Search Results (837)

This study presents an investigation of the factors (driven by coupled multi-factor corrosion mechanisms) which contribute to the degradation of the spirally wound armored steel wires used to protect core-structured, unarmored optical-fiber submarine cables. The influences of the physical properties of deep-sea sediments on the durability of unarmored cables, as well as the impact of ionizing radiation on optical fibers, are also assessed. The objective of this paper is to establish a scientific basis for cable longevity by integrating theoretical insights with empirical evidence. Although the steel utilized in armored cables is cost-effective and durable, it remains vulnerable to corrosion. Since the inaugural practical deployment of submarine communication cables between the UK and France in the 1850s, only a small number of studies worldwide have examined the corrosion and durability of cable armor. There is also limited literature examining the physical characteristics of the deep-sea surface sediments that directly affect the service life of the cables’ mechanically fragile polyethylene sheathing. An in-depth analysis of the cable damage and environmental conditions observed during maintenance operations provides valuable insights into the key environmental factors that influence armor corrosion and cable longevity. This research aims to guide future design and support strategies to improve the sustainability and durability of cable systems in marine environments. Full article

Recent deep exploration in the northern Sichuan Basin has advanced our understanding of Lower Cambrian Canglangpu Formation carbonate reservoirs. However, the characteristics, genesis, and distribution of the reservoir, as well as future exploration targets, remain unclear. Specifically, core and thin-section analyses indicate that these reservoirs are notably tight, with virtually no visible macroporosity and low permeability (0.01–1 mD). However, helium porosity measurements reveal values of 2–5%, suggesting significant storage potential. An integrated approach utilizing optical and scanning electron microscopy (SEM), high-pressure mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and micro-computed tomography (micro-CT) was employed to characterize the pore systems. Quantitative thin-section analysis reveals visible areal porosity markedly lower than helium porosity, indicating predominance of micropores; mercury intrusion and NMR demonstrate that intragranular and intergranular micropores constitute most pore volume, although effectively connected throat sizes remain below 1 µm. Comparative stratigraphic evaluations show that porosity is more developed in the dolomite-rich upper and middle intervals of the depositional cycles, whereas the lower intervals are less porous. Early subaerial exposure promoted dolomitization and dissolution, which facilitated pore development. However, the influence of sediment mixing led to a reduction in porosity. And deep burial subjected the rocks to intense compaction and cementation, destroying most of the primary pore space. Consequently, reservoir quality is ultimately governed by the interplay between the original depositional environment and the later diagenetic history, with paleotopographic highs identified as the most promising exploration targets. These findings establish a predictive framework for reservoir quality in tight carbonate rocks, which holds significant implications for analogous plays worldwide. Full article

Arid Central Asia (ACA) is a major source of atmospheric dust in the Northern Hemisphere; however, the evolutionary models and driving mechanisms of Holocene aeolian activity in this region remain debated. Based on 13 reliable AMS ¹⁴C dates from the Sayram Lake SLM2009 sediment core, this study reconstructs the Holocene sequence in aeolian activity through end-member modeling analysis (EMMA). It evaluates its relationship with regional atmospheric circulation. Four end-members were identified from base to top: EM1, with a modal grain size of 7.58 μm, represents low-energy suspension deposition; EM2 (26.30 μm) reflects lacustrine hydrodynamic processes; while EM3 (52.48 μm) and EM4 (416.86 μm) serve as proxies for regional aeolian activity. The results indicate that aeolian activity was relatively strong during the early Holocene (reaching peaks at 11.7–11.2 and 9.2–8.1 cal ka BP), significantly intensified during the mid-Holocene (7.3–5.3 cal ka BP), and gradually weakened in the late Holocene (since 4.0 cal ka BP). Comparison of the aeolian record from Lake Sayram with Greenland ice cores, North Atlantic ice-rafted debris events, and the GISP2 K⁺ record indicates that variations in aeolian activity in arid Central Asia are closely linked to the Northern Hemisphere climate system. We propose that these variations were primarily modulated by large-scale atmospheric circulation, driven by the synergistic interaction between the Siberian High and the mid-latitude westerlies. Full article

