Surface Sources Research Articles

Functional analysis, diversity, and distribution of the ean cluster responsible for 17β-estradiol degradation in sphingomonads.

17β-estradiol (E2) is a natural endocrine disruptor that is frequently detected in surface and groundwater sources, thereby threatening ecosystems and human health. The newly isolated E2-degrading strain Sphingomonas colocasiae C3-2 can degrade E2 through both the 4,5-seco pathway and the 9,10-seco pathway; the former is the primary pathway supporting the growth of this strain and the latter is a branching pathway. The novel gene cluster ean was found to be responsible for E2 degradation through the 4,5-seco pathway, where E2 is converted to estrone (E1) by EanA, which belongs to the short-chain dehydrogenases/reductases (SDR) superfamily. A three-component oxygenase system (including the P450 monooxygenase EanB1, the small iron-sulfur protein ferredoxin EanB2, and the ferredoxin reductase EanB3) was responsible for hydroxylating E1 to 4-hydroxyestrone (4-OH-E1). The enzymatic assay showed that the proportion of the three components is critical for its function. The dioxygenase EanC catalyzes ring A cleavage of 4-OH-E1, and the oxidoreductase EanD is responsible for the decarboxylation of the ring A-cleavage product of 4-OH-E1. EanR, a TetR family transcriptional regulator, acts as a transcriptional repressor of the ean cluster. The ean cluster was also found in other reported E2-degrading sphingomonads. In addition, the novel two-component monooxygenase EanE1E2 can open ring B of 4-OH-E1 via the 9,10-seco pathway, but its encoding genes are not located within the ean cluster. These results refine research on genes involved in E2 degradation and enrich the understanding of the cleavages of ring A and ring B of E2.IMPORTANCESteroid estrogens have been detected in diverse environments, ranging from oceans and rivers to soils and groundwater, posing serious risks to both human health and ecological safety. The United States National Toxicology Program and the World Health Organization have both classified estrogens as Group 1 carcinogens. Several model organisms (proteobacteria) have established the 4,5-seco pathway for estrogen degradation. In this study, the newly isolated Sphingomonas colocasiae C3-2 could degrade E2 through both the 4,5-seco pathway and the 9,10-seco pathway. The novel gene cluster ean (including eanA, eanB1, eanC, and eanD) responsible for E2 degradation by the 4,5-seco pathway was identified; the novel two-component monooxygenase EanE1E2 can open ring B of 4-OH-E1 through the 9,10-seco pathway. The TetR family transcriptional regulator EanR acts as a transcriptional repressor of the ean cluster. The cluster ean was also found to be present in other reported E2-degrading sphingomonads, indicating the ubiquity of the E2 metabolism in the environment.

Identification of agricultural surface source pollution in plain river network areas based on 3D-EEMs and convolutional neural networks.

Agricultural non-point sources, as major sources of organic pollution, continue to flow into the river network area of the Jiangnan Plain, posing a serious threat to the quality of water bodies, the ecological environment, and human health. Therefore, there is an urgent need for a method that can accurately identify various types of agricultural organic pollution to prevent the water ecosystems in the region from significant organic pollution. In this study, a network model called RA-GoogLeNet is proposed for accurately identifying agricultural organic pollution in the river network area of the Jiangnan Plain. RA-GoogLeNet uses fluorescence spectral data of agricultural non-point source water quality in Changzhou Changdang Lake Basin, based on GoogLeNet architecture, and adds an efficient channel attention (ECA) mechanism to its A-Inception module, which enables the model to automatically learn the importance of independent channel features. ResNet are used to connect each A-Reception module. The experimental results show that RA-GoogLeNet performs well in fluorescence spectral classification of water quality, with an accuracy of 96.3%, which is 1.2% higher than the baseline model, and has good recall and F1 score. This study provides powerful technical support for the traceability of agricultural organic pollution.

