Guangzhou Institute of Geochemistry
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Associations between anthropogenic heat emissions and serum lipids among adults in northeastern China
No full textFew epidemiological studies have investigated associations between anthropogenic heat emissions (AE) and serum lipids. We recruited 15,477 adults from 33 communities in northeastern China in 2009. We estimated AE flux by using data on energy consumption and socio-economic statistics covering building, transportation, industry, and human metabolism. We assessed the associations between AE and blood lipids and dyslipidemia prevalence using the restricted cubic spline models. The regression coefficients (beta) and the 95% CI of total cholesterol for the 75th and 95th percentiles of the exposure were 0.23 mmol/L (95% CI: 0.15, 0.30) and 0.25 mmol/L (95% CI: 0.18, 0.32). We also found AE was positively associated with dyslipidemia. Participants who were female or who had low incomes exhibited more pronounced associations. Our research showed that exposure to AE was significantly associated with serum lipids. These novel, valuable findings are useful to inform policymakers to estimate the risks to human health from anthropogenic heat
Inhibition Effect of H<sub>2</sub>O on the Heterogeneous Reaction between Isoprene and Fe-Substituted Cryptomelane
No full textThe transportation and transformation of biogenic isoprene are vital for the organic carbon cycle in the troposphere. As a typical mineral with high oxidation potential, Fe-substituted cryptomelane oxidizes the surface monolayer of isoprene into formic and acetic acids, and simultaneously, the Mn4+ ions in the structure are reduced to Mn3+ and Mn2+. The flow of H2O in isoprene decreases the adsorption and oxidation of isoprene significantly, even at low relative humidity (10%). As physisorbed H2O retains Fe-substituted cryptomelane's crystal structure and oxidation ability, the adsorption and oxidation capacity recovers when H2O is absent in the isoprene flow. Theoretical calculations on (001) surfaces show that isoprene prefers to be adsorbed by the Fe3+ site and H2O tends to form hydrogen bonds. Due to the decrease in total adsorption energy of H2O and isoprene, Fe-substituted cryptomelane favors the adsorption of H2O in the flow of humid isoprene. The low oxidation performance at ambient relative humidity suggests that direct oxidation by aerosols of mineral dust might not be the transformation pathway of biogenic isoprene at night
Identification of Hydroxylated Chlorinated Paraffins in Human Serum and Their Potential Metabolic Pathways
No full textShort- and medium-chain chlorinated paraffins (SCCPs and MCCPs) are frequently detected in humans. However, information regarding their metabolites is still very limited. Herein, target analysis and halogenation-guided nontarget and suspect screening were conducted on serum samples using UHPLC-Orbitrap-HRMS. The median concentrations of SCCPs and MCCPs were 7.76 and 4.31 ng/mL, respectively. A series of hydroxylated chlorinated paraffins (OH-CPs) were tentatively identified with an estimated average concentration of 1.80 ng/mL, which was approximately 9.9% of the total SCCPs and MCCPs. A chlorine distribution shift was observed from chlorinated paraffins (CPs) dominated by Cl6 and Cl7 to OH-CPs dominated by Cl5, Cl6, and Cl4. In human liver cytochrome P450 (CYP) enzyme incubation assays, the CPs in commercial mixtures were mainly metabolized into OH-CPs with various carbon lengths and chlorine substituents. The results obtained from human serum and in vitro experiments suggested the oxidative metabolism of SCCPs and MCCPs in humans. The metabolic pathways were then comprehensively explored using a CP monomer (1,1,1,3,10,11-hexachloroundecane) incubated with the same CYP enzymes, demonstrating that CPs can be metabolized through successive oxidative dechlorination and direct hydroxylation, with subsequent oxidation to carboxylic acids. Further studies should focus on the long-term toxicity of OH-CPs
Molybdenum isotope evidence for subduction-modified mantle beneath mid-ocean ridges
No full text"Ghost" arc geochemical signatures persistently occur in mid-oceanic ridge basalts (MORBs), yet their origin remains elusive. Here, we identified arc-like heavy Mo isotopic compositions in basalts from the St. Helena plume-influenced southern Mid-Atlantic Ridge. Their heavy Mo isotopic signature (delta 98/95Mo = -0.21 %o to +0.11 %o), along with relatively low (La/Sm)N, Nb/Zr, Ce/Pb, and Sr-Nd isotope ratios, cannot be explained by interactions of the depleted mantle with recycled crustal or lithospheric mantle materials or the influence of the St. Helena plume on their mantle source. By integrating seismic tomographic images and plate reconstruction models, we interpret these unique geochemical and heavy Mo isotopic signatures to reflect the inputs of fluidmodified mantle produced during the Mesozoic subduction beneath the southwestern Gondwana convergent margin. Our discovery provides crucial evidence for the role of the paleo-subduction-modified mantle in shaping present-day MORB-mantle heterogeneity and sheds light on the formation of ghost-arc signatures in global MORBs
Examining the reliability of current micro-and nano-indentation-based rock mechanical upscaling schemes: a comprehensive comparison with uniaxial/triaxial macroscopic mechanical testing
