Water Conductivity Research Articles

Salt removal capacity and nutrient status of a forage cropping system based on triticale and alfalfa when grown on a salinized calcareous soil

Managing soil salinization requires identifying a sustainable cropping system to improve soil quality by removing salts, particularly in the south Mediterranean area. The present study aimed to evaluate the efficiency of the forage crop succession containing triticale and alfalfa in removing salt from salinized calcareous soil. The experiment was conducted in field during two successive seasons. Five electrical conductivity levels of salinized soil (ECs) were tested: 0.3 (control), 0.8, 1.4, 1.8, and 2 dS m-1 (1:5extraction). The triticale was grown from November 2019 to April 2020. The alfalfa occupied the same soil from June 2020 to October 2021 (11cuts). The electrical conductivity of the irrigation water was ECi=1.1 dS m-1. The results revealed that the soil salinity and the exchangeable sodium percentage (ESP) decreased during the cropping seasons. The high ECs=2 dS m-1 and its ESP=85.2% became similar to control levels (ECs=0.25 dS m-1, ESP=5%) after the succession of triticale and fourth cuts of alfalfa. The NaCl uptake at the end of the cropping succession was 1433 kg ha-1 at an initial ECs=2 dS m-1. Concerning the nutrient status of the plants, nitrogen, phosphorus, and potassium contents were invariable with ECs levels. For alfalfa, a reduction in calcium and magnesium contents was noticed with soil salinity in the first season (2020). The results suggest that the insertion of triticale and alfalfa in the forage cropping system is an efficient solution for removing salt from salinized soils to ensure sustainable agricultural production.

Vertical profiles of community and activity of methanotrophs in large lake and reservoir of Southwest China

Microbial methane oxidation plays a significant role in regulating methane emissions from lakes and reservoirs. However, the differences in methane oxidation activity and methanotrophic community between lakes and reservoirs remain inadequately characterized. In this study, sediment and water samples were collected from the large shallow lake (Dianchi) and deep reservoirs (Dongfeng and Hongjiadu) located in karst area, Southwest China. The results indicated that the rates of aerobic oxidation of methane (AeOM) in lake sediment ranged from 7.1 to 27.7 μg g−1 d−1, which was higher than that in reservoirs sediment (1.92 to 11.56 μg g−1 d−1). Similarly, the average AeOM in the water column of lake (104.7 μg L−1 d−1) was much higher than that of reservoirs (46 μg L−1 d−1). The content of sediment organic carbon and dissolved inorganic carbon were important factors that influenced the rates of AeOM in sediment and water column, respectively. 16S rRNA genes sequencing revealed a higher relative abundance of methanotrophs in lake sediments compared to reservoir sediments. The dominant methanotrophic taxa in lake was Methylococcaceae (type Ib), while Methylomonadaceae (type Ia) was predominant in reservoirs. Meanwhile, anaerobic methane-oxidizing microorganisms Candidatus Methylomirabilis and Candidatus Methanoperedens were also abundant in sediments of reservoirs. However, metatranscriptomic analysis revealed that the type I methanotrophs, especially Methylobacter, was most active in the sediment of both lake and reservoir. Water depth and conductivity could be the key controlling factors of the structures of methanotrophic communities in sediment and water column, respectively. Metagenome-assembled genomes suggested that type I methanotrophs exhibited greater motility, as evidenced by a higher number of flagellar assembly genes, while type II methanotrophs demonstrated advantages in metabolic processes such as carbon, phosphorus, and methane metabolism.

