Guangzhou Institute of Geochemistry
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Unveiling the overlooked direct emissions of particulate organic nitrates from ship
No full textParticulate organic nitrates (pONs) have drawn growing interests due to their effects on nitrogen cycling, air pollution, and regional climate. While secondary formation is typically considered as the major source of pONs, direct emissions from various sources remain poorly explored. Ship exhausts have been known as an important source of reactive nitrogen species, yet pONs emissions from ship have been rarely characterized. In this study, we conducted atmospheric measurement of pONs during a ship-based cruise measurement campaign in the East China Sea and also emission measurement of pONs from ship exhausts. During the ship-based cruise, total five typical kinds of pONs were determined and the average total concentrations of five pONs were 479 +/- 193 and 250 +/- 139 ng m- 3 when sampling was influenced by ship emissions or not, respectively, indicating the notable impact of ship exhaust plumes on ambient pONs. Further, five typical pONs were successfully identified and quantified from ship exhausts, with the average total concentration of 1123 +/- 406 mu g m- 3. The much higher pONs levels in ship exhausts than in ambient particulate matters demonstrated ship emission as an important source for pONs. Additionally, their emission factors from ship exhausts were determined as at a range of 0.1-12.6 mg kWh-1. The chemical transport model simulations indicate that direct pONs emissions from ship exert a significant contribution to atmospheric pONs, especially in the clean marine atmosphere. These findings provide compelling evidence for direct emission of pONs from ship and its considerable effects. We call for further studies to better characterize the direct pONs emissions from ship and other potential sources, which should be incorporated into global and regional models
Crustal recycling and growth via mélange diapir in subduction zones: Insights from two episodes of magmatism in the Northern Yili Block, NW China
No full textArc magmatism can provide crucial information about crustal recycling and growth in subduction zones. However, the crustal material transfer process and mechanism from subducting slab to overlying mantle wedge are controversial. Here, we present detailed petrological, geochronological, geochemical, and Sr-Nd-Hf isotopic data, and previously published data for two episodes of subduction-related magmatism in the Northern Yili Block, NW China, to study these issues in relation to the recycling of continental crust and the growth of two separate magmatic episodes at 400-350 Ma and 350-300 Ma, respectively. The Nd-Sr isotope modeling results, low Nd/Sr, and variable Hf/Nd ratios demonstrate that the arc magmatism of these two episodes could be derived from two distinct melange sources that formed at the slab -mantle interface during subduction of the Junggar oceanic plate. In the first episode, magmatic rocks exhibit high Th/Yb and (La/Sm)N ratios and the decoupling of Nd-Hf isotopes, which leads to an interpretation that the primary magmas were derived from sources mainly mixed by sediments and mantle -wedge peridotites. In contrast, the magmas of the second episode exhibit high Ba/La and Ba/Th ratios and the coupling of Nd-Hf isotopes, which implies that these magmas were likely produced from melange diapirs dominated by the mixing of midoceanic -ridge basalts and mantle peridotites. The episodes of Nd-Hf isotopic decoupling and coupling coincided with crustal material recycling and crustal growth in subduction zones, respectively. Considering that the Northern Yili Block at 400-350 Ma was characterized mainly by enriched Nd-Hf isotopes of magmatic rocks and no development of the forearc accretionary complex, while the Northern Yili Block at 350-300 Ma featured high epsilon Hf(t)-epsilon Nd(t) values of magmatic rocks, occurrences of extension -related magmatism, and distribution of the forearc accretionary complex and immature back -arc basin, we propose that these two different melange sources probably developed in response to subduction transition. That is, one resulted from advancing and the other was relevant to retreating regime. The partial melting of these melanges in the mantle wedge generated intermediate felsic magmas, which might have acted as a leading mechanism for crustal recycling and growth of the accretionary orogenic belt
Succession of bacterial community during electroactive methanogenic biofilm development under microplastic manipulation
