Bacteria from the genus Polaromonas are dominant phylotypes found in a variety of low-temperature environments in polar regions. The diversity and biogeographic distribution of Polaromonas have been largely expanded on the basis of 16 S rRNA gene amplicon sequencing. However, the evolution and cold adaptation mechanisms of Polaromonas from polar regions are poorly understood at the genomic level. A total of 202 genomes of the genus Polaromonas were analyzed, and 121 different species were delineated on the basis of average nucleotide identity (ANI) and phylogenomic placements. Remarkably, 8 genomes recovered from polar environments clustered into a separate clade (‘polar group’ hereafter). The genome size, coding density and coding sequences (CDSs) of the polar group were significantly different from those of other nonpolar Polaromonas. Furthermore, the enrichment of genes involved in carbohydrate and peptide metabolism was evident in the polar group. In addition, genes encoding proteins related to betaine synthesis and transport were increased in the genomes from the polar group. Phylogenomic analysis revealed that two different evolutionary scenarios may explain the adaptation of Polaromonas to cold environments in polar regions. The global distribution of the genus Polaromonas highlights its strong adaptability in both polar and nonpolar environments. Species delineation significantly expands our understanding of the diversity of the Polaromonas genus on a global scale. In this study, a polar-specific clade was found, which may represent a specific ecotype well adapted to polar environments. Collectively, genomic insight into the metabolic diversity, evolution and adaptation of the genus Polaromonas at the genome level provides a genetic basis for understanding the potential response mechanisms of Polaromonas to global warming in polar regions.

Mountainous regions present severe risks, including damage to transportation infrastructure, due to the occurrence of geohazards such as rock avalanches and other types of landslides. Lessons learned from past damaging events are helpful for risk reduction in mountainous regions. In this paper, to study a rock avalanche impact on a bridge, a numerical modeling framework with the aid of the discrete element method (DEM) is developed; the progressive failure process of an expressway bridge that was damaged by a rock avalanche is reproduced, and the failure mechanisms and dynamic behaviors of the bridge under impact are assessed. The Yaxi Expressway bridge that was destroyed by the September 20, 2020, Yaoheba rock avalanche in southwest China is used as an illustrative example. A field investigation is carried out to identify geological conditions, characteristics, and the kinetic failure pattern of the rock avalanche and the bridge. The stereographic projection analyses indicate that this rock avalanche was initiated as a planar slide. A three-dimensional numerical model of the rock avalanche and bridge is developed based on the terrain data acquired. The critical parameters of the numerical model are calibrated based on results obtained from laboratory tests. Finally, the progressive failure process and failure mechanism of the impacted bridge are analyzed based on the constructed numerical model. The comprehensive analysis framework can be applied to similar events involving geohazard-structure interaction.

Arsenic in water environment can present significant threats to human health, and eliminating arsenic pollutants from wastewater is crucial. Based on our previously reported work, this study delved into the adsorption behavior and mechanism of different arsenic contaminants (p-ASA, ROX, As(V), and DMA) on the activated Febased metal-organic framework (activated MIL-88A). The results show that activated MIL-88A exhibits exceptional adsorption capabilities toward diverse arsenic pollutants. The adsorption process is endothermic, spontaneous, and viable, and chemical adsorption plays a leading role. The remarkable adsorption capacity of activated MIL-88A to various arsenic pollutants is primarily attributed to coordination, while hydrogen bonding also assumes a significant role in the elimination of p-ASA and ROX. Additionally, we investigated the impact of arsenic molecule shape and size, solution pH, and the existence of specific anions and dissolved organic matter (DOM) on the adsorption of different arsenic pollutants. This study can provide valuable insights for further exploring the selective adsorption of different kinds of arsenic species by Fe-based MOF materials and improving the adsorption efficiency of MOFs.