Livestock manure management contributes substantially to agricultural greenhouse gas emissions, making the adoption of low-carbon approaches urgent in ecologically sensitive regions. This study focuses on the County-wide Livestock Manure Resource Utilization Project in Danjiangkou City, the core water source area of China’s South-to-North Water Diversion Project. Based on field survey data, IPCC Guidelines, and a life cycle assessment framework, this study established a carbon accounting boundary covering excretion, collection, storage, treatment, and utilization stages. A scenario analysis was conducted to compare 2023 baseline emissions with 2026 project emissions and to quantify the carbon reduction potential. The research findings indicate that the overall carbon reduction rate following the project’s implementation reached 40.8%. However, the effectiveness varied considerably across the four management models. The Sedimentation–Crop Model and the Housing–Bedding Integrated Model, which employed integrated systemic interventions, achieved reductions of 61.50% and 60.09%, respectively. In contrast, the “124” Healthy Breeding Model and the Raised-Bedding Composting System, which relied primarily on single-stage upgrades, achieved reductions of only 32.04% and 27.70%. This disparity suggests that in decentralized livestock operations, isolated technological improvements fall short; meaningful decarbonization requires systemic interventions across the entire manure management chain. The findings provide a reference for low-carbon livestock manure management and regional development in ecologically sensitive areas. Full article

To investigate the influence of bioturbating organisms on the migration and degradation of chlorophenols in freshwater sediments, simulated experimental systems were established, with tubificid worms employed as the model bioturbator and 2,4,6-trichlorophenol (TCP) as a representative chlorophenol contaminant. The results showed that tubificid worms significantly promoted the removal of TCP in sediments, with this effect mainly concentrated in the surface sediment layer (0–2 cm) and limited impact on deeper sediment layers (2–6 cm). The removal efficiency was higher in the low-concentration TCP group than in the high-concentration group. TCP in the overlying water was predominantly in the dissolved phase, and the presence of tubificid worms reduced the TCP concentration in the aqueous phase, resulting in a greater amount of removal. The bioturbation of tubificid worms altered the physicochemical characteristics of the system, increasing the turbidity of the overlying water, decreasing its pH, elevating the redox potential across different sediment depths, and improving the organic matter conditions. Tubificid worms also modified the bacterial community structure in both the overlying water and the sediment. The core mechanism by which tubificid worms accelerate TCP removal is through promoting the migration of TCP from the sediment to the overlying water, while concurrently regulating the bacterial community structure in the overlying water to enhance the degradation capacity of chlorophenols in this layer. This highlights the important role of bioturbators in aquatic ecosystems, and ignoring their presence may lead to an erroneous underestimation of the system’s self-purification capacity. Full article

Sediment plumes generated by seafloor mining vehicles represent a major environmental concern in polymetallic nodule harvesting operations. This study investigates plume dispersion induced by sediment disturbances during mining using numerical simulations based on the similarity principle. A representative mining region is modeled, and the motion of mining vehicles is simulated to define the sediment disturbance source. The simulations employ the experimentally validated P-T Euler model (Particle–Turbulence Interaction Euler model) to examine the effects of sediment release velocity and ambient current velocity on plume dispersion characteristics. The results show that increasing the sediment release velocity primarily enhances the initial turbidity flux and significantly expands the plume core diffusion range, indicating that mining disturbances dominate near-field plume behavior. In contrast, the ambient current velocity strongly controls plume morphology and transport, promoting upward transport, long-range advection, and enhanced turbulent dissipation that governs far-field dispersion. Overall, plume diffusion is initially controlled by mining-induced sediment release but becomes increasingly dominated by ambient flow during large-scale transport. These findings provide a theoretical basis for predicting sediment plume behavior and assessing potential environmental impacts in deep-sea mining areas. Full article

Understanding the accumulation, ecological risk, and source interactions of potentially toxic elements (PTEs) in reservoir sediments is essential for protecting drinking water safety, yet such processes remain insufficiently understood in karst tea-plantation watersheds influenced by mixed anthropogenic activities. In this study, sediment cores collected from four sites (CY-1 to CY-4) during 2022–2024 were analyzed, and an integrated framework combining the Potential Ecological Risk Index (RI), Spearman correlation analysis, Principal Component Analysis (PCA), and Positive Matrix Factorization (PMF) was applied to evaluate contamination characteristics and quantify source contributions. The results revealed significant spatial–vertical heterogeneity of PTEs, with Zn (up to 153 mg/kg) and Cr (up to 64.6 mg/kg) showing the greatest variability, and strong co-enrichment among Cu, Zn, Pb, and Ni (r > 0.85, p < 0.01). Although the overall ecological risk was low (RI = 83.15–106.69), As contributed the highest proportion of risk (28–35%). PCA indicated distinct grouping patterns among elements, while PMF resolved three major sources: domestic sewage and agricultural runoff, agricultural and coal-combustion inputs, and industrial–traffic emissions. Notably, physicochemical parameters (TP, TN, and COD) played important roles in regulating the mobility and partitioning of PTEs by influencing nutrient-associated adsorption processes, organic matter complexation, and redox-related transformations. These findings highlight the multi-source-driven accumulation mechanisms of PTEs in karst reservoirs and provide a scientific basis for targeted pollution control and watershed management in agriculturally impacted regions. Full article

