Seepage Water Research Articles

Heavy metal concentrations and water quality assessment of different types of drinking water wells in the Erdenet Cu–Mo mining area

The Erdenet mine (Erdenet, Mongolia) is a copper–molybdenum open pit mine with a huge tailing pond and is located next to a residential area. As the sources of drinking water in this area rely on groundwater and can be categorized into public or private wells, we aimed to assess the groundwater quality of the different types of drinking water wells. To accomplish our goal, we analyzed 18 trace metals (As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Ga, Mo, Ni, Pb, Se, Sr, Th, U, V, Zn) and 8 major metals (Al, Ca, Fe, K, Mg, Mn, Na, Si) samples using ICP-MS and ICP-OES, and the heavy metal pollution index, heavy metal evaluation index, and degree of contamination were calculated. The most concerning point is that the Mo concentration of waste water in the Erdenet mine tailing pond and at a natural spring located 300 m from the tailing pond was 1100 μg/L, which greatly exceeds the WHO permissible concentration for Mo of 70 μg/L. Furthermore, high Ca and Mg concentrations at all private wells indicated that consumers of these wells are more vulnerable to any type of water pollution, as these wells are not built with any disinfection or treatment system. A modified categorization of the water quality indices showed that the public and private wells have low–medium contamination and that the tailing pond seepage water, along with its nearest spring, have a high degree of contamination. Because many private wells are located along the tailing pond and used directly without any treatment, we suggest a continuous evaluation and monitoring of the groundwater quality in this area.

Application of stable isotopes, mixing models, and K-means cluster analysis to detect recharge and salinity origins in Siwa Oasis, Egypt

Waterlogging, soil salinization, and groundwater depletion in non-rechargeable aquifers are among the causes endangering the sustainability of Siwa Oasis. The water resources include the tertiary carbonate aquifer (TCA), Nubian sandstone aquifer (NSSA), springs, drains, and hypersaline lakes. Geophysical logs were used to identify various aquifer systems. Stable isotopes, major ions, and heavy metals were examined. K-means cluster analysis based on principal component analysis (PCA), hydrochemistry, stable isotopes, and mixing models using NETPATH were applied in order to understand the complex hydrogeological conditions in the different aquifer systems. The results showed that all water samples were under-saturated (SI < 1) with respect to anhydrite, halite, and gypsum minerals, indicating the water's ability to dissolve more from these minerals and increase water salinity.In contrast, calcite, dolomite, Ca-montmorillonite, and illite minerals were supersaturated in most water samples (SI > 1), showing their ability to precipitate these minerals. There is no recharge for the aquifer systems, and all the groundwater resources have paleo meteoric origin, where the maximum values of δ18O and δ2H are −8.45 and −65.63, respectively. All of the springs originated from the TCA, as indicated from the K-mean cluster analysis. There is a rapid increase in the water salinity of the TCA from 1998 to 2022 due to evaporation, rock weathering, mixing with old trapped sea water, and seepage of saline water from salt lakes. The significant variations in the water salinity of the TCA aquifer are due to the mixing between fresh water of NSSA (dilution) and salt water from Zeituna and Siwa lakes through downward flow in some locations, where over-extraction of water for irrigation purposes has decreased the water pressure in the TCA. The mixing model confirmed salt lakes' contribution in increasing the TCA salinity by 2%–4%. Mixing water from TCA and NSSA could be the best management of the water resources in Siwa Oasis, as well as the application of subsurface drip irrigation.

A stress-controlled soil column test equipment for investigating water seepage-consolidation characteristics of the compacted soil

