Guangzhou Institute of Geochemistry
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Lithium isotope and mercury evidence for enhanced continental weathering and intense volcanism during the Ordovician-Silurian transition
No full textThe Ordovician-Silurian transition (OST) was characterised by climatic fluctuations (warming in the Katian and glaciation in the Hirnantian) and mass extinctions. However, the mechanisms driving the climatic and biological variability remain under debate. In order to reveal the relationships between volcanism, climate, and continental weathering, we measured lithium (Li) isotopes and mercury (Hg) concentrations in a carbonate-dominated marine section from South China. The reconstructed S7Liseawater values were generally 21 %o during the Ordovician-Silurian transition, with negative excursions towards 16 %o in the latest Katian and the latest Hirnantian intervals. We infer that changes in continental weathering affected dissolved riverine Li fluxes and S7Li values, and thereby exerted a major control on the seawater S7Li variations, while changes in temperature that influenced isotope fractionation during weathering and reverse weathering exerted a secondary control. In the Late Katian, intense volcanic activity (high Hg/TOC ratios and low S13C values) likely initiated the climatic warming (late Boda warming), which was sustained by enhanced clay formation (S7Liseawater values of 21 %o). The intense volcanism also contributed to the high primary productivity and expansion of ocean anoxia, accounting for the Katian extinction. In the latest Katian and latest Hirnantian, enhanced and more congruent weathering (S7Liseawater values of 16 %o) likely contributed to the initiation of global cooling and further glaciation. Meanwhile, the weathering-induced expansion of euxinic seawater could have driven the Late Ordovician Mass Extinction (LOME) events. During the Hirnantian glacial intervals, decreased and incongruent weathering could have contributed to reduced CO2 drawdown, ultimately allowing warming and climatic recovery. Overall, the climatic fluctuations during the OST were related to changes in continental weathering, while the multiphase biotic extinctions could be attributed to volcanism and/or weathering-induced oceanic anoxia
Evaluating Heavy Metal Contamination in Water and Tissues of <i>Tor putitora</i>: Implications for Human Health Risk Assessment
No full textAnthropogenic activities have led to the release of heavy metals, posing significant threats to both aquatic ecosystems and human health. This study focused on evaluating the concentrations of Chromium (Cr), Nickel (Ni), Zinc (Zn), Cadmium (Cd), and Lead (Pb) in water and Tor putitora fish along the River Kabul in Pakistan, considering upstream and downstream sites with varying anthropogenic influences. Our analysis revealed detectable levels of all studied heavy metals at both sites, with concentrations surpassing the permissible limits set by the World Health Organization (WHO), with except for Zinc. At Site-1, average concentrations (mg L- 1) were: Cr 1.46 +/- 1.03, Ni 1.61 +/- 0.53, Zn 0.65 +/- 1.09, Cd 0.23 +/- 0.28, and Pb 0.75 +/- 0.07, while Site-2 values were: Cr 1.57 +/- 0.03, Ni 1.54 +/- 0.94, Zn 1.55 +/- 0.98, Cd 1.12 +/- 0.46, and Pb 1.47 +/- 0.82. Analysis of Tor putitora fish indicated significant metal concentrations, particularly in metabolically active tissues such as the kidney and liver, with Cr showing significant accumulation across all tissues and Cd exhibiting the lowest accumulation. Notably, muscle, a less metabolically active tissue, demonstrated the lowest metal accumulation. Evaluation of the Target Hazard Quotient and Hazard Index revealed no considerable risk for non-carcinogenic effects. However, in Site-1, Pb exhibited a carcinogenic risk surpassing the acceptable threshold (< 1 x 10(- 4)), suggesting an elevated cancer risk associated with consuming Tor putitora. These findings emphasize the urgent need for comprehensive environmental policies in developing countries to address long-term heavy metal pollution and safeguard both ecosystems and human health
Pegmatite lithium deposits formed within low-temperature country rocks