Groundwater quality assessment in the La Mojana region of northern Colombia: implications for consumption, irrigation, and human health risks

Water quality is one of the most relevant issues related to water management, with water pollution and access to clean water for drinking and irrigation being common issues in developing countries. Groundwater is an available water source, especially where surface sources are scarce or unsuitable. In this sense, studies to improve knowledge of aquifers should be undertaken where information on groundwater resources is not available. In the current study, 50 groundwater samples were collected from rural and urban wells used by local communities for human consumption and to irrigate local crops. Several indices for drinking water and irrigation use have been used for the assessment of water quality. Conversely, the carcinogenic and noncarcinogenic human health risks due to exposure to heavy metals in the groundwater were estimated, as were the predominant hydrochemical characteristics. The groundwater water quality index (GWQI) shows values < 100 for all the samples; groundwater is recommended for drinking after disinfection. By contrast, the irrigation water quality index (IWQI) shows that 80% of groundwater samples pose a potential threat to irrigation, with restriction categories ranging from high to severe. The individual hazard quotients were < 1. However, the multielement and multipathway hazard index (HI) for children and adults were > 1, whereas As and Mn had a higher contribution to the HI. The Piper trilinear diagram shows that hydrochemical facies of Ca2+ and HCO3− are significantly dominant. By contrast, weathering of rocks and atmospheric precipitation is the dominant factors regulating the chemistry of groundwater in the aquifer system of La Mojana. Our findings indicate that there are significant potential noncarcinogenic health risks for local populations exposed to groundwater.

Water Resources, Pollution, Integrated Management and Practices in Nigeria – An Overview

This paper provides a comprehensive overview of Nigeria’s water landscape, focusing on its abundant surface and underground water sources and the agencies responsible for water resources development and management. Findings reveals that the country boasts vast freshwater reserves, encompassing surface and groundwater, intricate river drainage systems, numerous dams, and managed aquifer formations, primarily overseen by River Basin Development Authorities. Despite these resources, Nigeria faces severe pollution challenges, especially in the Niger Delta, resulting from oil-related activities and causing environmental degradation, health crises, and enduring ecosystem consequences. Approximately 13 million barrels of oil spills have adversely impacted coastal wetlands, mangroves, and agricultural lands. Elevated levels of heavy metal pollution, exceeding recommended guidelines, pose significant threats to public health, emphasizing the lasting impact of persistent oil spillage on fishery production and aquatic organisms. River Basin Development Authorities have made substantial contributions, challenges persist in catchment management and the indiscriminate disposal of hazardous substances. The absence of effective environmental policies necessitates urgent, coordinated action from federal and state governments. Nigeria must prioritize integrated water management practices to strike a delicate balance between resource utilization and preservation for the benefit of current and future generations. This manuscript relies on secondary sources, utilizing key search terms such as “water resources in Nigeria,” “water pollution in Nigeria,” “water supply and demand in Nigeria,” “water management in Nigeria,” and “integrated water practices in Nigeria.” Data were sourced from reputable institutions, including the Federal Ministry of Water Resources, The World Bank, United Nations Environmental Protection (UNEP), USAID’s Sustainable Water Partnership, and various scientific publications, ensuring the reliability of the presented data.

Simulation research on aerodynamic noise characteristics of a compressor under different working conditions.

The shear stress transport turbulence model is employed to conduct a detailed study of flow characteristics at the highest efficiency point and near-stall point in a full-channel 1.5-stage compressor in this paper. The simulation results for the compressor's total pressure ratio and efficiency exhibit good agreement with experimental data. Emphasis is placed on examining the internal flow structure in the tip area of the compressor rotor under near-stall conditions. The results reveal that significant differences in flow structure primarily occur in the tip area as the compressor approaches stall. Specifically, a reduction in turbulent kinetic energy is observed in a region spanning approximately 20%-60% of the chord length on the rotor suction face near-stall conditions. Two additional peak frequencies, at 0.8 and 1.6 times the blade passage frequency, are observed, and the intricate flow phenomena are elaborated at the near-stall point. The near-stall point exhibits greater noise levels than the highest efficiency point, where the intensity of the surface source increases by more than 10 dB, peaking at 20 dB. This additional peak serves as a significant supplementary noise source near the stall point, leading to a maximum increase of 33.3 dB in the free radiated sound power. The acoustic response within the duct indicates that the compressor operating at the near-stall point continues to produce substantial noise on the actual test bench, showing an average increase of 6 dB in noise levels, and the distribution of the additional peak single-tone noise at the entrance significantly differs from that observed at the highest efficiency point.

