Direction Of Water Flow Research Articles

Surface Water (SW) and Shallow Groundwater (SGW) Nutrient Concentrations in Riparian Wetlands of a Mixed Land-Use Catchment

Precipitation patterns, water flow direction, and local land-use practices affect surface water (SW) and shallow groundwater (SGW) nutrient concentrations in riparian wetlands. Given physical process complexities, spatiotemporal quantification of nutrients and physical factors influencing nutrient concentrations are needed to advance wetland water resource management. To address these needs, a study was conducted in riparian wetlands of a mixed land-use catchment in West Virginia (WV), USA. Observed data included SW–SGW levels and nutrient concentrations, including nitrate (NO3-N), nitrite (NO2-N), ammonium (NH4-N), orthophosphate (PO43-P), total nitrogen (total_N), and total phosphorus (total_P) from January 2020 to December 2021. Water samples were collected monthly from stream gauge sites (n = 4) and co-located piezometers (n = 13). Results showed that, on average, gaining stream conditions were observed in upstream sites, and losing stream conditions were observed in downstream sites. Observed nutrient profiles between SW and SGW included SW exhibiting a higher average NO3-N concentration (0.42 mg/L), while SGW displayed an elevated NH4-N concentration (1.55 mg/L) relative to other nitrogen species. Significantly high (p < 0.05) SW NO3- concentrations in summer and fall were attributed to increased precipitation and corresponding water level and, therefore, pressure head and transport fluctuations. Principal Component Analysis (PCA) showed differences in nutrient concentrations based on the water source type and catchment land use, explaining 65% of data variability. Spearman correlation analysis illustrated the correlation among nutrient concentrations, land use, and water level changes in SW and SGW environments. This study provides needed baseline data on nutrient dynamics for a riparian wetland in a mixed land-use catchment, supplying science-based information to advance land and water management practices in the study watershed and similar physiographic watersheds globally.

Mathematical model of the topological structure of the urban water supply network

To effectively manage urban water supply networks, utility companies providing water supply and drainage (hereinafter referred to as KP "Vodokanal") need to solve the following problems: - use of topographic maps of scales 1:500, 1:1000, 1:2000, which include both ground-based buildings , as well as adjacent underground communications - water supply and sewerage, electrical networks, gas supply networks, heat supply, communications, etc.; - hydraulic calculations of the water supply network to determine the condition, analysis and optimization of the network structure; - prompt elimination of emergency situations and re-sumption of the network after the emergency is eliminated; - control and management of drinking water quality; - availability of pressure, flow and piezometer monitoring devices; - automated control of pumping stations; - saving energy resources; – network inventory. A comprehensive solution to these problems is provided by a geoinformation automated water supply network management system. Automated network management is carried out using geoinformation technologies, mathematical and geoinformation models of the water supply network. The work proposes a mathematical model of the topological structure of the water supply network, defines geospatial data bases about network objects and the interrelation-ships of these objects, taking into account the topological structure of the network to provide geoinformation and mathematical modeling of the hydraulic state of the water supply net-work, solving problems of emergency processing, monitoring the quality of drinking water, and optimizing the network, energy saving. To construct a digital model of the branched-ring structure of a topological graph, digital vector topographic maps are used as follows: - based on the results of geodetic surveys, water supply network facilities are marked on the topog-raphic map with symbols; - analysis of information-graphic diagrams of well details indicates the presence of pressure/flow regulators and hydrants. If there are regulators, their symbols are applied to the polyline of the water supply section at the symbol of the well at the point where the water pipe is inserted into the well, their diameters and the percentage of opening are indicated; - if there is a hydrant, the symbol for a well without a hydrant is replaced with the symbol for a well with a hydrant; - for all objects of the water supply network, the values of technical and graphic parameters are determined; - the orientation of the graph is deter-mined - the direction of water flow; – a matrix of incidents of vertices and contours is formed.