Although alternatives to mercury (Hg) are available in most products and industrial activities, Hg continues to be an ingredient in some products, including fluorescent lamps and electrical and electronic equipment (EEE). In this work, low-cost passive air samplers (PASs) were used to investigate the atmospheric Hg pollution in Zhongshan, a large industrial city and major hub of mercury-added product manufacturing in South China. The GEM concentrations in the atmosphere were measured for two weeks during the summer of 2019 at a total of 144 sites across Zhongshan. Comparison with the results of active sampling confirmed that the PASs yielded accurate and reliable gaseous elemental mercury (GEM) concentrations and were thus well-suited for multi-site field monitoring. The mean GEM concentrations in the areas with mercury-added product manufacturing activities (5.1 +/- 0.4 ng m-3) were significantly higher than those in other parts of Zhongshan (1.5 +/- 0.4 ng m-3), indicating that local releases, rather than regional transport, were responsible for the atmospheric Hg pollution. Elevated GEM concentrations (up to 11.4 ng m-3) were found in the vicinity of fluorescent lamp and EEE factories and workshops, indicating significant Hg vapor emissions, presumably from the outdated production technologies and non-standard operation by under-trained workers. The Hg emissions from mercury-added product manufacturing were estimated to be 0.06 and 7.8 t yr-1 for Zhongshan and China, respectively, based on the scales of fluorescent lamp and EEE production. The non-carcinogenic health risk of Zhongshan residents from inhalation and ingestion was judged acceptable, whereby the inhalation exposure in Hg-polluted areas exceeded that of dietary ingestion. These findings demonstrate that mercury-added product manufacturing still contributes notably to anthropogenic gaseous Hg releases in the industrial areas with intense mercury-added product manufacturing activities.

The newly developed RECoverable Autonomous Sonde (RECAS) allows sampling and analysis of subglacial water while the subglacial lake remains isolated from the surface. The sonde was successfully tested in East Antarctica during the 2021–2022 field season: it reached the ice-sheet base at a depth of 200.3 m, sampled basal meltwater and measured its pressure, temperature, pH and conductivity and returned to the ice surface. The average downward penetration rate was 1.85 m h−1, and the average upward penetration rate was 2.94 m h−1. The successful test of a self-melting, recoverable probe in Antarctica marks further progress towards the clean exploration of subglacial water bodies.

Hypothesis: Organic arsenic pollutant p-arsanilic acid (p-ASA) in wastewater can be converted into highly toxic inorganic arsenic under natural conditions, causing serious harm to the environment and human health. In this study, an Fe-based metal-organic framework (MOF) material, activated MIL-88A, was synthesized as an adsorbent to remove p-ASA in water. Experiments: Various influencing factors in the material synthesis process, including temperature, time, solution, and annealing process, were investigated to obtain the optimal reaction conditions. The synthesized activated MIL-88A had great porosity and excellent adsorption capacity for p-ASA in a wide pH range (3 similar to 10). When the pH of the solution was 6, the activated MIL-88A achieved a great adsorption capacity of 813 mg?g(-1) for the p-ASA solution with an initial concentration of 0.334 mmol?L-1. In addition, it still had excellent adsorption capacity after 4 times of repeated usage and washing. Findings: The adsorption kinetics of p-ASA on the activated MIL-88A followed the pseudo-second-order models, and the adsorption isotherms can be fitted by the Langmuir models well. The adsorption behavior was spontaneous and endothermic, and was dominated by Fe-O-As coordination and hydrogen bonding. (C) 2022 Elsevier Inc. All rights reserved.

形状记忆聚合物防砂筛管在日本第二轮天然气水合物试采中成功应用,但形状记忆效应对聚合物孔渗特征和防砂性能等影响的研究较少.基于此,本文研发了一种以聚氨酯作为基质的形状记忆聚合物防砂材料,探究了聚合物形状记忆特性、形状记忆前后的孔渗特性和力学强度等的变化规律,并评价了防砂性能.实验结果表明:研制的多孔聚氨酯具有良好的形状记忆特性和孔渗特性,形状固定率>98%,形状恢复率为100%,形状记忆温度为59.8℃;回弹前后渗透率均维持在10 D左右,且回弹前后抗压强度均维持在1 MPa左右;压汞测试表明形状记忆是一个对材料内部大孔的压缩-回弹过程,会导致材料内部结构发生变化,造成抗压强度略有降低,但完全回弹后,渗透性会小幅度增加;防砂性能测试表明仅在实验初期会有少量砂产出,砂粒的产出会对聚氨酯渗透性有一定的损伤,但对完全回弹的聚氨酯的渗透率仍可保持在10 D左右.综合材料性能分析认为,研制的形状记忆聚氨酯材料可配合机械防砂筛管使用,能满足水合物开采井防砂的需求.