Occurrence of forever chemicals in Chennai waters, India

BackgroundPer- and polyfluoroalkyl substances (PFAS) are considered ‘contaminants of emerging concern’ due to their environmental persistence, bio-accumulative potential, and adverse effects on human health. They are widely employed in producing various goods used in daily life, such as non-stick cookware, cleaning agents, and many industrial applications in aerospace, automotive, construction, electronics, and military, all of which ultimately end up in different environmental matrices. India’s rapid economic growth necessitates a comprehensive understanding of its PFAS contamination levels and potential human and ecological exposure.ResultsThe present study reports the quantification of one long-chain and two short-chain perfluoroalkyl acids and three long-chain and two short-chain perfluorosulfonic acids and qualitative analysis using suspect screening in the waters of Chennai, Tamil Nadu, India. Samples were collected from surface and groundwater sources, including the Adyar river, Buckingham canal, Chembarambakkam lake, and the water treatment plant. The concentrations analyzed in all the samples ranged from 0.10 ng/L to 136.27 ng/L. Groundwater had some of the highest concentrations of PFAS. L-PFBS (up to 136.27 ng/L) and PFOA (up to 77.61 ng/L) are present in all the samples. The concentrations of all the target PFAS increased in the 5 to 103% range in the final treated water compared to the raw water of the water treatment plant. This treated water is distributed as a source of drinking water for the residents of Chennai. Additionally, the dominance of short-chain compounds (4–7 carbons) over long-chain compounds (> 7 carbons) was observed. Suspect screening revealed numerous precursors and other fluorinated compounds abundantly present in the samples.ConclusionsOur study revealed PFAS levels up to 136.27 ng/L in both surface and groundwater samples from Chennai. These findings raise concerns about potential risks to ecosystems and human well-being. The dominance of short-chain PFAS coupled with abundant precursors and unidentified fluorinated compounds indicates an ongoing shift toward alternatives. Conventional water treatment is ineffective in eliminating these chemicals from the water system; rather, increasing the PFAS concentrations from raw water to treated water necessitates advanced polishing steps. Industrial emissions, untreated domestic wastewater discharge, and open dump sites have been suspected as the significant sources of contamination, highlighting the need for further investigation to fully assess the extent of PFAS contamination in Chennai.Graphical

Influence of (1 1 1) texture on bonding strength in low-temperature bonding of nanotwinned Ag films: Experimental insights and void closure modeling

Low-temperature bonding of nanotwinned (NT-) metals holds great potential for enhancing the performance and reliability of electronic interconnections. In this study, we performed low-temperature bonding of (111)-oriented nanotwinned silver (NT-Ag) films and thoroughly investigated the influence of (111) texture on the interfacial microstructure and bonding strength of the joints. The results demonstrated that high-quality bonding of highly (111)-oriented NT-Ag films was achieved even at 200 °C in air. The defect-free, coherent Ag(111)Ag(111) bonding interface was formed via face-to-face bonding of the highly (111)-oriented columnar grains. The shear strength of the joints significantly increased with the rise in (111) texture intensity. Moreover, we developed the void closure model to quantitatively elucidate the contribution of (111) texture to void closure and bonding ratio. Modeling results revealed that the (111) texture, with the highest surface diffusion coefficient, greatly increased the interfacial bonding ratio by accelerating surface source diffusion, thereby enabling high-strength bonding at low temperatures. The experimental validation and modeling results presented here contribute a novel perspective for optimizing interfacial microstructure and bonding strength by regulating the surface texture in the solid-state bonding of metals.