This study establishes a facies-based framework for characterizing reservoir quality in the Upper Pannonian geothermal reservoirs of the Szentes field (Hungary). To evaluate vertical heterogeneity and optimize the selection of geothermal reinjection zones, an integrated core–log–statistical workflow was applied to data from boreholes SZT-1 and SZSZT-IX. The methodology combined petrophysical measurements, petrographic observations, and multivariate statistical analyses, including Hierarchical Cluster Analysis (HCA) and Linear Discriminant Analysis (LDA). The siliciclastic succession was classified into four distinct facies clusters representing a continuum of depositional energy regimes: Rolling, Graded Suspension with Rolling, fine-grained Suspension, and Uniform Suspension. The results demonstrate a dual control on reservoir quality: the primary pore framework is determined by depositional grain-size architecture and sediment transport processes, while mechanical compaction and diagenetic alteration subsequently modify pore connectivity and flow efficiency. Among the identified facies, deposits formed from Graded Suspension with Rolling represent the most favorable reservoir units, combining high porosity (up to 33%) with exceptionally high permeability (>1500 mD). In contrast, suspension-dominated facies deposited from Graded and Uniform Suspension exhibit significantly reduced permeability due to higher matrix content, cementation, and compaction. The results demonstrate that reservoir performance in the Szentes geothermal system is primarily controlled by facies-scale heterogeneity rather than by depth-based stratigraphic divisions alone. This integrated facies-based approach provides a predictive framework for extrapolating reservoir properties to uncored intervals and offers practical guidance for optimizing reinjection strategies and sustainable geothermal reservoir management. Full article

Today’s fluvioscape of the Hessische Ried (Upper Rhine Graben) is the consequence of human intervention on the natural drainage system that has transformed a large floodplain into an intensively used cultural landscape. Already, the Romans carried out river regulation and water management to guarantee the transportation of material and troops, securing the territory of the Roman Empire. To secure the so-called Rhein-Limes, burgi (fortlets) were constructed along small tributaries of the River Rhine under Valentinian I. (364–375). The burgus at Trebur-Astheim represents such a military site. It is located at the Schwarzbach/Landgraben fluvial system, which was actively used as a waterway and connected important military sites such as the castra “Auf Esch” (Groß-Gerau) with the River Rhine and, thus, with the provincial capital Mogontiacum (Mainz). Using a combination of magnetic gradiometry, frequency domain electromagnetic induction (FDEMI), electrical resistivity tomography (ERT), direct push-sensing (DP), and sediment coring, we were able to detect a 15 m wide and 2.5 m deep Roman canal between the burgus at Trebur-Astheim and the River Rhine, opening the Hessische Ried hinterland to wider trade routes. Radiocarbon dating further reveals that after a final re-excavation, the channel started to silt up in the 7th/8th century AD and finally fell out of use. This last period of use may be associated with the activities of the Carolingian Königspfalz (royal palace) Trebur. Our study shows that the fluvioscape of the Hessische Ried dates back to Roman times and that the canal at Trebur-Astheim is one of the few navigable canals known to have existed north of the Alps during the Roman period and the Early Middle Ages. Full article

Alluvial plains in the marginal zone of the monsoon system are sensitive to the climate–hydrology interaction. However, long term, high-resolution sedimentary records remain scarce in the Songnen Plain of Northeast China. This limited our understanding of the paleoclimate–paleohydrology coupling evolution over glacial–interglacial cycles. A 50.6 m continuous core was retrieved from the western Songnen Plain. The age–depth model and wavelet transform spectrum showed sedimentary continuity from ~885 ka B.P. (the late Early Pleistocene) to ~6 ka B.P. (the early Holocene), with no major hiatuses exceeding orbital resolution. Grain size analyses revealed 18 microfacies, which were synthesized into two major evolutionary cycles: a fan-delta front cycle (dominated by subaqueous mouth bars and distributary channels) and a fan-delta plain cycle (characterized by intertributary bays, floodplain lakes/swamps, and crevasse splays). The absence of pro-delta facies and the sediment succession record the oscillatory shrinkage of the Songnen paleolake. The pulsed enhancements of hydrodynamic energy, marked by grain size coarsening, coincide with major glacial–interglacial transitions (MIS 20/19, 18/17, 16/15, 14/13, 8/7, 6/5, 4/3, and 2/1), whereas fining grain sizes dominate warm interglacial periods (MIS 11, 9, 7, 5, 3, 1). These patterns are sensitive response of the alluvial plain to orbital-scale climate change. Cold–arid glacial background promoted vegetation loss and hydrological instability, and warm–humid interglacial background favored low-energy hydrological condition. This study demonstrates that the regional alluvial evolution was primarily controlled by global ice-volume fluctuations through variability of the East Asian summer monsoon. This study provides a reference for the muti-scale climate–hydrology coupling mechanism study in the northern marginal zone of EASM and highlights the importance of alluvial sediment succession in paleo-research. Full article

