Search Results (83)

In this paper, the results of several geophysical surveys developed with a Sub-Bottom Profiler in different regions of Spain are presented. This research forms part of a broader project aimed at developing innovative non-invasive methodologies for documenting Underwater Cultural Heritage (UCH). The 2001 UNESCO Convention on the Protection of the Underwater Heritage recommends the use of non-destructive techniques, in situ conservation, and prioritising exploration over recovery. Geophysical techniques allow the non-invasive documentation of UCH without altering archaeological remains. The Sub-Bottom Profiler was tested in several underwater archaeological surveys under different objectives, depths, and environmental conditions. The research questions addressed the amount of information obtainable without intrusion and the optimal use of the equipment for methodological innovation. Based on the results, methodological conclusions are drawn regarding the influence of seabed composition on acoustic performance, the importance of controlling navigation speed and vessel stability, and the strong impact of sea state on data quality. The need for frequency and motion-correction optimisation to balance resolution and penetration is also highlighted, as well as the usefulness of SBP for anomaly detection, site monitoring, and palaeolandscape reconstruction. These findings contribute to establishing a transferable methodological framework applicable to other case studies. Full article

In order to assess their influence on the marine hazard offshore the Cilento Promontory, the gassy sediments of the Cilento offshore have been thoroughly examined using the geological interpretation of a closely spaced grid of Sub-bottom Chirp profiles. Based on the general stratigraphic framework three areas have been previously identified, highlighting the different acoustic features occurring in the Cilento area. The acoustic anomalies include acoustic blanking, shallow gas pockets, and seismic units impregnated of gas, showing distinct acoustic responses. Understanding these anomalies and the related seismo-stratigraphic units in the offshore Cilento Promontory provides a valuable foundation for evaluating marine geohazards and may assist in developing strategies to mitigate geohazards in the Cilento area. Full article

Marine geological carbon sequestration (GCS) is crucial for achieving carbon neutrality, with site geological safety being paramount. To address the high cost of extensive multi-channel seismic (MCS) surveys during the early site screening stage, especially for those underexplored basins, this paper proposes an integrated and cost-effective exploration method that combines gravity, magnetic, and sub-bottom profiling (SBP) surveys. This method enables efficient areal scanning for initial assessment of geological safety during early-stage site screening. The Lishui Sag, which has relatively well-defined structural information, was selected as a test site to validate the effectiveness of this method. The survey results show that the faults identified from the horizontal gradient magnitude (HGM) of gravity and magnetic anomalies exhibit good consistency with the major faults interpreted from MCS profiles, with average horizontal position offsets of approximately 2.3 km and 2.4 km, and average strike deviations of about 5.7° and 7.2°, respectively. While SBP detection effectively reveals shallow geohazards such as shallow gases. By leveraging the complementary strengths of geophysical data, this method can reliably identify key geological risk factors of carbon sequestration (e.g., faults, magmatic intrusions, shallow gases) during the early-stage site screening phase (regional scale) while significantly reducing survey costs. Although this method is not intended to provide a comprehensive geological safety assessment for final CO₂ storage site approval, it offers an integrated survey approach that balances reliability and cost-effectiveness for early-stage, regional-scale risk assessment in site screening. Full article

Background/Objectives: Nitrogen (N) and phosphorus (P) are essential macronutrients for crop production. However, their losses throughout the agri-food system pose significant environmental and public health risks. India, with its diverse dietary cultures and large agricultural sector, presents a unique context for evaluating nutrient footprints. This study aims to provide the first sub-national assessment of food-related N and P footprints across Indian states and union territories, evaluating how vegetarian and non-vegetarian diets influence these footprints. Methods: This study employed a diet-sensitive bottom-up approach using national dietary consumption statistics from 2011–2012 to estimate food N and P footprints. The analysis incorporated regional dietary profiles and nutrient use efficiencies in crop production, along with food waste data, to quantify the affecting factors. Results: The national average food footprints were estimated at 13.11 kg-N capita⁻¹ year⁻¹ and 1.16 kg-P capita⁻¹ year⁻¹, with sub-national variation ranging from 52% to 144% of the national average for N, and 46% to 166% for P. Regions with prevalent non-vegetarian diets exhibited significantly higher footprints than those with vegetarian diets. Low nutrient use efficiencies (NUE 19%, PUE 31%) and consumer-level food waste (contributing nearly 4%) were also identified as key drivers of elevated footprints. Conclusions: The findings indicate that dietary choices, agricultural nutrient management, and food waste practices collectively contribute to the nutrient-related risks in India. Enhancing nutrient use efficiency, promoting plant-based diets, and improving waste management in culturally and regionally sensitive ways are crucial for reducing N and P losses. These findings provide actionable insights for the development of sustainable nutrition and agro-environmental policies. Full article