No full textShale and marlstone are two typical rocks for gas reservoirs and caprocks for the underground storage of carbon dioxide. Accurately estimating their mechanical properties is challenging due to these rocks' multiphase and multiscale structures. In this study, we conducted triaxial compressive, microindentation, and nanoindentation tests on samples collected in a borehole to investigate Young's modulus at different scales. To upscale the mechanical properties, we utilized existing homogenization models, namely Mori-Tanaka (MT), Self-Consistent (SC), and Voigt-Reuss-Hill average (VRH), and compared the moduli upscaled from the nanoindentation technique and rock mineralogical method with those measured from microindentation and triaxial compressive tests. Results showed that the rock mineralogy-based MT and SC methods produced higher moduli than the nanoindentation-based MT method, and all of these were significantly larger than those obtained from the triaxial compressive tests. Additionally, the nanoindentation-based VRH method and the microindentation test yielded close moduli but still exhibited a certain gap compared to the macroscopic mechanical test results. This suggests that the current indentation-based mechanical upgrading method cannot accurately estimate the rock mechanics at the macroscale. Nevertheless, in the absence of a better solution, the above two methods can still be considered. The difference between the moduli measured by the compressive test and those upscaled through these homogenization models was attributed to the underestimation caused by the low elastic stiffness of pores, fractures, and grain contacts in the rocks. Therefore, more advanced methods are required to develop to make mechanical upscaling closer to the real situation of rocks
Mechanistic insights into highly efficient oxygenation of 5-hydroxyme-thylfurfural to 2,5-furandicarboxylic acid over natural sepiolite-supported bimetallic PdAu catalysts
No full textThe oxygenation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is an important reaction for the production of value-added chemicals from biomass. However, developing highly efficient and stable catalysts for this process remains challenging. Sepiolite (Sep)-supported bimetallic PdAu catalysts were prepared for the selective oxygenation of HMF to FDCA. 1Pd1Au4/Sep catalyst exhibited the highest catalytic activity, reaching 100 % HMF conversion and 97 % FDCA yield after 10 min, with outstanding formation rate of FDCA of 2560.72 mmol center dot g- 1 center dot h- 1. This excellent catalytic performance is attributable to rich surface active sites on PdAu/Sep. High specific surface area and special porous structure of Sep can enable its unique adsorption capacities for reactants. Importantly, there are oxygen vacancies (Ov) on surface of Sep, which promotes the activation of O2. What's more, the metal catalytically active sites of PdAu alloy nanoparticles efficiently facilitated the oxygenation of HMF to FDCA. In particular, the kinetic results further reveal that the synergistic effects between Pd and Au accelerated the oxidation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). Additionally, the 1Pd1Au4/Sep catalyst had high stability and reusability, without loss of activity after five runs. This study reveals the catalytic mechanisms of the Sep-supported PdAu catalysts for the efficient oxygenation of HMF to FDCA
Evolution of alkaline magmas and enrichment of rare earth elements: Insights from the geochemistry of apatite in the Saima alkaline igneous complex, Liaodong Peninsula, China
No full textRare earth element (REE) mineralization related to alkaline magmas is an important source of REEs, and some deposits are enriched in heavy REEs (HREEs). However, the mechanisms of HREE enrichment in alkaline igneous rocks are unclear. In this study, we conducted petrographic, U-Pb geochronological, and in situ elemental and isotopic analyses of apatite in the Saima alkaline igneous complex, Liaodong Peninsula, China, the aim was to constrain the HREE geochemical behavior during alkaline magma evolution. The Saima complex consists of hornblende-pyroxene syenite, biotite syenite, syenite, nepheline syenite, and lujavrite (in order of magmatic evolution). Apatite U-Pb geochronology has yielded Late Triassic (hornblende-pyroxene syenite: 223 f 5 Ma; biotite syenite: 220 f 3 Ma; syenite: 219 f 6 Ma; nepheline syenite: 219 f 10 Ma) ages. Apatite in the hornblende-pyroxene syenite, biotite syenite, and syenite has similar geochemical compositions and textures, contains melt inclusions, and is classified as type I apatite that formed in a purely magmatic system. Two types of apatite occur in the nepheline syenite. The type II apatite has high Sr/Y and non-chondritic Y/Ho ratios, contains melt inclusions and scarce fluid inclusions, and is formed in a H2O-saturated magmatic system. The type III apatite is characterized by abundant fluid inclusions and has higher Sr contents, Th/U ratios, and 147Sm/144Nd ratios than the other apatite types. It has lower light REE (LREE) contents and higher HREE contents as compared with the type II apatite and is formed by the reaction of type II apatite with Cl-rich fluids. The calculated REE patterns of the equilibrium melt, based on Dapatite- melt values, are different from the corresponding whole-rock geochemical data. This finding, combined with the results of a Rayleigh fractionation model, indicates that a crystal mush accumulation model can explain the generation of the Saima complex. The enrichment of volatile components (e.g., H2O) and crystal accumulation during the evolution of the magma mush were key controls on the anomalous HREE enrichment in the evolved rocks of the complex
