusion fluid's have absolute Na values of 69.9-2606.2 mmol kg-1 and Cl values of 106.7 - 1995.5 mmol kg-1. Most of the values are much less than those of seawater; Na, 485 mmol kg-1 and Cl, 566 mmol kg-1, respectively; the salinity measured from fluid inclusions of the deposits ranges from 2.47 wt% to 15.78 wt% NaCl equiv. The mineralizing brine has been diluted. The δ18O and δD values of ore-forming fluids vary from -8.21‰ to 9.51‰ and from -40.3‰ to -94.3‰ respectively. The δD values of meteoric water in this region varied from -80‰ to - 100‰ during the Jurassic. This evidenced that the ore-forming fluids are the mixture of seawater and meteoric water. Highly evaporated seawater was responsible for leaching and extracting Pb, Zn and Fe, and mixed with and diluted by descending meteoric water, which resulted in the formation of ores. [ABSTRACT FROM AUTHOR]

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, water body and stream sediment. An environmental geochemical investigation was carried out in and around the Panzhihua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study are. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly contaminated. Geochemical maps of I[subgeo] of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elements come mainly from dusts resultant from mining activities and other three-waste-effluents. The are needs to be monitored regularly for trace metal, especially heavy metal enrichment. [ABSTRACT FROM AUTHOR]

Isolating relevant microorganisms is still a substantial challenge that limits the use of bacteria in the maintenance of human health. To confirm which media and which bacterial colony densities can enrich certain kinds of bacteria, we selected eight common media and used them to enrich the gut microorganisms on agar plates. Then, we calculated the numbers of bacterial colonies and collected the bacterial culture mixtures from each kind of medium. Using the Illumina HiSeq platform, we analyzed the composition and diversity of the culture-enriched gut bacterial community. Our data suggested that medium supplemented with blood could increase the diversity of the bacterial community. In addition, beef powder and peptone could significantly change the culture-enriched bacterial community. A moderate density (100–150 colony-forming units per plate) was optimal for obtaining the highest diversity on the agar. Similarly, membrane transport was significantly enriched in the moderate-density group, which indicated a more active metabolism in this density range. Overall, these results reveal the optimal culture conditions, including the densities of colonies and nutritional components for various gut bacteria, that provide a novel strategy for isolating bacteria in a way that is targeted and avoids blinded and repetitive work. [ABSTRACT FROM AUTHOR]

The 87Sr/86Sr minimum of the Capitanian seawater is one of the most significant features in the Phanerozoic seawater 87Sr/86Sr history. In order to assess possible contribution of the Emeishan large igneous provinces (LIPs) to strontium isotope evolution of the Capitanian seawater, 87Sr/86Sr ratios were measured from the Capitanian limestones which are locally interlayered with the Emeishan basalts. The limestones underlying the Emeishan basalts have high 87Sr/86Sr ratios (0.7070–0.7074). However, extremely low 87Sr/86Sr ratios (0.7068–0.7070) were identified in the late Capitanian Jinogondolella prexuanhanensis–J. xuanhanensis zones, which correspond to the eruption time of the Emeishan LIP. The temporal coincidence of these two phenomena supports the idea of a potential linkage between Capitanian 87Sr/86Sr minimum and eruption of this igneous province. The strong submarine hydrothermal activity and erosion of the Emeishan LIP could have released large amounts of non-radiogenic Sr to the oceans and play an important role in strontium isotope evolution of the seawater. [ABSTRACT FROM AUTHOR]