Research on Ship Automatic Berthing Algorithm Based on Flow Matching and Velocity Matching

Addressing the automatic berthing task for vessels, this study introduces the Flow Matching Double Section Bezier Berth Method (FM-DSB) for handling downstream and upstream berthing instructions. By considering the orientation relationship between the direction of water flow and the berth, combined with berthing modes, the algorithm determines the vessel’s entry angle into the berth and plans the berthing path using double-section Bezier curves. Effective control of vessel speed post-path determination is essential. Therefore, based on the response of vessels to propeller inputs, this study introduces the Berthing Path Velocity Matching Method (BPVM). The BPVM ensures speed matching along the berthing path through analysis of vessel acceleration and deceleration capabilities. Subsequently, simulation experiments are conducted to validate the planning algorithm for both long-distance and short-distance berthing. Furthermore, the feasibility and effectiveness of the berthing path are verified using a dual-loop path tracker based on the planned results. Experimental outcomes illustrate the adaptability of the proposed algorithm in planning berthing paths that align with vessel motion characteristics, effectively guiding vessels into berths through the designed dual-loop control system.

Anisotropic Fluorinated‐Elastomer‐Blended Micro‐Dominoes for Wearable Triboelectric Nanogenerators

AbstractTriboelectric nanogenerators (TENGs) have emerged as promising portable and sustainable energy sources in daily life, harvesting energy from human motion, water, and wind. However, they still face limitations in aspects such as contact area, deformability, wettability, and manufacturing method. Here, a wearable TENG incorporating an anisotropic domino structure based on a fluorinated elastomer blend is presented. Because of its thin, elongated structure with broad sides, the TENG achieves substantially larger contact areas and high bendability. Introducing a fluorinated elastomer into the polydimethylsiloxane matrix via a simple blending process not only enhances the triboelectric performance but also reduces surface energy and improves the stretchability of elastomers. The anisotropic arrangement of dominoes, in synergy with the fluorinated elastomer, mimics the surface physicochemical properties of natural rice leaves, resulting in anisotropic superhydrophobic wetting behavior with a self‐cleaning effect and controlled directional water flow for efficient water energy harvesting. Therefore, the TENG functions as an energy‐harvesting leaf that captures energy from wind and water droplets, as well as a wearable energy‐harvesting wristband that generates power from human motions such as touching, shaking, and hand washing.

Elucidation of the dominant factors influencing N2O emission in water-level fluctuation zones in a karst canyon reservoir, southwest China

The water-level fluctuations zones (WLFZs) are crucial transitional interfaces within river-reservoir systems, serving as hotspots for N2O emission. However, the comprehension of response patterns and mechanisms governing N2O emission under hydrological fluctuation remains limited, especially in karstic canyon reservoirs, which introduces significant uncertainty to N2O flux assessments. Soil samples were collected from the WLFZs of the Hongjiadu (HJD) Reservoir along the water flow direction from transition zone (T1 and T2) to lacustrine zone (T3, T4 and T5) at three elevations for each site. These soil columns were used to conduct simulation experiments under various water-filled pore space gradients (WFPSs) to investigate the potential N2O flux pattern and elucidate the underlying mechanism. Our results showed that nutrient distribution and N2O flux pattern differed significantly between two zones, with the highest N2O fluxes in the transition zone sites and lacustrine zone sites were found at 75 % and 95 % WFPS, respectively. Soil nutrient loss in lower elevation areas is influenced by prolonged impoundment durations. The higher N2O fluxes in the lacustrine zone can be attributed to increased nutrient levels resulting from anthropogenic activities. Furthermore, correlation analysis revealed that soil bulk density significantly impacted N2O fluxes across all sites, while NO3−and SOC facilitated N2O emissions in T1-T2 and T4-T5, respectively. It was evident that N2O production primarily contributed to nitrification in the transition zone and was constrained by the mineralization process, whereas denitrification dominated in the lacustrine zone. Notably, the annual N2O efflux from WLFZs accounted for 27 % of that from the water-air interface in HJD Reservoir, indicating a considerably lower contribution than anticipated. Nevertheless, this study highlights the significance of WLFZs as a vital potential source of N2O emission, particularly under the influence of anthropogenic activities and high WFPS gradient.