No full textThe global climate crisis is likely to lead to a potential supply risk of lithium (Li) over the coming decades. More than half of the world's production of Li is derived from Li-bearing pegmatites. Although pegmatites are widespread, only a small fraction host economically relevant Li mineralization. Revealing which factors cause some pegmatites to be enriched in Li and others to be barren is critical for understanding Li pegmatite formation and for guiding exploration for new Li resources. In this study, we used an approach involving the analysis of natural samples from the Jiajika pegmatite deposit (China), combined with thermal and diffusion modeling. Here we show that Li contents in pegmatites are controlled not only by the initial Li contents in pegmatite melts but also by the temperature of the surrounding country rocks at the time of pegmatite emplacement. Lithium-mineralized pegmatites form preferentially when Li-rich pegmatite melts intrude low-temperature country rocks
Protracted post-eruptive basaltic weathering of the Emeishan large igneous province constrained by U-Pb CA-ID-TIMS geochronology
No full textThe post eruptive basaltic weathering of the Emeishan large igneous province is proposed to cause early Wuchiapingian cooling globally. However, the endpoint of this cooling event has not been evaluated yet, preventing the further understanding of long-term interaction between climate and weathering. In this study, abundant thick and highly weathered basaltic paleosols at the Emeishan volcanic landscapes have been identified, providing direct evidence for intense post-eruptive basaltic weathering. By using CA-TIMS zircon U-Pb dating on paleosols and adjacent tuffs, the onset and the termination of the intense weathering are constrained to similar to 259.6 Ma and similar to 253.4 Ma, respectively. The onset of intense weathering is coincident with the early Wuchiapingian cooling, supporting the CO2-forced cooling model triggered by the post-eruptive basaltic weathering of the Emeishan large igneous province. Moreover, the temporal correlation between the long-term weathering and the paleoclimate and carbon isotope records indicate that this cooling is possible persisting until at similar to 253.4 Ma
Coupled effects of iron (hydr)oxides and clay minerals on the heterogeneous oxidation of aqueous Mn(II) and crystallization of manganese (hydr)oxides
No full textThe formation of nanominerals and mineral nanoparticles (NMMNs) has drawn broad attention due to their high reactivity and omnipresence in the environment. While the heterogeneous formation of NMMNs on surfaces of various minerals has been extensively studied, there is limited understanding of how mineral heteroaggregates influence this process. In this study, we investigated how heteroaggregates of iron (hydr)oxides and clay minerals affect the heterogeneous oxidation of aqueous Mn(II) and crystallization of manganese (hydr)oxides (MnOx). Our results revealed that iron (hydr)oxides (ferrihydrite) and clay minerals (kaolinite or montmorillonite) in heteroaggregates exerted coupled effects on these processes, dictating the distribution of Mn and the morphology of MnOx. Specifically, ferrihydrite catalyzed gradual oxidative removal of Mn(II) and triggered MnOx nucleation; in contrast, kaolinite/montmorillonite rapidly adsorbed Mn(II) but hardly catalyzed its oxidation. These reactions collectively resulted in fast adsorption and gradual oxidation of Mn(II) on the heteroaggregates. Further, MnOx nanoparticles formed on ferrihydrite surfaces migrated to kaolinite/montmorillonite surfaces, leading to interactions between MnOx and various component minerals within the heteroaggregates. This significantly altered the subsequent growth pathways and the eventual morphology of MnOx. Consequently, while MnOx nanoparticles in the ferrihydrite-only system aggregated freely and formed well-extended nanowires, those in the ferrihydrite-kaolinite system predominantly became short nanorods due to the immobilization by kaolinite surfaces; in the ferrihydrite-montmorillonite system, considerable MnOx nanoparticles attached to montmorillonite surfaces due to strong electrostatic attraction, and subsequently grew into blocky particles via particle attachment. These findings illustrate that surface reactivities of heteroaggregated ferrihydrite and kaolinite/ montmorillonite are coupled when they interact with aqueous Mn(II) or MnOx. Our work exemplifies, for the first time, the cooperation between surfaces of various minerals during the heterogeneous formation of NMMNs. Findings from this study also enhance our understanding of MnOx formation on surfaces with diverse atomic structures, and contribute to the knowledge of Mn cycling in the environment