A complete and accurate set of thermodynamic data for aqueous uranium species is necessary in order to determine the toxicity of uranium in water, to predict its fate in the environment and to design possible remediation strategies for polluted environments. Comparisons of the completeness and accuracy of the thermodynamic databases for aqueous uranyl complexes involving common inorganic anions (OH−, SO 4 2−, PO 4 3−, CO 3 2−, SO 4 2−, Cl−,F−, I−, Br−) and some organic ligands have been made between a number of publicly-available thermodynamic databases (MINTEQ, LLNL, WATEQ4F, ThermoChimie, NEA-TDB, and PSI/Nagra). The results indicates that: (1) stability constants for most aqueous inorganic uranium species in the ThermoChimie, NEA-TDB, and PSI/Nagra databases are broadly similar, but ThermoChimie includes a greater number of organic uranium species; (2) ThermoChimie and two other modern developing databases (NEA-TDB, and PSI/Nagra) are recommended for calculating uranium speciation in natural/polluted waters except for those containing high concentrations of inorganic phosphate; (3) the stability constant for U(OH) 4 from the LLNL database is much greater than the values found in the other databases (by four orders of magnitude) and needs to be replaced; (4) the MINTEQ, LLNL, and WATEQ4F databases need updating for many important uranium species including Ca 2 UO 2 (CO 3) 3 , UO 2 (H 2 AsO 4) 2 and all the organic uranium species, and (5) the MINTEQ database does not include U(IV)‑bromine, U(IV)‑iodine or U(IV)-nitrate complexes, while the other databases do not include U(IV)-phosphate complexes. A case study of the water chemistry in a phosphate mining region of China, including river water from close to a fertilizer plant, indicates that the calculated uranium speciation varies greatly between the different databases. In particular, the existence and stability of the UO 2 (HPO 4) 2 2− species needs confirmation and quantification including supporting spectroscopic measurements. Although the stability of the stronger bioavailable uranyl-phosphate complexes remains uncertain, the available thermodynamic data suggests that the proportion and toxicity of most uranyl-phosphate complexes will be negligible when the pH exceeds 8.5 and the inorganic phosphate concentration (as PO 4 3−) is <2 mg/L. • Stability constants of aqueous uranium species of six thermodynamic databases available were investigated and compared. • ThermoChimie and two other databases are recommended for most waters except those with high inorganic phosphate. • Most uranyl phosphate complexes are negligible when pH exceeds 8.5 for water with phosphate (as PO 4 3–) is ≤ 2 mg/l. [ABSTRACT FROM AUTHOR]

The contemporaneous mafic and intermediate dikes of a continental magmatic arc provide a window into the magma feeding system at depth. Here we integrate data on the elemental and Sr-Nd-Hf isotope geochemistry, petrology, mineralogy, and zircon geochronology of late Permian dikes in the East Kunlun Orogen, northern Tibetan Plateau, discuss the petrogenesis of the dikes, and reconstruct the nature and relationship of different magma reservoirs. The dikes are porphyritic diabases, lamprophyres and diorite porphyries that crystallized between 259 and 255 Ma, coeval with their host granodiorites. Geochemical and Sr-Nd-Hf isotopic data indicate the parental magma of the porphyritic diabases and lamprophyres was derived from enriched lithospheric mantle. This magma underplated the crust and underwent varying degrees of magma recharging, crustal assimilation, and fractional crystallization dominated by olivine, pyroxene, and hornblende. This evolved basaltic magmas ascended through the crust, undergoing further differentiation, and some magma entered mid-crustal reservoirs occupied by felsic crystal mushes, rejuvenating the mushes. The subsequent mixing of mafic and felsic materials formed the precursor magmas of the intermediate dikes. Our new data reveal that the magmas stagnated mainly in reservoirs at two levels, 26–32 and 9–18 km, based on hornblende barometry. The underplating, assimilation, and replenishment of basaltic magmas in the lower crust, and their eventual emplacement and differentiation in a mid-crustal reservoir, controlled the mineralogy and geochemistry of the mafic dikes, while the rejuvenation of crystal mushes, the mixing of mafic and felsic materials, and differentiation account for the compositional features of the diorite porphyries. This study shows that the trans-crustal magma feeding system, which controls the compositions of several dispersed but interconnected magma reservoirs, is the key to understanding the compositional diversity and igneous petrogenesis in continental arcs. • Intermediate-mafic dikes in the EKOB were coevally formed at ca. 259–255 Ma. • Magma reservoirs stagnated at two different depths were identified. • Multiple magma processes controlled the compositional diversity of dike swarms. • Mush rejuvenation and magma mixing played key role in magma feeding system. [ABSTRACT FROM AUTHOR]