The organization of safe industrial waste management is an integral part of the global sustainable development strategy. This study provides a preliminary assessment of the processing and recycling potential of strongly alkaline (pH 11–12) sediments accumulated in an abandoned sludge pond (Berezniki, Perm Krai, Russia), based on the initial characterization of their material composition. Sediment samples from the sludge pond were collected, layer-by-layer, over the entire depths of four sediment cores. The collected samples have the following characteristics: sediment particles are composed of up to 80% fine particles < 0.05 mm, with up to 20% fine particles < 0.002 mm. XRD data showed that the sediment consisted of calcite (67.7 wt.%), halite (11.5 wt.%), and other hydrogenic and terrigenous minerals. XRF data also found that the primary constituents in the sediment are CaO (up to 40%), Cl (up to 13%), and LOI (up to 35%). The results of the material composition study indicate a high degree of similarity between the accumulated sediments and solid waste from soda ash production, known as ammonia–soda residue (ASR). Based on experience with calcium-containing waste, this study recommends options for the secondary use of sludge, identifying two main possibilities: environmental protection and construction. We have developed an algorithm for the recycling and reuse of sludge that identifies risks, limitations, and recommended next steps. However, significant knowledge gaps regarding the environmental, toxicological, and the physical–mechanical properties of sludge prevent us from recommending a specific disposal option. The results of this review will serve as guidelines to help develop a roadmap for the disposal process. They will also inform decision-makers about sustainability issues related to industrial waste disposal. Full article

The Xujiaweizi Fault Depression in the Songliao Basin is a significant area for deep natural gas exploration, and the Shahezi Formation has been recognized as the primary hydrocarbon-source rock. This research integrates core, logging, and seismic data from Well SK2, the world’s first scientific drilling well to reach a depth of 7018 m and obtain 2624 m of continuous cores from the Shahezi Formation. The study aims to redefine the stratigraphic framework, resource characteristics, and sedimentary evolution of the formation in the Cretaceous period. The Shahezi Formation, dating from 118 to 112 Ma (mid-Aptian to early Albian), is divided into five third-order sequences (SQ1–SQ5). The upper section of SQ5 and SQ2 shows the highest potential for deep gas, featuring high-maturity Type III kerogen, 35 gas anomaly layers with a total thickness of 79 m, and a 59% proportion of dark mudstone. A three-stage sedimentary evolution model, including initial faulting, intense faulting, and contraction, is proposed, establishing a link between terrestrial sedimentation and global Early Cretaceous events (e.g., OAE1b). This research provides crucial insights for deep gas exploration and global marine–terrestrial sedimentary comparisons. Full article

Intrabasinal low uplifts in lacustrine rift basins are key targets for sedimentological and petroleum geological research, as they can act as local source areas and exert critical controls on intrabasinal “source-to-sink” systems. Due to the discontinuous sediment supply, these systems often demonstrate the subtle and intermittent nature, and their roles in the development of depositional systems are usually overlooked. To clarify the controlling effect of intrabasinal local provenances on sedimentary system evolution, this study reconstructed the dynamic tectonic evolution of the Weixinan Low Uplift in the Beibuwan Basin, and systematically analyzed its control on “source-to-sink” systems and sedimentary filling using integrated high-resolution 3D seismic, core, well logging and geochemical data. Our results demonstrate that the activity of Fault 3 dominated the paleogeomorphic evolution of the Weixinan Low Uplift and its surrounding areas, which further governed the spatiotemporal development of the “source-to-sink” system and the distribution of sedimentary systems, with distinct evolutionary stages as follows: During the Ls2 Member stage (48.6–40.4 Ma), Fault 3 was inactive, the Weixinan Low Uplift was manifested as a gently dipping subaqueous slope under the influence of regional lacustrine transgression, and only small-scale braided river deltas were developed on the slope belt with weak sediment supply from the Qixi Uplift. During the Ls1 Member stage (40.4–33.9 Ma), the Ls13 Sub-member stage (lower Ls1 Member stage) was characterized by initiation of Fault 3 with segmented activity, triggering the formation of the Eastern Sub-sag of the Haizhong Sag and subaqueous uplift of the Weixinan Low Uplift; clastic sediments from the central Qixi Uplift were transported northeastward, developed braided river deltas and large-scale basin-floor lacustrine fans. In the Ls12 Sub-member stage (middle Ls1 Member stage), Fault 3 continued to propagate and was gradually linked, leading to further uplift of the Weixinan Low Uplift and expansion of the Haizhong Sag; Clastic materials from the central Qixi Uplift were almost entirely trapped in the Eastern Sub-sag of the Haizhong Sag. During the Ls11 Sub-member stage (upper Ls1 Member stage), further intensification of Fault 3 activity caused the Weixinan Low Uplift to be subaerially exposed and evolve into an intrabasinal local provenance, which supplied clastic sediments to surrounding sags and developed braided river deltas on the gentle slope belts and small-scale lacustrine fans on the lower slope. This study demonstrates that the tectonic evolution of the Weixinan Low Uplift has induced prominent changes in the basin paleogeomorphology, which in turn triggered dynamic shifts in the provenance and sediment transport pathways, and thus gave rise to complex local “source-to-sink” systems and depositional styles. Full article