Comparative study of the cavitation situation and the non-cavitation situation under unsteady flow phenomena of a centrifugal pump

Numerical simulations in three dimensions, both with and without cavitation, were conducted to determine the influence of cavitation on a centrifugal pump. The reliability and accuracy of the numerical model were demonstrated through satisfactory agreement between the experimental and numerical values of the pump’s performance. An in-depth analysis of the correlation between performance characteristics and cavitation was undertaken. The research results indicate that cavity bubbles initially appear near the suction surface of the blade and gradually extend toward the middle of the blade-channel as cavitation intensifies. Moreover, based on the simulation results, it can be concluded that head characteristics are linked to the development of cavitation on the suction surface of the leading edge of the blade runner. A detailed analysis of experimental data and simulation results reveals that cavitation obstructs the flow channel and alters water flow direction, thereby diminishing operational capacity.

Assessment of Blue Water Migration and Efficiency in Water-Saving Irrigation Paddy Rice Fields Using the Water Flow Tracking Method

Although irrigation systems largely sustain global agricultural production, their efficiency is often alarmingly low. While irrigation water (blue water) is critical for the water-saving irrigation of rice with a high water demand, the process and efficiency of irrigation water utilization need clarification. In this study, we examined the three commonly used irrigation and drainage patterns (frequent shallow irrigation (FSI), wet and shallow irrigation (WSI), and rain-catching and controlled irrigation (RCI)) in rice fields. We developed a tracking method for irrigation water flow decomposition, which includes irrigation water evapotranspiration (IET), irrigation water drainage (IDR), irrigation water leakage (IPC), and irrigation water field residual (IRE). Using this method, we established an irrigation water efficiency evaluation index system and a comprehensive evaluation method. Our tracking method is relevant to describing the irrigation water performance under varying irrigation and drainage patterns. The results revealed that the average irrigation water input for the three irrigation and drainage patterns between 2015 and 2018 was roughly 312.5 mm, wherein IET accounted for 148 mm. However, more than 50% of the irrigation water outflow, comprising IDR, IPC, and IRE, exceeded the total amount of irrigation water input. The mean values of the gross irrigation efficiency (GIE), net irrigation efficiency (NIE), and effective consumption ratio (ECR) for all treatments in the three-year period were 0.63, 0.47, and 0.75, respectively. Additionally, the irrigation water use efficiency was significantly higher in dry years compared to wet years. The fuzzy composite rating values of the three irrigation and drainage models from 2015 to 2018 were RCI, WSI, and FSI, in descending order, under varying precipitation conditions. The RCI patterns maintained a high composite rating value (greater than 3.0) under different precipitation conditions. Previous efficiency calculations disregarded the blue–green water migration process and did not differentiate the blue–green water flow direction in agricultural fields, creating significant biases in the outcomes. This study’s method offers a new approach to evaluate the use of blue water resources in farmland.

Unraveling the mystery: Extraction and component analysis of irrecoverable foulants of end-of-life membrane from large-scale MBR

Membrane bioreactors (MBRs) are increasingly employed in municipal wastewater treatment, with membranes inevitably reaching their end-of-life (EOL) primarily due to the accumulation of irrecoverable fouling. Nevertheless, the composition and properties of irrecoverable fouling remain ambiguous due to the lack of appropriate extraction and analytical methods. Herein, we developed a temperature-regulated organic solvent extraction method to extract and analyze irrecoverable foulants in EOL ultrafiltration membranes at various locations within a large-scale MBR for municipal wastewater treatment. The irrecoverable foulants encompassed a high molecular weight fraction not observed in the influent, potentially induced by aggregation from organic-inorganic foulant interaction. The terrestrial humic acid (HA)-like substance dominated the organic components of irrecoverable foulants, and the chelating cation Ca emerged as a dominant inorganic compound. Unexpectedly, we noticed the enrichment of Al, Fe, and Si in the irrecoverable fouling, despite their relatively low rejections by the EOL membrane. The potential complex interactions among HA-like substances, Ca, Al, Fe, and Si were revealed by correlation and cluster analysis. The strong bridging potentials of [Al(OH)4]-, Fe(OH)3 at neutral pH, coupled with the colloidal property of Si, may facilitate the aggregation of organic and inorganic compounds, forming complex irrecoverable foulants with strong affinity for the membrane matrix. Besides, the irrecoverable fouling exhibited an increasing trend along the water flow direction. The mystery of irrecoverable fouling of EOL membrane was, for the first time, systematically unraveled, establishing a foundation for the development of effective membrane cleaning and regeneration technology.