• Neoproterozoic I- and A-type granites were identified in the Yili Block, CAOB. • Transition from syn-collision to post-collisional extension occurred at ca. 890 Ma. • Reworking controlled the early Neoproterozoic crustal evolution in the Yili Block. • The Precambrian evolution of the Yili Block is distinct from that of the Tarim Craton. The Yili Block in NW China and NE Kazakhstan is a continental fragment within the Central Asian Orogenic Belt (CAOB). We present a systematic study of whole-rock geochemistry, Sr–Nd–Hf isotopic compositions, and U–Pb geochronology of newly identified Neoproterozoic granitic plutons from the southern Yili Block to further constrain the Proterozoic evolution of microcontinents constituting the CAOB. Gneissic, augen, and mylonitized granites yield intrusion 206Pb/238U ages of 947 ± 4 Ma, 889 ± 5 Ma, and 892 ± 5 Ma, respectively. The gneissic granites display affinities to calc-alkaline, weakly peraluminous, magnesian I-type granites (Mg# = 33–34; FeOT/MgO = 3.49–3.59). The augen and mylonitized granites lie on the ferroan, calc-alkaline, highly fractionated A-type granite trend (Mg# = 11–21, FeOT/MgO = 6.52–14.58, SiO 2 > 74 wt%, 10000*Ga/Al = 2.80–3.26). The markedly enriched Sr–Nd–Hf isotopic compositions of the ca. 947 Ma magnesian I-type granites suggest a derivation from ca. 2.0 Ga MgO-rich basement rocks. The varied initial 87Sr/86Sr ratios (0.716530–0.720543), chondrite-like εHf(t) values (−2.11 to 0.72), and differentiated incompatible elements of the ca. 890 Ma A-type granites suggest a derivation from partial melting of ca. 1.8 Ga crustal sources, followed by strong fractional crystallization. The Yili Block probably constituted part of an exterior orogen that developed along the margin of the Rodinia supercontinent during the early Neoproterozoic, undergoing a tectonic transition from syn-collisional to post-collisional extension at ca. 890 Ma. This study reveals that crustal reworking played a key role in Neoproterozoic crustal evolution in the Yili Block and that this block has a tectonic affinity to the Central Tianshan Block but is distinct from the Tarim Craton. [ABSTRACT FROM AUTHOR]