Restoration of the Performance of Membranes Fouled and Wetted in a Pilot-scale Membrane Distillation Process

Objectives : The fouling and wetting of membranes in membrane distillation processes can significantly reduce membrane performance, thereby affecting overall process efficiency. The purpose of this study is to develop methods for restoring the performance of membranes used in a membrane distillation pilot plant operated in the Middle East by testing and optimizing various cleaning methods. This aims to maintain the long-term performance and improve the operational efficiency of the pilot plant through the reuse of restored membranes.Methods : To analyze the main fouling substances on the hollow fiber membranes collected from a module operated in a pilot plant, FTIR, XRD, and SEM analysis techniques were employed. A lab-scale module was fabricated using the collected membranes, and cleaning methods were applied. Citric acid was used for cleaning to restore membrane performance, which was evaluated by measuring water permeability and conductivity before and after cleaning.Results and Discussion : FTIR and XRD analyses revealed that the main fouling substances on the membranes used in the pilot plant were NaCl, CaCO<sub>3</sub>, and CaSO<sub>4</sub>. SEM and ICP analyses confirmed that the membranes near the feed inlet of the module experienced severer fouling compared to those near the outlet. The cleaning method involving pump circulation after inducing artificial wetting was found to be the most effective for restoring membrane performance. Notably, when a high concentration of citric acid was used, almost all fouling substances on the membrane surface were removed, restoring membrane performance to nearly its original state.Conclusion : The cleaning method involving artificial wetting followed by pump circulation was determined to be the optimal method for successfully restoring the performance of membranes fouled and wetted in membrane distillation processes.

Pre-pilot forward osmosis – Membrane distillation hybrid system for sustainable produced water treatment and reducing volume of hazardous waste in oil and gas industry

This study introduces pre-pilot scale hybrid forward osmosis - membrane distillation (FO-MD) module, designed for the simultaneous treatment of different challenging produced water (PW) streams from Oil &Gas Industry. In this module, hot draw solution simultaneously serves as MD feed solution. The performance of this module was assessed with synthetic and real PW streams for extended operating times. The MD permeate production was doubled and comprised 0.4 L/h for 7:1 MD/FO area ratio (0.105 m2 and 0.015 m2, respectively) compared to permeate production that was observed with equal MD and FO membrane area (0.015 m2 each). The conductivity of the final product water was 364.9 ± 2.7 μS/cm, comparable to the typical potable water conductivity, implying its potential for reuse applications and minimizing volume of hazardous waste. Analysis of MD permeate quality showed that concentration of major ions was reduced by >99 % and chemical oxygen demand was removed by 90.1 %. Continuous operation with real produced streams led to partial pore wetting on the MD active layer. The microscopy showed organic fouling caused by oil and grease deposition and NaCl/CaSO4 scaling was found on both sides of FO membrane. These results suggest that PW pretreatment should be implemented to alleviate membrane fouling and pore wetting. We also observed reverse solute flux of 7.07 g/m2 h in experiments utilizing real DE and WO streams. The results of this study helped to identify challenges arising from the system scale-up and provide grounds for integrating hybrid FO-MD technology to recover water from oil and gas facilities.

A mechanistic model for the complex conductivity of clay materials. I. Theory

Summary Clay materials are ubiquitous in the Earth's continental and oceanic crusts. They are characterized by a large specific surface area, and, in contact with water, they have remarkable adsorption, catalytic and containment properties. Clay materials also exhibit a high electrical conductivity response associated with their large surface. However, sedimentary clay minerals have a complex microstructure and electrochemistry that are not fully understood and make the quantitative petrophysical interpretation of geoelectrical measurements difficult. In this study, we have developed a new mechanistic model to better understand and predict the complex conductivity of clay materials from their microstructure and electrical double layer properties. For the conductive component, our model considers ion electromigration in bulk water, clay electrical diffuse layer, and interlayer space, if any. Concerning polarisation, it takes into account ion back-diffusion in the Stern layer and in the interlayer space, if any, and also Maxwell-Wagner effect. Water and clay surface conductivities, formation factor, cementation exponent and sample electrically connected porosity can be extracted from the comparison of the model to experimental data. This study is a step forward to better understand and quantify the complex conductivity of clays observed during electrical and electromagnetic measurements, from laboratory to geological formation scales.