For deep-filled building site, it is not acceptable to neglect water seepage and land settlement caused by the coupling effect of wetting and loading. However, previous soil column tests employed in investigating the water seepage always failed to consider the vertical stress. In this article, a stress-controlled soil column test was conducted to investigate the effect of vertical stress on water seepage and deformation of the compacted soil. The soil column was equipped with a vertical loading device and a water-recharge device to control the boundary conditions and water sensors, tensiometers, dial indicators and a data collector to monitor the displacement and water movement. The soil column test was utilised to perform seepage tests on compacted loess with vertical stresses of 0 and 400 kPa. The time-history data of wetting front depth, volumetric water content (VWC), suction and vertical displacement have been monitored directly. The VWC and suction profiles, soil–water characteristic curves and hydraulic conductivity curves were then obtained with the monitored data. The test results demonstrated that the vertical stress affected the water seepage and consolidation of the compacted soil, but this effect gradually decreased as the depth of the soil column increased. Moreover, the reliability of the proposed test method was verified by the comparison of some available test results. The findings of this study contribute to a better understanding of water seepage and consolidation characteristics of the compacted soil subjected to vertical stress.

Sedimentary characteristics and model of seasonal deltaic sandstone: a case study on the continental red bed from the Cretaceous Baxigai Formation, Tarim Basin, NW China

Seasonal delta is a sandy fan-shaped sedimentary system formed by seasonal river flooding in continental basins. Modern sedimentary finds that seasonal deltas mainly develop in an arid-semi-arid climate environment with gentle terrain. However, the study of seasonal deltas in ancient rock records is still insufficient, leading to misinterpretations as other sedimentary systems, which poses challenges to the correct understanding of the origin and spatial distribution of sand body deposits. In this study, the red bed deposits of the Cretaceous Baxigai Formation in the west of the Tabei Uplift were selected as the research object. Based on core observation and description, a comprehensive analysis of the sedimentary environment, sedimentary characteristics and sedimentary model of the Baxigai Formation was carried out using data such as well-logging and analytical testing, combined with modern depositional characteristics. Research shows that the sedimentary sequence of the Baxigai Formation red bed developed a seasonal delta sedimentary system in the arid climate. The seasonal delta deposits provide an opportunity to understand the influencing of river flow and total sedimentary loading vary greatly on the sedimentary model, sedimentary mechanism, and distribution of sand bodies in arid climates. The sedimentary process of the seasonal delta in the Baxigai Formation was controlled by the dual-stage sedimentation process in an arid paleoclimate. During the flood period, the supercritical flow sedimentary structures are widely developed in the major distributary channels, and the distributary channels migrate and bifurcate frequently. On the delta plain, crevasse channels are formed through the avulsion of major distributary channels. During the dry period, due to the consumption of water seepage and evaporation transfer, terminal distributary channels are abandoned, crevasse channels are not developed, and the sediment is exposed. The density of the distributary channels is reduced, and the total sedimentary loading is low. The distributary channels sand body is the skeleton sand body of the seasonal delta. This study is of great significance for accurately explaining the formation process of seasonal deltas and provides a useful reference for further exploration and deployment of oil and gas reservoirs and paleogeographic reconstruction in the study area.

Water inflow prediction and waterproof-drainage system optimization in undersea tunnel

This study focuses on the Shantou Bay Undersea Tunnel and engages in theoretical research to develop a water inflow prediction formula associated with pore water pressure, building upon Darcy’s law. The formula has stronger adaptability. Moreover, Grey Relational Analysis is conducted based on theoretical formulas considering various factors to identify the factors influencing the circumferential water inflow ranking in the tunnel. Subsequently, stability analysis of undersea tunnel waterproof and drainage systems is carried out, considering three forms of waterproof and drainage: full-encapsulation non-discharge, full-encapsulation controlled-discharge, and semi-encapsulation free-discharge. The results indicate that, in cases involving grouting, the water inflow prediction formula correlates with seven factors, including the grouting ring permeability coefficient and tunnel dimensions. Grey Relational Analysis reveals that the three most influential factors affecting water inflow in the undersea tunnel are, respectively, the far-field hydraulic head, tunnel outer diameter, and grouting ring permeability coefficient. Analyzing the seepage field distribution around the tunnel bore, it is observed that grouting has the most significant improvement in the seepage field for the full-encapsulation controlled-discharge form. Regarding water seepage, grouting has the most substantial impact on improving water seepage for the semi-encapsulation free-discharge form. Considering the displacement field, reductions are more pronounced in both the full-encapsulation controlled-discharge and semi-encapsulation free-discharge forms. Therefore, in conjunction with radial grouting, adopting a full-encapsulation controlled-discharge drainage system is more suitable for practical engineering applications. This approach reduces both economic costs and the risk of water inflow in the undersea tunnel.