在冰层钻进时,热融钻具往往会发生倾斜,导致其偏离目标冰层,无法完成既定钻探任务,因此必须对热融钻具的倾斜进行预防和纠正.为此,本文首先分析了热融钻具发生倾斜的原因,并将其归纳为热融钻头底部冰层受热不均、热融钻具结构稳定性差、放缆速度高于钻进速度、钻孔直径过大等;然后,从热力法、重力法、浮力法、推靠法、扶正器法、导向杆嫁接法、钻孔直径减小法等方面归纳总结了热融钻具的防/纠斜方法,从而为进一步开展热融钻具防/纠斜研究奠定了基础.

Hydraulic fracturing is a technology used to improve the fluid flow performance of hydrate-bearing sediments (HBSs). It enhances the pore structure of HBSs and increases the porosity and permeability, thereby improving the exploitation efficiency of natural gas hydrates. However, most of the analytical models are two-dimensional, and there is an obvious gap between the critical parameters of cracks and the experimental results. In this study, a new single-cluster model of hydraulic fracturing for the horizontal well is established with available data from site GMGS3-W19 of the South China Sea (SCS) based on the three-dimensional (3D) extended finite element method (XFEM). The hydraulic fracturing behavior of HBSs for different perforation angles, hydrate saturation, horizontal in situ geo-stress coefficient, and injection rate is investigated, and the initiation and propagation mechanism of hydraulic fractures is revealed in a three-dimensional scale. The results showed that with the increase of hydrate saturation, the ability of hydrate to connect the sediment skeleton is enhanced, and the HBSs have a more vital ability to resist fluid pressure. The remaining pores in the HBSs are filled; the degree of pressure holding in the fracture increases; the fracture development is hindered; and the difficulty of fracture initiation increases.

南极大陆冰盖下存在液态水,形成了由冰下湖、冰下河/溪、冰封湖和冰架下水体等组成的冰下水生态系统,具有低温、黑暗和寡营养等极端的环境条件特征.微生物主导了南极冰下水生态系统,其具有丰富多样的种群构成、功能形式和独特的适应机制,在生源元素生物地球化学循环过程中起了重要作用.研究南极冰下微生物群落的生态特征及其参与的生源元素地球化学循环过程,可为揭示地球生命演化和探索外星生命提供指示,具有重要的科学意义.本文综述了南极冰下水生态系统的极端环境条件、冰下微生物的多样性、冰下微生物参与的生物地球化学循环以及冰下微生物的适极机理,最后基于研究现状展望了南极冰下微生物的未来研究方向.

The melting water produced from ice during hot-point drilling can easily freeze and cause the hot-point drill to stick. Two different thermal anti-freezing methods exist to prevent water-filled boreholes from refreezing: the heating cable method and lateral heating method. However, the required power density and ice temperature distribution when using these two methods have not been fully discussed. In this study, heat transfer models of the two thermal anti-freezing methods were first developed based on a simplified heat conduction equation by considering the downward movement of the hot-point drill. Subsequently, case studies were conducted to determine the characteristics of the heat transfer during hot-point drilling. Finally, the variations in the power density, power consumption, borehole closure time, borehole closure length, and thermal layer thickness for both thermal anti-freezing methods were evaluated. We recommend that the heating cable method should be used to drill boreholes with shallow depths or small diameters in temperate ice, whereas the lateral heating method can be applied to a wide range of ice temperatures, borehole diameters, and borehole depths. Generally, the paper presents useful guidance for designing the heating cable and lateral heater and reducing the risk of borehole freezing.

The existing hydrate exploitation technology is characterized by low gas production in single wells and a small exploitation range, owing to the low porosity and low permeability of submarine hydrate reservoirs; therefore, commercial exploitation is difficult to achieve. There is an urgent need to improve exploitation efficiency by means of reservoir reconstruction. Hydraulic fracturing technology may be useful for low-permeability reservoirs such as silty hydrate reservoirs in the South China Sea (SCS). In this study, we established a new hydraulic fracturing model of a horizontal single well for gas-hydrate-bearing-sediments (GHBS) using the cohesive zone method (CZM) based on the extended finite element method (XFEM). To this end, we utilized field measured data of GHBS at site GMGS3-W19. The effect of fluid-solid coupling was considered, and the fracture propagation criterion was set as the maximum principal stress criterion to analyze the hydraulic fracture propagation law of hydrate reservoirs in the SCS. First, we illustrated the effectiveness of the CZM based on XFEM in simulating the fracture morphology of GHBS hydraulic fracturing. A Parametric study showed that the hydrate saturation, horizontal geo-stress coefficient, perforation angle, and injection rate play crucial roles in the fracture propagation path and characteristic parameters of GHBS hydraulic fractures. The fracture development pattern and propagation law of a silty hydrate reservoir within the SCS were theoretically obtained. The results of the present study partly provide theoretical support for hydrate exploitation engineering in the SCS.