Effects of increased rainfall on heat and mass transfer and deformation of sulfate saline soil: An experimental investigation

To study the effect of increased rainfall on the heat and mass transfer and deformation characteristics of sulfate saline soil, a geometric similarity ratio model (1:6) of the natural site was created inside the self-developed indoor baseplate-atmospheric dual-temperature control model box. For the first time, combined with the characteristics of the surface energy change, the characteristics of water-heat-salt-mechanical coupling changes within sulfate saline soil under normal rainfall and twice the increase in rainfall were studied. The results show that the increased rainfall leads to a more significant decrease in upward shortwave radiation and downward longwave radiation, as well as a more significant increase in the surface net radiation and surface evaporation rate. Additionally, the increase in rainfall leads to an obvious cooling trend in the surface temperature. Compared with normal rainfall, an increase in rainfall leads to a significant increase in soil water content and conductivity, while soil heat flux and temperature significantly decrease. The increased rainfall caused a temperature drop of 1.6 °C at 5 cm of saline soil. Moreover, the increased rainfall leads to an increase in the heat release time of sulfate saline soil. Meanwhile, the impact of increased rainfall on the soil water content, conductivity, and temperature gradually weakens with increasing depth. The increased rainfall can exacerbate thawing settlement deformation and alleviate salt frost heave deformation. Compared with normal rainfall, twice the increase in rainfall results in a 0.9 mm increase in thawing settlement deformation and a 2.5 mm decrease in salt frost heave deformation.

Water desalination using atmospheric pressure plasma combined with thermal treatment

Herein, a novel method is presented for enhancing the thermal desalination process of saline water and seawater using atmospheric pressure plasma (APP). The effect of APP treatment combined with thermal heating (APP-TH) on the energy consumption, conductivity, and pH of seawater and saline water is investigated. Utilizing scanning electron microscopy and X-ray diffractometry, the evolution of the morphology, structure, and chemical composition of precipitated crystals is characterized. The APP-TH method reduces the energy consumption for desalination by 40.5% for saline water and by 52.82% for seawater when compared to the TH-only method. The pH value remains approximately unchanged, decreasing slightly for the saline water from 7.1 for untreated saline water to 7.05 after APP-TH treatment. However, after APP-TH treatment, the pH value of the seawater increased slightly, from 7 to 7.8. The total dissolved salts decreased after APP-TH treatment, lowering the conductivity of the saline water from 65,000 µS/cm to 160 µS/cm and the conductivity of the seawater from 58,200 µS/cm to 243 µS/cm. Moreover, the size of precipitated crystals from saline water is 31.47 nm after APP-TH treatment, compared to 55.59 nm after TH-only treatment. They also dropped from 41 nm to 39.5 nm for seawater. Compared with traditional approaches, this research proposes an optimistic solution to address global potable water scarcity issues.

How Can Restoration Improve the Environmental Conditions of a Meromictic Urban Lake?

This study was conducted on Klasztorne Małe Lake located in the city of Kartuzy. For about 100 years, the lake served as a receiver of domestic, industrial, and rain sewage. The lake was completely degraded. In addition, excessive sewage inflow caused the accumulation of dense pollution in the area of the lake’s deepest part, which caused the formation of a monimolimnion layer. The bradymictic KML became a meromictic lake. After cutting off the inflow of pollutants, the lake was restored by the P inactivation method using coagulants PIX 111 and PAX 18. Before the restoration process of this lake, concentrations of nutrients in the bottom water layers achieved very high values of TN (total N) 65 mg/L and TP (total P) 30 mg/L. An average concentration of chlorophyll was 65 µg/L and visibility did not exceed 1 m. The method used brought very good results. In the entire volume of water, over 90% reduction in TP and a several-fold decrease in the content of TN were noted. The withdrawal of mineral P from the water limited the production processes in the lake, which was reflected in the reduction in chlorophyll amounts (19 µg/L) and the increase in water visibility (2 m). In addition, oxygen conditions in the lake improved. The application of coagulants caused a decrease in the density of the monimolimnion water, which was indicated by a significant decrease in water conductivity. However, the restoration method did not improve the water dynamics.

