Search Results (73)

The Arctic ice layer serves as an excellent cover for strategic nuclear submarine forces, but it also poses significant challenges when submarines surface. This paper proposes a method for breaking through the ice layer and surfacing in polar environments based on the principle of resonance. This method eliminates the need for direct contact between the submarine and the ice layer, solving the current issues with submarine ice-breaking methods that demand high strength from the submarine and pose risks to both the submarine and its crew. Through theoretical analysis, numerical simulation and experimental verification, the vibration characteristics and fracture mechanism of the ice layer under the action of excitation loads were studied. Experiments showed that when the excitation frequency matched the fundamental eigenfrequency Ω1 of the ice layer, obvious resonance occurred and cracks appeared in the ice layer. A dynamic model of the ice layer was established using Abaqus software, and modal extraction and stress analysis were carried out. The error between the Ω1 obtained by numerical simulation and the experimental results was only 0.53%, verifying the reliability of the model. After applying the excitation load with a frequency of Ω1, the stress in the ice layer gradually expanded to the strength limit of the ice, achieving an ice-breaking effect consistent with the experimental results. Experimental and simulation results showed that the use of Ω1 for resonance ice-breaking had the best effect. When the ice layer resonated, the stress increased first and then stabilized, and cracks occurred before the stress stabilized to achieve the ice-breaking effect. Full article

The sampling and observation of subglacial lakes play a vital role in studying the physical and chemical properties as well as the microbial characteristics of water within these Antarctic subglacial lakes. Compared to existing techniques, such as deep ice core drilling and clean hot water drilling, recoverable autonomous sondes, inspired by the spinning and reeling silk behavior of spiders, offer several advantages, including lightweight design, low power consumption, and minimal external pollution. Over the past six years, Jilin University, with support from the Ministry of Science and Technology of China, has developed an environmentally friendly sampling and observation system for Antarctic subglacial lakes, utilizing a recoverable autonomous sonde. The whole system includes a melting sonde, detection and control unit, scientific load platform, and ice surface auxiliaries. Extensive laboratory and joint system tests were conducted, both on key components and the complete system, including field tests in ice lakes. The results of these tests validated the feasibility of the underlying principles, the long-term reliability of the system operation, and the cleanliness of the drilling process. Ice penetration speed up to 2.14 m/h was reached with 6~6.5 kW melting tip power and a 660 mL lake water sample was collected. The relevant design concepts and technologies of the system are expected to play an important role in the clean detection and sampling of subglacial lakes in Antarctica, Greenland, and other regions. Full article

Current studies have paid extensive attention to the occurrence of brominated flame retardants (BFRs) in aquatic environments; however, there is a lack of exploration of BFRs in ice media in freshwater environments, and there are fewer studies on the distribution patterns and ecological risks of BFRs in different media. In order to fill this gap in the current research status, this study conducted four seasonal samplings in the Songhua River wetland in Northeast China. The distribution and risk of 14 polybrominated diphenyl ethers (PBDEs) and 22 new brominated flame retardants (NBFRs) in water, ice, sediment, and soil were analyzed using liquid–liquid extraction sample pretreatment and gas chromatography–mass spectrometry instrumentation. A total of 18, 5, 8, 19, and 18 BFRs were detected in non-ice-covered water, ice-covered water, ice, sediment, and soil, respectively. NBFRs dominated contaminant concentrations in each medium. Significant correlations were found between BFRs in ice and subglacial water, suggesting that the sources of BFRs in these two media are similar and there is an exchange between them. The ice enrichment factor (IEF) revealed the water–ice distribution mechanism of BFRs, indicating that wetland ice acts as a temporary sink for 2-(Allyloxy)-1,3,5-tribromobenzene (ATE), 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (α-TBECH), 1,2,5,6-Tetrabromocyclooctane (TBCO), and 2-Bromoallyl 2,4,6-tribromophenyl ether (BATE). In order to achieve dynamic equilibrium, the exchange profile of BFRs between water and sediment requires the release of BFRs into water. The risk quotient (RQ) indicated that TBCO in water and ice poses a moderate risk to aquatic organisms, and its potential impact on wetland ecology cannot be ignored. Full article