This paper presents the development of OpenCHIRP, an innovative sub-bottom profiler (SBP) designed for high-resolution seismic reflection surveys in shallow-water marine and lacustrine environments. The instrument employs chirped (frequency-modulated) impulses to penetrate the first few meters of unconsolidated sediments below the seafloor. Key characteristics include low cost, light weight, and low energy consumption, making it particularly suitable for deployment onboard Autonomous Surface Vehicles (ASVs). We discuss design, functionality, and potential applications of this innovative instrument, as well as results of the preliminary tests. Full article

Background: Lung cancer is a leading cause of cancer-related mortality, with disparities in incidence and outcomes observed across different racial and sex groups. Identifying both patient-specific and cohort-specific disparity biomarkers is critical for developing targeted treatments. The lung cancer dataset is highly imbalanced across races, leading to biased results in disparity information if classification is based on race. Method: This study developed an explainable artificial intelligence-based framework, TILDA-X, which designs classification models based on disease conditions instead of races to mitigate racial imbalance in the dataset and applies explainable AI to delineate patient-specific disparity information. A lung cancer transcriptome dataset with three disease conditions—lung adenocarcinoma, lung squamous cell carcinoma, and healthy samples—was used to develop classification models. Applying a bottom-up approach from patient-specific disparity information, the cohort-specific disparity information is discovered for different racial and sex groups, African American males, European American males, African American females, and European American females. Results: Classification based on disease conditions achieved accuracy between 88% and 100% for minority groups (African American males and females), whereas it was only between 0% and 16% for race-based classification, which underscores the significance of the proposed approach. Functional analysis of sub-cohort-specific biomarker genes revealed unique pathways associated with lung cancers in different races and sexes. Among the significant pathways identified, over ~63% overlapped with previously reported lung cancer-related studies, supporting the biological validity of our findings. Overall, combining disease conditions-based classification with explainable AI, this study provides a robust, interpretable framework for characterizing race- and sex-specific disparities in lung cancer, offering a foundation for precision oncology and equitable therapeutic development based on transcriptome profile only. Full article

This study addresses the applicability of conventional marine acoustic technologies for detecting non-metal artifacts. Based on the typical environment in Xiamen Bay, we evaluated the detection efficacy of common multibeam sonar, side-scan sonar, and sub-bottom profiling sonar through a controlled model experiment system. We employed ceramic artifact replicas (ranging in size from 10 to 70 cm) and incorporated acoustic parameter optimization to elucidate the applicability boundaries of different technologies. The results indicate that multibeam sonar can identify clustered targets larger than 0.5 m, but is limited in resolving small individual targets (less than 30 cm) due to terrain detail constraints. Side-scan sonar, under low-speed (less than 4 knots) and near-bottom operating conditions, effectively captures the high-intensity echo characteristics of ceramic targets, achieving a maximum effective detection range of more than 40 m. High-frequency sub-bottom profiler (94–110 kHz) offers resolution advantages for exposed artifacts, while low-frequency signals (5–15 kHz) provide theoretical support for detecting subsequently buried targets. Furthermore, the study quantifies the coupling effects of substrate type, target size, and surface roughness on acoustic responses. We propose a synergistic detection workflow comprising “multibeam initial screening—side-scan fine mapping—sub-bottom profiling validation,” which provides empirical support for the optimization and standardization of underwater archeological technologies in complex marine environments. Full article

In marine seismic surveys, the indistinguishability of subsurface boundaries caused by the superimposition of the acoustic signals reflected from it, particularly at specific frequency ranges characterized by strong spectral interference, reduces the resolution of the seismic record. We processed sub-bottom profiler data, acquired using a Bubble Pulser (nominal central frequency: ~400 Hz; effective bandwidth extending to ~1 kHz), (i) by extracting continuous wavelet transform (CWT) coefficients at the dominant energy scale to form the envelope and (ii) by applying Hilbert-based instantaneous frequency analysis to characterize medium-dependent spectral shifts. Envelope accuracy was benchmarked against four conventional filters using the sum of squared error (SSE) relative to a cubic-spline reference. CWT yielded the lowest SSE, outperforming low-pass 1 kHz and band-pass 400–1000 Hz; band-pass 400–650 Hz and low-pass 650 Hz were the least effective. Instantaneous-frequency trends differentiated rock, sand, and mud layers. Thus, compared to fixed-band filters, the scale-adaptive CWT envelope replicates raw energy more faithfully, while frequency attributes improve sediment classification. Low-pass filtering at 1000 Hz provides a more accurate representation of energy distribution than does bandpass filtering, particularly in the 400–650 Hz range. The integrated workflow—a robust, parameter-light alternative for high-resolution stratigraphic interpretation—enhances offshore engineering safety. Full article