Prediction of Wet Area of Underwater Tunnel Lining

The issue of water seepage poses a significant challenge in tunnel infrastructure. Wet areas are commonly used to evaluate the degree of water seepage in tunnel projects. To investigate the feasibility for numerical simulation to predict a wet area, we selected concrete test blocks with two types of defects—holes and cracks—as the research specimens. Numerical models for various seepage conditions were constructed using TOUGH2, and the results were validated through laboratory experiments. Additionally, the Shenjiamen Subsea Tunnel was simplified into a numerical model, employing TOUGH2 to forecast its future wet area performance within the scope of national standards. The outcomes of our research revealed that point seepage and line seepage exhibited circular and elliptical morphologies, respectively. Moreover, external water pressure and defect size exerted a significant influence on the expansion of the wet area. Notably, the impact of crack width surpassed that of hole diameter. Encouragingly, the numerical models generated using TOUGH2 for unsaturated concrete demonstrated excellent agreement with laboratory test results concerning the geometry, size, and pattern of the wet area. These findings signified the potential of TOUGH2 numerical simulation as a valuable tool in predicting the lifespan of tunnels.

Spatial and temporal groundwater dynamics in extreme arid basins

AbstractTo accurately obtain the spatial distribution characteristics of groundwater level in an extremely arid zone and its dynamic change patterns under the influence of human activities, based on the data of 55 groundwater observation wells in the middle and lower reaches of the Kriya River, spatial interpolation of regional groundwater level data were performed using the inverse distance weight, spline function, trend surface, and the ordinary kriging methods. The optimal interpolation method was selected by its accuracy to spatially interpolate the groundwater level data in the study area from 2019 to 2021. The results show that: (1) the ordinary kriging method has the highest interpolation accuracy (MAE = 7.1393, MRE = 0.0058, RMSE = 9.4314) and reflects the spatial and temporal variability and distribution characteristics of groundwater levels with great accuracy. (2)The relationship between surface water–groundwater recharge and discharge in different areas of the river channel in the desert section varies depending on geological structure, surface water seepage, and other elements. (3) Groundwater in the Taklamakan Desert has little effect on groundwater recharge in the Dariyabui Oasis, and changes in groundwater dynamics in the oasis are predominantly influenced by surface runoff. (4) Monthly changes in groundwater levels in the Yutian Oasis are continuous, with ‘V’ shaped fluctuations, a declining trend in the southern part, no significant change in the central part, and a slight increase in the northern part. These results contribute to the sustainable management of water resources in the Kriya River Basin, provide a basis for groundwater prediction, and offer a reference for studies of other, similar extreme desert area basins.

Green synthesis and characterization of copper nanoparticles (CuNPs) and composites (CuC) using the Echinochloa pyramidalis extract and their application in the remediation of PAHsin water

Abstract In this study, we synthesized copper nanoparticles and nanocomposites (i.e. copper-based) using different parts of Echinochloa pyramidalis plant. The products were applied to remove seven types of PAHs identified in bitumen seepage water through adsorption. Phytochemical screening of the plant indicated phenol, tannin and saponins, which supported their ability to convert CuSO4·5H2SO4 to copper nanoparticles. Nanocomposites were also produced from the nanoparticles obtained from the respective parts of the plant. They were characterized using X-ray diffractometer (XRD), Brunauer -Emmett -Teller (BET), Fourier transformed infrared spectrophotometer (FTIR), ulraviolet visible spectrophotometer (UV), scanning electron microscope (SEM) and transmission electron microscope (TEM). We observed pore size characteristics describing microporous and mesoporous dimensions for the nanoparticles and the corresponding composites, respectively. Based on UV-visible analysis, bandgaps ranging from 3.16 to 3.40 eV were observed for the nanoparticles. The nanoparticles from the leaf, stem and root showed average crystallite sizes of 0.1623, 0.1582 and 0.2145 nm, respectively, and showed comparative d-spacing parameters. The root-, stem- and leaf-based nanoparticles exhibited adsorption removal efficiencies ranging from 74.32 to 81.70, 74.28 to 83.45 and 76.34 to 83.98%, respectively. However, the nanocomposites of the leaf, stem and root showed better efficiencies defined by the following ranges: 79.93–83.86, 79.16–83.49 and 83.23–84.01%, respectively.