Marine ranching, as a pivotal strategy for enhancing the ocean’s carbon sequestration potential, offers significant potential to mitigate nearshore fishery depletion and restore marine ecosystems amid the global carbon neutrality agenda. However, the mechanistic pathways linking sediment total organic carbon (TOC) to various environmental factors in tropical marine ranches remain insufficiently quantified. This study selected the Wuzhizhou Island Marine Ranch in Hainan Province—a representative tropical marine ranch—as the research site. Field investigations and sampling were conducted during the dry (March 2024) and wet (September 2024) seasons to quantify TOC in surface sediments and associated environmental variables. A two-step analytical framework, integrating Principal Component Analysis (PCA) and Generalized Additive Models (GAM), was employed to elucidate the environmental drivers governing the spatiotemporal dynamics of TOC. The results show that the surface sediment TOC at Wuzhizhou Island Marine Ranch exhibits a distinct spatial gradient—Core Reef > Atoll > Control > Estuarine, and a pronounced seasonal pattern with elevated concentrations in the dry season relative to the wet season. The spatiotemporal differentiation of TOC is mainly driven by a gradient (explaining 52.1% of variation) that encompasses processes related to carbon accumulation from terrestrial inputs and primary production, as well as organic matter degradation promoted by nutrients and higher water temperatures. Sediment total nitrogen (TN) emerges as the primary environmental driver of TOC distribution, contributing up to 46.9% of the variance at an extremely significant level (p < 0.001). Furthermore, total phosphorus (TP), pH, and water temperature (WT) have relatively minor influences on the distribution of sedimentary TOC. Our study offers a crucial reference for elucidating the key processes governing the carbon cycle in tropical marine ranches and provides essential theoretical support for optimizing ocean carbon sink strategies in the context of global climate change. Full article

The constituent elements of source-to-sink systems and their coupling relationships are key controls on the development of sedimentary systems and the spatial distribution of sand bodies. Taking the Paleogene strata in the southern Laizhouwan Sag of the Bohai Bay Basin as a case study, we integrate drilling, logging, core, thin-section, and high-resolution 3D seismic data to quantitatively characterize basement lithology and effective provenance area, drainage-unit subdivision, types and scales of sediment transport pathways, and geometric parameters of depositional fans, within a source-to-sink analytical framework. The results show that: (1) Two distinct provenance types are developed in the southern Laizhouwan Sag, including Proterozoic granitic–gneissic basement and Mesozoic volcanic–clastic basement. These provenance types exhibit pronounced differences in effective source area, vertical relief, and drainage-network configuration across different sequence stages. (2) Two main categories of sediment transport pathways are identified, namely paleo-valleys and fault-controlled troughs. V-shaped, U-shaped, and W-shaped paleo-valleys show systematic morphological transitions along topographic gradients. The width-to-depth ratio of transport channels exerts a significant control on depositional fan scale, with U-shaped valleys exhibiting the highest sediment transport efficiency. Finally, (3) the depositional domain is dominated by near-source fan-delta systems, whose scale shows a strong positive correlation with effective provenance area and transport-channel morphology. Overall, the southern Laizhouwan Sag is characterized by a typical fault-controlled, steep-slope source-to-sink system, in which sedimentary system distribution is jointly governed by effective provenance area, sediment transport pathway geometry, and fault-related slope-break zones. This study provides a quantitative example and methodological reference for source-to-sink system characterization and prediction of favorable sand body distribution in continental rift basins. Full article