In this study, the loaded diatomite was prepared with Changbai Mountain diatomite as the carrier according to different Fe/Al molar ratios. The structure and adsorption of the above materials were characterized by XRD, SEM, and ICP-OES. The effects of Fe/Al molar ratio, adsorption time, initial concentration of V(V), and the initial pH value of the solution on the adsorption performance of loaded diatomite were explored. The diatomite loaded with Fe/Al compounds could significantly improve the removal efficiency of V(V), and the removal efficiency of loaded diatomite prepared according to a Fe/Al molar ratio of 1:3 was better. Reaction equilibrium time is 24 h and the pseudo second-order kinetic equation can better describe the adsorption kinetic behavior of V(V) on loaded diatomite. When the initial concentration of V(V) increased from 15.85 mg/L to 122.5 mg/L, the unit adsorption capacity and removal rate of V(V) by loaded diatomite increased continuously. The adsorption behavior of V(V) on loaded diatomaceous earth belongs to the chemical adsorption via the multi-molecular layer, which is consistent with the Freundlich isotherm adsorption model. A weak acid environment is beneficial to the adsorption behavior of V(V) on loaded diatomaceous earth and the strong alkaline environment should be avoided. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Au elemental maps show a single Au event instead of multistage mineralization. • Two kinds of sulfur sources in pyrite have been identified. • The core of the zoned pyrite is synsedimentary, whereas the rim is magmatic pyrite. • Au mineralization is likely related to the late magmatic event in Yangshan. Abstract The Yangshan gold ore belt contains a series of sediment-hosted disseminated gold deposits in the southern subzone of the western Qinling orogen. The ore deposits formed in the Middle Devonian carbonaceous clastic-carbonate sequences that underwent strong deformation and low greenschist facies regional metamorphism. The shapes and distribution of the ore bodies are strictly confined by the E-W-trending Anchanghe-Guanyinba thrust fault zone. Pyrite and arsenopyrite are the major Au-carrying minerals. Microthermometric results show that the ore-forming fluids are CO 2 -rich aqueous solutions. The homogenization temperatures range from 221 to 303.5 °C, and salinities range from 2.0 to 7.2 wt% NaCl equiv. These characteristics are consistent with orogenic gold deposit. Noble gas isotopic measurement shows that 3He/4He ratios of pyrite and quartz grains inherited from the mineralized carbonaceous phyllite, ranging from 0.033 to 0.081 Ra, implying that the origins of ore fluids are restricted within the crustal regime. The 40Ar/36Ar ratios range from 434 to 863, indicating 34 to 68% crust-derived radiogenic 40Ar* in the ore fluids. Based on the backscattered electron (BSE) maps of pyrite, three generations (i.e. core, mantle, rim) are distinguished: pre-ore pyrite including framboidal pyrites and the cores of zoned pyrites both in the phyllite and plagiogranite dikes; ore stage pyrites including the middle zones of the three-zoned pyrites in the granitic dikes and the outer zones of the zoned pyrites in the phyllite; post-ore pyrites, i.e. the outermost rims of the zoned pyrites in the dikes. The arsenopyrite in the phyllite has similar texture to the pyrite, and is regarded as the peak of the mineralization due to its highest Au concentrations. High spatial resolution NanoSIMS multi-elemental maps of the pyrites reveal that (i) gold is distributed heterogeneously as lattice-bounded Au in the zoned pyrites with higher Au (As) in the middle zones and lower Au (As) in the inner and outermost zones. No nano-particles of native gold was identified in pyrite; (ii) gold mineralization occurred in a single event instead of multistage ore formation; (iii) gold precipitation event is followed by an overgrown zone with low Au and As concentrations. In situ sulfur isotopes of Au-bearing pyrite identified two types of sulfur sources: one is framboidal pyrite and the barren core of pyrite in the carbonaceous phyllite, which have very negative δ34S values (<−20%); the other is the Au-bearing overgrowth zone of pyrite both from the granitic dike and phyllite, which have higher δ34S values ranging from −7.3 to 1.3%. This result indicates that the barren pyrites have the sulfur isotopic feature of reduction of seawater sulfate, whereas the As-, Au-bearing pyrites are likely derived from a magmatic sulfur contaminated by a sedimentary sulfur. Combining Au concentrations with the corresponding δ34S values in the pyrites reveals that the zones with high Au have lower δ34S values (and vice versa). This coupling relation between Au and S isotope has been also identified in other orogenic and Carlin-type gold deposits. The oxidation of ore fluid is taken as the key for gold precipitation during formation of orogenic gold deposit. However, the oxidation of ore fluids accompanied by the escape of reduced gas (e.g. H 2 S) should result in high Au coupled with high δ34S. Therefore, we propose that the Yangshan gold deposit forms through partitioning aqueous vapor with high Au, As, and lower δ34S from a deep magma chamber under the ore field, which leads to overgrowth of the pre-existing pyrites. Based on the geological features, texture of pyrite, and sulfur isotopic characteristics, we suggested that the Yangshan gold deposits have the characteristics between Carlin-type and orogenic gold deposits. They are the product of the western Qinling orogeny during the Late Triassic. [ABSTRACT FROM AUTHOR]

