Guangzhou Institute of Geochemistry
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Electron transfer mediated photo-Fenton-like synergistic catalysis of Fe, Cu-doped MIL-101 coupled with Ag 3 PO 4: Quantitative evaluation and DFT calculations
No full textWidespread use of tetracycline (TC) results in its persistent residue and bioaccumulation in aquatic environments, posing a high toxicity to non -target organisms. In this study, a bimetal -doped composite material Ag 3 PO 4 / MIL-101(Fe,Cu) has been designed for the treatment of TC in aqueous solutions. As the molar ratio of Fe/Cu in composite is 1:1, the obtained material AP/MFe 1 Cu 1 is placed in an aqueous environment under visible light irradiation in the presence of 3 mM peroxydisulfate (PDS), which forms a photo -Fenton -like catalytic system that can completely degrade TC (10 mg/L) within 60 min. Further, the degradation rate constant (0.0668 min - 1 ) is 5.66 and 7.34 times higher than that of AP/MFe and AP/MCu, respectively, demonstrating a significant advantage over single metal -doped catalysts. DFT calculations confirm the strong adsorption capacity and activation advantage of PDS on the composite surface. Therefore, the continuous photogenerated electrons ( e - ) accelerate the activation of PDS and the production of SO 4 center dot- , resulting in the stripping of abundant photogenerated h + for TC oxidation. Meanwhile, the internal circulation of Fe III /Fe II and Cu II /Cu III in composite also greatly enhances the photo -Fenton -like catalytic stability. According to the competitive dynamic experiments, SO 4 center dot- have the greatest contribution to TC degradation (58.93%), followed by 1 O 2 (23.80%). The degradation intermediates (products) identified by high-performance liquid chromatography -mass spectrometry (HPLC/MS) technique indicate the involvement of various processes in TC degradation, such as dehydroxylation, deamination, N-demethylation, and ring opening. Furthermore, as the reaction proceeds, the toxicity of the intermediates produced during TC degradation gradually decreases, which can ensure the safety of the aquatic ecosystem. Overall, this work reveals the synergy mechanism of PDS catalysis and photocatalysis, as well as provides technical support for removal of TC-contaminated wastewater
Evolution of Arc-Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central-Southern Palawan
No full textThe evolution of arc-continent collision between the Palawan microcontinental block and the Cagayan Ridge in the southeastern margin of the South China Sea (SCS) is vital to understand how this collision correlated with seafloor spreading of the SCS. To address the evolution of arc-continent collision, we studied the biostratigraphy and provenance of syn-collisional sediments in the Isugod Basin in central-southern Palawan. Microfossil analysis indicates a Late Miocene age (11.5-5.6 Ma) for the Isugod and Alfonso XIII Formations and rapid subsidence during initiation of the basin which may have been triggered by local extensional collapse of the wedge in response to forearc uplift. Multidisciplinary provenance analysis reveals that the Isugod and Alfonso XIII Formations were derived from the Middle Eocene-lower Oligocene Panas-Pandian Formation on the Palawan wedge and the Late Eocene Central Palawan Ophiolite. These results suggest the emergence of both the orogenic wedge and obducted forearc ophiolite at similar to 11.5 Ma, implying collision onset before similar to 11.5 Ma. The collision initiation in Palawan could be better constrained to similar to 18 Ma, based on the drowning of the Nido carbonate platform in the foreland. Therefore, the gravitational collapse of the Palawan wedge and the subsidence/formation of the Isugod Basin might reflect a significant uplift pulse in the hinterland of the wedge beginning within 13.4-11.5 Ma in the late stage of collision. It indicates that although compression originated from spreading of the SCS had ceased at 16-15 Ma, arc-continent collision in Palawan did not stop and was sustained by compression from the upper plate afterward.
The Palawan microcontinental block is a continental fragment separated from the South China margin along with the seafloor spreading of the South China Sea (SCS). It finally collided with the Cagayan Ridge volcanic arc because of southward subduction of the Proto-SCS. Therefore, precisely constraining the evolution of arc-continent collision could help us to understand its association with the ending of the SCS spreading. To constrain the evolution of arc-continent collision, we determined the depositional age and source of syn-collisional sediments in the Isugod Basin in central-southern Palawan. Our results shows that the Isugod Basin sediments were deposited during the Late Miocene (11.5-5.6 Ma) following local gravitational collapse of the Palawan orogenic wedge driven by uplift and oversteepening. Isugod Basin sediments were eroded from both the orogenic wedge and obducted forearc ophiolite that were uplifted and exposed subaerially, indicating collision began before similar to 11.5 Ma. As the onset of collision could be constrained to similar to 18 Ma, we propose a significant uplift pulse in the hinterland of the wedge began at 13.4-11.5 Ma in the late stage of collision. This further indicates that arc-continent collision in Palawan did not stop although compression derived from spreading of the SCS had ceased at 16-15 Ma.
