Hydrodynamic Factors Research Articles

Scale-dependent spatial variabilities of hydrological exchange flows and transit time in a large regulated river

Hydrological exchange flows (HEFs) across the river-aquifer interface and the associated transit time of river water in the aquifer have important implications for contaminant plume migration and biogeochemical processes in the river corridor. HEFs and transit time are influenced by both subsurface physical features and hydrologic forcing related to the transport process, which can exhibit complex spatial and temporal variations. In this study, we used a massively parallel subsurface flow model and a particle-tracking model to study the influences of different control factors on spatial variability of HEFs and transit time distributions in the Hanford Reach of the Columbia River in Washington State. 100 million particles were randomly injected in time and space and then tracked in a model domain that covers a 51-km2 area (15.1million model cells). We used hourly river stages and groundwater levels to drive the model to provide dynamic velocity fields for the particle tracking in the two + -year simulation period. The groundwater flow simulation and particle-tracking results provide a comprehensive assessment of the spatial distribution of HEFs and transit time in a large, complex river corridor. Our results show that the aquifer hydrogeological structure has strong correlations with the extent and magnitude of exchange flux. The transit time exhibits complex patterns that are affected by all the river geomorphologic, hydrodynamic, and hydrogeologic factors and are strongly correlated with the downwelling ratio of exchange flux. The new insights gained through this study can be used to support the development of reduced-order models of HEFs and transit time distributions for large complex river systems.

CONDITIONING FACTORS OF “TERRAS CAÍDAS” IN LOWER SOLIMÕES RIVER - BRAZIL

The term “Terras Caídas” is used in Amazon to refer to processes of fluvial erosion and mass movements of large and moderate scale. It is a dynamic and complex multi-causal process that involves hydrodynamic, hydrostatic, climatic, neotectonic, lithological and anthropic factors, occurring together or separately. The objective of this work is to understand the conditioning factors of the phenomenon "Terras Caídas" in lower Solimões River - Brazil. For this purpose, the study area was monitored for 2 years (2017-2018) and data from satellite images; water discharge; flow velocity; suspended sediments; water level; precipitation; wind direction; seismic activity were obtained. The hydrodynamic factors and the rain influence the “Terras Caídas” more intensely during the river flood, the processes influenced by the wind direction occur throughout the hydrological year, but with greater intensity during storms. Hydrostatic pressure occurs more frequently in ebb causing landslides. The lithology influences the stability of the banks due to unconsolidated sediments, providing erosion and mass movements. It is observed that neotectonics was not important in increasing the intensity of the "Terras Caídas" in the study area in recent years. Human activity influences destroying riparian forests and the basal erosion caused by waves formed by boats the region.

HYDROCARBON GENERATION AND MIGRATION FROM BARREMIAN – APTIAN SOURCE ROCKS, NORTHERN ORANGE BASIN, OFFSHORE WESTERN SOUTH AFRICA: A 3D NUMERICAL MODELLING STUDY

A 3D numerical modelling workflow was applied to the Barremian—Aptian source rock interval in a shelfal to lower slope area of the northern Orange Basin, offshore western South Africa. The main objective was to investigate the timing of hydrocarbon generation and migration. Hydrocarbon migration has previously been investigated in the south of the basin by relating gas escape features with structural elements as seen on seismic sections, but migration pathways are still poorly understood. The modelling study was based on data from three exploration wells (AO‐1, AE‐1 and AF‐1) together with 42 2D seismic sections totalling 3537 km in length, and a 3D seismic cube covering an area of 750 sq. km.Modelled formation temperatures increase from north to south in the study area and were consistent with downhole temperatures at well locations. However, there is variation between measured and modelled values of vitrinite reflectance (VR), especially in the Turonian and Cenomanian intervals. The measured VR is lower than the modelled VR within the Turonian section in the north of the study area, suggesting that erosion has affected the thermal maturity of the sediments. However, in the Cenomanian interval, the measured VR is higher than the modelled VR. Uplift, increased erosion in the hinterland and sediment transport to the coastal areas resulted in Cenomanian progradation of the Orange Basin fill. This together with a heat flow pulse resulted in increased thermal maturities in the study area.Modelling results show that hydrocarbon generation began in the central part of the study area by 116 Ma and reached a peak in the Late Cretaceous (65 Ma). Hydrocarbon migration began at about 110 Ma with an expulsion efficiency of 0.77. At the present day, ∼100% transformation of reactive kerogen into hydrocarbons has taken place in the central part of the study area, with random gas migration within Cenomanian and Albian reservoirs. Modelled oil migration likely influenced by hydrodynamic factors is down‐dip (westwards), towards deeper‐water, more distal parts of the basin.Gas saturation on a reactivated listric fault, which was ∼100% saturated at 93 Ma, declined to ∼15% by 65 Ma. This decrease in gas saturation is linked to uplift of the African margin in the Late Cretaceous which resulted in fault reactivation and re‐migration of gas.Despite the uncertainties which are associated with petroleum systems modelling, the study provides an insight into hydrocarbon migration in the northern part of the Orange Basin and contributes to the de‐risking of future oil and gas exploration in this area.