Coexisting hematite induces and accelerates the transformation of ferrihydrite: Pathway and underlying mechanisms
No full textCrystallization induced by heterogeneous surfaces is an important process in geochemistry, biomineralization, and material synthesis, but the effects of heterogeneous surfaces on the transformation of metastable phases into new crystals remain poorly understood. In this work, we studied the transformation behaviors of ferrihydrite (Fhy) in the presence of hematite (Hem) nanoplates with specific exposed facets ({001} and {113}) at different pH (4, 7, and 12). Our results reveal that the Hem nano-plates can induce the transformation of Fhy to Hem/Gth (goethite) and accelerate the transformation rate. This effect is primarily achieved by modulating the dissolution-recrystallization process, i.e., accelerating the dissolution of Fhy and promoting the heterogeneous crystallization (to form new Hem/Gth) at the surface of added Hem nanoplates, and solution pH plays a crucial role in these processes. Specifically, a relatively low supply of dissolved Fe3+ from Fhy at pH 4 favors island growth of new Hem at the {001} facets of Hem nanoplates and layer-by-layer growth at the {113} facets, which eventually results in the formation of thermodynamically stable pseudo-cubic morphology (exposing {012} facets). Because of the very low solubility of Fhy at pH 7, the induced transformation of Fhy by Hem nanoplates is relatively weak. While at pH 12, a high supply of dissolved Fe3+ from Fhy benefits the layer-by-layer growth at {001} facets of Hem and the significant heteroepitaxial growth of Gth at the {113} facets. Besides the induced transformation, the direct solid-state transformation of Fhy into Hem and the homogeneous crystallization of dissolved Fe3+ also contribute to the transformation of Fhy. This study reveals the mechanisms of induced transformation of Fhy in the presence of Hem nanoparticles, which will advance our understanding of the significant effects of heterogeneous surfaces in modulating metastable phases and supplement the transformation mechanisms of Fhy
On using an aerosol thermodynamic model to calculate aerosol acidity of coarse particles
No full textThermodynamic modeling is still the most widely used method to characterize aerosol acidity, a critical physicochemical property of atmospheric aerosols. However, it remain unclear whether gas-aerosol partitioning should be incorporated when thermodynamic models are employed to estimate the acidity of coarse particles. In this work, field measurements were conducted at a coastal city in northem China across three seasons, and covered wide ranges of temperature, relative humidity and NH3 concentrations. We examined the performance of different modes of ISORROPIA-II (a widely used aerosol thermodynamic model) in estimating aerosol acidity of coarse and fine particles. The M0 mode, which incorporates gas-phase data and runs the model in the forward mode, provided reasonable estimation of aerosol acidity for coarse and fine particles. Compared to M0, the M1 mode, which runs the model in the forward mode but does not include gas-phase data, may capture the general trend of aerosol acidity but underestimates pH for both coarse and fine particles; M2, which runs the model in the reverse mode, results in large errors in estimated aerosol pH for both coarse and fine particles and should not be used for aerosol acidity calculations. However, M1 significantly underestimates liquid water contents for both fine and coarse particles, while M2 provides reliable estimation of liquid water contents. In summary, our work highlights the importance of incorporating gas -aerosol partitioning when estimating coarse particle acidity, and thus may help improve our understanding of acidity of coarse particles. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V
Meteorological effects on sources and future projection of nitrogen deposition to lakes in China
No full textLake ecosystems are extremely sensitive to nitrogen growth, which leads to water quality degradation and ecosystem health decline. Nitrogen depositions, as one of the main sources of nitrogen in water, are expected to change under future climate change scenarios. However, it remains not clear how nitrogen deposition to lakes respond to future meteorological conditions. In this study, a source-oriented version of Community Multiscale Air Quality (CMAQ) Model was used to estimate nitrogen deposition to 263 lakes in 2013 and under three RCP scenarios (4.5, 6.0 and 8.5) in 2046. Annual total deposition of 58.2 Gg nitrogen was predicted for all lakes, with 23.3 Gg N by wet deposition and 34.9 Gg N by dry deposition. Nitrate and ammonium in aerosol phase are the major forms of wet deposition, while NH 3 and HNO 3 in gas phase are the major forms of dry deposition. Agriculture emissions contribute to 57% of wet deposition and 44% of dry deposition. Under future meteorological conditions, wet deposition is predicted to increase by 5.5% to 16.4%, while dry deposition would decrease by 0.3% to 13.0%. Changes in wind speed, temperature, relative humidity (RH), and precipitation rates are correlated with dry and wet deposition changes. The predicted changes in deposition to lakes driven by meteorological changes can lead to significant changes in aquatic chemistry and ecosystem functions. Apart from future emission scenarios, different climate scenarios should be considered in future ecosystem health evaluation in response to nitrogen deposition. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V