Sediments in the Isugod Basin were deposited at 11.5-5.6 Ma following local gravitational collapse of the Palawan wedge driven by uplift The Isugod Basin sediments were supplied by erosion of the Palawan wedge and obducted forearc ophiolite exposed subaerially since similar to 11.5 Ma Onset of Palawan arc-continent collision at similar to 18 Ma followed by a significant uplift pulse in the Palawan wedge beginning within 13.4-11.5 M
Evolution of Arc-Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central-Southern Palawan
No full textThe evolution of arc-continent collision between the Palawan microcontinental block and the Cagayan Ridge in the southeastern margin of the South China Sea (SCS) is vital to understand how this collision correlated with seafloor spreading of the SCS. To address the evolution of arc-continent collision, we studied the biostratigraphy and provenance of syn-collisional sediments in the Isugod Basin in central-southern Palawan. Microfossil analysis indicates a Late Miocene age (11.5-5.6 Ma) for the Isugod and Alfonso XIII Formations and rapid subsidence during initiation of the basin which may have been triggered by local extensional collapse of the wedge in response to forearc uplift. Multidisciplinary provenance analysis reveals that the Isugod and Alfonso XIII Formations were derived from the Middle Eocene-lower Oligocene Panas-Pandian Formation on the Palawan wedge and the Late Eocene Central Palawan Ophiolite. These results suggest the emergence of both the orogenic wedge and obducted forearc ophiolite at similar to 11.5 Ma, implying collision onset before similar to 11.5 Ma. The collision initiation in Palawan could be better constrained to similar to 18 Ma, based on the drowning of the Nido carbonate platform in the foreland. Therefore, the gravitational collapse of the Palawan wedge and the subsidence/formation of the Isugod Basin might reflect a significant uplift pulse in the hinterland of the wedge beginning within 13.4-11.5 Ma in the late stage of collision. It indicates that although compression originated from spreading of the SCS had ceased at 16-15 Ma, arc-continent collision in Palawan did not stop and was sustained by compression from the upper plate afterward.
The Palawan microcontinental block is a continental fragment separated from the South China margin along with the seafloor spreading of the South China Sea (SCS). It finally collided with the Cagayan Ridge volcanic arc because of southward subduction of the Proto-SCS. Therefore, precisely constraining the evolution of arc-continent collision could help us to understand its association with the ending of the SCS spreading. To constrain the evolution of arc-continent collision, we determined the depositional age and source of syn-collisional sediments in the Isugod Basin in central-southern Palawan. Our results shows that the Isugod Basin sediments were deposited during the Late Miocene (11.5-5.6 Ma) following local gravitational collapse of the Palawan orogenic wedge driven by uplift and oversteepening. Isugod Basin sediments were eroded from both the orogenic wedge and obducted forearc ophiolite that were uplifted and exposed subaerially, indicating collision began before similar to 11.5 Ma. As the onset of collision could be constrained to similar to 18 Ma, we propose a significant uplift pulse in the hinterland of the wedge began at 13.4-11.5 Ma in the late stage of collision. This further indicates that arc-continent collision in Palawan did not stop although compression derived from spreading of the SCS had ceased at 16-15 Ma.
