Presence Of Salt Water Research Articles

Quantifying salinity in heterogeneous coastal aquifers through ERT and IP: Insights from laboratory and field investigations

The lithological and stratigraphical heterogeneity of coastal aquifers has a great influence on saltwater intrusion (SI). This makes it difficult to predict SI pathways and their persistence in time. In this context, electrical resistivity tomography (ERT) and induced polarization (IP) methods are receiving increasing attention regarding the discrimination between saltwater-bearing and clayey sediments. To simplify the interpretation of ERT data, it is commonly assumed that the bulk conductivity mostly depends on the conductivity of pore-filling fluids, while surface conductivity is generally disregarded in the spatial and temporal variability of the aquifers, particularly, once the aquifer is affected by the presence of saltwater. Quantifying salinities based on a simplified petrophysical relationship can lead to misinterpretation in aquifers constituted by clay-rich sediments. In this study, we rely on co-located data from drilled boreholes to formulate petrophysical relationships between bulk and fluid conductivity for clay-bearing and clay-free sediments. First, the sedimentary samples from the drilled wells were classified according to their particle size distribution and analyzed in the lab using spectral IP in controlled salinity conditions to derive their formation factors, surface conductivity, and normalized chargeability. Second, the deduced thresholds are applied on the field to distinguish clay-bearing sediments from brackish sandy sediments. The results are validated with logging data and direct salinity measurements on water samples. We applied the approach along the Luy River catchment and found that the formation factors and surface conductivity of the different unconsolidated sedimentary classifications vary from 4.0 to 8.9 for coarse-grained sand and clay-bearing mixtures, while normalized chargeability above 1.0 mS.m−1 indicates the presence of clay. The clay-bearing sediments are mostly distributed in discontinuous small lenses. The assumption of homogenous geological media is therefore leading to overestimating SI in the heterogeneous clay-bearing aquifers.

Stabilization of Soft Clay Soil by Deep Mixing with Lime and Cement in the Presence of Salt Water

Stabilization of Soft Clay Soil by Deep Mixing with Lime and Cement in the Presence of Salt Water

Effects of water salinity on cadmium availability at soil-water interface: implication for salt water intrusion.

Low-lying paddy fields in estuaries can be affected by salt water intrusion; however, it remains unclear how salt water intrusion influences the availability of heavy metals in paddy soil. In this study, batch adsorption and incubation experiments of soil were conducted with different salt water sampled along the estuary to investigate the effects of salt water intrusion on cadmium (Cd) availability. The surface complexation model (SCM) was established to assess the effects of pH on Cd adsorption behavior, which presented typical pH-dependent characteristics. The results of SCM also showed that Cd-chloro complexes became the dominant species when the ionic strength increased. The results of Cd fractions in the incubation experiments revealed a significant increase in dissolved Cd with increasing ionic strength. This may be attributed to the increased point of zero charge (pHpzc) in the presence of salt water with higher salinity, which likely formed more positive charges on soil surfaces, causing an inhibition of Cd adsorption via electrostatic repulsion. Moreover, higher concentrations of Cl- in salt water favored the formation of Cd-chloro complexes, facilitating Cd release from soil particles. This study provides mechanistic insights into the impact of salt water intrusion on Cd availability at the soil-water interface of paddy soil along the estuary.

Forecasting saltwater intrusion volume and sulfate content in a wastewater collection system. Case study: Barreiro/Moita WWTP, Portugal

Abstract The presence of salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewater Treatment Plant (WWTP), Portugal. The intrusion occurs throughout damaged sections and direct vectors in the wastewater collection system, during high tide levels, changing the wastewater characteristics and impacting the WWTP process. This study designed models to quantify this problem, enabling more effective countermeasures within the right timing. The proposed models estimate the average volume of salt water and sulfate () load for each high tide period. The laboratory results show strong correlations between the influent electrical conductivity (EC) and percentage of salt water in WWTP inflow (0.9909), and between EC and concentration in WWTP influent (0.9797). The forecast models also show good correlation between the high tide levels with volume of salt water (0.9145) and load (0.9162) entering the system. Considering the total monthly inflow, the highest percentage of salt water registered in WWTP inflow was 3.6%. During high tide periods, critical situations have been assessed with up to 53.9% of salt water in the WWTP inflow, increasing energy consumption and costs in pumping stations.