No full textElectrochemical methanogenesis is a promising and reliable process to convert waste streams into CH4, where the electroactive methanogenic biofilms play a key role. However, given that microplastics (MP) have now been spread ubiquitously in the environment, their regulation on the performance and succession of methanogenesis biofilm remains an enigma. Herein, we developed the single-chamber electrochemical methanogenic systems to investigate how poly (ethylene terephthalate) MP (PET-MP) regulates methanogenic biofilm formation and microbial metabolisms. The microbial volume of biofilm formed under MP exposure was similar to that without exposure. However, the live/dead cell ratio of the microbes in the biofilm under the PET-MP exposure decreased significantly (p < 0.05). Correspondingly, the richness and diversity of the microbial community in the presence of MP were also lower. Network analysis implied the interspecific cooperation among the microbial communities to cope with the MP stress. Meanwhile, the biofilm produced more extracellular polymer substrates during the biofilm thickening, possibly as a defense against MP invasion. At the gene level, the content of methanogenic gene mcrA was found to positively linearly correlate with the cultivation cycles, both in presence (r = 0.945, p < 0.05) or absence of PET-MP (r = 0.913, p < 0.05). The outcomes of this study could provide insights into the practical application of electrochemical methanogenesis technology to upcycle the MP-polluted biowastes and to implement the Power&Waste-to-X concept better
Extremely low δ56Fe in arc tholeiites linked to ferrocarbonate recycling: Implications for Fe enrichment in the Awulale Arc, Central Asia
No full textRecycling of Fe -rich materials through subduction may affect the element budgets and redox properties of the mantle, thus influencing the differentiation trends and mineralization types of mantle -derived magmas. However, the effects of different recycled Ferich materials on the mantle are dependent on their lithologies, which are still poorly constrained. Stable Fe isotopes can act as useful tracers for distinguishing among different recycled Fe -rich lithologies, and their imprints may be documented in mantle -derived magmas. This study focuses on the Fe isotopes of ferrobasalts and the associated dacites and magnetite ores in the Chagangnuoer Fe deposit of the Awulale Arc, Central Asia, to identify recycled Fe -rich materials and explore the Fe enrichment mechanism in continental arcs. Our results indicate that the ferrobasalts and dacites possess the lowest known 656Fe, -0.40%o +/- 0.04%o (2SE), among their counterparts worldwide. The low 656Fe signatures are considered to originate from a hybridized mantle source, which may have been modified by recycled ferrocarbonates. The recycled ferrocarbonates may have melted during the decompressional heating stage of the slab subduction of the South Tianshan Ocean, coupled with asthenospheric upwelling under "wet" mantle conditions. The addition of ferrocarbonate melts to the mantle might have decreased the oxygen fugacity of the mantle wedge to below the fayalite-magnetite-quartz buffer, accounting for the Fe enrichment in arc tholeiites and large-scale Fe mineralization along the Awulale. Notably, our study reveals a novel carbonate recycling pathway in the cold subduction zones, where ferrocarbonates were subducted into the mantle and then recycled by the upwelling asthenosphere to mix with the fluid-metasomatized mantle through mantle convection
Highly efficient recovery of Zn2+/Cu2+from water by using hydrotalcite as crystal seeds
No full textThe efficient and waste-free recovery of heavy metals is critical for heavy metal wastewater treatment. In this work, we explored how heavy metals can be recovered as valuable chemicals in the presence of crystal seeds. Hydrotalcite (one kind of layered double hydroxides (LDHs)) was used as crystal seeds to recover Zn2+ in the presence of Al3+ from water (i.e., seed-Zn2+-Al3+ system), which was compared with the monometallic heterogeneous system (seed-Zn2+) and direct coprecipitation (Zn2+-Al3+) system. Our results demonstrated that the seed-Zn2+-Al3+ system possessed a recovery rate of 2.6-2.8 times and a recovery kinetic rate of 2.7-5.9 times higher than those of the other two systems. Differing from the latter two systems, hydrotalcite seeds could induce Zn2+ and Al3+ to form ZnAl-LDH in seed-Zn2+-Al3+. Interestingly, the ZnAl-LDH presents a compositional divalent/trivalent cation molar ratio of ca. 3, which is comparable with the value in the hydrotalcite. It was demonstrated that the hydrotalcite seeds could act as a template to significantly induce the formation of ZnAlLDH complying with the seed's structure and compositional ratio. Similar induction effect of seeds as the Zn2+ system was further verified in Cu2+ systems. This work provides a novel strategy for efficient recovery of heavy metals with product selectivity
Layered intrusions: Fundamentals, novel observations and concepts, and controversial issues