Two-Phase Flow Through the PTL of PEM Water Electrolyzer: MRI Experiments and Numerical Modeling Using Phase-Field Theory

In 2021, estimation shows that the worldwide annual hydrogen production is around 94 Mt. Exploitation of native hydrogen being not mature, it is obtained by its separation from other elements by different methods such as steam methane reforming, and electrolysis of water. The latter supplied by a renewable power source will take part in the development of a green hydrogen economy [1]. In this context, Proton Exchange Membrane (PEM) Electrolyzer is a promising technology due to its flexibility and very quick adaptation to load variations. However, its current development still confronts some limitations at a large industrial scale. For instance, efficiency and durability are directly impacted by the mass transport and electrical transfer within the porous materials at the anode side. Limitation of the water supply to the catalyst layer happens once there is a poor oxygen evacuation which decreases the performance of the device by inducing high overpotential. Furthermore, the PTL has an important role as an electrical conductor for charge transfer from the catalyst layer [1]. The efficiency of all the transport phenomena through the PTL and porous electrode assembly depends on their transport properties which are related to their microstructure and operating conditions. For instance, PTL with a large pore size allows good water and gas transport, while produced electrons choose a long-distance path generating an electrical resistance higher than that in the case of PTL with a small pore size [1]. So, controlled and optimum porosity and pore size could contribute to efficient water, gas, and electron transport. To define the best porous layers morphologies, a deep and accurate understanding of the phenomena is developed in this work by combining modeling and experiments.The magnetic resonance imaging (MRI) technique was used to quantify the water content within the porous layer during the two-phase flow. Instead of the real PTL made of titanium which is paramagnetic and cannot be used in the MRI, borosilicate filters with thickness, porosity, and pore size similar to the PTL were used. After positioning the sample in the 600 MHz vertical imager (Figure 1-A), a constant water flow rate is introduced while the gas flow rate is varied. The saturation profiles measured through the porous material depend on the gas flow rate and a semi-dryness of the sample occurs (Figure 1-B) with a residual quantity trapped between pores (minimum stable water content). The water flow rate variation in the channel does not affect saturation, but a higher gas flow rate is needed to reach a minimum stable water content for higher water flow rate.The gas pressure drop through the porous medium was measured and bubble formation in the channel was also analyzed. The results show that the pressure drops and types of flow (slug, annular, and bubble flow) depend on orientation of the water channel (horizontally and vertically) and flow direction (up or downward), and on the water and gas flow rates.To reach a better understanding of the dynamic characteristics of water and oxygen transport over the PTL, the phase-field model based on the Cahn-Hilliard theory was used to simulate the two-phase flow through a porous medium [2]. In this model, the modified Navier-Stokes equations for two phases are coupled with a phase-field equation for describing the diffuse interface. Numerical simulations performed in the COMSOL® multiphysics software were carried on 2D geometries composed of spherical solid grains of different sizes, having properties similar to the PTL used in the MRI experiments. Gas is injected on one side of the sample and flows through the porous medium initially saturated and evacuated on another side in contact with the water channel (Figure 1-C). Gas flow in the porous medium and bubble formation in the water channel are studied while varying the gas and water flow rates. The simulation results give information about the gas pathways within the porous medium and the saturation profiles over time, depending on the gas/water flow rates, which will be compared with experimental results.[1] J. Parra-Restrepo, “Caractérisation des hétérogénéités de fonctionnement et de dégradation au sein d’un électrolyseur à membrane échangeuse de protons (PEM),” Université de Lorraine, 2020.[2] J. W. Cahn and J. E. Hilliard, “Free Energy of a Nonuniform System. I. Interfacial Free Energy,” The Journal of Chemical Physics, vol. 28, no. 2, pp. 258–267, Feb. 1958. Figure 1