Durable and Highly Dissipative Fibrous Composites for Strengthening Coastal Military Constructions

Reinforced concrete strategic structures for military purposes are often established in coastalor offshore areas, widely subjected to chemical attacks, mainly due to an aggressive saline and acidenvironments. Porosity of cementitious conglomerates favour penetration of chlorides, which tend tocorrode the internal metallic rebar. The reinforcement of structures with fibrous composite materialsis a viable solution to restore the initial requirements of the building, especially when it exerts defence purposes. Among synthetic fibres, polyphenylenebenzobisoxazole (PBO) is an organic fibre based on linked aromatic structures with high elastic modulus and tensile strength and highly dissipative attitudes. In this work, the assessment of durability of continuous fibrereinforced cementitious mortar (FRCM) composites is carried out comparing the mechanical performance of laminates subjected to uniaxial tensile tests. It is found that PBOFRCM presents high resistance against aggressive environments and specifically preserve its mechanical strength in the presence of saltwater, where other reinforcing materials undergo to a dramatic degradation process.

Prediction of methane hydrate formation conditions in salt water using machine learning algorithms

Predicting formation conditions of gas hydrates in salt water is important for the management of hydrate in processes such as flow assurance, deep-water drilling, and hydrate-based technology development. This paper applied and compared five machine learning algorithms to develop prediction tools for the estimation of methane hydrate formation temperature in the presence of salt water. These machine learning algorithms are Multiple Linear Regression, k-Nearest Neighbor, Support Vector Regression, Random Forest, and Gradient Boosting Regression. In total, 702 experimental data points in literature from 1951 to 2020 were collected for modeling purposes. The experimental data span salt concentrations up to 29.2 wt% and pressures up to 200 MPa. Among these five machine learning methods, Gradient Boosting Regression gives the best prediction with R2=0.998 and AARD = 0.074%. Thus, the methods of Gradient Boosting Regression function as an accurate tool for predicting the formation conditions of methane hydrates in salt water.

Saltwater based fractionation and valorisation of macroalgae

AbstractBACKGROUNDMacroalgae are gaining increasing interest as an important biomass feedstock. Yet when valorising marine biomass, the presence of salt can pose a substantial obstacle to the effectiveness of downstream biological and chemical processes, as well as the engineering infrastructure required. Accordingly, dewatering, washing and drying are often considered the first and crucial primary steps in processing marine biomass such macroalgae. The high costs of these processes can make further marine biorefinery commercialisation prohibitive. This investigation assesses simple pre‐treatments for macroalgal biomass in saltwater, thereby reducing the freshwater footprint, and removing the need for an energy‐intensive washing and drying stage.RESULTSUsing acid and basic catalysts, the carbohydrate and soluble protein components were fractionated into a soluble aqueous phase, for further fermentation and a solid phase suitable for hydrothermal liquefaction. The presence of saltwater was found to aid the fractionation process, solubilising more of the biomass. The use of H2SO4 produced more monosaccharides, whereas NaOH solubilised higher levels of biomass at lower temperatures. The aqueous phase was demonstrated to be suitable for biological processing with the salt tolerant yeast Metschnikowia pulcherrima, and the residual solids suitable for processing via hydrothermal liquefaction.CONCLUSIONBy contrast with existing pre‐treatment strategies, we demonstrate that an entirely salt‐based biochemical conversion route is a potentially viable option. For the first time this work demonstrates that, rather than a hindrance, the presence of saltwater can be advantageous, and could provide an alternative, more cost‐effective pathway to achieving a successful macroalgal‐based biorefinery.

Boundary Effects of Vertical Buoyant Jets in a Stagnant Fluid in a Crossflow

This study includes an experimental study of a buoyant jet in an open channel. For this reason experiments to measure the mean axial velocity at the centreline of a buoyant jet which is discharged vertically upwards from a source, into a denser fluid (water) contained in an open channel a) without flow and b) into flowing environment, were performed. The presence of a buoyant jet is studied experimentally using 2D Particle Image Velocimetrer (PIV). For the flow visualization of the buoyant jet, the water, was dyed with either rhodamin (red color) or fluorescein (green color), aiming to the best appearance of the buoyant jet field. The velocity fields of the buoyant jet were determined with the analysis of a lot of pairs of photographs in each experiment. These fields were used to quantify the behaviour of the buoyant jet in the surrounding fluid (salt water) with several densities and flow depths. Also were used to quantify the different behaviour of the buoyant jet into flowing environment in comparison to the behaviour of the buoyant jet without flow. Results show that the depth and density of salt water can affect the flow dynamics. Flow velocity is reduced with the increase of the depth of salt water, due to the proximity to the free surface, while an increase in the salt density increase the buoyant forces and hence the velocity rate. Also the presence of salt water can affect the flow dynamics of the buoyant jet in different way into flowing environment in comparison to the buoyant jet without flow.