Multivariate water environmental risk analysis in long-distance water supply project: A case study in China

The variation of water quality in long-distance water supply projects is often different from that in natural water bodies, especially the environmental risks of artificial open canal water transfer projects are seldom studied. The spatial heterogeneity of algae growth and the absence of universal reference standards for algae control often lead to water quality problems in these projects. The Middle Route (MR) of the South-to-North Water Transfer Project of China (SNWTPC), the world’s largest inter-basin water transfer project, has operated stably for six years. Its water resources have benefited more than 60 million people and an ecosystem cover more than 160,000 km2. To understand the water environment risk of this mega hydro-project, this study focused on the relationships among three key parameters: water temperature (T), water discharge (Q), flow rate (V) and analyzed the spatial–temporal variation characteristics of the algal cell density (ACD) in the MR of the SNWTPC from January 2016 to December 2018, 36 months in total. The Copula functions were applied to identify and evaluate the multivariate risk variation of the water environment. Our result demonstrated that there was a significant positive correlation between T and ACD, and the ACD at the downstream has a 50% risk higher than 700 × 104 cell/L in summer. Overall, the water quality status of the MR of the SNWTPC is quite well, and the ACD kept at an average level of 106 cells/L during the monitoring period. Additionally, the ACD increased from upstream to downstream, showing the relatively higher ACD in summer and autumn than in spring and winter, with the ranges of 500 ~ 700 × 104 cells/L and 200 ~ 300 × 104 cells/L, respectively. The water temperature affected the ACD over the early-warning thresholds at different canal sections were as follows: 29, 26, and 21℃ from upstream to downstream, respectively. The influences of the hydrodynamic factors, water discharge and flow rate, impact on the ACD variation were analyzed to achieve the purpose of specific algae control for different canal reaches. Our study verified that the growth probabilities of the ACD under higher water temperature and water discharge in the MR of the SNWTPC than other natural water bodies.

Synthesis and properties of porous ester-silica nanoparticles

Ester-silica nanoparticles (NPs) were prepared using a facile two-surfactant synthesis route in neutral medium involving silica (tetraethyl orthosilicate, TEOS) and organosilica (3-(trimethoxysilyl)propyl 5-(trimethoxysilyl)pentanoate, P Me ) precursors. The ester hydrolysis generates carboxylic acid groups, which confer a strongly negative zeta potential to the NPs at neutral pH. The extent of hydrolysis during the synthesis was quantified by FTIR. The NP size was shown to be highly dependent on hydrodynamic factors such as stir bar size and stirring speed, enabling to fine-tune the NP diameter. The textural properties of the NPs could be monitored using appropriate fraction x of silica precursor, x = [TEOS]/([TEOS]+2 [P Me ]). For NPs with a silica fraction x higher than 0.5, a significant porosity could be observed, with mesoporosity appearing for x ≥ 0.7. The physicochemical and textural properties of the prepared materials open applications for water pollution abatement of specific organic compounds. This is exemplified by the efficient adsorption of rhodamine B from the liquid phase by the prepared NPs due to their physicochemical and textural parameters, including a high specific surface area and porosity, strong electrostatic forces and lipophilicity of the pore walls. Porous ester-silica nanoparticles containing free carboxylic acid groups can be prepared and used for dye encapsulation. • Ester-silica NPs can be prepared using a two-surfactants method in buffered medium at pH 7. • The size of the NPs can be tuned by varying the hydrodynamic factors during the synthesis, such as stir bar size and stirring speed. • The porosity of the NPs ranges from non-porous (pure silsesquioxanes) to microporous then mesoporous for organosilane fraction equal or lower than 30%. • The extent of ester cleavage during the synthesis depends on the organic fraction, and can be easily determined by FTIR. Most of it arises during the elimination of the surfactant. • The carboxylic acid groups in the NPs lead to a strongly negative ζ potential, and enables high loadings of rhodamine B.