Sediments in the Isugod Basin were deposited at 11.5-5.6 Ma following local gravitational collapse of the Palawan wedge driven by uplift The Isugod Basin sediments were supplied by erosion of the Palawan wedge and obducted forearc ophiolite exposed subaerially since similar to 11.5 Ma Onset of Palawan arc-continent collision at similar to 18 Ma followed by a significant uplift pulse in the Palawan wedge beginning within 13.4-11.5 M
Recovery of Rare Earth Elements from Ion-Adsorption Deposits Using Electrokinetic Technology: The Soil Conductivity Mechanism Study
No full textRare earth elements (REEs) are essential raw materials for modern industries but mining them has caused severe environmental issues, particularly the recovery of heavy REEs (HREEs) from ion-adsorption deposits (IADs). Very recently, an emerging technology, electrokinetic mining (EKM), has been proposed for the green and efficient recovery of REEs from IADs. However, the conduction mechanism of the weathering crust soil, which is also a prerequisite for EKM, remains unclear, making the EKM process unpredictable. Here, we systematically investigated the conductivity of weathering crust soil in the presence of light REEs (LREEs, i.e., La3+ and Sm3+) and HREEs (Er3+ and Y3+), respectively. Results suggested that the voltage was dynamically and spatially redistributed by the movement of REEs and water during EKM, and the conventional assumption of the linear distribution of voltage leads to an inaccurate description of soil voltage. We proposed an improved Archie's equation by coupling the mechanisms of liquid phase and solid-liquid interface conduction, which can predict soil conductivity more precisely. Moreover, the extended Archie's equation is able to recalculate the voltage distribution at distinct times and spaces well during EKM. More importantly, the water content in field-scale weathered-crust soils can be retrieved by the newly proposed Archie's equation, which helps optimize the leaching wells and improve the recovery rate of REE. This study focuses on the conduction mechanism of weathering crust soil, which provides a theoretical basis for better use of the EKM technology and promotes mining efficiency fundamentally
Baddeleyite U-Pb age and whole-rock geochemical characteristics of-1670 Ma diabase dyke in the Shennongjia area: Implications for the tectonic setting of northern Yangtze Craton during the late Paleoproterozoic
No full textThe Shennongjia Group in the northern margin of the Yangtze Craton consists mainly of thick carbonate rocks interlayered with some intervals of volcanic and terrigenous clastic rocks. With the geochronological achievements in recent years, the depositional age of this group can be constrained into the time span of 1400 -1000 Ma at present, belonging to the Mesoproterozoic Ectasian period. It is also a potential candidate interval for the "Undefined System/Period " in the Regional Chronostratigraphic Chart of China. According to the 1:200,000scale conventional regional geological survey in the '1960 -1970 s ', at the northwest side of the dominant peak of the Mt. Shennongding, it shows a ring-shaped gabbro-diabase dyke intruded in these Ectasian formations. However, due to the lack of comprehensive studies, there are lots of controversy both about the intrusion time and the tectonic setting of the mafic dyke. In this study, by means of the LA-ICP-MS and SHRIMP method successfully, the baddeleyite from the Banbiyan gabbro-diabase dyke yielded gained the weighted average 207 Pb/ 206 Pb age 1668.3 +/- 5 Ma (MSWD = 1, N = 53) and 1667.8 +/- 7 Ma (MSWD = 0.7, N = 23), respectively. It represents an unambiguous late Paleoproterozoic Statherian Period magmatic event in northern Yangtze Craton. Further, for the first time, it indicates the existence of the geological records prior to - 1.67 Ga in the Shennongjia area. In addition, Banbiyan gabbro-diabase samples have relatively concentrated SiO 2 (48.33 % to 49.65 %) and high whole iron content (10.25 % to 12.78 %). They show Na 2 O + K 2 O ranging from 2.9 % to 4.64 % and TiO 2 from 1.36 % to 1.62 %. All samples are enriched in LILE, e.g., Rb, K, and Ba. The REE pattern shows a moderately right-inclined curve between E-MORB and OIB. These geochemiacal characteristics are agreed with contemporaneous magmatic event in the southwestern Yangtze Craton, indicating a within-plate rifting background and should correspond to the rifting of the Columbia Supercontinent
Insights into anthropogenic impact on atmospheric inorganic aerosols in the largest city of the Tibetan Plateau through multidimensional isotope analysis