To clarify the impact of developing world-class REE and V-Ti magnetite mines on the distribution of potentially toxic elements (As, Cd, Co, Cu, Cr, Hg, Ni, Pb, Tl, U, and Zn) in adjacent aqueous sediments, thirty sediment samples from the Anning River and seventeen ore samples from the Panxi Rift of China were investigated. The results from this study suggest the following: (1) Mining activities have resulted in severe pollution of sediment by potentially toxic elements, especially Pb with an average concentration of 213.8 mg/kg, which is much higher than the probable effect concentration (PEC) and background values. (2) Different kinds of mines caused the enrichment of different elements in surface sediments. Heavy to extreme enrichment of Pb (EF = 45) and U (EF = 12) was observed in sediment near the Mianning REE mine, and severe enrichment of Pb (EF = 54), As (EF = 18), Cd (EF = 13) and U (EF = 8) was observed in sediment near the Lugu iron mine. (3) Concentrations of Pb and As in sediment that were extremely higher than the PEC indicate probable toxicity and support the need for further speciation analysis. (4) The joint application of distribution characteristics analysis (DCA) and robust regression (RR) was useful in identifying the source of potentially toxic elements in sediment near mining areas. Distribution characteristics analysis of risk elements can qualitatively suggest outliers, and robust regression can quantitatively identify whether a high concentration of a risk element can be classified as an outlier compared to a reference element. [ABSTRACT FROM AUTHOR]

The article discusses a study on lead isotopic geochemistry of Nuri copper-tungsten-molybdenum (Cu-W-Mo) Deposit and highlights its implications in Shannan Area, Southern Tibet, China. It mentions that ore sulphides of Nuri deposit have the same lead isotopic compositions as magmatic rocks. It states that ore sulphides have localized distributions within Gangdese batholith range. It also mentions that ore-bearing intrusions and ore sulphides have lead isotopic composition.

Cu-Au mineralization is rare in the Jurassic-Early Tertiary batholiths related to the India-Asia collision. Geochemical analysis and U-Pb isotope chronology was carried out on Shuangbujiere biotite hornblende granodiorite from the Zedong area. Zircon grains of the biotite hornblende granodiorite show oscillatory growth zonation and have high Th/U ratios of 1.08-2.39, indicating a magmatic origin for the zircons. Geochrological test yielded a LA-ICP-MS U-Pb age of 51.5±1.0 Ma, suggesting that the emplacement age of the biotite hornblende granodiorite is Early Eocene. The Shuangbujiere biotite hornblende granodiorites have geochemical features characteristic of adakite and are associated with a calc-alkaline metaluminous I-type granite enriched in Sr, high in Mg# (49.6-54.9) and Sr/Y, and depleted in Y and Yb. These results indicate that this intrusion formation may have been associated with crustal thickening caused by the early collision of the Indian and Eurasian Plates. As the process of crustal thickening continued, the heating of the underplated basaltic magma caused the thickened lower crust amphibolite to dehydrate the melt and form a high-K calc-alkaline adakitic melt at about 848°C. Meanwhile, magma mixing of the underplated basaltic melt and high-K calc-alkaline adakitic melt formed a high-Mg# adakite representative of the sys-collisional tectonic setting. [ABSTRACT FROM AUTHOR]

The article describes a bienzyme visual system for aptamer-based assay of Hg(II) at nanomolar levels. The detection scheme is based on the finding that Hg(II) ions captured by aptamer-functionalized magnetic beads are capable of inhibiting the enzymatic activity of uricase and thus affect the formation of HO and the blue product, i.e., oxidized tetramethylbenzidine. This strategy allows for a visual detection of Hg(II) at nanomolar levels without additional amplification procedure. Measuring the absorbance at 650 nm, the logarithmic calibration plot is linear in the concentration range of 0.5-50 nM and the limit of detection (LOD) is 0.15 nM. This is as low as the LOD obtained by atomic fluorescence spectrometry (AFS). The ions K, Mg, Na, Ca, Cu, Zn, Fe, Al, Co, AsO , Ni, Cd and Pb do not have a significant effect on color formation. The method was applied to the analysis of (spiked) river water, lake water, mineral water, tap water and certified reference water samples, and the results agreed well with those obtained by AFS or certified values, with recoveries ranging from 97% to 109%. The relative standard deviation for five parallel detections at a 10 nM Hg(II) level is 5.2%. [ABSTRACT FROM AUTHOR]