Deposition of iron oxides in supercritical water reactor: A review

Low-temperature corrosion of the system and external input make it difficult to avoid the entering Fe ions in the supercritical reactor. Fe ions crystallize into particles in supercritical water and deposit on the surface of the reactor, causing safety threats and economic losses. In this paper, research on the Fe ion deposition process, from crystallization, to oxide particle formulation and to completely adhering to the wall surface, is reviewed. The literature mainly includes theoretical and experimental research on the nucleation and growth process of Fe oxide particles in a supercritical water (SCW) environment, particle movement and experimental observation methods in trans-critical turbulence, and the effects of Derjaguin-Landau-Verwey-Overbeek (DLVO) and collisions considered in the process of particle attachment. The particle deposition process involves particle formation, particle movement and surface adhesion. These three dynamic processes have cross-influencing factors that include geometric factors (the size of the particles themselves, the roughness of the wall), hydrodynamic factors (turbulence and transcritical conditions), and environmental parameters (temperature, pH). Independent research on dynamic processes is no longer suitable. The review aims to clarify the mechanism of three dynamic processes and their roles in the particle deposition process so that they can be comprehensively considered in the study of particle deposition in actual operating systems in the future.

Effect of buoyant turbulence and water quality factors on the CO2 net atmospheric flux changes in a stratified reservoir

The temporal variations in CO2 net atmospheric flux (NAF) in stratified reservoirs are controlled by both physical and biological factors. However, research on the factors and processes affecting CO2 NAF variability over time is insufficient, and as a result, there is considerable uncertainty in present estimations of global reservoir CO2 emissions. In the present study, we analyzed the effects of hydrodynamic and water quality factors on CO2 NAF variability in a stratified reservoir based on field studies and data modeling. Three empirical and four surface renewal gas transfer models were used to characterize the effects of hydrodynamic factors on gas transfer rate and CO2 NAF at the air–water interface. Buoyant turbulence notably affected CO2 NAF when the stratification strength was reduced. As a result, the CO2 NAF (1485 mg-CO2 m−2 day−1) estimated using surface renewal models that considered the effects of buoyant turbulence were twice greater than the NAFs estimated using empirical models that only considered wind force (724 mg-CO2 m−2 day−1). The best linear regression model explained 81.6% of the temporal variation in CO2 NAF using water temperature (Tw), electrical conductivity (EC), pH, chlorophyll a, total organic C (TOC), and alkalinity. The nonlinear parsimonious random forest model explained 84.4% of the temporal change in CO2 NAF using only three independent variables (EC, dissolved oxygen, and TOC). Principal component analysis revealed that the CO2 NAF tended to be large under low Tw, weak stratification, and low pH. These results indicate that the temporal variability of CO2 NAF in the stratified reservoir can be predicted using data-driven modeling with minimal water quality variables and selection of an appropriate gas exchange model. The findings improve the accuracy of estimates of CO2 emissions and monitoring activities in stratified reservoirs.

Deformation characteristics, mechanisms, and influencing factors of hydrodynamic pressure landslides in the Three Gorges Reservoir: a case study and model test study