Thermal ice drilling technology is extensively used in drilling operations such as temperature measurement holes and subglacial water environment investigations in Antarctica owing to its advantages of compactness, light weight, and ease of operation. However, thermal drilling disturbs the initial temperature of the surrounding ice, making it impossible to obtain the true ice temperature through a borehole within a short period. Meltwater refreezing also causes the borehole to shrink and close, posing a threat to drilling safety. Therefore, obtaining an accurate characterization of the temperature field around the hole and assessing the meltwater refreezing rate are crucial for determining the appropriate temperature measurement duration and optimizing drilling parameters. To address this issue, a temperature measurement platform for the ice surrounding the borehole was developed. Experimental investigations were conducted to analyze the temperature fields during thermal drilling using both small-diameter thermal heads and RECoverable Autonomous Sonde (RECAS) thermal heads. This study clarifies the temperature field changes in the surrounding ice during and after thermal drilling. It also elucidates the effects of parameters such as the ice temperature, thermal head heating power, and thermal head diameter on the temperature field around the hole and estimates the meltwater refreezing rate inside the borehole. The results indicated that the temperature of the surrounding ice peaked approximately 5–7 h after drilling and subsequently decreased and returned to the original temperature within 48 h. The thermal disturbance radius in the surrounding ice was approximately 1.1 to 1.7 times the borehole radius when the thermal head passed through. However, after the thermal head passed, the thermal disturbance radius continued to expand owing to the heat released from meltwater refreezing, reaching 9.7 to 12.5 times the borehole radius. The average meltwater refreezing rate, estimated from temperature measurement tests at −16 °C, was 3.6 mm/h. Full article

The Antarctic region holds significant scientific research value and potential resources. Currently, limited research exists on the use of seismic exploration methods for Antarctic subglacial lakes compared to their use on other continents. Moreover, few reports are available on systems capable of multi-channel seismic data acquisition, remote data quality monitoring, and high-speed real-time data recycling in the extremely low temperatures of Antarctica. In this study, we developed a Zynq-based seismic acquisition station for polar exploration. The system features a compact design, lightweight construction, high data collection accuracy, excellent cold resistance, low power consumption, and real-time control. The software and hardware design of the system are described here, and validity testing is presented. The main controller utilizes a Zynq series system-on-chip integrated with an FPGA (Field-Programmable Gate Array) and an ARM (Advanced RISC Machine), enabling functions such as local data storage on a secure digital card, Wi-Fi wireless human–machine interaction, and high-speed Ethernet data transmission. Furthermore, to enhance data acquisition accuracy under low-temperature conditions, a neural network was employed for the temperature drift correction of the analog-to-digital converter chip. The validity test results showed that the station operated stably, was easy to use, and met the high-standard requirements for polar exploration. Full article

Arctic tidewater glaciers are retreating, serving as key indicators of global warming. This study aims to assess how subglacial hydrology affects glacier front retreat by comparing two glacier–fjord models of the Hansbreen glacier: one incorporating a detailed subglacial hydrology model and another simplifying the subglacial discharge to a single channel centered in the flow line. We first validate the subglacial hydrology model by comparing its discharge channels with observations of plume activity. Simulations conducted from April to December 2010 revealed that the glacier front position aligns more closely with the observations in the coupled model than in the simplified version. Furthermore, the mass loss due to calving and submarine melting is greater in the coupled model, with the calving mass loss reaching 6 Mt by the end of the simulation compared to 4 Mt in the simplified model. These findings highlight the critical role of subglacial hydrology in predicting glacier dynamics and emphasize the importance of detailed modeling in understanding the responses of Arctic tidewater glaciers to climate change. Full article

Deep-seated gravitational slope deformations (DSGSDs) consist of gravity-induced, large-scale, gradual rock mass movements. In the Aosta Valley region (Valle d’Aosta NW Italy), DSGDs affect wide valley slopes and produce several interconnected morpho-structures that involve bedrock and Quaternary cover. Some DSGSD effects are not visible at the surface because of subglacial abrasion or burial by sediments and, therefore, are difficult to map with standard geomorphological surveys. This is the case for the Pointe Leysser DSGSD in the Aosta Valley, which is heavily influenced by the historical movements of the Verrogne-Clusellaz Glacier and its tributaries. We conducted a new geological investigation, integrated with deep electrical resistivity tomography geophysical surveys (ERTs). The ERT results were initially compared with geological/geomorphological evidence at the surface to define the correlation between the values and spatial distributions of electrical resistivity and the sediments, rocks, or morpho-structures. The resistivity values at various depths were subsequently analysed, interpreted, and discussed in conjunction with geological hypotheses. The geological and geophysical survey revealed three wide buried glacial valleys filled with glacial sediments and mapped the locations of gravitational morpho-structures at depth. These new data allowed us to draw a relationship between glacialism and gravitational evolution, distinguishing between pre-singlacial movements and postglacial movements. Full article