Valorization of alcohol industry residues into solid, gaseous and liquid biofuels: A comprehensive review
No full textAlcohol industry residues (AIRs) are typical organic solid wastes from a major light industry while belong to renewable biomass resource, and their annual accumulation amount is significant and rapidly increasing worldwide. The clean and efficient utilization of AIRs is urgently needed, driving the development of valorization technologies with the waste-to-energy strategy which is considered as the most practical and sustainable method. In recent decades, significant attention has focused on unlocking the energy potential of AIRs. However, current technologies face significant challenges in producing desirable biofuels from AIRs in an eco-friendly, carbon- neutral, and economically efficient manner, credit to the restriction of their unfavorable properties such as high initial moisture, nitrogen, and oxygen contents. In this review, the energy valorization of AIRs using thermo- and bio-chemical conversion technologies is comprehensively reviewed and compared. The preparation methods, properties, and thermal use of various biofuels are systematically summarized. Low or medium-temperature hydrothermal technology demonstrates significant advantages in converting AIRs into desired biofuels, either as a pretreatment or preparation method. This strategy can produce modified solid biofuel by upgrading and denitrogenating capabilities, and improve biogas and bioethanol yields through boosted hydrolysis reactions. Combining hydrothermal with other conversion methods would be a promising research avenue for valorizing AIRs into energy, enabling the poly-generation of targeted biofuels by selectively regulating the evolution of specific elements. This review can offer an overview and insights into effectively managing and utilizing AIRs for researchers in the field
Paleozoic tectonothermal history of the amalgamation of the Tarim-North China and Mongolian collages
No full textIn the Mongolian Collage, metamorphic pressure-temperature (P-T) and timing reveal a one-stage evolution defined by a duality of late Neoproterozoic-Ordovician subduction-related low T/P metamorphism and suprasubduction high T/P metamorphism recorded in the Mongolia-Manchuria and Baikal-Sayan belts. This was followed by gradual prevalence of suprasubduction high T/P metamorphism towards the late Paleozoic corresponding to the Altai and South Altai cycles. In the Tarim-North China Collage, metamorphic P-T and timing reveal a two-stage evolution, from dominant intermediate T/P metamorphism possibly resulting from Ordovician-Devonian amalgamation and Andean-type evolution of the collage, to dual low and high T/P metamorphism in the Carboniferous-Permian reflecting subduction-collision processes along the South Tianshan suture in the west and a suprasubduction evolution along the Solonker suture in the east. Altogether, the Paleozoic tectonometamorphic evolution of the two collages in the Central Asian Orogenic Belt shows remarkable differences, with the Mongolian Collage displaying features typical of peripheral accretionary style reflecting recurrent tectonic switches that can be regarded as a single orogenic system, and a two-stage evolution of the Tarim-North China Collage with features of both peripheral-accretionary and interior-collisional orogenic cycles, but mostly related to recurrent subductions of interior oceans
Crystallinity and dissolution-recrystallization mechanism controlled As(V) retention by calcium phosphate