No full textParticulate inorganic nitrogen aerosols (PIN) significantly influence air pollution and pose health risks world-wide. Despite extensive observations on ammonium (pNH(4)(+)) and nitrate (pNO(3)) aerosols in various regions, their key sources and mechanisms in the Tibetan Plateau remain poorly understood. To bridge this gap, this study conducted a sampling campaign in Lhasa, the Tibetan Plateau's largest city, with a focus on analyzing the multiple isotopic signatures (delta N-15, Delta O-17). These isotopes were integrated into a Bayesian mixing model to quantify the source contributions and oxidation pathways for pNH(4)(+) and pNO(3)(-). Our results showed that traffic was the largest contributor to pNH(4)(+) (31.8 %), followed by livestock (25.4 %), waste (21.8 %), and fertilizer (21.0 %), underscoring the impact of vehicular emissions on urban NH3 levels in Lhasa. For pNO(3)(-), coal combustion emerged as the largest contributor (27.3 %), succeeded by biomass burning (26.3 %), traffic emission (25.3 %), and soil emission (21.1 %). In addition, the Delta O-17-based model indicated a dominant role of NO2 + OH (52.9 %) in pNO(3)(-) production in Lhasa, which was similar to previous observations. However, it should be noted that the NO3 + volatile organic component (VOC) contributed up to 18.5 % to pNO(3)(-) production, which was four times higher than the Tibetan Plateau's background regions. Taken together, the multidimensional isotope analysis performed in this study elucidates the pronounced influence of anthropogenic activities on PIN in the atmospheric environment of Lhasa
Ozone Chemistry on Greasy Glass Surfaces Affects the Levels of Volatile Organic Compounds in Indoor Environments
No full textThe chemistry of ozone (O-3) on indoor surfaces leads to secondary pollution, aggravating the air quality in indoor environments. Here, we assess the heterogeneous chemistry of gaseous O-3 with glass plates after being 1 month in two different kitchens where Chinese and Western styles of cooking were applied, respectively. The uptake coefficients of O-3 on the authentic glass plates were measured in the dark and under UV light irradiation typical for indoor environments (320 nm < lambda < 400 nm) at different relative humidities. The gas-phase product compounds formed upon reactions of O-3 with the glass plates were evaluated in real time by a proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometer. We observed typical aldehydes formed by the O-3 reactions with the unsaturated fatty acid constituents of cooking oils. The formation of decanal, 6-methyl-5-hepten-2-one (6-MHO), and 4-oxopentanal (4-OPA) was also observed. The employed dynamic mass balance model shows that the estimated mixing ratios of hexanal, octanal, nonanal, decanal, undecanal, 6-MHO, and 4-OPA due to O-3 chemistry with authentic grime-coated kitchen glass surfaces are higher in the kitchen where Chinese food was cooked compared to that where Western food was cooked. These results show that O-3 chemistry on greasy glass surfaces leads to enhanced VOC levels in indoor environments
Recent advances made by reaction experiments on melting of heavily metasomatized hydrous mantle
No full textMantle-derived magmas are traditionally assumed to originate by melting of an upper mantle consisting of uniform spinel- or garnet peridotite dominated by olivine. However, extensive studies of mantle-derived basalts suggest that the mantle is more mineralogically heterogeneous, so that the genesis of even the most common magmas requires consideration of mixed source regions within the mantle involving pyroxenites and hydrous minerals. We refer to these with the group term metasomes. However, most experimental studies on mantle melting have assumed a homogeneous source composition, presenting a challenge in quantifying the impact of these heterogeneities. This paper provides a comprehensive review of recent advances in reaction experiments that depart from traditional approaches assuming a homogeneous mantle. We begin by assembling evidence for the existence of metasomes, discussing their formation and integration into basaltic melts. Further, we introduce the reaction experiments combining peridotite with hydrous assemblages, such as phlogopite, amphiboles, and apatite, leading to more accurate simulations of natural magmatic processes. These experiments reveal that the melting of hydrous metasomes and subsequent melt-peridotite interactions are key to producing the high alkali contents observed in natural lavas. The melting of hydrous metasomes occurs at lower temperatures than peridotite, resulting in diverse melt compositions. The interaction between metasome-derived melts and peridotite further modifies these melts, influenced by the pressure-dependent melting behaviors of minerals like orthopyroxene and olivine. This dynamic process leads to the generation of K- and Na-alkaline melts with varying silica and alkali contents, reflecting the complex interplay of melting and reaction mechanisms in the mantle. Formation of hydrous metasomes have also been studied by reaction experiments. Experimental studies have predominantly focused on potassium-rich systems due to the geochemical signatures of potassic igneous rocks suggesting sedimentary rock contributions to their sources. These studies simulate interactions between melts and mantle peridotite, particularly in sub-arc regions, leading to potassium-rich metasomes. More experimental studies are needed on sodium-rich alkaline systems to understand the formation of amphibole-rich metasomes and bridge knowledge gaps. Future studies should emphasize the detailed compositional variability of melts from metasomes, their reactions with peridotites, and comparisons with surface lavas. Understanding the kinetics of these reactions and the melting mechanisms of metasome-derived melts is essential. However, the considerable mineralogical diversity of hydrous metasomes poses a primary challenge facing experimental studies. It underscores the need for more experiments on additional melt source rocks and their reaction with peridotites, as the story about the reaction of melts from hydrous metasomes with mantle peridotites has only just begun