Remote Sensing &amp; GIS Integration Bases Evaluation of Ground Water Quality in Telangana State, India

About 85% of drinking water needs in rural and 40% drinking water needs in urban areas are met from groundwater resources in Telangana state. There is a huge demand of ground water for different uses like agriculture, drinking and industrial purposes as the command area is very low in the state and it is evidenced by the fact that around 70% irrigation is dependent on ground water sources as compared to other surface sources like Tanks/Canals/Reservoirs etc. Climate change has affected the hydrological cycle with uncertain and increased variability in rainfall followed by with high rainfall in a short span of time resulting more surface runoff which ultimately decreases there charge to groundwater. Decreased recharge to the groundwater and excess withdrawal of groundwater has accelerated the depletion of groundwater resources there by resulting in stress on groundwater regime in terms of quality as well as quantity. The groundwater quality evaluation of Telangana state is carried out by using legacy quality data (2012-14) collected from Rural Water Supply &amp; Sanitation Department, Government of Telangana. Contamination spread of groundwater is one of the most important concerns that have received attention at regional, local and global levels because of their importance on public health and its further impact in ecosystems. The spatial distribution of chemical parameters like pH, Total Dissolved Solids (TDS), Total Hardness (TH), Total Alkalinity (TA), Fluoride (F), Chloride (Cl), Iron (Fe), Nitrate (NO3) and Sulfate (SO4) are examined with respect to its contamination level. The spatial distribution and concentration of chemical elements is carried out by using spatial interpolation technique namely Inverse Distance Weightage (IDW) method from the point source data. The distribution maps reveal important information to understand the hot spot areas of the groundwater systems and for identification of potential areas for providing safe drinking water supply. Site specific water conservation and artificial recharge measures are needed to be taken up with scientific lines by using Remote Sensing &amp; GIS techniques, for enhancing the groundwater storage and also improving its quality.

Temperature-Automated Calibration Methods for a Large-Area Blackbody Radiation Source.

High-precision temperature control of large-area blackbodies has a pivotal role in temperature calibration and thermal imaging correction. Meanwhile, it is necessary to correct the temperature difference between the radiating (surface of use) and back surfaces (where the temperature sensor is installed) of the blackbody during the testing phase. Moreover, large-area blackbodies are usually composed of multiple temperature control channels, and manual correction in this scenario is error-prone and inefficient. At present, there is no method that can achieve temperature-automated calibration for a large-area blackbody radiation source. Therefore, this article is dedicated to achieving temperature-automated calibration for a large-area blackbody radiation source. First, utilizing two calibrated infrared thermometers, the optimal temperature measurement location was determined using a focusing algorithm. Then, a three-axis movement system was used to obtain the true temperature at the same measurement location on a large-area blackbody surface from different channels. This temperature was subtracted from the blackbody's back surface. The temperature difference was calculated employing a weighted algorithm to derive the parameters for calibration. Finally, regarding experimental verification, the consistency error of the temperature measurement point was reduced by 85.4%, the temperature uniformity of the surface source was improved by 40.4%, and the average temperature measurement deviation decreased by 43.8%. In addition, this system demonstrated the characteristics of strong environmental adaptability that was able to perform temperature calibration under the working conditions of a blackbody surface temperature from 100 K to 573 K, which decreased the calibration time by 9.82 times.

Exploring a planet with infrasound: Challenges in probing the subsurface and the atmosphere

Infrasound waves have shown great potential to retrieve a range of geophysical parameters across scales, such as atmospheric structures, surface and buried source characteristics, and seismic velocity structures. In particular, infrasound generated by seismic waves coupling to the atmosphere can provide unique insight into a planet's interior. However, utilizing infrasound data require efficient forward wave simulation techniques and an accurate description of waveform sensitivity to source and medium parameters. Even under idealized conditions, many of the inverse problems associated with infrasound-based probing are inherently ill-posed, requiring regularization or other approaches to yield reliable output. In this contribution, we highlight recent research results from our group and collaborators, tackling atmospheric probing at smaller and global scales, as well as innovative approaches to speed up infrasonic wave propagation modeling. We also call attention to the objectives and early results from a newly launched project focusing on the feasibility of exploring the interior of Venus using infrasound recorded from balloon platforms.