Assessment of engineering geology and grouting applications in Yalnızardıç Dam Site (Antalya, Türkiye)

The Yalnızardıç roller compacted concrete (RCC) dam, constructed in 2015, is located in the Mediterranean region of Turkey, intended for electric power production. It is approximately 303 m long and 92 m in height. In this paper, it is aimed to determine the performance of the grouting method, conducted to control the water seepage and improve the foundation of the Yalnızardıç dam. The engineering properties of the site were introduced by geological mapping, drilling, and laboratory tests. The seepage of the foundation was determined by the in-situ Lugeon test method, also referred to as a water pressure test, which is estimate the mean hydraulic conductivity of rock mass. As a result of the tests, high-permeable and permeable zones were determined in the dam axis area. To make a barrier layer for these permeable zones, grout curtains were built in the left abutment, thalweg and right abutment with two lines of grouting holes which is proposed according to the Lugeon test and rock quality designation (RQD) results. Consolidation grouts were built to increase the density of the soil which makes the strength of the dam's foundation. After the groutings, check boreholes were drilled and water pressure tests were performed to control the seepage along the foundation and dam site. The results indicated that average Lugeon (LU) values reduced, and the values were within the recommended limit. The process shows considerable accuracy in evaluating grouting efficiency.

Optimasi Parameter Pembuatan Genteng Keramik Pres Terhadap Respon Kuat Lentur dan Kuat Serap Air

Roof tiles are roof coverings that function to protect the lower part from the heat of the sun and rain. Roof tiles are usually made from earth, either pressed or printed and from cement. Good quality roof tiles do not leak easily, are neat when arranged, have a uniform size and shape, and do not break easily or become mossy. This research aims to determine the quality of roof tiles in terms of the parameters of strength against water seepage and strength to withstand bending loads. The results of calculating the signal-to-noise ratio for the strength to withstand the bending load of roof tiles from several variations of tests that have been carried out show that the A1 factor is 49.2469. To minimize the value of water absorption strength (%), a combination of level factors is needed, including a roller diameter (A) of 250 mm, engine rpm (B) of 1000 rpm, gap between rollers (C) of 3 mm, and material mixture ratio ( D) the mixture of ingredients used is kaolin: water: clay: sand is 0.35: 0:25. 1: 0.5. The optimal combination of factor levels, for both responses, the strength to withstand bending loads and the strength to resist water seepage, have the same maximum value (A3 B1 C3 D2), so there is no need to carry out a confirmation test. From the calculation of the signal-to-noise ratio for the strength to resist water seepage, it can be seen that the coefficient that responds is coefficient A1 is -25.4842. Keywords: Ceramic tiles, Factors, Flexural strength, Level, Water absorption

Research on the Deformation Law of Foundation Excavation and Support Based on Fluid-Solid Coupling Theory.

To investigate the impact of underground water seepage and soil stress fields on the deformation of excavation and support structures, this study initially identified the key influencing factors on excavation deformation. Subsequently, through a finite element simulation analysis using Plaxis, this study explored the effects of critical factors, such as the excavation support form, groundwater lowering depth, permeability coefficient, excavation layer, and sequence on excavation deformation. Furthermore, a comprehensive consideration of various adverse factors was integrated to establish excavation support early warning thresholds, and optimal dewatering strategies. Finally, this study validated the simulation analysis through an on-site in situ testing with wireless sensors in the context of a physical construction site. The research results indicate that the internal support system within the excavation piles exhibited better stability compared to the external anchor support system, resulting in a 34.5% reduction in the overall deformation. Within the internal support system, the factors influencing the excavation deformation were ranked in the following order: water level (35.5%) > permeability coefficient (17.62%) > excavation layer (11.4%). High water levels, high permeability coefficients, and multi-layered soils were identified as the most unfavorable factors for excavation deformation. The maximum deformation under the coupled effect of these factors was established as the excavation support early warning threshold, and the optimal dewatering strategy involved lowering the water level at the excavation to 0.5 m below the excavation face. The on-site in situ monitoring data obtained through wireless sensors exhibited low discrepancies compared to the finite element simulation data, indicating the high precision of the finite element model for considering the fluid-structure interaction.