Hydrodynamic Pressure landslides are the most typical landslides affected by the water level in the Three Gorges Reservoir. These types of landslides are large and cause severe deformation. Therefore, they may significantly affect the safe operation of the Three Gorges Reservoir once losing stability. Taking the Shuping landslide in the Three Gorges Reservoir as a typical case, this study explored the deformation characteristics and influencing factors of the Hydrodynamic Pressure landslide using monitoring data of its surface deformation, 17 years of GPS displacement data, automatic displacement metre of surface cracks, and groundwater level. To determine the deformation mechanism of the Hydrodynamic Pressure landslide, the model of Hydrodynamic Pressure landslide was designed and carried out to simulate the fluctuation of reservoir water level. The results showed that the hydrodynamic pressure landslides deformation was mainly affected by the overall deformation of the front edge of the landslide, and the amount of deformation was relatively large. The back part of the landslide mainly encountered tensile deformation. The Hydrodynamic Pressure landslides are a typical retrogressive deformation. The deformation of Hydrodynamic Pressure landslide was affected by the periodic change in the reservoir water level and the overall deformation trend is increasing. The intrinsic factor influencing the deformation of the hydrodynamic pressure landslide is the low permeability coefficient of the sliding mass, and the extrinsic factor is the drawdown of the reservoir water level. When the reservoir water table drawdown occurred, there was a noticeable water level difference with the underground water level in the landslide mass and generated hydrodynamic pressure. The Hydrodynamic Pressure landslide model results showed that the pore-water pressure, effective stress, and groundwater level in the landslide were consistent with the reservoir water level but with noticeable hysteresis. The key hydrodynamic factor for the deformation of this type of landslide was the hydrodynamic pressure towards the outside of the slope, formed when the reservoir water level dropped. Moreover, it was found that the faster reservoir water-level drawdown rates led to an increased influence on the stability of the landslide.

Hydrodynamics Factors Correspond to the Weather Criterion Applied to an Indonesian Ro-Ro Ferry with Different Weight Distributions

The effect of weight distribution on hydrodynamics factors in the weather criterion was investigated. Two types of weight distribution were examined. With the first type of distribution, the weight was concentrated near the centerline of the mode

Stratigraphic architecture and depositional environment of the Paleocene-Lower Eocene aquifers system (Douala onshore basin, SW Cameroon)

The Paleocene-Lower Eocene N'kapa Formation has long been considered as an important groundwater and hydrocarbon resource in the eastern edge of the Douala Basin. The present study’s aim is to establish a possible link between the geological nature of this formation and the quality of potential aquifers using Gamma Ray well log, cuttings and outcrops through sedimentology and sequence stratigraphy studies. The results obtained from this study show that: lithofacies are dominated by clays, silts and sands/sandstones; gamma ray electrofacies are funnel-shaped to cylindrical-shaped with some bell-shaped; depositional environments are continental to shallow marine dominated by fluvial and sometimes tidal processes; fluvial channel-fill, tidal channel-fill and delta front bars sands are potential aquifers; sequence stratigraphy analysis reveals two transgressive–regressive cycles of second order (Danian to Selandian and Thanetian to Ypresian), two Highstand System Tracts, one Transgressive System Tract and one Lowstand System Tract; the high-resolution geometry of these sandy/sandstone sedimentary bodies shows that their distribution is linked to the hydrodynamic factors and the topography of the depositional environment. A total of two types of lithological facies of the reservoir levels were defined according to the volume of clay: clean sandstone (0–15%) and low clayey sandstone (15–30%). The gamma ray well log correlation shows that the thickness of the reservoir levels is variable and that the clay content (Vsh%) increases from the NE to the SW. As a result, the best potential aquifers appear to correspond to the fluvial channel-fill sands deposited during the base-level fall of Upper Paleocene age (Lower Thanetian).

Characteristics and driving factors of thermal stratification evolution in Daheiting Reservoir

Thermal stratification which is common in water bodies is subject to such factors as the water depth of the water body (a lake or reservoir, for instance), the fluidity of the water and the local meteorological conditions. The stable thermal stratification in reservoirs will lead to changes in the physical and chemical properties of the water as well as distribution of aquatic creatures, hence leaving an impact on the water quality. The Daheiting Reservoir was taken as the research object in this study. Based on the continuous monitored water temperature data in the reservoir, the tempo-spatial change features of the water temperature structure in the reservoir were analyzed, and the driving factors of thermal stratification in the reservoir was studied. The research found that air temperature, wind speed, and hydrodynamic factors are the driving factors for the thermal stratification and corresponding water temperature change patterns in Daheiting Reservoir. Among these factors, air temperature is the fundamental precondition, the wind speed is the auxiliary precondition, and the hydrodynamic factors are the disturbance factors for thermal stratification in the Reservoir. All these factors act together to cause the thermal stratification pattern and evolution features in Daheiting Reservoir.