Investigation of the treatment efficiency and mechanism of microporous flocculation magnetic fluidized bed (MFMFB) reactor for Pb(II)-containing wastewater

In this study, a novel microporous flocculation magnetic fluidized bed (MFMFB) reactor was proposed for the treatment of low concentration lead-polluted groundwater in Gansu Province, China. It introduced a magnetic levitation layer and non-coincident counterflow inlet by using flocculants of polyaluminum chloride (PAC) and polyacrylamide (PAM). And Particle Image Velocimetry (PIV) was used in conjunction with flocculation experiments. The results showed that when the dosage of poly PAC and PAM was 120 mg/L and 1 mg/L, respectively, at the same time the water inflow was 0.013–0.020 m3/h, the removal efficiency of Pb(II) and turbidity reached a steady level of over 98% in low turbidity and concentration Pb(II)-containing simulated wastewater. The reactor created favorable conditions for enhanced flocculation in terms of water flow direction, velocity gradient, effective energy consumption and microporous flocculation. Microporous flocculation form on the surface of the magnetic levitation layer, where fine particles contributed to both mixing and adsorption. The reactor possessed comprehensive flocculation effects such as anisotropy, micro-vortex, and microporous, and has the potential to treat low Pb(II)-containing groundwater.

Analysis of the hydraulic interference between the baffles and the composite hydraulic structure

The purpose of the present study is to examine the influence of baffles presence at downstream system on weir gate hydraulic response. Two baffles configuration (triangle and angle shapes) are installed in bed flume. Two different spacing are used between the baffles and two different directions for baffles are also adopted. The study tries to investigate the variation in upstream Froude number, downstream Froude number, Reynolds number, actual discharge, discharge coefficient, downstream average water depth and the hydraulic system efficiency which is expressed as function of downstream water depth. It has been shown that the number of baffles has a direct and significant impact on flow hydraulic characteristics of weir-gate structure regardless of the spacing between baffles and the direction of baffles related to flow. Baffles number and spacing have essential impact on the water flow velocity of system and this impact leads to increase the flow resistance. The results clarify that the upstream Froude number, downstream Froude number, Reynolds number, actual discharge and discharge coefficient are decreased with the increase in baffles number except the average downstream water depth which increases with increase in baffles number. The efficiency of hydraulic system gives a good indicator for using baffles with weir-gate structure. At the end this paper shows a fruitful result of efficiency. This experiment run condense on the baffle’s numbers and directions with respect to the water flow direction at the downstream regime. So, the rises in the water level relies on the numbers and directions of the baffles as compare to the case without using baffles at the flume downstream region. The actual discharge and weir-gate discharge coefficient are more sensitive to the increase in the baffles’ numbers and the baffles direction with respect to the water flow direction

The influence of environmental parameters on spatial variation in zoobenthic density and stable isotopes (δ13C, δ15N, and δ34S) within a large lake