Accurate analysis of osmium is important in geochemistry and geochronology. The current osmium analytical methods often suffer from low sensitivity, multi-step extraction, high procedural blank, and severe memory effect. In this work, a highly sensitive and simple method for the determination of osmium in natural waters was developed by coupling inductively coupled plasma-mass spectrometry with photochemical vapor generation. The procedural blank is low due to the needlessness of high concentration strong oxidant. What's more, the memory effect was successfully solved by using 5.0% ammonium hydroxide elution instead of using concentrated inorganic acid or oxidant reagent reported before. The influences of the concentration of nitric acid, the flow rate of carrier gas, the photo irradiation time on osmium detection were investigated. Under optimized conditions, the detection limit was 0.8 pg mL − 1 . A precision of 3.2% (RSD, n = 5) was achieved at a concentration of 1 ng mL − 1 . The accuracy is successfully validated in several natural water samples with spike recoveries from 97% to 106%. The proposed method is sensitive, simple, low blank, and memory effect-free, which has a great potential in relevant geochemistry and geochronology study. [ABSTRACT FROM AUTHOR]

This article describes a nonenzymatic chemiluminescence resonance energy transfer (CRET) system for highly sensitive determination of hydroquinone. It was found that the Co(II)-catalyzed luminescence of luminol in pH 11.5 solution is transferred to CdTe quantum dots (QDs) via a CRET mechanism. Hydroquinone is oxidized by HO to benzoquinone which quenches the fluorescence of the QDs. The enhancement is attributed to the adsorption of Co(II) on the surface of the negatively charged QDs. The CRET system was applied in an assay for hydroquinone that has a detection limit of 0.17 nmol L. The detection limit was lower by factors between 100 and 250,000 than earlier reported methods. The assay was successfully applied to the quantitation of hydroquinone in (spiked) water samples, with recoveries ranging from 95 % to 106 %, and relative standard deviations between 0.5 % and 2.4 %. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Air pollution is becoming increasingly serious along with social and economic development in the southwest of China. The distribution characteristics of particle matter (PM) were studied in Chengdu from 2016 to 2017, and the changes of PM bearing water-soluble ions and heavy metals and the distribution of secondary ions were analyzed during the haze episode. The results showed that at different pollution levels, heavy metals were more likely to be enriched in fine particles and may be used as a tracer of primary pollution sources. The water-soluble ions in PM2.5 were mainly Sulfate-Nitrate-Ammonium (SNA) accounting for 43.02%, 24.23%, 23.50%, respectively. SO42−, NO3−, NH4+ in PM10 accounted for 34.56%, 27.43%, 19.18%, respectively. It was mainly SO42− in PM at Clean levels (PM2.5 = 0~75 μg/m3, PM10 = 0~150 μg/m3), and mainly NH4+ and NO3− at Light-Medium levels (PM2.5 = 75~150 μg/m3, PM10 = 150~350 μg/m3). At Heavy levels (PM2.5 = 150~250 μg/m3, PM10 = 350~420 μg/m3), it is mainly SO42− in PM2.5, and mainly NH4+ and NO3− in PM10. The contribution of mobile sources to the formation of haze in the study area was significant. SNA had significant contributions to the PM during the haze episode, and more attention should be paid to them in order to improve air quality. [ABSTRACT FROM AUTHOR]

• Results of this study indicated that contaminants in soils located in the hills upslope of the slag dump were coal and derivative products, and that these soils are isotopically distinct from downslope deltaic soils. • Contaminants in downslope soils were slag and derivative products from V processing. • The study also demonstrated the use of Pb isotopic tracers in low-to-moderate contaminant levels to predict potential sources, and also indicate that Pb is a viable surrogate to trace potential Cd contamination in a large vanadium titano-magnetite mine region. Concentrations of Pb and Cd in topsoil from 24 locations along the Baguan River near a smelting dump in west Panzhihua were measured using ICP-MS to examine the spatial distributions of these toxic heavy metals. Twenty-one profile samples, 7 from each of 3 locations down to 80 cm, were also analyzed to establish background levels and Pb - Cd correlations. Lead isotopic ratios in all 45 samples and potential sources of soil contamination were determined using MC-ICP-MS. Contamination levels of Pb and Cd in soils from both sides of the river ranged from low to moderate, and the concentrations of Pb and Cd exhibited highly correlated behavior. Results of an isotope-tracer technique determined the number of end-member contaminants and background compositions contributing to the compositions of topsoils. Results of a binary mixing model indicated that contaminants in upslope soils from relatively higher elevations were coal and derivative products, and that these soils are isotopically distinct from downslope soils. Contaminants in downslope soils were slag and derivative products from V processing. Results demonstrate the use of Pb isotopic tracers in low-to-moderate contaminant levels to predict potential sources and Pb is a viable surrogate to trace potential Cd contamination in Panzhihua region. [ABSTRACT FROM AUTHOR]