No full textLayered intrusions are fossilized natural laboratories that historically have constrained many fundamental principles of igneous petrology. Layered intrusions are typically stratiform, usually sill-like bodies of cumulate rocks, at least a few hundred metres to as much as 10 km thick, characterized by the presence of a variety of different types of layering over a range of length scales. They are the solid record of crystallization, differentiation and solidification processes of mainly basaltic magmas. The importance of layered intrusions also lies in hosting a significant proportion of the world's known reserves and resources of important critical metals: particularly, the majority of the global resource of platinum-group elements (PGE), chromium (Cr) and vanadium (V) and also very large resources of nickel (Ni), copper (Cu) and cobalt (Co). This paper summarizes the progress that has been made in the study of layered intrusions during the last three decades. The progress is marked by a number of novel observations from layered intrusions. Among them are: (1) draping of igneous layering over a few-km-high sloping step in the chamber floor; (2) development of igneous layering on the overturned to undercutting portions of a chamber floor; (3) magmatic karstification of the floor cumulates, (4) existence of threedimensional framework of crystals in (oxide) cumulates; (5) systematic variations in dihedral angles between touching grains, and other microtextural features; (6) Cr-rich structures at the base of magnetitite layers; (7) coexistence of melt inclusions of contrasting composition in minerals; (8) thermal and chemical histories recorded by plagioclase; (9) textural and chemical features of minerals revealed by X-ray microscopy, (10) intrusion-scale to mineral-scale isotopic heterogeneity; (11) out-of-sequence zircon ages; and (12) skeletal/dendritic growth of minerals revealed by minor element zonation. The progress is also evident from development of several new concepts and refinement of some established ones. These include: (1) time and length scales in layered intrusion processes, (2) catastrophically fast growth of magma chambers, (3) out-of-sequence emplacement in layered intrusions, (4) large-scale slumping and mineral sorting in layered intrusions, (5) production of monomineralic cumulates from single phase-saturated melts, (6) origin of non-cotectic cumulate by in situ growth, (7) the arrival of new phases on the liquidus, (8) inward propagation of solidification fronts, (9) mushy and hard chamber floor, (10) absence of roof sequences due to their disruption, (11) basal reversals and chilled margins, (12) adcumulus growth theory, (13) compositionally stratified magma chambers, (14) melt-sediment interactions during magma chamber growth, (15) lateral reactive infiltration in a crystal mush, (16) reactions involving conjugate immiscible liquids in crystal mushes, and (17) constraints on subsolidus processes from non-traditional Fe-Mg-Cr stable isotopes. Finally, we show that the major controversies regarding layered intrusions currently revolve around whether: (a) the microstructure of igneous rocks are primary or secondary , (b) compaction in layered in-trusions is pervasive or non-existent (c) large, long-lived and entirely-molten magma chambers exist or not.
The review shows that layered intrusions provide ground-truth information on the processes of magma crystalliza-tion, differentiation , solidification in crustal chambers as well as on mechanisms of ore-forming elements concentration into economically viable mineral deposits. We propose a few lines for future research that may potentially raise igneous petrology to a new level of understanding of the processes that govern the evolution of terrestrial magmatic systems
Exhumation of the Cuonadong Sn-W-Be polymetallic deposit, Tethyan Himalaya: Implications for exploration
No full textThe Cuonadong Sn-W-Be polymetallic ore deposit is the first rare-metal deposit related to leucogranites with giant mineralization potential to be discovered in the Himalayan Orogen. However, the post-mineralization exhumation and preservation processes of this deposit have not yet been studied in detail, although these factors are key to the exploration and evaluation of rare-metal deposits in the Himalaya. Geophysical data have revealed that a hidden fault (i.e., the Jisong secondary fault) cuts the southern part of the Cuonadong ore deposit. In order to determine the effects of the Jisong secondary fault on the exhumation of the Cuonadong deposit, we undertook zircon and apatite (U-Th)/He dating, apatite fission-track dating, and forward and inverse thermal history modeling of the footwall and hanging wall of the Jisong secondary fault. Our results show that the Cuonadong deposit experienced two stages of rapid, post-mineralization exhumation at ca. 10-9 and ca. 5-4 Ma, separated by a period of differential exhumation at ca. 9-5 Ma. These exhumation events were likely caused successively by the arc-shaped Nading Fault, normal faulting on the Jisong secondary fault, and thrusting on the Main Himalayan Thrust, although climate-related erosion may have also had a role in the exhumation. Owing to normal displacement on the Jisong secondary fault, the Cuonadong ore deposit underwent differential exhumation of 300-700 m. This implies that the eastern part of the deposit is more favorable for exploration than its western part if the deposit has the same mineralization depth. This study demonstrates that low-temperature thermochronological methods can be useful in the exploration for rare-metal deposits in the Himalayan Orogen