AbstractThe use of baselines in stable isotope studies to interpret food web structure is essential, but baseline isotope values are often assumed to be spatially homogeneous, even in large aquatic ecosystems. To test this assumption in large lakes, we quantified spatial variation in δ13C, δ15N (deposit‐feeding Oligochaeta and filter‐feeding Dreissena spp.), and δ34S (Dreissena spp. only) and density in Lake Erie between 2014 and 2016. Lake Erie's three distinct basins differ in size, bathymetry, and nutrient loading, making it an excellent system for exploring spatial variation in stable isotopes of baseline organisms. Dreissena spp. densities were highest in the western and lowest in the seasonally hypoxic central basin, while Oligochaeta densities were relatively consistent throughout Lake Erie. Values of δ13C, δ15N, and δ34S exhibited distinct spatial trends that were not related to population densities but followed the west to east direction of water flow within the lake. For both taxa, δ13C was lower in the deeper, oligotrophic east basin than the shallow, mesotrophic west basin, and δ15N and δ34S increased from west to east. Spatial patterns of low δ34S in Dreissena spp. in the western and central basins were likely related to hypoxia, whereas patterns of δ15N in both taxa were probably related to the greater influence of agricultural land uses in the western basin. Spatial trends of stable isotopes in large lake zoobenthos are driven by complex interactions of environmental gradients, which could introduce bias in evaluations of trophic structures within aquatic ecosystems that use stable isotopes.

Biomass-derived 3D evaporator with antifouling and salt-rejecting toward solar-enabled steam generation, desalination, and electricity generation

Solar-driven interfacial evaporation is currently considered as one of the most effective and sustainable strategies to address water scarcity and energy shortages issues. Whereas, challenges in developing durable, eco-friendly, and low-cost solar evaporators from readily available materials still exist. Herein, we have reported a facile strategy to construct a robust natural sorghum stalk pith solar evaporator. With advantageous features of gradient honeycomb structure and hydrophilic polymer chains, the constructed evaporator exhibits broadband light absorption, efficient light to heat conversion, fast water transport, and multi-channel release of steam performances, leading to an ultrahigh evaporation rate of 3.79 kg m−2h−1 under one sun irradiation and outstanding salt-resistant ability at a high evaporation rate of 2.6 kg·m−2·h−1 in a highly concentrated brine (20 wt% NaCl), accompanied with anti-oil-fouling performances, as well as high oil removal efficiency (>99.8 %) for oil-in-water emulsion, outperforming most previously reported solar evaporators. Additionally, solar irradiation can further promote the directional water flow, contributing to a high photovoltage of 68 mV under one sun illumination. This paves the way for designing durable biomass-based steam generators, not only scaling up sustainable clean water production, sewage depuration and desalination, but also discovering promising application in the field of electricity generation.

The Coupling Effects Between Floating Insulation Plates and the Thermal Convection in their Bottoms---- An Understanding of Continental Drift

The phenomenon of dumpling drift was discovered during a cooking process, which triggered our thinking of the continental drift. After refining the existing common problems, an experiment on the thermal convection interaction between the floating heat insulation plates and the bottoms is designed. Through controlling variables, this paper investigates the floating patterns of floating insulation plates of different sizes on a thermally convective surface and the principles behind them. The findings show that the appropriate sizing of a floating plate can result in the manifestation of cyclic reciprocating movement on the water’s surface. The periodic movement observed in this phenomenon can be attributed to the obstruction of heat exchange between the water surface and the surrounding air by the floating plate. Consequently, alterations in the direction of water flow induce corresponding shifts in water temperature, which subsequently affect the movement direction of the floating plate. The final outcome is characterized by a periodic reciprocal movement of the floating plate as it interacts with the heat convection occurring at the bottom. Floating plates that are either undersized or oversized would remain stationary without exhibiting any cyclic drift. The decrease in water depth leads to a diminished thermal drive, thereby amplifying the cyclical nature of the motion shown by the floating plate. The above findings indicate that the dimensions of the continental plates present on the Earth's surface have an impact on both the velocity and duration of their movement. The observation that a plate that is too small stagnates on top of a subduction current, while a plate that is too large stagnates on top of an upwelling current, suggests that the smaller continent of New Zealand is likely to experience a decrease in elevation due to its location above a subduction current. Conversely, the larger continent of Africa is expected to undergo uplift and attain a higher elevation as a result of its position above an upwelling current.