Thermal Performance Enhancement of Ice Storage Capsule by Dandelion-Shaped Fins

Limited thermal conductivity of water hinders the performance of ice storage systems. This study proposes a novel approach to enhance ice storage performance using nature-inspired, dandelion-shaped fins with multi-level branches within spherical capsules. We aim to optimize the fin configuration to maximize the cooling energy storage capacity. Based on the enthalpy-porosity method, the solidification of water inside spherical ice storage capsules is investigated numerically. Compared to finless capsules, dandelion-shaped fins significantly improve heat transfer. Fins with two levels of branches outperform other fin types that averagely 34.64% increment in dimensionless cooling energy storage capacity per unit time is achieved with less than 6% loss in dimensionless cooling energy storage capacity per unit weight. Notably, a higher fractal dimension of length further enhances the performance of fins. Aluminum is identified as the optimal fin material due to its efficiency and cost-effectiveness. Finally, a normalized equation is proposed to predict the ice volume fraction under different cooling temperatures.

Evaluating the Influence of Thin Film of Water on the Frequency Dependences of Transmission Line S-Parameters at Positive and Negative Temperatures

Relevance. Provision of reliable and uninterrupted radio communication is critically important under changing climatic conditions of its operation. The combined effect of temperature and humidity can lead to changes in the electrical characteristics of transceiving devices and thereby disrupt the communication channel. In difficult climatic conditions of operation, due to constant temperature changes on the surface of the printed circuit boards, which are part of them, condensation can form, affecting the performance of the entire device. In this regard, the electrical characteristics change, which must be taken into account when designing critical REE. When designing transmission lines on printed circuit boards, it is reasonable to evaluate climatic impacts on it in a wide frequency range, which requires the development of new models and methods that allow taking into account these impacts.Goal of the work: to evaluate the influence of the temperature of a thin film of water on the surface of a microstrip transmission line on its frequency dependences of S-parameters. Finite element methods and laboratory experiment were used.Results. A methodology to account for the effects of ambient temperature and humidity on the electrical characteristics of a microstrip transmission line (MTL) is presented, which allows evaluating the variation of the S-parameters of the line over wide ranges of frequencies, air temperature and humidity, as well as the chemical composition of the environment. The S-parameters of water in a container placed inside a coaxial chamber are measured over the frequency and temperature ranges of 10 MHz to 12 GHz and minus 50 to 100℃, respectively. Using the presented model, the frequency dependences of the electrical conductivity of water at different temperatures are calculated. It is shown that at positive temperature, the electrical conductivity can reach 6.5 Sm/m and at negative temperature it can reach 1.3 Sm/m. Using the developed methodology, the influence of different water electrical conductivity on the S-parameters of MTLs is evaluated. The influence of water and ice layer thickness on the S-parameters of MTLs was shown. It is found that models describing the electrical conductivity of water have an excellent influence on the electrical parameters of the transmission line. Novelty. A method of accounting for the influence of ambient temperature and humidity on the S-parameters of the transmission line is presented, which is characterized by the use of a model of water conductivity based on insertion losses calculated from the measured S-parameters of a coaxial chamber with water in the container when its temperature is changed. Practical significance: a model and a methodology for taking into account the impact of temperature and humidity of the environment on the MTL characteristics are presented, allowing estimating the S-parameters of the line in a wide range of frequencies, air temperature and humidity, as well as the chemical composition of the environment.