Deep Learning Bridged Bioactivity, Structure, and GC-HRMS-Readable Evidence to Decipher Nontarget Toxicants in Sediments
No full textIdentifying causative toxicants in mixtures is critical, but this task is challenging when mixtures contain multiple chemical classes. Effect-based methods are used to complement chemical analyses to identify toxicants, yet conventional bioassays typically rely on an apical and/or single endpoint, providing limited diagnostic potential to guide chemical prioritization. We proposed an event-driven taxonomy framework for mixture risk assessment that relied on high-throughput screening bioassays and toxicant identification integrated by deep learning. In this work, the framework was evaluated using chemical mixtures in sediments eliciting aryl-hydrocarbon receptor activation and oxidative stress response. Mixture prediction using target analysis explained <10% of observed sediment bioactivity. To identify additional contaminants, two deep learning models were developed to predict fingerprints of a pool of bioactive substances (event driver fingerprint, EDFP) and convert these candidates to MS-readable information (event driver ion, EDION) for nontarget analysis. Two libraries with 121 and 118 fingerprints were established, and 247 bioactive compounds were identified at confidence level 2 or 3 in sediment extract using GC-qToF-MS. Among them, 12 toxicants were analytically confirmed using reference standards. Collectively, we present a "bioactivity-signature-toxicant" strategy to deconvolute mixtures and to connect patchy data sets and guide nontarget analysis for diverse chemicals that elicit the same bioactivity
Quantification of Water Content in Glass at Nanoscale Using Atom Probe Tomography
No full textWater is a critical volatile component in planetary bodies and plays a key role in the Earth's dynamic evolution. Traditional methods to analyze water in either mineral or glass phases are usually limited to areas larger than 10 microns. The advent of secondary ion mass spectrometry (SIMS), especially nanoscale SIMS (NanoSIMS), has enabled in situ analysis at micron- to submicron scales. However, there is an increasing demand to quantify water content at much finer scales, including those recovered from high-pressure experiments or nanoscale planetary materials. This study demonstrates the ability of atom probe tomography (APT) to investigate the distribution of hydroxyl water in glass at sub-nanoscale resolution. Five glass working standards with trace amounts of water were analyzed to demonstrate that the OH + mass spectrum obtained by APT could potentially represent the hydroxyl content of the glass. The detection limit of the APT was determined to be better than 0.02 atomic %. The heterogeneity of APT OH + in the form of nanoclusters in glass was readily discerned, and its concentration in the nanoclusters increased proportionally to the water content in the studied samples. These findings provide valuable insights into the sub-nanoscale distribution of hydroxyl water in glasses and establish APT as a promising tool for characterizing water at an ultrahigh spatial resolution
Occurrence and maturation transformation of organic and inorganic nitrogen in the Lower Cambrian shelf-slope facies shale: Implications for overmature N<sub>2</sub>-rich shale reservoirs in Southern China
No full textThermogenic molecular nitrogen (N-2) is one of the primary sources of high N-2 content in overmature shale gas reservoirs. However, it remains uncertain whether N-2 is released from organic or inorganic sources because the occurrence and thermal stability of different nitrogen species vary. This study investigates the Lower Cambrian shale samples from a well in southeastern Guizhou, China to determine the abundance, occurrence, and source of nitrogen in marine shale. A sealed gold tube pyrolysis experiment was further conducted on isolated kerogen and organic matter (OM)-ashed samples from one typical shale to explore the maturation transformation of organic nitrogen (N-org) and inorganic nitrogen (N-inorg). The results reveal that the studied shale exhibits a high nitrogen content, with the N-org content being less than that of N-inorg. The predominant functionality of N-org is pyrrolic-N, and N-inorg occurs primarily in silicates (NH4+-bearing illite and (NH4+, K, Ba)-feldspar). The structural characteristics of the different nitrogen functionalities cause them to vary in their thermal transformation behavior. The pyrolysis experiment results indicate that the nitrogen release of the shale increases rapidly when EqVRo >3.7%, and the N-2 yields for typically shelf-slope facies shales are primarily 1-2 m(3)/t at EqVRo 4.0%-4.2%, to which the N-inorg has a dominant contribution. Further evidence that the high N-2 shale gas reservoirs occur at EqVRo >3.5% is provided by compiled gas composition data from various risk wells. It is proposed that the Lower Cambrian shale gas exploration should address the considerably increased N-2 risk in the shelf-slope facies area