Regulatory content of the category “safety of mining works”

Purpose.To study the main elements of mining safety, as well as to formulate the definition of the concept of mining safety for its use in legal regulations of mining relations from the viewpoint of scientific literature and the norms of current legislation. Methodology.The results were obtained after applying a set of methods: a) general philosophical methods (dialectical, anthropological);b) general scientific methods (abstraction, analysis and synthesis, system analysis, classification);c) legal methods (historical and legal, comparative legal, semantic and legal). Findings.Based on the analysis of the main categories of general security theory and their application in the legislation of Ukraine, the etymology of the legal term security is studied and it is shown that the definition of this concept depends on the context of the normative legal act in which it is used. This necessitates the improvement of the conceptual apparatus of mining legislation and the development of the category mining safety. It is argued that unification of this legal category and clarification of its authentic definition will contribute to the achievement of unity and consistency of the current mining legislation, the proper regulation of public relations to ensure protection of Ukraines national interests in the field of subsoil use. The necessity of expanding the list of possible hazards of geological study and subsoil use provided for by the current legislation was substantiated. It is proposed to consolidate the authors definition of mining safety in the corresponding paragraph of Article 1 of the Mining Law of Ukraine. Originality.As a result of lexical and legal analysis, it was concluded that the definition of security depending on the context of the legal act in which it is used and the characteristics of the subject of legal regulation of certain social relations is defined as: security; security status; provision (regulatory compliance); set of measures; aggregate of nonuniform resources. Taking into account the geospheric characteristics of subsoil, as well as the peculiarities of hazard occurrence and manifestation during subsoil use, the authors put forward a classification of hazards manifestation during mining operations (geomorphological, lithospheric, geodynamic, gas-dynamic, hydrodynamic, geopathogenic, microbiological hazards, as well as the hazards of mineral nanoparticles). The additions are substantiated to the current legislation (part 1 of Article 1 of the Mining Law of Ukraine) with the following definition of the safety of mining operations: protection of vital interests of a person, society and the state from negative manifestations of geomorphological, lithospheric, geodynamic, gas-dynamic, hydrodynamic, geopathogenic, microbiological and other factors in the course of processes aimed at carrying out, securing and maintaining mine workings and withdrawing mining rocks. Practical value.The practical significance of the results is based on the fact that they can be used by the subjects of legislative initiative when improving the provisions of the current legislation of Ukraine, as well as by practical workers to organize and conduct mining operations.

Experimental Study on Weather Criterion Applied to South Sulawesi Traditional Wooden Boats

The general stability criteria of International Maritime Organization (IMO) seem to be difficult to apply to the South Sulawesi traditional wooden boats because the down-flooding angle of most traditional wooden boats was smaller than 30 degrees. The weather criterion may be used to assess the stability of traditional wooden boats because limitation of heel angle depending only on the down-flooding angle. However the criterion was developed based on geometric characteristics of ships different from the South Sulawesi traditional wooden boats. In this paper, the hydrodynamics factors correspond to the parameters of weather criterion are determined by model experiments consist of roll decay test and test in regular beam waves. The critical metacentric height for different wave steepness is determined by using the weather criterion with parameters values based on model experiments. The damping factor due to breadth-to-draught ratio was larger than that provide in the weather criterion for corresponding breadth-to-draught ratio of 4.28. The effective wave slope coefficients for wave steepness of 0.004 and 0.006 are smaller than that obtained by the formula of weather criterion. However, a larger value was obtained for wave steepness of 0.008 and 0.01. The bilge keels position with slope of 15 degrees provided the largest damping moment. The South Sulawesi traditional wooden boats comply with the weather criterion when the wave steepness smaller than 0.08. The weather criterion can be applied to the traditional wooden boats if the parameters values of weather criterion formula have been developed.

One-step preparation of bioactive enzyme/inorganic materials.