Groundwater quality and potential analysis using geospatial techniques: The case of Ashanti Region in Ghana

The ecosystem and economy's reliance on clean water is influenced by various factors such as geology, topography, soil types, activities, and the presence of plants and animals. The Ghana Water Company is encountering difficulties in delivering water to consumers in the Ashanti Region due to the shortage of surface water resources, leading to water rationing in the area. Furthermore, poor waste disposal practices, illegal mining, use of fertilizers, and industrial activities have resulted in surface and groundwater source damage. Therefore, there is a need to implement a reliable, simple, and timely method to assess groundwater quality. This study aims to employ GIS and RS techniques to evaluate groundwater quality and potential in the Ashanti Region, Ghana. The Water Quality Index (WQI) was estimated using pH, Total Dissolve Solid (TDS), Chloride, Total Hardness (TH), Nitrate, Temperature, Turbidity, Iron, and Electrical Conductivity (EC). The study then used the WQI distribution to conduct a groundwater potential analysis to identify suitable areas for borehole placement. Digital thematic layers and maps were developed to expose the spatial distribution of water quality parameters, enabling the identification of groundwater pollution control and remedial measures. The study estimated the region's groundwater potential using an integrated GIS and Analytical Hierarchical Process (AHP) technique, grouping under excellent, good, fair, and poor potential. The WQI in the Ashanti Region ranged from 5.208 to 134.232, with 32.252% of the study area having an excellent WQI and 60.168% of the study area having a good WQI. Poor water quality covered 7.550% of the study area. The results showed that the GIS-based AHP approach accurately mapped the spatial distribution of WQI and Groundwater Potential Zones (GWPZ). This information is helpful to planners in water resource management in groundwater exploration and future planning. Policymakers and stakeholders must ensure that groundwater sources are protected from pollution.

Surface and Underwater Acoustic Source Recognition Using Array Feature Extraction Based on Machine Learning

Sound source recognition is an important application of passive sonar. How to distinguish between surface and underwater sound sources is always a difficult problem. In order to solve the problem of S/U sound source identification, this paper proposes a machine learning method based on array feature extraction, which has certain innovative value. Firstly, according to the experimental environment of SACLANT 1993, simulation data is generated based on KRAKEN. Secondly, the simulation data and experimental data are used to extract the array features. Thirdly, the accuracy, recall rate, F1 and accuracy of GBDT classifier in three different frequency bands are evaluated. The results show that the training model established by using the array feature extraction method can effectively solve the problem of poor accuracy of some channels in the single channel classification, and obtain good experimental accuracy. Finally, the experimental accuracy of the three bandwidths is 0.9920, 0.9857 and 0.9713, respectively.

Impact of Intercropping on Nitrogen and Phosphorus Nutrient Loss in Camellia oleifera Forests on Entisol Soil

Soil and water loss represent a significant environmental challenge in purple soil cropland in China. However, the quantity and mechanism of nutrient loss from purple soil remain unclear. To understand water and soil conservation and address nitrogen (N) and phosphorus (P) mitigation in Camellia oleifera forest stands on purple soil slope farmland, this study aimed to explore the resistance control effect of forest stands on N and P loss in such agricultural landscapes. In the study, a runoff plot experiment was conducted in purple soil slope farmland. The experiment included three distinct treatments: intercropping of oil tea (Camellia oleifera) and ryegrass (Lolium perenne L.), Camellia oleifera monoculture, and barren land served as the control treatment (CK). Water samples were collected and analyzed from the soil surface runoff and the middle soil layer at a depth of 20 cm (interflow) in three treatment plots under natural rainfall conditions in 2023. Various nutrient components, including total nitrogen (TN), dissolved nitrogen (DN), nitrate nitrogen (NO3−-N), ammonium nitrogen (NH4+-N), particulate nitrogen (PN), total phosphorus (TP), dissolved phosphorus (DP), phosphate (PO4+-P), and particulate phosphorus (PP), were measured in the water samples. The results indicated that intercropping effectively mitigated the loss of various forms of N and P in both surface runoff and interflow within purple soil slope farmland. Compared to the CK, the ryegrass intercropping reduced TN and TP loss by 29.3%–37.3% and 25.7%–38.9%, respectively. The ryegrass intercropping led to a decrease in the average total loss of TN, DN, NO3—N, and NH4+-N by 63.0, 24.3, 4.5, and 6.8 g/ha, corresponding to reductions of 33.3%, 47.6%, 58.3%, and 49.1%, respectively, compared to the CK. The average total loss of TP, DP, and PP decreased by 4.4, 1.8, and 1.4 g/hm2 in the intercropping, reflecting reductions of 32.3%, 31.3%, and 31.1%, respectively. The most significant proportion was observed in PN and PP within the runoff water solution, accounting for 53.3%–74.8% and 56.9%–61.0% of the TN and TP, respectively. These findings establish a foundation for purple soil and water conservation. The research provides valuable insights for land management and policymakers in developing erosion prevention and control programs for sloping cultivated land with Camellia oleifera forests in purple soils. Additionally, it offers guidance for soil and water conservation and prevention of surface source pollution in purple soil regions.