Methane Dynamics Associated with Tidal Processes in the Lower Columbia River

Tidally varying methane (CH4) concentrations in estuaries may arise from physical advection and by chemical effects tied to varying exposure to salinity. An investigation of spatial and temporal variability in water-column CH4 was conducted in the lower Columbia River using shipboard surveys and time series data from fixed stations. Peaks in CH4 coincided with ebb tides at multiple sites located along the flank of the estuary adjacent to tidal flats and wetlands. High-resolution measurements taken at the outflow of a shallow lateral bay revealed that these CH4 peaks were positively related to tidal amplitude when the lateral bay was exposed exclusively to freshwater over the tide cycle; in contrast, this relationship was inversed when brackish waters were involved. A positive relationship between tidal amplitude and CH4 is consistent with a mechanism of tidal pumping from bottom sediments in the bay. In the presence of saltwater, however, a higher-than-expected flux of CH4 could occur via suppression of removal processes such as biological oxidation. We present a conceptual model of tidal pumping modified by diurnal inequality in tidal amplitude and effects of salinity on sediment CH4 oxidation to explain CH4 variability on tidal to seasonal time-scales. The combined influences of tides and salinity likely affect CH4 emissions in estuaries worldwide, making sea level rise and estuarine geomorphological change relevant factors for consideration when accounting for estuarine contributions to global methane budgets.

Salt Water-Triggered Ionic Cross-Linking of Polymer Composites by Controlled Release of Functional Ions.

A composite that undergoes ionic cross-linking in the presence of salt water is presented as a viable strategy for the development of chemically responsive materials. The permeation of salt water through the composite activates embedded inorganic fillers, resulting in the release of functional ions and subsequent cross-linking with the functional groups of the polymer matrix. The release of a cross-linking agent from the inorganic filler and composite is evaluated along with the impact of the cross-linking on composite properties. The new methodology is then coupled with a dopamine-functionalized polymer in order to evaluate the potential of this approach for environmentally triggered self-healing materials.

IDENTIFICATION OF SALTWATER DISTRIBUTION USING ELECTRICAL RESISTIVITY TOMOGRAPHY IN BANJARSARI, GROBOGAN REGENCY, INDONESIA

Banjarsari village is located to the south of the Bledug Kuwu, the famous of mud volcano in Central Java province. In this location there are surface manifestations such as the mudflow and the saltwater explosion. In this village there are traditional salt mines, therefore a study of the potential source of salt mines is necessary. The aims of this research are detecting and mapping subsurface area of the saltwater intrusion. The direct measurement was conducted using OYO model 2119C resistivitymeter by using Wenner-Schlumberger array configuration and an electrode spacing is 30 meters. The direction of line one (A-A’) and three (C-C’) are from the south to the north and line two (B-B’) is the from east to the west. Based on the distribution of resistivity, the saltwater with highest salinity indicated have the lowest resistivity (0020 – 0.190 ohm.m). The presence of saltwater with highest salinity is expected to be at 30 until 93.8 meters depth. The final result shows that the saltwater every line has a similar correlation, it means that the saltwater is very harsh. Article DOI: https://dx.doi.org/10.20319/mijst.2018.33.286294 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Extension of the group contribution NRTL-PRA EoS for the modeling of mixtures containing light gases and alcohols with water and salts

The offshore exploitation of petroleum fluids in normal conditions of pressure and temperature of transport and in presence of salt water is concerned with the prevention of gas hydrate formation, generally thanks to continuous injection of inhibitors, or punctual injection of methanol in start-up and shut-down operations. Hence, models of interest should provide both, satisfactory phase equilibrium estimations of hydrocarbon and alcohol mixtures with water and reliable predictions of their behavior in presence of salts.In this work, the NRTL-PRA EoS is extended to the prediction of phase equilibria in mixtures containing strong electrolytes. The proposed model assumes that the a and b parameters of the cubic EoS only depend on the solvent mole fractions (salt-free), while the gEoSE excess Gibbs energy describes all the interactions between solvents and ions with only two contributions: the SMR term, specific of “Short and Middle Range” interactions between solvents and salts, and the LR relation proposed by Pitzer-Debye-Hückel, for the description of “Long Range” electrostatic interactions. The proposed electrolyte version of the NRTL-PRA model was successfully extended to the modeling of phase behavior of mixtures of light gases at high pressures (methane, carbon dioxide, nitrogen and hydrogen sulfide) and alcohols (methanol, ethanol and 1-propanol) with water and salts (mainly, ternary mixtures containing sodium chloride). As far as possible, results were compared with those provided, for the same systems, by other literature models (cubic Eos, SAFT and CPA equations).