Induced polarization of clay-rich materials. 4. Water content and temperature effects in bentonites

Deep geological disposals (DGDs) are widely seen to be the best solution to contain high-level radioactive wastes safely. Compacted bentonite and bentonite-sand mixtures are considered the most appropriate buffers or sealing materials for access drifts, ramps, and shafts due to their favorable physicochemical and hydro-mechanical properties. Bentonite-sand mixtures are expected to swell and seal all voids when in contact with water, forming an impermeable barrier to radioactive elements. The parameters that will most affect the hydraulic performance of these seals are their water content, dry density, water salinity, and temperature. Monitoring and assessing these parameters are, therefore, crucial to confirm that the seals’ safety functions are fulfilled during the life of a DGD. Induced polarization (IP) is a nonintrusive geophysical method able to perform this task. However, the underlying physics of bentonite sand mixtures has not been checked. The complex conductivity spectra of 42 compacted bentonite-sand mixtures were measured in the frequency range of 1 Hz–45 kHz in order to develop workable relationships between in-phase and quadrature conductivities versus water content and saturation, pore water conductivity, bentonite-sand ratio (10% to 100%), temperature (10°C–60°C), and dry density (0.97 to 1.64 g cm−3). We observe that conductivity is mostly dominated by surface conductivity associated with the Stern layer (SL) coating the surface of smectite, the main component of bentonite. At a given salinity and temperature, the in-phase and quadrature conductivities obey the power law relationships with water content and saturation. The in-phase and quadrature conductivities depend on the temperature according to a classical linear relationship with the same temperature coefficient. An SL-based model is used to explain the dependence of the complex conductivity with water content, dry density, water salinity, and temperature. It could be used to interpret the IP field data to monitor the efficiency of the seal of DGD facilities.

Evaluation of carbonated fossil bone consolidation by induction of calcium hydroxide nanoparticles in a Miocene Cheirogaster richardi specimen

In this research, calcium hydroxide nanoparticles, as a carbonate consolidation method, have been evaluated on carbonated fossil bone samples from decontextualized Cheirogaster richardi specimens’ fragments.The main objective was to assess whether the treatment improved fossil bone surface cohesion and mechanical strength by creating a consolidated carbonate matrix in fossil substrate. Treatment penetration capacity and chemical compatibility without causing observable alterations in substrate porosity and external appearance were considered as significant questions to be assessed. Samples were analysed both before and after treatment using scanning electron microscopy, spectrophotometry, weight measurement control, water absorption assessment, conductivity and pH measurement, Vickers microindentation and tape testing. During analysis and evaluation, changes in fossil bone after treatment compared to its original condition have been taken into account.Results point out that hardness and cohesion increased significantly after treatment, bonding together disaggregated particles via a calcium carbonate micrometric layer, with almost negligible changes in surface topography and colour. In addition, calcium hydroxide nanoparticles penetration depth was remarkable. Conductivity, pH and weight hardly changed and porosity reduction was observed without complete pore blockage. To sum up, the treatment was effective and suitable for carbonate fossil bones having a highly compatibility with carbonate fossil bones substrates.

Теплоотдача при движении воды в трубе при температурах, близких к температурам кипения в переходном режиме