AbstractA series of new synthetic armored cables were developed and tested to ensure that they were suitable for use with the RECoverable Autonomous Sonde (RECAS), which is a newly designed freezing-in thermal ice probe. The final version of the cable consists of two concentric conductors that can be used as the power and signal lines. Two polyfluoroalkoxy jackets are used for electrical insulation (one for insulation between conductors, and the other for insulation of the outer conductor). The outer insulation layer is coated by polyurethane jacket to seal the connections between the cable and electrical units. The 0.65 mm thick strength member is made from aramid fibers woven together. To hold these aramid fibers in place, a sheathing layer was produced from a polyamide fabric cover net. The outer diameter of the final version of the cable is ~6.1 mm. The permissible bending radius is as low as 17–20 mm. The maximal breaking force under straight tension is ~12.2 kN. The cable weight is only ~0.061 kg m−1. The mechanical and electrical properties and environmental suitability of the cable were determined through laboratory testing and joint testing with the probe.

极地钻探是获取极地冰层或冰下环境样品和在极地冰层或冰下布放科学观测仪器的最直接方法,是开展极地科学研究的必要技术手段.美国是开展极地钻探较早的国家之一,也是极地钻探强国.相比美国,我国极地钻探技术尚处于起步阶段.本文以《美国冰钻委员会长期科学规划2021-2031》为基础,结合其官方网站和相关文献资料,梳理了美国极地钻探科学目标和极地钻探技术现状,并简要介绍了过去10年美国极地钻探的现场工作情况及其在未来3年的工作计划,以期为我国极地钻探发展提供参考.

The transfer rate of photo-generated electrons is a critical factor that determines the photocatalytic efficiency of Z-scheme photocatalytic systems. Here, a novel Z-scheme g-C3N4-AQ-MoO3 photocatalyst with anthraquinone (AQ) serving as an e- transfer channel for hydrogen production was proposed. Its enhanced photocatalytic activity is due to the accelerated transfer of e(-) in the form of charge inside AQ, which also suppresses the recombination of photo-generated e(-) and h(+). In addition, the reduction area is significantly increased by the exfoliation of g-C3N4 into thin layers. Due to the synergistic effect of rapid e(-) transfer and large reduction area, Z-scheme g-C3N4-AQ-MoO3 has a high hydrogen production efficiency that can reach 2018 mu mol/g with the presence of triethanolamine as a hole sacrificial agent after 180 min of simulated sunlight illumination. This work provides a new strategy to design and develop Z-scheme photocatalytic systems with excellent electron migration rates and high charge separation efficiency.

我国于2012年1月在南极Dome A区域正式开展实施了南极昆仑站深冰芯科学钻探工程,截至2021年,钻孔深度已达803.54 m.该工程是我国第一个深冰芯钻探工程,也是国际上第一个在Dome A地区开展的深冰芯钻探项目.本文介绍了昆仑站深冰芯科学钻探工程实施的整体情况,对过去近10年的钻探活动以及取得的成果和经验进行了总结,以期为后续的深冰芯钻探工作提供理论和经验指导.

本文基于我国第一轮海域天然气水合物试采地质模型,利用Tough+Hydrate对近井储层改造后的水合物藏进行降压开采模拟研究.探究了多孔骨架渗流通道对气/水输送、压降传播、水合物分解等的影响机制,评估了近井储层改造在不同开采层位和整个开采过程中对产能提高的贡献大小.模拟结果表明:多孔骨架渗流通道内气/水流速高,可以起到导流、防砂的作用;近井储层改造可促进压降传播,加快水合物分解,但骨架通道的增产作用随开采时间增加逐渐减弱;近井储层改造在不同开采层位起到的增产效果不同,三相层中的增产效果最明显,但由于模拟改造范围较小、形成的多孔骨架渗流通道渗透性较低,增产效果不明显,多孔骨架渗流通道高度为50 cm时,2年产气量仅提高11.7％.