Silicone rubber RTV-1 aging in the presence of aqueous salt

In our previous research on the effect of salt on aging of Room Temperature Vulcanized one-component (RTV-1) silicone rubber material we reported a strong relationship between losses in material mass and hydrophobicity, and potentially significant changes in the mechanical properties of the materials. This is further investigated in the present study, which examines the effects of aging in aqueous salt solution at elevated temperature on the hardness, hydrophobicity, and damage of a selected high quality RTV-1 material. A simple mechanical approach is suggested, which could be used in service to evaluate the amount of aging of RTV materials by correlating changes in hardness with surface conditions such as hydrophobicity. In addition, a new model of aging of RTVs based on the formation of hypochlorous acid in the presence of saltwater on energized silicone rubber surfaces is suggested and supported by Molecular Dynamics (MD) simulations. The diffusion rates of hypochlorous acid, salt ions, water, and nitric acid were numerically compared to determine which aging compound could be primarily responsible for material damage to RTVs under both laboratory and in-service conditions.

Extraordinary structure and properties of mussel byssus protein fibers

A naturally available single protein fiber that is stiff and strong at one end but at the same time highly flexible with moderate strength at the other end is quite exceptional. Such exceptional protein fibers called byssus threads are produced by mussels. A unique arrangement of collagen proteins along the length of the fibers and a specific amount and distribution of the β-sheet and α-helix regions provide extraordinary properties to byssus threads. Due to the unique configuration of the threads and a distinct adhesive plaque, mussels are able to adhere to substrates and withstand large amounts of external forces. However, significant variations in composition and tensile properties exist between the mussels threads obtained from different species and even along the length of a single byssal thread. Similarly, environmental conditions such as the presence of salt water and chemicals affect the properties of the fibers. Extensive studies have been done to understand the composition, the structure and the properties of the byssal threads. This review provides an insight into the unique structure and properties of the byssal threads and discusses the potential of developing biomimetic materials based on the mussel byssal threads.

The Behaviour of a Turbulent Buoyant Jet into Flowing Environment

In this study the mean axial velocity at the centreline of a buoyant jet which is discharged vertically upwards from a source, into flowing environment inside a denser ambient fluid (water), in an open channel, is investigated. The presence of a buoyant jet is studied experimentally using a 2DParticle Image Velocimetry (PIV).For this reason individual experiments were conducted. Salt water is used as the ambient fluid and fresh water as the jet fluid. Experiments were made for flowing ambient fluid. For the flow visualization of the buoyant jet, the water, was dyed with either rhodamin (red color) or fluorescein (green color), aiming to the best appearance of the buoyant jet field. The velocity fields of the buoyant jet were determined analysing 200 pairs of photographs in each experiment. These fields were used to quantify the different behaviour of the buoyant jet into flowing environment.Results show that the presence of salt water can affect the flow dynamics with different way into flowing environment. The present findings are discussed and compared with other experimental data in similar conditions reported in the literature. These findings from experimental data analysis should be useful for the verification of numerical models.

Saloplastics: processing compact polyelectrolyte complexes.

Polyelectrolyte complexes (PECs) are prepared by mixing solutions of oppositely charged polyelectrolytes. These diffuse, amorphous precipitates may be compacted into dense materials, CoPECs, by ultracentrifugation (ucPECs) or extrusion (exPECs). The presence of salt water is essential in plasticizing PECs to allow them to be reformed and fused. When hydrated, CoPECs are versatile, rugged, biocompatible, elastic materials with applications including bioinspired materials, supports for enzymes and (nano)composites. In this review, various methods for making CoPECs are described, as well as fundamental responses of CoPEC mechanical properties to salt concentration. Possible applications as synthetic cartilage, enzymatically active biocomposites, self-healing materials, and magnetic nanocomposites are presented.