Simultaneous exfoliation of crystalline α-zirconium phosphate (α-ZrP) nanosheets and enzyme binding, induced by shearing, without the addition of any toxic additives is reported here for the first time. These materials were thoroughly characterized and used for applications. The bulk α-ZrP material (20 mg mL-1) was exfoliated with low concentrations of a protein such as bovine serum albumin (BSA, 3 mg mL-1) in a shear reactor at 10k rpm for <80 minutes. Exfoliation was monitored by powder X-ray diffraction with samples displaying a gradual but complete loss of the 7.6 Å (002) peak, which is characteristic of bulk α-ZrP. The fully exfoliated sample loaded with the protein was characterized by transmission and scanning electron microscopy in addition to other biophysical methods. Lysozyme, glucose oxidase, met-hemoglobin, and ovalbumin also induced exfoliation and directly produced enzyme/ZrP biocatalysts. Thus, exfoliation, biophilization and enzyme binding are accomplished in a single step. Several factors contributed to the exfoliation kinetics, and the rate increased with α-ZrP and BSA concentrations and decreased with pH. However, the exfoliation efficiency inversely depended on the isoelectric point of the protein with ovalbumin (pI = 4.5) being the best and lysozyme (pI = 11.1) being the worst. A strong correlation between the protein size and exfoliation efficiency was noted, and the latter suggests the role of hydrodynamic factors in the process. Exfoliation was also achieved by simple stirring using a magnetic stirrer, under low volumes, and model enzymes, indicating 60-90% retention of bound enzymatic activities. The addition of BSA to enzymes as the diluent and stabilizing agent also prevents enzymes from the denaturing effect caused by stirring. This new method requires no pre-treatment of α-ZrP with toxic exfoliating agents such as tetrabutyl ammonium hydroxide and provides bioactive enzyme/inorganic materials in a single step. These protein-loaded biocompatible nanosheets may be useful for biocatalysis and biomedical applications.

TURBULENT BORES-INDUCED SCOUR AND PORE PRESSURE VARIATION AROUND A VERTICAL STRUCTURE

Pore pressure and scour formation around coastal structures have been investigated in the past which led to a relationship between the hydrodynamics of tsunami waves and sediment erosion around coastal structures. With the objective of developing a comprehensive model to assess the interaction of hydrodynamic conditions, induced scour, soil pore pressure, and beach slopes, this novel study aims to examine (1) the effect of hydrodynamic forcing factors such as bore depth on scour and pore pressure generation on both horizontal and inclined bed conditions and (2) the effect of bed slope on the scour and pore pressure development and (3) the influence of the soil pore pressure on scour around a square shaped structure.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/dTQ-_GLhtzs

A Novel Glass Fiber Coated with Sol-Gel Poly-Diphenylsiloxane Sorbent for the On-Line Determination of Toxic Metals Using Flow Injection Column Preconcentration Platform Coupled with Flame Atomic Absorption Spectrometry.

A novel simple and sensitive, time-based flow injection solid phase extraction system was developed for the automated determination of metals at low concentration. The potential of the proposed scheme, coupled with flame atomic absorption spectrometry (FAAS), was demonstrated for trace lead and chromium(VI) determination in environmental water samples. The method, which was based on a new sorptive extraction system, consisted of a microcolumn packed with glass fiber coated with sol–gel poly (diphenylsiloxane) (sol–gel PDPS), which is presented here for the first time. The analytical procedure involves the on-line chelate complex formation of target species with ammonium pyrrolidine dithiocarbamate (APDC), retention onto the hydrophobic sol–gel sorbent coated surface of glass fibers, and finally elution with methyl isobutyl ketone prior to atomization. All main chemical and hydrodynamic factors, which affect the complex formation, retention, and elution of the metal, were optimized thoroughly. Furthermore, the tolerance to potential interfering ions appearing in environmental samples was also explored. Enhancement factors of 215 and 70, detection limits (3 s) of 1.1 μg·L−1 and 1.2 μg·L−1, and relative standard deviations (RSD) of 3.0% (at 20.0 μg·L−1) and 3.2% (at 20.0 μg·L−1) were obtained for lead and chromium(VI), respec tively, for 120 s preconcentration time. The trueness of the developed method was estimated by analyzing certified reference materials and spiked environmental water samples.

Interval Analysis of the Loss of Life Caused by Dam Failure

AbstractBoth hydrodynamic factors and social factors have large impacts on the loss of life caused by dam failure. Relatively large uncertainty intervals of the influencing factors lead to changes ...