Generally, most inversion approaches model the seabed as a stack of range-independent homogeneous layers with unknown geoacoustic parameters and layer numbers. In our previous study, we established a layered geoacoustic seabed model based on sub-bottom profiler data to characterize low-frequency (100–500 Hz) airgun signal propagation at short ranges (0–20 km). However, when applying the same model to simulate high-frequency (500–1000 Hz) explosive sound signal propagation, it failed to adequately reproduce the observed significant transmission loss phenomenon. Through systematic analysis of transmission loss (including water column sound speed profiles, seabed topography, and sediment properties), this study proposes a range-dependent layered geoacoustic model using the Range-dependent Acoustic Model–Parabolic Equation (RAM-PE). Stepwise inversion implementation has successfully explained the observed experimental phenomena. To generalize the proposed model, this study further introduces a trans-dimensional inversion framework that automatically resolves sediment property interfaces along propagation paths. The method effectively combines prior information with trans-dimensional inversion techniques, providing improved characterization of range-dependent seabed environments. Full article

Accurate and efficient acquisition of the acoustic reflection properties of sediments with different grain sizes is key for sediment substrate classification and the construction of seafloor acoustic scattering models. To accurately measure surface sediments on the seafloor, an in-depth investigation of the acoustic properties of sediments with different grain sizes at different measurement distances is an indispensable prerequisite. While previous studies have extensively explored the acoustic reflection properties of sediments in mid- and low-frequency bands (e.g., 6–85 kHz), research on high-frequency reflectivity (95–125 kHz) remains limited. Existing equipment often suffers from large beam angles (e.g., >10°), leading to challenges in standardising laboratory measurements. To this end, we developed a technique using a high-frequency submersible sub-bottom profiler (HF-SSBP) to measure the high-frequency reflection intensity of homogeneous sediments screened by grain size. To ensure stable measurements of the high-frequency reflection intensity, we conducted experiments using standard acrylic plates. This demonstrates the dependability of the HF-SSBP and determines the absolute measurement error of the HF-SSBP. Variations in radiofrequency reflection intensity across different sediment types with different grain sizes in a frequency range of 95–125 kHz were investigated. The reflectance amplitude was measured and the reflectance coefficients were calculated for six uniform sediments with different grain sizes ranging from 0.1–0.3 to 2.0–2.5 mm. The scattering intensity of the six sediments with a uniform grain size distribution at the same measurement distance varies to some extent. There is variation in the intensity of acoustic wave reflections for different grain sizes, but some of the differences are not statistically significant. The dispersion coefficients of the acoustic reflection intensities for all sediments, except for those with a grain size of 1.0–1.5 mm, are less than 5% at different measurement distances. These coefficients are almost independent of the detection distance. Full article

Offshore wind turbines, especially the fixed-bottom type, have been commercialized and installed in recent years. Generally, an offshore sub-structure such as a monopile or a jacket foundation is adopted to secure offshore wind turbines. There have been concerns raised by surfers regarding the reduction in wave elevations downstream due to the installation of offshore sub-structures in the sea. This study is therefore dedicated to understanding the near-field and far-field wave effects of fixed-bottom foundations. To this end, 1.6% scale models of a (i) monopile foundation and (ii) jacket foundation were crafted, and near-field wave elevations downstream of the model were measured in a water tank under regular waves. A calculation method based on linear potential theory was implemented and validated with the experimental results. The calculated far-field wave elevations downstream of the monopile and jacket foundations were then analyzed for a range of wave periods and wave profiles were plotted at various distances from the foundations. It was found that the effect of monopile foundations on wave elevation was limited except around the edges of the foundation. Further, the wave elevation reduction was minimal at less than 1% at a distance of 750 m or more and less than 0.7% at a distance of more than 2000 m from the monopile foundation. The jacket foundations had no effect on the wave elevation downstream. Full article

The complex topography of deep sea presents numerous challenges for the accurate exploration of sub-bottom profiles. These include real-time tracking of seafloor reflectors, acquisition and storage of deep-sea long-term reflection data, and splicing of successive profiles. Based on the actual survey data of deep sea, we have developed automatic positioning and noise suppression algorithms, namely the double-difference threshold of proximity points. Furthermore, we have created automatic algorithms, namely content expansion and group data moving, based on extremum in seafloor’s depth. These have been designed to automatically suppress the random noise and effectively splice the sub-bottom profile data in deep water. The aforementioned processing techniques facilitate the enhancement of the quality of deep-water sub-bottom profile data, thereby enabling the provision of a comprehensive and successively long profile for interpretation in the context of deep-water sub-bottom profile data. Full article