Direct numerical simulation of a wall source dispersion in a turbulent channel flow

A comprehensive direct numerical simulation (DNS) is conducted to analyze the turbulent mixing process of a surface source dispersion emitting from the bottom wall in a turbulent channel flow. A comparative analysis of ten test cases has been conducted to examine the turbulent mixing process and its relationship with the source strength. The study involves an examination of the dispersion process in both physical and spectral spaces, which includes an evaluation of statistical moments of the concentration field, pre-multiplied spatial spectra of the velocity and concentration fields, as well as an analysis of the coherent turbulent structures in the flow. Upon normalization by friction concentration, the DNS analysis reveals that the first- and second-order statistical moments of the concentration field remain unaffected by variations in the source strength. Conversely, the relative intensity of concentration fluctuations and the thickness of the concentration boundary layer exhibit significant susceptibility to variations in the source strength. It has been observed that the dispersion process within the channel is significantly influenced by the small-scale eddies in cases where the source strength is not particularly intense. When confronted with high source strength scenarios, analysis of the simulation results establishes that both small- and large-scale eddies are crucial players in the dispersion phenomena, as evinced by a comparison of the pre-multiplied spectra of concentration and velocity fields. Furthermore, hairpin vortices have been recognized as the primary source of turbulence in the dispersal of substances from regions of high shear to the center of the channel.

Simulation method of airborne γ radiation detector response based on the equivalent transformation

In airborne gamma radiation measurement, radiation detectors' responses are simulated using the direct simulation method. However, the number of particles recorded by the detector is significantly lower than the number of particles emitted from the radiation source. This imbalance leads to low simulation efficiency, making it challenging to achieve an acceptable level of statistical uncertainty within a limited computer time. To address this inefficiency, we have theoretically proven the equivalent transformation and utilized that to devise a fast Monte Carlo simulation method known as the equivalent transformation method. Simulation results from a large body and a large surface source demonstrate that the detector response spectrum calculated using the equivalent transformation method closely agrees with those obtained through the direct simulation method. Furthermore, the efficiency ratio for the equivalent transformation method, in comparison to the direct simulation method, stands at 2.37 × 106 and 2.67 × 106 for a large body and a large surface source, respectively. These findings solidify the validity and effectiveness of the equivalent transformation method in enhancing simulation efficiency for the research on airborne gamma radiation measurement.

Study on Desulfovibrio desulfuricans mediated copper corrosion and its inhibition using bio-wax of Colocasia esculenta

In the present study, the bio-wax was extracted from Colocasia esculenta and was tested for its corrosion inhibiting property against Desulfovibrio desulfuricans. Inhibition of copper corrosion by bio wax from Colocasia was observed using weight loss method, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Results obtained from the weight loss studies and impedance measurements provided similar trends of inhibition efficiency. Cu coupon coated with bio-wax showed significant reduction in corrosion rate i.e. Rcorr of 0.0011mmpy. This result gives an idea about the protective nature of thick bio-wax coated copper coupons from bacterial adherence and bacterial metabolites. The impedance value in the bio wax coated coupon was found to be from 188.67 to 781.25 ohms at 1 Volt. The wax FTIR analysis in a spectral region of 4000 cm- 1 - 400 cm -1 showed peaks at 2918.75 cm -1 and 2849.73 cm -1 confirming the presence of hydrophobic hydrocarbon. Morphological changes were observed after coating the bio wax as shown from SEM analysis. The incorporation of the hydrophobic property of bio-wax showed sufficient reduction in MIC of copper. Bio-wax acted as a protective covering inhibiting the adherence of corroding bacteria on the surface. Inhibition efficiency results are in good agreement to use Colocasia bio wax as a source of sustainable and renewable surface coating material. This property might be used in future as an ingredient in anti-rust paint used in coating metal surfaces like ship parts, pipelines systems of petroleum industry and other metal made machines etc.