This study explored the dynamics of bacterial community composition, response to environmental factors, and co-occurrence network models across different habitats of Wuliangsuhai Lake during the glacial period. Water quality analysis and high-throughput sequencing were performed at 14 monitoring sites within the lake. Additionally, a co-occurrence network between the two bacterial operational taxonomic unit (OTU)-OTUs was established. The results indicated significant differences in water quality indices, namely total nitrogen (TN), chemical oxygen demand (COD), total dissolved solids (TDS), salinity (SAL), chlorophyll-a (Chl.a), and electrical conductivity (EC), between the ice bodies of Wuliangsuhai Lake and subglacial water. Although there were no significant differences in α diversity across various media, substantial differences were observed in β diversity. The VIF and RDA analyses revealed that lake water quality factors significantly affected the microbial community structure and COD and TDS had the highest explanation for the community composition change. Network analysis demonstrated that competition dominated the bacterial community in water bodies with higher complexity and stability and ice body bacteria exhibited more reciprocal relationships and weaker resistance to external environmental disturbances. The co-occurrence network demonstrated a modular structure in the external environment, with g_Flavobacterium, f_Arcobacteraceae, and g_Sphingobacteriaceae being the main keystone species. Investigating the habitat heterogeneity of lake bacterial communities and identifying major groups and key species using molecular ecological network models and their topological effects can provide a theoretical foundation for monitoring and assessing the structural stability of lake ecosystems in cold regions. Full article

Subglacial lakes and hydrological systems play crucial roles in Antarctic subglacial hydrology, water balance, subglacial geomorphology, and ice dynamics. Satellite altimetry has revealed that some recurrent water exchange occurs in subglacial lakes. They are referred to as ’active lakes’, which prominently influence a majority of subglacial hydrological processes. Our analysis indicates that active subglacial lakes are more likely to be situated in regions with higher surface ice flow velocities. Nevertheless, the origin of subglacial lakes still remains enigmatic and uncertain. They could have potential associations with geothermal heat, ice sheets melting, and ice flow dynamics. Subglacial lake drilling and water sampling have the potential to provide valuable insights into the origin of subglacial lakes and subglacial hydrological processes. Moreover, they could also offer unique opportunities for the exploration of subglacial microbiology, evolution of the Antarctic ice sheets, and various fundamental scientific inquiries. To date, successful drilling and sampling has been accomplished in Lake Vostok, Lake Mercer, and Lake Whillans. However, the use of drilling fluids caused the water sample contamination in Lake Vostok, and the drilling attempt at Lake Ellsworth failed due to technical issues. To explore more of the conditions of the Antarctic subglacial lakes, the Lake Centro de Estudios Científicos (Lake CECs) and Lake Snow Eagle (LSE) drilling projects are upcoming and in preparation. In this study, we aim to address the following: (1) introduce various aspects of Antarctic subglacial lakes, subglacial hydrological elements, subglacial hydrology, and the interactions between ice sheets and the ocean; and (2) provide an overview and outlook of subglacial lakes drilling projects. Full article

The Lac Fallère area in the upper Clusellaz Valley (tributary of the middle Aosta Valley) is shaped in micaschist and gneiss (Mont Fort Unit, Middle Penninic) and in calcschist and marble (Aouilletta Unit, Combin Zone). Lac Fallère exhibits an elongated shape and is hosted in a WSW–ENE-trending depression, according to the slope direction. This lake also shows a semi-submerged WSW–ENE rocky ridge that longitudinally divides the lake. This evidence, in addition to the extremely fractured rocks, indicates a wide, deep-seated gravitational slope deformation (DSGSD), even if this area is not yet included within the regional landslide inventory of the Aosta Valley Region. The Lac Fallère area also shows reliefs involved in glacial erosion (roches moutonnée), an extensive cover of subglacial sediments, and many moraines essentially referred to as Lateglacial. The DSGSD evolution in a glacial environment produced, as observed in other areas, effects on the facies of Quaternary sediments and the formation of a lot of wide moraines. Glacial slope sectors and lateral moraines displaced by minor scarps and counterscarps, and glaciers using trenches forming several arched moraines, suggest an interplay between glacial and gravitational processes, which share part of their evolution history. Full article

The Princess Elizabeth Land landscape in East Antarctica was shaped by a complex process, involving the supercontinent’s breakup and convergence cycle. However, the lack of geological knowledge about the subglacial bedrock has made it challenging to understand this process. Our study aimed to investigate the structural characteristics of the subglacial bedrock in the Mount Brown region, utilizing airborne geophysical data collected from the China Antarctic Scientific Expedition in 2015–2017. We reconstructed bedrock density contrast and magnetic susceptibility models by leveraging Tikhonov regularized gravity and magnetic inversions. The deep bedrock in the inland direction exhibited different physical properties, indicating the presence of distinct basement sources. The east–west discontinuity of bedrock changed in the inland areas, suggesting the possibility of large fault structures or amalgamation belts. We also identified several normal faults in the western sedimentary basin, intersected by the southwest section of these survey lines. Furthermore, lithologic separators and sinistral strike-slip faults may exist in the northeast section, demarcating the boundary between Princess Elizabeth Land and Knox Valley. Our study provides new insights into the subglacial geological structure in this region, highlighting the violent impact of the I-A-A-S (Indo-Australo-Antarctic Suture) on the subglacial basement composition. Additionally, by identifying and describing different bedrock types, our study redefines the potential contribution of this region to the paleocontinent splicing process and East Antarctic basement remodeling. Full article