A high-efficiency Z-scheme Bi2MoO6/AgI heterojunction was designed and fabricated via in situ growth of AgI on Bi2MoO6. Its photocatalytic activity was investigated with the degradation of malachite green (MG). After 40 min of visible light irradiation, near complete degradation of MG (20 mg/L) occurred when BA11 (Bi2MoO6:AgI = 1:1, 2.0 g/L) was present, while only 29.0% and 49.7% of the MG could be degraded in the presence of Bi2MoO6 and AgI, respectively. The excellent photocatalytic activity of BA11 results from strong visible light absorption and the low recombination efficiency of photogenerated electron-hole pairs induced by the formation of heterojunction. Density function theory (DFT) calculations revealed that the formation of built-in electric field at the interface between Bi2MoO6 and AgI facilitates the effective separation and transfer of photogenerated charge carriers. Results of reuse experiments indicated that the heterostructured photocatalyst has excellent stability. Radical scavenging experiments and electron spin resonance spectra showed that superoxide radicals (O2−) and hydroxyl radicals (OH) were the major reactive oxygen species in the photocatalytic system. The photocatalytic degradation pathway of MG was proposed based on the organic degradation intermediates detected. These findings demonstrate that the mediator-free Z-scheme Bi2MoO6/AgI heterojunction could serve as a promising photocatalyst in photocatalytic treatment of organic pollutants.

自1970年至今,前苏联和俄罗斯在南极东方站持续进行了近50年的冰层钻探活动,先后攻克了包含粒雪层、冰层、冰岩夹层和湖水冻结冰的复杂冰层钻进难题,逐渐形成了一套集热融取芯钻探、电动机械取芯钻探和分支孔钻探等为一体的深冰芯钻探技术.创造了冰层最深干孔钻进深度记录(952.4 m)、最深热融取芯钻进记录(2755 m)、最深冰芯钻探记录(3769.3 m),累计进尺达13000 m,并获取了总长超46 m的含湖水冻结冰样品的冰芯.东方站的钻探活动对极地冰层钻探技术的发展起到了巨大的推动和引领作用,同时积累了宝贵的深冰钻探经验.通过对东方站深冰钻探技术的系统梳理,将为我国正在实施的深冰芯钻探和即将开启的冰下湖科学钻探提供重要的借鉴.

HYPOTHESIS:Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into the environment. Bimetal ferrites are recognized as promising sorbents in removal of organoarsenicals with formation of FeOAs complexes, and their high saturation magnetization also allows easy sorbent separation. EXPERIMENTS:Herein, a flower-like CoFe2O4 sorbent was synthesized through an environmental-friendly process. FINDINGS:The flower-like CoFe2O4 particles have abundant mesopores and a large specific surface area of 48.4 m2/g. At an equilibrium concentration of 80 μmol/L, the sorption capacities towards p-arsanilic acid (p-ASA), roxarsone (ROX), 4-hydroxyphenylarsonic acid (4-HPAA), 2-aminophenylarsonic acid (2-APAA), phenylarsonic acid (PAA), and 2-nitrophenylarsonic acid (2-NPAA) were 38.1, 45.7, 38.7, 39.3, 33.0, and 32.8 mg/g, respectively. Langmuir model and pseudo-second-order kinetics could well fit the sorption isotherms and rates. The sorption performance was better under acidic conditions due to enhanced electrostatic attraction. Humic acid (HA) and PO43- inhibited the sorption through competing for sorption sites, while Fe3+ promoted sorption due to formation of additional FeOAs complexes on sorbent surface. The experimental observations, spectroscopic insights, and density functional theory (DFT) calculations consistently indicate that the sorption of aromatic organoarsenicals on the flower-like CoFe2O4 particles occurs mainly through formation of inner-sphere complexes. The flower-like CoFe2O4 could be regenerated and reused over multiple cycles. The high sorption capacities, together with its magnetic property, make the flower-like CoFe2O4 an attractive sorbent for removing aromatic organoarsenicals from wastewater.