Mobility of Nitrates and Phosphates from Animal Manure-Amended Soil to Runoff and Seepage Water from a Sweet Potato Field

Ammonia, nitrate, and phosphate in animal manure used as fertilizer reduce environmental quality by running off agricultural fields into natural water resources. Runoff and seepage water from five soil management practices (chicken manure CM, sewage sludge SS, chitin CH, biochar Bio, and no-amendment NA control plots), were investigated for their potential nutrient catching down the field slope of a sweet potato, Ipomoea balata field. The results revealed that CM-amended soil released the greatest runoff water volume (172.6 L plot −1) compared to the control treatment (98.6 L plot −1), indicating a 75% increase in the runoff water volume. CM also increased the percolated water into the rhizosphere of the growing plants by 55% compared to the control, whereas SS reduced the runoff water volume and increased the leaching water by 36% and 82%, respectively (a desirable attribute of water conservation), compared to the control plots. The concentration of PO4−3 ions in the percolated water from the biochar treatment was significantly greater compared to the other treatments, indicating there was no impact of biochar on binding PO4−3 ions. SS reduced the nitrate concentrations in the runoff and increased the seepage water volume percolated towards the roots of the growing plants; a desired attribute for preventing surface water contamination by nitrates. Observing the precipitation pattern and improving the N application rate are recommended.

Elaboration and application of the nested multi-coupling model test system for an artificial dam seepage simulation under combined action of dynamic and static loads

Outdated coal mining technologies involve considerable mine water resource waste. For coal mines located in water-starved western regions of China, this jeopardizes the sustainable coal mining development, local eco-environment, and agricultural production. Coal mine underground reservoirs furnish conservation and cyclic utilization of water resources in the coal mining process. The weakest links of underground reservoirs are artificial dams that are prone to frequent occurrence of water seepage and instability failures. Aiming to explore the deformation rules of artificial dams under fluid–solid coupling action, this study developed a nested multi-coupling test system comprising a model shelf, a mine pressure simulation device, a water pressure simulation device, and a monitoring system, The maximum size of the model shelf is 1400 mm * 1300 mm * 200 mm. The mine pressure simulation device was composed of static-load and vibration-load oil cylinders of various sizes. A servo motor mainly controlled the water pressure device; with a water pressure sensor and high-precision flowmeter, water pressure could be accurately adjusted. By taking the underground reservoir in the Wulanmulun Coal Mine as an example, the deformation failure characteristics of the MB-1 dam under fluid–solid coupling conditions were simulated to validate the reasonability and feasibility of the developed system. The obtained experimental results indicated that the artificial dam damage was induced by increased mine pressure, leading to shear compression failure. The artificial dam underwent plastic deformation at a water pressure of 11.43 kPa, accompanied with the generation of microfractures, which rapid propagation under vibration loading violated the dam’s stability.

Thermal consolidation of layered saturated soil under time‐dependent loadings and heating considering interfacial flow contact resistance effect

AbstractDue to the presence of tiny gaps at the interface of two layers of saturated soil, water seepage occurs at a slower rate within these gaps, resulting in laminar flow at the interface. Based on the Hagen‐Poiseuille law, a general imperfect flow contact model was established for layered saturated soil interfaces by introducing the flow contact transfer coefficient Rω and the flow partition coefficient ηω. The investigation focused on the thermal consolidation behavior of layered saturated soil foundations under variable loadings considering the flow contact resistance effect at the interface. By employing the Laplace transform and its inverse transform, a semi‐analytical solution for the thermal consolidation of layered saturated soil foundations was derived. In the context of a two‐layer soil system, the effects of Rω, ηω, and permeability coefficient k on the consolidation process were examined. The obtained results were then compared with three other interfacial contact models, thereby confirming the rationality of the presented model. The study findings revealed that the flow contact resistance effect leads to a clear jump in the pore water pressure. Furthermore, an increase in Rω and a decrease in ηω were found to significantly enhance displacement and pore water pressure, while having minimal impact on the temperature increment. These insights contribute to a more comprehensive understanding of the thermal consolidation behavior of layered saturated soil foundations and underscore the significance of accounting for the flow contact resistance effect in such analyses.