Effect of hydrodynamic tilting at fluid contacts to reservoir production performance

Down-flush hydrodynamic movement of fluids at at transitional zones towards areas with low pressure gradients have been reported to directly influence the accurate prediction of petroleum reservoir’s production performances over time. Fluctuations in the fluid-fluid interactions and pressure changes around the reference line was the major cause for the discrepancy. In this research, a sensitivity study on the influence of hydrodynamic tilt factor h to oil, water and gas production was carried-out by means of the commercial software Eclipse Black oil simulator using the openSource Norne field data. The constant h is a function of the corrected shut-in pressure, fluid specific gravity at contact base-lines, pressure at the reference elevation and at the oil-water contact. The error in the contact depth was captured using the difference between the initial and calculated true vertical depths of the fluid’s contact zones. The obtained information was fed into the simulator to model the process dynamics. Findings revealed that the error margin for the first case hA (gas-oil contact) was insignificant. However, a mean deviation in the reservoir’s production predictions of atleast 8% for approximately a 6.5% change in the interacting fluids density was attained in-contrast to the base case.

Effects of water flow on ventilation rate and plasma cortisol in Nile tilapia introduced into novel environment

Water flow is a typical hydrodynamic variable of natural occurrence in fish’s lifetime and understanding its impact on biological processes (e.g. stress) can contribute to improve welfare in captive/farmed fish. For that, we tested whether water flow is a stressor by itself in a non-rheophilic (i.e. theoretically sensitive to water flow) fish species: Nile tilapia (Oreochromis niloticus). Additionally, this species was chosen due to its importance for world aquaculture and because is cultivated in a number of systems which the water flow could potentially be a stressor such as indoor tanks, recirculating aquaculture systems, biofloc system and cages. Here, we exposed fish to a novel environment with (520 L h−1) or without a deliberated water flow, and we measured plasma cortisol and ventilation rate (VR) as indicators of stress. In a first experiment, the VR was reduced by flow immediately after tilapia transference to a novel environment (16 min of evaluation), but cortisol was not affected. The plasma cortisol levels were also measured in a second experiment, 30 min, 1, 2 and 4 h after transference to a novel environment, but was also not affected by the presence of flow. In a theoretical perspective, flow is not a stressor by itself in a non-rheophilic species. It acted as a hydrodynamic factor that decrease the magnitude of ventilation response in a fish introduced into a novel environment, without effects on plasma cortisol levels. Therefore, the water flow eventually can be used to assist fish oxygenation after a disturbance event, such as introduction into a novel environment.

How much fluctuating asymmetry in fish is affected by mercury concentration in the Guanabara Bay, Brazil?

This study aims to analyze if the fluctuating asymmetry (FA) of the Corocoro grunt Orthopristis ruber is affected by mercury concentration in Brazilian Southeastern eutrophicated bay. The O. ruber fishes were collected in two areas of the Guanabara Bay, Rio de Janeiro, Brazil: Vermelha Beach, influenced to ocean waters, and Paquetá Island, for greater freshwater loads of the rivers of the region, both in wet and dry seasons. Possibly availability of food resources, exposure to other pollutants and harmful agents (pesticide, algal toxicity, among others), and environmental and oceanographic factors may be reflecting on the FA detected for the O. ruber population. Mercury (Hg) is a harmful trace metal when present in the food, because of the high toxicity, high levels of absorption, and low excretion rate. Hg accumulates in human organisms through fish consumption, which may represent a risk to health. Analytical determinations of THg were performed by Direct Mercury Analyzer, following the manufacture's recommendations and following the procedure proposed by Guimarães et al. (Food Sci Nutr 4:398-408, 2015). No evidenced in the influence of THg on FA. In turn, the THg was significantly different between areas. Higher THg levels were found in O. ruber populations in the Vermelha Beach, with mean values ​​of HgT 0.08 ± 0.01mg/kg-1, and the Paquetá Island with HgT 0.05 ± 0.01mg/kg-1. Likely higher THg on the Vermelha Beach occurred due to hydrodynamic factors, increasing the bioavailability of THg from the sediment and incorporated into the food web. This indicates that the higher THg levels in the outermost area of the Guanabara Bay can directly influence the bioaccumulation of this metal in the commercially important species present in this region, through the trophic chain because O. ruber constitutes an important part of the diet of themselves.