Identification of point and nonpoint emission sources of neonicotinoid pollution in regional surface water

Neonicotinoid insecticides are widely applied in farmland, with high detection rates in soils and surface waters, posing potential risks to biodiversity and human health. As a nonpoint emission, surface runoff is widely regarded as the major source of neonicotinoid pollution in surface waters, but few studies have determined the point source contribution to rivers that may be primarily from wastewater treatment plants (WWTPs). Here, we collected the surface water from eight river basins in Zhejiang Province of China and quantified residual concentrations of eight widely commercialized neonicotinoids. Four of these were detected in all samples, with concentrations of dinotefuran and nitenpyram of 119 ± 166 and 87.6 ± 25.3 ng/L, respectively, representing more than 90 % of the total (282 ± 174 ng/L). Neonicotinoid residues were higher in tributaries due to nearby farmland and more dilution effects in the mainstream, and the residues were higher in lower reaches which can be explained by the water flow direction. Significant spatial differences in neonicotinoid distribution between surface water and agricultural soils result from environmental factors (e.g., water turbidity, precipitation, temperature) impacting migration and transport processes. Neonicotinoid residues in surface water showed a significant positive correlation with total WWTP emissions after adjusting for environmental factors. Conversely, no significant association was observed with cropland density (a nonpoint emission source), indicating that point emission source (contributing 20.6 %) predominantly influenced neonicotinoid residue spatial variation in river basin-scale surface water.

Application of passive sampling device for exploring the occurrence, distribution, and risk of pharmaceuticals and pesticides in surface water

Pharmaceuticals and pesticides are compounds of high concern in surface waters around the world. However, few studies have used passive sampling methods to screen and detect these compounds in natural waters. In this study, a self-developed passive sampler was employed to measure pharmaceuticals and pesticides in the rivers of Nanjing, China. A total of 41 pharmaceuticals and 11 pesticides were detected, among which antibiotic and insecticide were the predominant classes, respectively. Valproic acid, caffeine and triclosan from the pharmaceuticals, and isoprocarb and imidacloprid from the pesticides were found frequently with high concentrations. At most sampling sites, the concentration ratios of caffeine versus carbamazepine exceeded 10, and even above 50, indicating relatively poor efficiency of wastewater treatment, or possibly the direct discharge of raw sewage, or other unknown source of pollution. It was found that the concentrations and ecological risks in the northern area of Yangtze River were higher than those in the southern area of Yangtze River, implying that economic development and population density were not the main contributors to the discovered pollution. The total concentration of pharmaceuticals and pesticides in Qinhuai River increased gradually with the direction of water flow, demonstrating the success of water diversion project in flushing and scouring pollutants.

Role of traveling microplastics as bacterial carriers based on spatial and temporal dynamics of bacterial communities

Microplastics (MPs) are considered as distinct substrates for bacterial colonization, they can carry bacterial communities to travel around environments. The bacterial communities on traveling MPs prefer to be gradually consistent with those on local MPs that were always in the same environment, and this process of change in the bacterial communities on traveling MPs was called ‘localization’. However, the dynamics of localization process and their influencing factors are still unclear. Therefore, we simulated the MPs migration process along the water flow direction in the estuary. We used quantitative analysis to study the dynamics of bacterial communities on the migrated MPs. We found the localization characteristics depended on the differences between the former and latter environments, as well as the preexisting bacteria. The localization degree was higher when the former and latter environments were similar. In most cases, compared with the first cultivation of pristine MPs, the time for localization was shorter. Moreover, although the entire bacterial communities tended to be localized, the preexisting bacteria on the migrated MPs had selective effects on subsequent bacterial colonization. Furthermore, the preexisting bacteria on MPs could set up the connections with the bacteria that existed at the latter site, and the stability of the entire bacterial communities on the migrated MPs increased with time. Overall, our findings indicated that the localization characteristics of bacterial communities on traveling MPs were related to the precultured time and environmental differences, which were helpful to understand the colonized bacteria transportation and MPs ecological effects.