Currently, there is a problem of developing effective methods to calculate heat and mass transfer processes during steam condensation from a vapor-gas mixture in industrial devices. This is due to the need to create new reliable and highly efficient designs of heat exchangers for various purposes. The finite element method has been used in the ANSYS Fluent software package during the numerical simulation. An experimental plant is tested in the pipeline of an industrial enterprise at the production site of the Technopolis KHIMGRAD industrial park (Kazan-city). The applicability of the Lee model to solve problems of water flow in a pipeline with partial evaporation is proved. This model allows you to accurately account for the processes of evaporation and condensation, which is important for the design of cooling and air conditioning systems. The authors have designed a three-dimensional model of the flow area of the experimental module and a CFD model to calculate temperatures, phase velocities and their concentrations, considering the peculiarities of the ongoing processes of heat and mass transfer. A slight effect on the heat flow of a 180° rotation during the flow of a liquid medium in the range of the Reynolds numbers 1800–2600 is shown. The developed model is verified with the results obtained at the experimental plant. It is established that the model reproduces experimental data well. An analysis of studies of heat and mass transfer processes during the fluid flow in channels in the presence of phase transitions is carried out. The problems of calculating the parameters of heat transfer during the movement of a fluid in a transient mode are revealed, especially at values of the Reynolds number close to 2000. The experimental plant diagram is presented. It is found that in the range of Reynolds numbers of 2600–3600, the calculated temperature values differ from the temperature values obtained experimentally by less than 0,42 %. During the partial transition of water into steam in the range of Reynolds numbers of 1800–2600, the deviations were less than 6 %, which confirms the adequacy of numerical modeling of calculating the heat transfer process in a pipe. It is shown that considering the influence of temperature on surface tension, the coefficient of thermal conductivity of water and the coefficient of dynamic viscosity of water is important to obtain accurate results. The proposed approach can be used to optimize the operating parameters of condensers and evaporators, as well as to accurately calculate the heat transfer coefficient and determine the areas of vapor formation. It will improve the energy efficiency of industrial installations and reduce the cost of equipment operation.

Characterizing groundwater contamination flow-paths and heavy metal mobilization near a waste site in Southwestern Nigeria

This study investigates potential groundwater contamination near a waste disposal site in southwestern Nigeria. The area's complex geological setting, characterized by fractured rock formations, posed significant challenges for traditional monitoring methods. To address these challenges and comprehensively assess groundwater conditions, we employed a combined approach utilizing Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), and geochemical analysis of heavy metals and water conductivity. This approach enabled the investigation of groundwater levels, identification of potential contamination zones, and delineation of contaminant flow paths. GPR identified a shallow zone, termed the “shadow zone,” with conductive residues indicating contaminants with anomalous conductivity ranging from 1 to 1.5 m. An intermittent reflection zone at a depth of 1.5–3.5 m suggested the potential presence of leachate-impacted groundwater. ERT confirmed a shallow resistive layer at depths of 0–2 m, attributed to compacted waste and topsoil, around the abandoned main dumpsite. Below this layer, a zone of low resistivity, decreasing downward through a porous weathered zone, was observed. This corresponded to high water conductivity in well data, ranging from 21 to 147 mS/m (equivalent to 6.80 to 47.62 Ω-m), indicating a high conductive anomaly suspected to be a leachate plume at depths of 2–10 m in a sandy-gravelly weathered zone. Validation against ground truth data confirmed the correlation between radar signatures, geoelectrical imaging, and subsurface lithology. Analysis of well and soil samples revealed concerningly elevated concentrations of cadmium, mercury, lead, arsenic, and cobalt, ranging from 641 to 1175 ppb, exceeding established safety limits for drinking water. Additionally, soil samples showed elevated levels of nickel and chromium, generally ranging from <0 to <1 ppb. These findings highlight the significant risk of groundwater contamination due to the proximity of the leachate zone to the groundwater table in the weathered basement complex. This study demonstrates the effective integration of geophysical and geochemical methods for comprehensive mapping of contaminated zones and identification of preferential pathways for contaminant migration. The findings underscore the critical need for implementing comprehensive risk assessment methodologies in similar complex geological settings.

Assessment of groundwater mineralization in the arid steppe region of the Messaad plateau aquifer, Southern Algeria

Water scarcity is severely high in the North Africa and the Middle East (MENA) regions. The deterioration of water quality has an impact on the human health as well as on the development of agricultural activities, especially in arid regions, where precipitations are less frequent. The aim of this work is to identify and evaluate the chemistry of the groundwater aquifer in the region of Messaad plateau. This region is located 370 km south of Algiers in southern Algeria. A dozen of samples were collected from wells and analyzed using physic-chemical technics, and the results were processed statistically. The distribution of the conductivity values and the various chemical parameters suggest that the groundwater in the Messad wadi area is overall highly mineralized, with the EC ranging from 550 µS . cm–1 to 8790.13 µS . cm–1, with a predominance of calcium sulphate facies and calcium chloride facies. The level of mineralization noted in the southern and southeastern portions of the research area sheds light on the source of natural contamination. The SO42–, Cl– , Ca2+ , Na+ ions are the most important factors influencing the electrical conductivity of water and the groundwater chemistry. These ions are the result of the continuous dissolution of gypsum and halite in the clays and marls of the Barremian formations.