• Three episodes of magmatism and mineralization occurred at 317–263, 262–235, and 233–202 Ma. • Subduction and collision-related felsic plutonism and volcanism as well as associated mineralization are well defined. • An improved Paleo-Tethyan tectonomagmatic model has been established for TSOB. The Truong Son orogenic belt (TSOB) is part of the eastern Tethyan mineral deposit domain, and preserves a near-complete record of Paleo-Tethyan orogeny-related magmatism and mineralization. By compiling and evaluating the data of plutonic and (sub)volcanic rocks and associated deposits on a regional scale, and combining with new data of typical igneous rocks and mineral deposits, we establish a unified Paleo-Tethyan evolutionary model to help understanding the metallogeny in the TSOB. The geochronological data reveal the felsic magmatism and associated mineralization occurred in Carboniferous–Triassic (ca. 317–202 Ma) with a magmatic lull at ca. 270–263 Ma. Before the lull, most igneous rocks are high-Mg#, sodic, metaluminous I-type granitoids (or volcanic equivalents) with depleted Hf isotopes, which were derived from a juvenile crustal source with significant mantle contribution. After the lull, the igneous rocks (ca. 262–235 Ma) consist of metaluminous I-type granitoids and abundant S-type granitoids with geochemical features of low-Mg#, potassic, peraluminous and enriched Hf isotopes, suggesting their derivation from ancient continental crust without obvious mantle contribution. This magmatic lull corresponds to the tectonic transition from subduction to initial collision, which reasonably accounts for the changing of petrogenetic types and magma sources of the associated igneous rocks in the TSOB. The slightly depleted Hf isotopes of the ca. 234–202 Ma rocks possibly suggest another episode of tectonic transition in Late Triassic. The distinct mineralization styles and S isotopes of ore deposits of each episode indicate that mineralization was related to the tectonic evolution and magmatism in each stage. Here, we propose an evolutionary model for the Paleo-Tethys orogeny in the TSOB, as follows: (1) low-angle subduction beneath the TSOB during Late Carboniferous-Late Permian, favored the formation of juvenile crust-derived adakitic rocks and high-Mg# I-type felsic rocks as well as associated porphyry Cu ± Au, skarn Fe ± Cu ± Au and epithermal Au–Ag mineralization; (2) subsequent collision during Late Permian-Middle Triassic not only accounted for the generation of Precambrian crust-derived I-type granitoids and intrusion-related Au ± Ag deposits, but also resulted in the formation of low-Mg# S-type rocks, minor volcanic rocks and associated porphyry and/or skarn Sn ± Zn ± Pb deposits; (3) possible post-collisional extension during Late Triassic may be favorable for the formation of metaluminous, high-K (±high Mg#) I-type granitoids and volcanic rocks, and Carlin Au, porphyry and/or skarn mineralization. [ABSTRACT FROM AUTHOR]

The article focuses on a research paper analyzing the platinum-group element (PGE) constraint on the origin mechanism of the Hetaoshu PGE deposit in the Xiaoguanhe Region in Panxi Area, China. The concentrations of PGE, copper and nickel in rock samples show that the ore forming elements consists of nickel and copper. It also evaluates the impact of sulfide segregation on the ore-forming process of Hetaoshu deposit.