Recovery of ammonium from stormwater by ion exchange: Purifying seepage water in laboratory and pilot scales

Ammonium removal from seepage water (representative stormwater) by ion exchange was investigated experimentally on laboratory and pilot scales. The results present the removal of ammonium from the worst-case scenario of stormwater, which is seepage water. Ammonium removal was efficiently accomplished with commercial resin CS16GC in proton and sodium forms. With the resin in H+ form, simultaneous removal of Na+, K+, Ca2+, and Mg2+ was achieved, whereas with the resin in Na+ form, other metals except Na+ were removed. Resin regeneration could be done efficiently with 2 mol/L HCl and 2 mol/L NaCl. Cyclic (7 cycles) ammonium removal runs were conducted with the CS16GC resin in Na+ form on both laboratory and pilot scale. Qualitatively, the results obtained from the cyclic runs done on laboratory and pilot scales were similar; however, some differences were observed because of slightly different feed compositions. In the pilot-scale run, 95–100% ammonium removal was obtained. The performance of the commercial resin was efficient compared with novel materials reported in the literature in an analysis method proposed by the authors. Ion exchange–based ammonium removal was shown to be an efficient method, and further investigation on the long-term stability of the process is warranted.

Application and testing technology of new road materials in highways

Abstract In the face of annual highway construction and highway maintenance projects, traditional road materials and road testing technology are difficult to meet the current highway construction needs. Based on this research background, the article first discusses the three-dimensional ground-penetrating radar nondestructive testing technology, analyzes the detection principle from the fluctuation equation of electromagnetic wave, the propagation characteristics of electromagnetic wave, and the propagation speed in the medium, and specifically analyzes its detection performance and application in the detection of the thickness of the structural layer. Finally, some sections of the Shanzhan Expressway are chosen as test objects and test experiments are designed and implemented. The test results show that the strength of the road material with water water-reducing agent increases compared to the material without water water-reducing agent. By using red mud instead of cement, road materials can have a relatively high strength. Therefore, using red mud as a substitute for conventional materials is entirely feasible and can save costs. The cracking rate of the highway was reduced by using the “leaching recycled” material, and the small cracks of less than 2mm were basically sealed, while the cracks of more than 2mm were alleviated. There is no water seepage on the pavement at 28 points of the 7 sections tested, so the “leaching regeneration” material has a better waterproof effect on the highway pavement.

Numerical analysis of seepage law for radial fluid flow in a single fracture: Comparison between smooth and rough fractures

This paper investigated the differences for the hydraulic characteristics in a single fracture between using the Navier–Stokes (N–S) equation and Darcy's law, which would be benefit to understand the seepage mechanism in the fracture. A numerical model of the radial flow was established considering the aperture size and water injection flow rate. Some conclusion could be given. First, the Darcy's law only described the seepage characteristics when the flow rate was small when the flow rate and pressure response have a linear relationship. While the N–S equation could describe the linear and nonlinear seepage characteristics, resulting in a better model of the actual fracture seepage flow. Second, the aperture size had a limited influence on the water pressure and seepage velocity inside the fracture when the flow rate was small. It began to have a significant impact influence on the seepage characteristics inside the fracture with the aperture increased. Third, the flow–pressure response conformed to the Forchheimer equation in the fracture. The critical Reynold number would decrease from 1.2 to 0.0116 when fracture aperture decreased from 3 to 0.5 mm using the N–S equation. The degree of nonlinearity of the fluid flow increases with fracture roughness increasing. This work gave a guidance to the difference in the two seepage theories and correction for the result by Darcy law, which was widely used in the engineering calculation.