No full textRetention of toxic metals/metalloids like arsenic via mineral-water interaction plays a crucial role in the environmental behavior of pollutants. However, the influence of mineral crystallinity on the retention of toxic elements, the evolution of liquid composition, and the interaction mechanism are poorly understood. This study investigated the interaction between As(V) and calcium phosphate (CaP) under oxic conditions with varying crystallinities, particularly amorphous CaP (ACP), across varying As(V) concentrations and pH conditions. Results revealed that the amorphous phase substantially influenced As(V) fate, with the As(V) retention potential of ACP and poorly crystalline hydroxylapatite (HAP) being 13.65 and 12.61 times higher than highly crystalline HAP, respectively. As(V) retention involves the dissolution of ACP and the recrystallization of As(V)-substituted HAP, correlated with three distinct ACP transformation stages during recrystallization. The lower pH (7.5) facilitated ACP dissolution, and the elevated Ca2+ concentration enhanced the volume of CaP recrystallization. Conversely, higher pH levels (8.0, 8.5, and 9.0) promoted a higher degree of recrystallization, evidenced by reduced residual Ca2+ levels after 48 hrs (post-crystallization stage). Meanwhile, As-bearing CaP forms with greater competition between PO43-and AsO43- at higher initial As(V) concentrations than lower ones. Addi- tionally, lattice distortion, increases in species of surface bond groups, and reduced crystallinity were observed in the As(V)-bearing CaP product. Overall, this study underscores the pivotal role of ACP and its poorly crystalline counterparts in arsenic retention through the dissolution-recrystallization mechanism
Effects of solvent extraction on pore structure properties and oil distribution in shales of alkaline lacustrine basins
No full textShale contains numerous nano-scale pores, whose pore structure property changes affect petroleum flow, complicating shale oil accumulation and exploration. Twelve shale samples from the Permian Fengcheng Formation in the Mahu Sag and the Permian Lucaogou Formation in the Jimusar Sag in northwestern China were analyzed to investigate the coupled oil distribution and pore structure in shales from alkaline lacustrine basins. Shale samples were comprehensively analyzed before and after solvent extraction using X-ray diffraction, total organic carbon measurement, Rock-Eval analyses, field emission-scanning electron microscopy, nitrogen physisorption (NP), and (ultra) small-angle X-ray scattering [(U)SAXS] to assess nanoscale pore structure (2-300 nm in diameter) and oil distribution. Solvent extraction increased total pore volume and specific surface area (SSA). However, the accessibility of nanoscale pores remains limited. Additionally, even after retained oil removal, (U) SAXS-derived total pore volumes are 1-10.4 times larger than NP-derived connected pore volumes. Complex variations in pore volume and SSA mainly result from the removal of extractable organic matter (EOM) and the refilling of small pores by organic matter. Despite the relatively small pore volume of mesopores (2-50 nm), the amount of EOM distribution in mesopores is comparable to that in macropores (50-300 nm); therefore, it is crucial not to overlook the retention capacity of mesopores for EOM. Macropores, particularly interparticle pores associated with quartz and feldspar, play a crucial role in oil mobility. The quantity and composition of EOM, along with other factors, can alter pore structure before and after solvent extraction and should be considered in evaluating the distribution and content of free oil
Monsoon-regulated marine carbon reservoir effect in the northern South China Sea
No full textThe ubiquitous marine radiocarbon reservoir effect (MRE) constrains the construction of reliable chronologies for marine sediments and the further comparison of paleoclimate records. Different reference values were suggested from various archives. However, it remains unclear how climate and MREs interact. Here we studied two pre-bomb corals from the Hainan Island and Xisha Island in the northern South China Sea (SCS), to examine the relationship between MRE and regional climate change. We find that the MRE from east of Hainan Island is mainly modulated by the Southern Asian Summer Monsoon-induced precipitation (with 11.4% contributed to seawater), rather than wind induced upwelling. In contrast, in the relatively open seawater of Xisha Island, the MRE is dominated by the East Asian Winter Monsoon, with relatively more negative (lower) Delta R values associated with high wind speeds, implying horizontal transport of seawater. The average SCS Delta R value relative to the Marine20 curve is -161 +/- 39 14C years. Our finding highlights the essential role of monsoon in regulating the MRE in the northern SCS, in particularly the tight bond between east Asian winter monsoon and regional MRE