Genetic Characterization and Breeding Habitats of Black Fly (Diptera, Simuliidae) Vector Species in Laos

Genetic diversity and ecology are two important aspects of vector species crucial to a full understanding of disease epidemiology. In this study, we examined genetic diversity, genetic structure and the physiochemical parameters of the breeding habitats of the two significant black fly vector species, Simulium chumpornense Takaoka and Kuvangkadilok and S. nodosum Puri, from Laos. Genetic diversity of S. chumpornense in Laos was relatively high with maximum genetic divergence of 3.05% but no significant genetic differentiation between populations. Comparisons with conspecific populations from Thailand also found no genetic differentiation between the two countries. This possibly related to the recent history of this species, as a very recent (31,000 years ago) historical population expansion was detected. Physicochemical parameters of the breeding habitats suggest the ability to utilize diverse stream sizes from small flows (1 m wide) to huge rivers (290 m or more wide). Populations of S. nodosum from Laos had low genetic diversity with maximum genetic divergence of 2.56% and no genetic structuring among populations. Comparisons with those reported from other countries revealed five genetically divergent lineages (I–V) with minimum genetic divergence of 1.36%. The majority (42 of 52) of specimens from Laos belonged to lineage I and the remaining (10) comprised lineage II. Lineage I is the largest and representative of specimens from Thailand, Myanmar, Vietnam, Taiwan and Laos. Population history analysis revealed that lineage I had undergone recent demographic expansion dating back to 7000 years ago. This very recent population expansion resembles others reported from Thailand and possibly indicates a response to increasing human and domestic animals following the agricultural revolution. Breeding sites of S. nodosum are diverse in respect to elevation, velocity, water conductivity and streambed particle size. The ability to utilize a wide variety of breeding sites could promote the production of a large adult population, which can be a pest for humans and other animals.

Environmental impact assessment of SONARA's oil sludge landfill in BATOKE, south-west Cameroon

The focus of this study was to assess the environmental impact of the BATOKE oil sludge dump. A field visit was conducted to evaluate the condition of the site, followed by the sampling of oil sludge, BATOKE river water, soil, and locally grown manioc and macabo tubers. Subsequent physico-chemical characterization revealed parameters such as pH, electrical conductivity, total hydrocarbons, COD, BOD5, TSS, major cations and anions, as well as heavy metals including iron, copper, zinc, nickel, chromium, lead, cadmium, mercury, arsenic, calcium, potassium, titanium, zirconium, and rubidium. The environmental impact was assessed using the Contamination Index calculation and the Correlation Matrix. Results indicated that most physical parameters met standards, except for the electrical conductivity of water and soil. However, elevated levels of iron, chromium, lead, cadmium, mercury, arsenic, and ammonium ion were found in the BATOKE River water. The soil showed heavy contamination with various metals, and cassava and macabo tubers were also found to be contaminated. The contamination index calculations confirmed severe pollution in the BATOKE environment, with a risk of further escalation without remediation efforts.