A leaf age-dependent light use efficiency model for remote sensing the gross primary productivity seasonality over pantropical evergreen broadleaved forests
No full textTropical and subtropical evergreen broadleaved forests (TEFs) contribute more than one-third of terrestrial gross primary productivity (GPP). However, the continental-scale leaf phenology-photosynthesis nexus over TEFs is still poorly understood to date. This knowledge gap hinders most light use efficiency (LUE) models from accurately simulating the GPP seasonality in TEFs. Leaf age is the crucial plant trait to link the dynamics of leaf phenology with GPP seasonality. Thus, here we incorporated the seasonal leaf area index of different leaf age cohorts into a widely used LUE model (i.e., EC-LUE) and proposed a novel leaf age-dependent LUE model (denoted as LA-LUE model). At the site level, the LA-LUE model (average R2 = .59, average root-mean-square error [RMSE] = 1.23 gC m-2 day-1) performs better than the EC-LUE model in simulating the GPP seasonality across the nine TEFs sites (average R2 = .18; average RMSE = 1.87 gC m-2 day-1). At the continental scale, the monthly GPP estimates from the LA-LUE model are consistent with FLUXCOM GPP data (R2 = .80; average RMSE = 1.74 gC m-2 day-1), and satellite-based GPP data retrieved from the global Orbiting Carbon Observatory-2 (OCO-2) based solar-induced chlorophyll fluorescence (SIF) product (GOSIF) (R2 = .64; average RMSE = 1.90 gC m-2 day-1) and the reconstructed TROPOspheric Monitoring Instrument SIF dataset using machine learning algorithms (RTSIF) (R2 = .78; average RMSE = 1.88 gC m-2 day-1). Typically, the estimated monthly GPP not only successfully represents the unimodal GPP seasonality near the Tropics of Cancer and Capricorn, but also captures well the bimodal GPP seasonality near the Equator. Overall, this study for the first time integrates the leaf age information into the satellite-based LUE model and provides a feasible implementation for mapping the continental-scale GPP seasonality over the entire TEFs.
This study incorporated leaf age information into a widely used light use efficiency (LUE) model (i.e., EC-LUE) and proposed a novel leaf age-dependent LUE model (i.e., LA-LUE model) to estimate the monthly gross primary productivity (GPP) over pantropical evergreen broadleaved forests. The GPP estimations from the LA-LUE model showed superior performance than the EC-LUE model against in situ measurements. The new model also demonstrated good capacity in representing both the unimodal GPP seasonality near the Tropics of Cancer and Capricorn and the bimodal GPP seasonality near the Equator. The new model provides a feasible implementation for predicting the future continental-scale GPP seasonality.imag
Anaerobic oxidation of methane and greigite formation: Evidence of isotopically heavy pyrite in Pleistocene coastal sediments from the South Yellow Sea
No full textDiagenetic alteration of magnetic minerals, driven by closely linked C-S-Fe cycles, is highly likely to complicate the paleomagnetic record. In addition to the anomalous diagenetic paleomagnetic signatures caused by ferromagnetic greigite growth, pyrite sulfur isotope compositions are often "heavy" (i.e., delta(34)Spyr > 0). However, the dependencies and mechanistic origins of these signatures remain controversial. This study presents a highresolution delta(34)Spyr record of a long sediment core collected from the South Yellow Sea, China. Ferromagnetic greigite is prominently identified in two coastal deposits within this core. The delta(34)Spyr values of these coastal deposits are isotopically (super) heavy, ranging from -10.6 to 22.8%o and from -14.5 to 26.5%o, with mean and 1 sigma values of 5.9 +/- 10.3%o (n = 15) and 12.2 +/- 9.8%o (n = 33), respectively. Additionally, magnetic parameters show positive trends with delta(34)Spyr values throughout the sediment core. These positive trends, along with the enrichment of ferrous iron and sedimentary microtextural evidence of the authigenic growth sequence of framboidal pyrite, siderite, euhedral pyrite, and greigite, indicate that anaerobic oxidation of methane (AOM) is a fundamental factor for ferromagnetic greigite formation in coastal sediments with sulfate limitation. We estimate the delay time of greigite formation relative to the depositional age of surrounding sediments to be a few hundred years due to the rapid sedimentation rates and shallow burial depths of the sulfate-methane transition zone (SMTZ) in coastal deposits. Conversely, the deep burial of SMTZ likely suggests that a longer delay time is prevailing for greigite formation in hemipelagic sediments. This study highlights the role of AOM in controlling the formations of greigite and coeval (super) heavy pyrite