Marine sand, in addition to oil and gas resources, is the second-largest marine mineral resource. The rational development and utilization of marine sand resources are conducive to the growth of the marine economy. In the process of marketing marine sand in China, local authorities are required to delineate auctioned sand mining areas after a general survey, commonly referred to as preliminary exploration. Marine sand can be categorized into surface marine sand and buried marine sand. Buried marine sand deposits are buried beneath the sea floor, making it challenging to locate them due to their thin thickness. Consequently, there exist numerous technical difficulties associated with marine sand exploration. We conducted the preliminary research work in the waters off Guangdong Province of the South China Sea, employing a reduced drilling and identifying a potentially extensive deposit of marine sand ore. In this study, various geophysical methods such as sub-bottom profile survey, single-channel seismic survey, and drilling engineering were employed in the northern offshore waters of the South China Sea. As a result, two distinct marine sand bodies were delineated within the study area. Additionally, five reflective interfaces (R₁, R₂, R₃, R₄, and R₅) were identified from top to bottom. These interfaces can be divided into five seismic sequences: A₁, B₁, C₁, D₁, and E₁, respectively. Three sets of strata were recognized: the Holocene Marine facies sediment layer (Q₄^m), the Pleistocene alluvial and pluvial facies sediment layer (Q₃^al+pl), as well as the Pleistocene Marine facies sedimentary layer (Q₃^m). In total, two placers containing marine sand have been discovered during this study. We estimated the volume of marine sand and achieved highly favorable results of the concept that we are proposing a geologic exploration approach that does not involve any previous outcropping analogue study. Full article

This study aims to investigate the stratigraphic features and rare earth element (REE) mechanisms of deep-sea REE-rich sediments in the West Pacific Pigafetta Basin using acoustic rapid detection technology. Through an analysis of sub-bottom profile data and synthesis of existing studies, this study reveals the acoustic properties and thickness distribution of the REE-rich sediments. Acoustic spectral records identify three distinct acoustic facies: opaque (O), transparent (T), and laminated (L). This study maps the thickness and spatial distribution of the REE-rich sediment layer in the research area, ranging from approximately 6 to 36 m in thickness. Regions with REE-rich sediments exceeding 30 m in depth are identified, showing concentrated distribution along the northwest–southeast axis and a contiguous zone in the southwest corner of the study area. The method employed in this study can determine the potential bottom boundary of the REE-rich layer by assessing the thickness range of the sedimentary layer, overcoming limitations of traditional sampling methods. Furthermore, the thickness distribution characteristics of the REE-rich sedimentary layer in the study area provide valuable insights for future research on resource evaluation and estimation. Full article

The Amapá margin, part of the Brazilian Equatorial Margin (BEM), is a key region that plays a strategic role in the global climate balance between the North and South Atlantic Ocean as it is strictly tied to equatorial heat conveyance and the fresh/salt water equilibrium with the Amazon River. We performed a new scientific expedition on the Amapá continental shelf (ACS, northern part of the Amazon continental platform) collecting sediment and using instrumental observation at an unstudied site. We show here the preliminary outcomes following the applied methodologies for investigation. Geophysical, geological, and biological surveys were carried out within the ACS to (1) perform bathymetric and sonographic mapping, high-resolution sub-surface geophysical characterization of the deep environment of the margin of the continental platform, (2) characterize the habitats and benthic communities through underwater images and biological sampling, (3) collect benthic organisms for ecological and taxonomic studies, (4) define the mineralogical and (5) elemental components of sediments from the study region, and (6) identify their provenance. The geophysical data collection included the use of bathymetry, a sub-bottom profiler, side scan sonar, bathythermograph acquisition, moving vessel profiler, and a thermosalinograph. The geological data were obtained through mineralogical, elemental, and grain size analysis. The biological investigation involved epifauna/infauna characterization, microbial analysis, and eDNA analysis. The preliminary results of the geophysical mapping, shallow seismic, and ultrasonographic surveys endorsed the identification of a hard substrate in a mesophotic environment. The preliminary geological data allowed the identification of amphibole, feldspar, biotite, as well as other minerals (e.g., calcite, quartz, goethite, ilmenite) present in the substrata of the Amapá continental shelf. Silicon, iron, calcium, and aluminum composes ~85% of sediments from the ACS. Sand and clay are the main fraction from these sediments. Within the sediments, Polychaeta (Annelida) dominated, followed by Crustacea (Arthropoda), and Ophiuroidea (Echinodermata). Through TowCam videos, 35 taxons with diverse epifauna were recorded, including polychaetes, hydroids, algae, gastropods, anemones, cephalopods, crustaceans, fishes, and sea stars. Full article