Glaciers retreating due to global warming create important new habitats, particularly suitable for studying ecosystem development where nitrogen is a limiting factor. Nitrogen availability mainly results from microbial decomposition and transformation processes, including nitrification. AOA and AOB perform the first and rate-limiting step of nitrification. Investigating the abundance and diversity of AOA and AOB is essential for understanding early ecosystem development. The dynamics of AOA and AOB community structure along a soil chronosequence in Tianshan No. 1 Glacier foreland were analyzed using qPCR and clone library methods. The results consistently showed low quantities of both AOA and AOB throughout the chronosequence. Initially, the copy numbers of AOB were higher than those of AOA, but they decreased in later stages. The AOB community was dominated by “Nitrosospira cluster ME”, while the AOA community was dominated by “the soil and sediment 1”. Both communities were potentially connected to supra- and subglacial microbial communities during early stages. Correlation analysis revealed a significant positive correlation between the ratios of AOA and AOB with soil ammonium and total nitrogen levels. These results suggest that variations in abundance and diversity of AOA and AOB along the chronosequences were influenced by ammonium availability during glacier retreat. Full article

The latest laser altimetry technology employed by NASA’s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) enables the capture of denser and more precise spatial details. Here, we utilize ICESat-2 data from September 2018 to July 2022 to replicate and analyze the dynamics of the recovery ice stream’s subglacial lake system. To investigate the pathways of subglacial water transfer and determine the outline of subglacial lakes, we employ the differential digital elevation model (DEM) method to depict the surface elevation changes of each subglacial lake at monthly intervals. Our findings indicate significant migration in the activity location of 4 lakes. Notably, Rec1, previously regarded as a single lake, performed as two distinct lakes during the study. Furthermore, we identify two large-scale lakes with subglacial water flux reaching 0.5 km³. Full article

This paper aims to solve the limitations of traditional gravity physical property inversion methods such as insufficient depth resolution and difficulties in parameter selection, by proposing an improved 3D gravity inversion method based on deep learning. The deep learning network model is established using the fully convolutional U-net network. To enhance the generalization ability of the sample set, the large-scale training set and test set are generated by the random walk, based on the forward theory. Founded on the traditional loss function’s definition, this paper introduces an improvement incorporating a physical constraint to measure the degree of data fitting between the predicted and the real gravity data. This improvement significantly boosted the accuracy of the deep learning inversion method, as verified through both a single model and an intricate combination model. Finally, we applied this improved inversion method to the gravity data from the Gamburtsev Subglacial Mountains in the interior of East Antarctica, obtaining a comprehensive 3D crustal density structure. The results provide new evidence for the presence of a dense crustal root situated beneath the central Gamburtsev Province near the Gamburtsev Suture. Full article

Antarctica is of great importance in terms of global warming, the sustainability of resources, and the conservation of biodiversity. However, due to 99.66% of the continent being covered in ice and snow, geological research and geoscientific study in Antarctica face huge challenges. Geophysical surveys play a crucial role in enhancing comprehension of the fundamental structure of Antarctica. This study used bibliometric analysis to analyze citation data retrieved from the Web of Science for the period from 1982 to 2022 with geophysical research on Antarctica as the topic. According to the analysis results, the amount of Antarctic geophysical research has been steadily growing over the past four decades as related research countries/regions have become increasingly invested in issues pertaining to global warming and sustainability, and international cooperation is in sight. Moreover, based on keyword clustering and an analysis of highly cited papers, six popular research topics have been identified: Antarctic ice sheet instability and sea level change, Southern Ocean and Sea Ice, tectonic activity of the West Antarctic rift system, the paleocontinental rift and reorganization, magmatism and volcanism, and subglacial lakes and subglacial hydrology. This paper provides a detailed overview of these popular research topics and discusses the applications and advantages of the geophysical methods used in each field. Finally, based on keywords regarding abrupt changes, we identify and examine the thematic evolution of the nexus over three consecutive sub-periods (i.e., 1990–1995, 1996–2005, and 2006–2022). The relevance of using geophysics to support numerous and diverse scientific activities in Antarctica becomes very clear after analyzing this set of scientific publications, as is the importance of using multiple geophysical methods (satellite, airborne, surface, and borehole technology) to revolutionize the acquisition of new data in greater detail from inaccessible or hard-to-reach areas. Many of the advances that they have enabled be seen in the Antarctic terrestrial areas (detailed mapping of the geological structures of West and East Antarctica), ice, and snow (tracking glaciers and sea ice, along with the depth and features of ice sheets). These valuable results help identify potential future research opportunities in the field of Antarctic geophysical research and aid academic professionals in keeping up with recent advances. Full article