Chironomid Pupal Exuviae Technique in Ecological Research of Man-Made Water Bodies

Reservoirs serve functional purposes such as irrigation and power generation. However, concerns are raised due to the alterations of the connected riverine ecosystems. Chironomidae (Diptera), a diverse aquatic macroinvertebrate group, are vital to the functioning of ecosystems and serve as water quality indicators. Their holometabolous development includes the pupal stage after four larval stages. The chironomid pupal skin (exuvia) is used in environmental assessments, where the Chironomid Pupal Exuvial Technique (CPET) is a recognized standard. The CPET method is adaptable to different freshwater environments and here was applied in the study of 28 man-made lakes in the Pannonian Lowlands and Dinaric Western Balkan Ecoregion in Croatia to obtain information on chironomid diversity and analyze the potential influence of environmental factors on the chironomid community. The lake surface was skimmed with an exuvial hand net (mesh size of 300 µm) along the lake edge with a transect length of 10 m in the area of accumulated debris of organic and inorganic matter. Individual exuviae were mounted in a Berlese mounting medium and identified by morphological characteristics to the lowest taxonomic level. During the study, 5698 chironomid pupal skins were collected, and 141 taxa (including 97 species) belonging to five subfamilies were identified. The tribe Tanytarsini comprised 40% of the identified taxa, with Paratanytarsus spp. being the most abundant. In the Dinaric ecoregion, Paratanytarsus bituberculatus dominated, while Microchironomus tener and the genus Cricotopus were the dominant taxa in the Pannonian ecoregion. Community structure in the Pannonian ecoregion was influenced by total organic carbon (TOC) and orthophosphates (PO43−), indicating higher anthropogenic pressure compared to the Dinaric ecoregion, where water conductivity influenced Chironomidae assemblages. The research has provided valuable and useful information on the chironomid diversity in man-made and highly altered water bodies, as some of the most vulnerable aquatic habitats to anthropogenic influence. The CPET method could be a useful tool for the ecological studies and bioassessment of water quality in Croatia.

Advances in Wood Anatomy: Cutting-Edge Techniques for Identifying Wood and Analyzing Its Structural Modifications

Wood, a natural lignocellulosic polymer, plays several important roles in trees, including water conduction, structural support, and nutrient storage [...]

Structural Characteristics of Phytoplankton Communities and Its Relationship with Environmental Factors in Different Habitats of Hedi Reservoir

To explore the characteristics of phytoplankton communities and their relationship with environmental factors in different habitats of Hedi Reservoir, the inflow rivers, estuaries, and reservoir area of Hedi Reservoir were investigated in February （recession period）, April （flood period）, July （flood period）, and December （recession period） of 2022. During the investigation, 231 species of phytoplankton that belong to seven phyla were identified, and the cell density of phytoplankton ranged from 2.94 × 106 - 8.04 × 108 cells·L-1. Phytoplankton cell density in flood periods were higher than that in recession periods, and that was higher in estuaries and the reservoir area than that in inflow rivers. Meanwhile, the cell density of phytoplankton in the estuarine and reservoir area was dominated by Cyanobacteria throughout the year, especially Raphidiopsis raciborskii, whereas the cell density of phytoplankton in inflow rivers was dominated by Cyanophyta, Chlorophyta, and Bacillariophyta. In the inflow river area, the dominant species of cyanobacteria were Microcystis aeruginosa, Limnothrix redekei, Pseudanabaena circinalis, and Merismopedia punctata； the dominant species of Chlorophyta were Chlorella vulgaris and Crucigenia tetrapedia； and the dominant species of Bacillariophyta were Chlorella vulgaris and Melosira granulate. The highest biodiversity （Shannon-Wiener Index, Pielou index, and Margalef index） were observed in the inflow river area of Hedi Reservoir. The correlation analysis （Pearson） indicated that the environmental factors that were significantly correlated to phytoplankton communities included water temperature, dissolved oxygen, pH, conductivity, nitrogen, and phosphorus concentration. The RDA analysis indicated that phytoplankton communities in the inflow river area were mainly affected by pH and total nitrogen concentration, which were majorly affected by water temperature and pH in the estuarine area and chiefly affected by turbidity and pH in the reservoir. The pH affected the changes in phytoplankton communities in all three different habitats, whereas the inflow river area was significantly affected by total nitrogen concentration, and the estuarine and reservoir were significantly affected by water temperature and turbidity, respectively.