Source Depth Discrimination Using Intensity Striations in the Frequency–Depth Plane in Shallow Water with a Thermocline

A source depth discrimination method based on intensity striations in the frequency–depth plane with a vertical linear array in a shallow water environment is proposed and studied theoretically and experimentally. To quantify the orientation of the interference patterns, a generalized waveguide variant (GWV) η is introduced. Due to the different dominance of the mode groups, the GWV distribution in the surface source is sharply peaked, indicating the presence of striations in the interferogram and the slope associated with the source–array range, while the distribution of the submerged source is more diffuse, and its interferogram is chaotic. The existence or lack of a distinct peak is used to separate the surface and submerged source classes. The method does not demand prior knowledge of the sound speed profile or the relative movement between the source and the array. In addition, it is the presence of the striations, not the value of η, that is exploited to separate the surface and submerged source classes, which means the source–array range can be unknown. The proposed method is validated using experimental data on the towing ship in SWellEx–96 and numerical modeling. The method’s performance under noise situations and for different source–array ranges is also investigated.

3D isogeometric indirect BEM solution based on virtual surface sources on the boundaries of Helmholtz acoustic problems

A solution for 3D Helmholtz acoustic problems is introduced based on an indirect boundary element method (indirect BEM) coupled with isogeometric analysis (IGA). The novelty of this work arises from using virtual surface sources placed directly on the scatterer boundaries, producing robust results. These virtual surface sources are discretized by the same Non-Uniform Rational B-Splines (NURBS) approximating the scatterer CAD model. This allows modeling of general irregular geometries. The proposed solution has the same features of BEM approaches, which do not need any domain discretization or truncation boundaries at the far-field. It shows an additional merit by arranging the linear system of equations directly depending on a single coefficient matrix, consuming less computational time compared to other BEM methods. A Greville abscissae collocation scheme is proposed with offsets at C0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C^0$$\\end{document}-continuities. This collocation scheme allows for easy evaluation for both free-terms and normals at the collocation points. The performance of the proposed solution is discussed on 3D numerical exterior problems and compared against other BEM methods. Then, the practical interior muffler problem with internal extended thin tubes is studied and the obtained results are compared against other numerical methods in addition to the available experimental data, showing the capability of the proposed solution in handling thin-walled geometries.

Seismic Reprocessing Overcomes Uncertainty in Offshore Egyptian Field

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214066, “Seismic Reprocessing Leads to New Breakthroughs—A Successful Case in the ASH Field, AG Basin in Egypt,” by Mohamed Elokr and Ahmed Lotfy, Kuwait Energy Egypt, and Wei Xing, United Energy Group, et al. The paper has not been peer reviewed. _ The ASH oil field is in the eastern portion of the AG Basin in Egypt. The Lower Cretaceous Alam El Bueib is the main oil-producing formation. Because of the high heterogeneity of the Abu Roash succession, in addition to the influence of thick limestone of the Upper Cretaceous and the influence of multiple complex faults, the quality of seismic data is very poor, requiring seismic reprocessing. Two key techniques were used to achieve the goal: New vertical seismic profile (VSP) well data were acquired to adjust the velocity model, and common reflection angle migration (CRAM) prestack depth migration (PSDM) was used for reprocessing. Introduction The ASH field produces oil from the Aptian Lower Cretaceous reservoir. The ASH structure is interpreted as an elongated east-northeast/west-southwest anticline with intensive breaching on the downthrown side of northwest/southeast to west-northwest/east-southeast-oriented normal faults with obvious signature of synsedimentary activities. The entire area was subject to a series of tectonic events affecting the Western Desert, which led to a complex fault regime clearly recognized in the ASH structure by a series of horizontal displacement across the northwest/southeast faults. Strike/slip to oblique-slip faults also are observed from thicknesses of the cretaceous formations, creating significant difficulty in fault definition. The 3D seismic data acquired in 2007 suffered from losing amplitude of the Lower Cretaceous and deep Jurassic reflectors because of the complex structure. The strong carbonate markers disappear north of the field, where high, dense fault intersection is present closing from the main bounding fault. Loss of seismic amplitude could have severe effects on of the future economics of the field. The seismic survey was reprocessed two times without significant enhancement of the fault imaging. PSDM was run without velocity control, resulting in an uncertain velocity model with inaccurate fault imaging and a mismatching between actual and prognosed depths of the drilled wells of greater than 50 m. This contradiction in reservoir mapping meant that the northern portion of the field remained unexplored. Acquiring VSP in the recently drilled well encouraged reprocessing of the 3D seismic survey using well velocity as a control point in adjusting the seismic velocity model, and application of CRAM technology to improve fault imaging and appraise the uncertain area of the ASH field. CRAM Methodology CRAM was developed as a type of beam migration. Asymptotic ray tracing is performed, assuming that one-way diffraction rays from the subsurface image point to the surface sources and receivers. The takeoff angles from the image point are measured around a given local normal to a background reflection surface for each source ray and receiver ray. A system of source and receiver ray pairs is formed, and the recorded seismic data can be mapped into a local angle domain based on the reflection angles at the subsurface image points.​​​​