Review and analysis of RC bridge half-joints strengthening techniques

In the past, the extensive use of the Gerber scheme in the construction of existing bridges has been justified by the advantages in terms of reduced stresses of the statically determined scheme and rapid execution. On the other hand, the presence of junction elements at the ends of the beams has over time led to a series of issues, especially related to their durability. In fact, the half-joints’ geometric configuration leads to the accumulation of degradation due to platform water seepage, resulting in the initiation of reinforcement corrosion, especially in the presence of chlorides derived from de-icing salts used in the winter season. Furthermore, these elements have been designed for lower loads than those specified in current regulations, and therefore, they may be in critical conditions where the strength reduction, due to existing degradation, can lead to failure. For these reasons, local repairs and/or strengthening interventions are necessary to ensure adequate levels of safety. Within this study, the topic of reinforcing half-joints is addressed, first by describing the currently available intervention techniques in the literature, and then by deepening an intervention technique based on the use of external post-tensioned bars, applied to a case study bridge through nonlinear numerical simulations. These analyses allow quantifying the performance improvements of this technique under both service conditions and ultimate loads, considering various parameters, including the pre-stress value applied to the external tendons and different scenarios of chloride-induced corrosion.

Sinkhole Investigation using Resistivity Method in Universiti Malaysia Kelantan, Jeli Campus

The discovery of sinkholes on the road at Universiti Malaysia Kelantan, Jeli campus is concerning as it is risky to road users, especially Universiti Malaysia Kelantan students and staff. The study presents an investigation of the sinkhole based on the resistivity approach. By using the Electrical Resistivity Imaging (ERI) method, we can understand the subsurface materials that cause sinkhole occurrence. The resistivity data were collected on the sinkhole area using two survey lines of 50m Schlumberger array and 100m of Gradient array. The results of pseudosection showed a dominantly low resistivity area with a value between 1 Ωm to 100 Ωm indicating the presence of high water content in the subsurface materials due to water seepage from the surface. The highest resistivity value, 600 Ωm showed the presence of compacted material in the subsurface. From the resistivity method, the sinkhole formation in the study area is caused by water saturating the subsurface material which is likely due to rainwater seeping and washing away the unconsolidated material underneath.

Fontisubflavum oceani gen. nov., sp. nov., isolated from the deep-sea cold seep water of South China Sea.

In this study, we report a Gram-stain-negative, rod-shaped, atrichous and aerobic bacterial strain named CSW1921T, which was isolated from the deep-sea water of a cold seep in South China Sea. Growth of strain CSW1921T occurred at 10.0-35.0 °C (optimum, 30 °C), pH 5.0-10.0 (optimum, pH 8.0-9.0) and with 0-9.0 % (w/v) NaCl (optimum, 1.0-2.0 %). Phylogenetic tree analysis based on 16S rRNA gene sequence or the genomic sequence indicated that strain CSW1921T belonged to the family Rhodobacteraceae and was closely related to Rhodophyticola porphyridii MA-7-27T (97.5 % sequence similarity). Genomic analysis indicated that strain CSW1921T contains a circular chromosome of 3 592 879 bp with G+C content of 60.5 mol%. The predominant respiratory quinone of CSW1921T was ubiquinone-10. The polar lipids of CSW1921T contained phosphatidylglycerol, three unidentified aminolipids, two unidentified phospholipids and two unidentified lipids. The major fatty acids of strain CSW1921T contained C16 : 0, C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c). The average nucleotide identity, DNA-DNA hybridization and average amino acid identity values between strain CSW1921T and members of its related species were 68.02-69.08 %, 12.7-12.9 % and 46.87-48.08 %, respectively, which were lower than the recommended threshold values for bacterial species or genus delineation. Phylogenetic, physiological, biochemical and morphological analyses suggested that strain CSW1921T represents a novel genus and a novel species of the family Rhodobacteraceae, and the name Fontisubflavum oceani gen. nov., sp. nov. is proposed with the type strain CSW1921T (=MCCC 1K08371T=KCTC 92834T).