Estimation of depth to fresh–salt water interface and its implications for sustainable groundwater resource management: a case study of the Coastal strip of Dar es Salaam, Tanzania

Dar es Salaam City is highly depending on groundwater resources since 1997. The resulting overexploitation is entailing the risk of seawater intrusion. This problem has been systematically investigated for the first time, and appears to be wide-spread. Determining the depth of the fresh–salt water interface was deemed crucial in the view of sustainable exploitation of the Dar es Salaam quaternary coastal aquifer system. Vertical electrical soundings (VES) and horizontal resistivity profiles have shown a decrease of resistivity with depth and toward the coastline. Cross sections have shown the presence of salt water in the aquifer near the coastline, and the boundary between fresh and saline waters is mapped. The surface prospection resistivity data showed comparable results as reflected in hydrochemical/lithological cross sections and resistivity well logs. Salt water was found mostly in the area within 2 km of the coastline, and the depth to the interface in this zone is ranging from 1.3 to 20 m. Away from the coastline, the interface (if present) is at greater depth. VES executed at Kurasini (4 km from the sea) showed the fresh–salt water interface at a greater depth (43 m).

Soil Phosphorus Dynamics and Saltwater Intrusion in a Florida Estuary

Soils in riparian wetlands are thought to stifle eutrophication in coastal water bodies by entraining and transforming nutrients. Altered hydrology and sea level rise underscore the need to evaluate the role of salinity in nutrient cycling within these settings. We studied three intertidal wetlands along the St. Johns River estuary, Florida in order to relate soil phosphorus composition with the distribution of saltwater. Sites represented a tidal freshwater forest, a brackish marsh, and a saltmarsh. Total phosphorus and organic composition decreased along the axis of the estuary as ambient salinity increased. At upstream wetlands, porewater revealed an inverse correlation between PO4 3− and the presence of saltwater (Cl− and SO4 2−) suggesting soil efflux. During experiments, aerobic soils did not liberate PO4 3− when exposed to seawater. During anaerobic experiments, SO4 2− amended soils from a saltmarsh mobilized substantial amounts of PO4 3− but the same effect was not observed in low-salinity wetland soils. Results indicate that P availability is shaped by saltwater access in the estuary and that SO4 2− reduction may regenerate PO4 3− in the saltmarsh. We suggest this is relevant to the St. John’s river in light of ongoing eutrophication and planned surfacewater withdrawals, which may draw saline water farther upstream.

Identification of MnCr 2O 4 nano-octahedron in catalysing pitting corrosion of austenitic stainless steels

Pitting corrosion of stainless steels, one of the classical problems in materials science and electrochemistry, is generally believed to originate from the local dissolution in MnS inclusions, which are more or less ubiquitous in stainless steels. However, the initial location where MnS dissolution preferentially occurs is known to be unpredictable, which makes pitting corrosion a major concern. In this work we show, at an atomic scale, the initial site where MnS starts to dissolve in the presence of salt water. Using in situ ex-environment transmission electron microscopy (TEM), we found a number of nano-sized octahedral MnCr 2O 4 crystals (with a spinel structure and a space group of Fd 3 ¯ m) embedded in the MnS medium, generating local MnCr 2O 4/MnS nano-galvanic cells. The TEM experiments combined with first-principles calculations clarified that the nano-octahedron, enclosed by eight {1 1 1} facets with metal terminations, is “malignant”, and this acts as the reactive site and catalyses the dissolution of MnS. This work not only uncovers the origin of MnS dissolution in stainless steels, but also presents an atomic-scale evolution in a material’s failure which may occur in a wide range of engineering alloys and biomedical instruments serving in wet environments.

Gas Hydrate Formation and Transport in an Acidic Crude Oil: Influence of Salt and pH

The anti-agglomerant (AA) performances of an acidic crude oil are evaluated in flow conditions using a high-pressure (HP) hydrate laboratory loop at a water cut of 10 wt %. The test procedure includes a 24 h fluid circulation in the hydrate stability zone, followed by a 3 h shut-in, and finally the restart of the flow. The influence of salts (NaCl, CaCl2, and mixture) and pH of the water on the AA property has been investigated. The results obtained in flow conditions are consistent with previous tests in HP kinetic reactors and a HP rheological cell. The acidic crude oil with pure water exhibits moderate AA property. The AA property decreases in the presence of salt water and is lost with alkaline pH. This work confirms that, although naphthenic acids and mainly naphthenates (formed at alkaline pH) are surface-active compounds, they do not act as efficient natural AAs.