Quality of drinking water and risk to the health of the population of the south Baikal region (Russia)

Providing good quality water in sufficient quantities is a major challenge in the world. The purpose of the study is to assess the quality of drinking water and the health risk of various population groups in the southern Baikal region (Siberia, Russia) under changing hydrological conditions. Lake Baikal is the largest freshwater body of water and is one of the sites protected by UNESCO. Materials and methods. An analysis of centralized and non-centralized water supply was carried out in the south-eastern part of the Irkutsk region, adjacent to Lake Baikal. The data used are from the Baikal (regional) Information Center for 2011–2022, and they include the results of monitoring the water quality of the centralized domestic and drinking water supply (CDW) with 140 thousand samples, and non-centralized domestic and drinking water supply (NDW) with 108 thousand samples. In all samples, 17 substances were determined. In addition, during the flood period, accompanied by additional water disinfection, trihalomethanes were determined in populated areas exposed to negative impacts. The quality of drinking water was assessed in comparison with the maximum permissible concentrations of substances (MPCs) approved by regulatory documents of Russia. An assessment of the characteristics of drinking water consumption by the population of the Baikal region was carried out, based on interview data from sample groups of the population. The assessment of the risk to public health, due to chronic oral intake of chemicals, was carried out using the values of the hazard coefficient (HQi), the hazard index (HI), individual carcinogenic risk (ICR), and population carcinogenic risk (PCR).Village residents more often use underground water sources (centralized and non-centralized). Residents of cities are provided with water from surface sources (Lake Baikal and the Angara River). Significant concentrations of iron, nitrates, and manganese were found in drinking water used by villagers. Average concentrations of iron - 2.25 mg/dl, manganese - 0.6 mg/dl, nitrates - 135 mg/dl were recorded in the water of underground springs in villages of the Irkutsk region. Among rural residents of the Irkutsk region, 60.8 % live in settlements with non-water supply systems, 28.4 % have mixed water supply.The non-carcinogenic risk for the adult and child population was calculated; HI > 1 was identified for the population using underground water sources. the non-carcinogenic hazard for the adult population, it was found that HI in the Irkutsk region slightly exceeded the standard value (1), amounting to 1.3, and for the child population - 1.6, the main contribution to the hazard index is represented by nitrates. For children of individual rural settlements of the Angarsk region HI = 1.38. The carcinogenic risk for water from underground sources reached in the range 1.56 × 10−5- 2.1 × 10−4 (in some settlements). Priority carcinogens were identified: arsenic (the contribution of which is 56.3–100 %), hexavalent chromium (29.9–35.8 %). A carcinogenic risk for city residents arises from increased disinfection during periods of microbiological contamination (floods, rains, high water levels), and it is associated with the formation of halogen-containing compounds. ConclusionThe need to strengthen the drinking water quality monitoring system in risk areas has been proven by increasing the number and frequency of sampling during flood periods.