Subsurface mapping of petroleum product (diesel) spillage in Apapa, Lagos, Nigeria from geophysical, lithological, and hydrogeological studies

A multi-disciplinary method has been applied for the subsurface mapping of a diesel (refined petroleum product) spillage in the Apapa area of Lagos, Nigeria. The methods include geological, geophysical, hydrogeological, and geoinformatics approaches. Apapa is located within the eastern sector of the Dahomey Basin, Nigeria. Twelve profiles were probed, adopting a 2D Wenner configuration. Three 3D resistivity images were produced from the 2D profiles using ZONDRES 3D and SURFER 16. Additionally, six boreholes were drilled for lithological information and the determination of groundwater flow directions of the area. The study area is characterized by loose, fine to coarse grained sand underlain by peat. The sands were observed to be partly contaminated by diesel (spilled diesel). The 3D resistivity images revealed that the area is composed of 3 geoelectric layers; an organic debris layer (<15 Ωm), overlain by a clean sandy layer (15–54 Ωm), as well as a contaminated sand layer (>55 Ωm). The results showed that higher resistivity values were obtained at shallow depths ≤3 m which depicts the diesel contaminated sand. The 3D model also showed that the magnitude of contamination decreases from the southern part (close to the source of contamination) towards the north of the area. These results are in tandem with the principal flow direction of water which is from south to north, confirming that the pollution source is from the southern part of the area. The combination of the resistivity, groundwater flow direction, and lithological information, therefore, unraveled the source, direction, and extent of contamination in the study area for a successful remediation plan.

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

AbstractThe Yellow River flows through multiple provinces in China, shaping the North China Plain, the largest alluvial plain in China. As the control node of basin ecological environment, the confluence of Weihe River and Yellow River is deemed as the gateway to North China Plain. In this study, a numerical simulation of the Weihe River–Yellow River confluence is conducted using a 2D hydrodynamic model and a coupled transport model for dissolved oxygen–biochemical oxygen demand. The results show that: (i) The typical flow field with multiple backflow areas is formed at the stagnant area where main stream and tributary converge and abrupt channel change area in different hydrological periods. The spur dike here mainly affects the velocity of the Weihe River outlet. (ii) There is an obvious concentration transition mixing zone downstream of the confluence, and the width of the mixing zone gradually linear increases with the direction of water flow. (iii) The self‐purification ability of the confluence is strongest in dry period, weaker in level period, and weakest in wet period. Water bodies have stronger self‐purification capacity on riverbanks than in the middle, and it is stronger in the upper reaches of Weihe River compared to Yellow River. Lower reaches also have a stronger self‐purification capacity than upper reaches. The study results can serve as a scientific reference for protecting the ecological environment of the Yellow River.

Groundwater Level Analysis of Sathyamangalam Region, Tamil Nadu, India Using GIS

The Morphometric and groundwater analysis (water level and flow direction) of Sathyamangalam, having total area of 2.24 lakhs hectares was carried out using geographical information system (GIS). The Watershed characteristics such as slope, size, shape and Morphological Analysis such as linear aspects namely Stream order, Bifurcation ratio, Stream length, Length ratio and Areal aspects in particular Drainage density are analysed using ArcGIS software. And also, groundwater level for four years (2008, 2011, 2014 and 2017) and groundwater flow directions using Piezometric well data were also analyzed. In Watershed characteristics, the size of the study area is 2.24 Lakh ha and designated as sub- catchment watershed. The shape is circular i.e. Fan shape. The total length of contour line is about 11055.86 km and the average slope was 24.68% for 50m interval contour. In Morphological analysis, totally 6487 streams were observed and the total length of stream was 3758.2 km. The study location has bifurcation ratio ranging from 1.56 to 3.62 and length ratio of stream was calculated as 1.678 km/km2. In Piezometric analysis, the major water level changes occur in Northwest of Sathyamangalam. Here, the depth of water from the earth surface decreases from 12.67 m in the year of 2008 to 3.95 m in the year of 2017.