Reduction In Chloride Concentration Research Articles

Optimising groundwater recharge to counteract seawater intrusion through an inverse modelling approach and identifying efficient recharge structure locations

In semi-arid coastal urban regions, groundwater faces challenges from seawater intrusion due to reduced recharge and increased extraction. This study employs advanced numerical modeling to comprehensively assess seawater intrusion along the South Chennai coast from 2018 to 2022. The inverse modelling approach utilizes observed data, such as groundwater heads or concentrations, to estimate aquifer properties, like hydraulic conductivity, by minimizing the disparity between model predictions and actual measurements to identify the best-fit parameter values. This inverse method forecasts the necessary recharge rate to address seawater intrusion by increasing groundwater head and decreasing chloride concentrations. The estimation of recharge incorporates variables such as rainfall, soil infiltration capacity, land use, and the vital groundwater draft calculated based on per capita consumption and population. The study uses FEFLOW software to develop a robust conceptual model, simulating groundwater flow and chloride transport. The inverse modeling approach resulted in critical recharge adjustments, enhancing rates by 40%–60% in specific regions. The predictive scenarios, integrating proposed recharge structures, show promising results, notably with a 50% reduction in chloride concentration during the post-monsoon season compared to the pre-monsoon period in wells 8 and 3. A notable decrease in chloride concentration of over 90% was observed during May 2025 in well no: 15 due to its proximity to the Adayar River. These fluctuations are influenced by seasonal variations resulting from climatic changes in South India, with intense rainfall accompanying northeast monsoon winds playing a significant role. Increased recharge rates and strategically placed structures along the Buckingham Canal provide significant relief in the most impacted northern coastal area, acting as effective barriers. These interventions successfully reduce chloride concentration, providing a sustainable and effective solution to mitigate the persistent challenge of seawater intrusion.

Field evaluation of corrosion mitigation on reinforced concrete in marine exposure conditions

The Arabian Gulf is one of the most unfriendly environments for concrete structures due to the harsh chloride attack to reinforcing steel. Durability of concrete is improved by the addition of Supplementary Cementitious Materials (SCMs) and/or chemical agents to concrete mixtures. A marine exposure site was constructed on the west coast of the Gulf in order to study the influence of SCMs and chemical admixtures on corrosion activities in reinforced concrete. Plain and reinforced concrete blocks made from eight mixes, containing cement Type I and Type V with different SCMs and corrosion inhibitors (MCI, CNI, and Caltite), were subjected to natural marine weathering process in exposure zones; tidal, splash and atmospheric for twelve months. Eight blocks, four plain and four reinforced with four black steel bars with various cover depth, were made from each mix. The blocks were monitored and their performance were evaluated in terms of chloride ingress and steel corrosion activity. Corrosion inhibitors showed better effectiveness with cover depth increase. Fly ash and slag cement showed the best performance of corrosion mitigation. Caltite showed marginal reductions in chloride concentrations and a slight improvement in corrosion rates compared to control blocks. The atmospheric-exposed samples showed marginal increase in chloride surface concentration unlike the tidal-exposed ones. The results illustrate the importance of ensuring adequate cover depth for achieving a long service life in harsh environment.

Effect of ad libitum intake of an electrolyte repository in horses that underwent a polo game

The objective of this study was to assess the effects of an electrolyte and energy repository on the hematologic and biochemical variables of horses after a polo game and compare them to the effects of a commercial electrolyte repository and water. Twelve healthy horses, aged 5 to 10 years, mean body weight 356.25 ± 25.6 kg and in training for polo games, were randomly divided into three groups of four animals each and received one of three treatments. Animals participated in a 7-minute polo game. At the end of the match, they were taken to individual stalls where they received treatments for spontaneous hydration for 6 hours. Treatments were Hydroelectrolytic and Energy Repository (RHE) containing sodium, chloride, potassium, calcium, magnesium, dextrose, maltodextrin and, sucrose; and Commercial Paste (PCO) containing calcium, fructooligosaccharides, glycine, magnesium, potassium, sodium, and ad libitum water. The control group (Water) received water. Blood samples were collected as follows: just before the beginning of exercise (T0), immediately after exercise (T1), 3 hours after the end of exercise (T3), and 6 hours after the end of exercise (T6). The volume of voluntary intake was measured at T3 and T6. Packed cell volume and serum concentrations of sodium, potassium, chloride, calcium, magnesium, phosphorus, creatinine, total protein, plasma glucose, and lactate were measured. Data were submitted to descriptive statistics (mean ± standard deviation), Lilliefors and Cochran & Bartlett tests, analysis of variance (ANOVA), and Tukey or Duncan tests at a 5% significance level. The net volume ingested by the RHE group was higher than the PCO and control groups. In all groups, a reduction in chloride concentration and increases in packed cell volume, protein, creatinine, glucose, and lactate concentrations were observed in T1. These variables returned to the values found at T0 throughout the rehydration phase (T3 and T6). It is concluded that the ingestion of the hydroelectrolytic energy repository does not cause alteration in the biochemical profile of the animals.

Impact of switching crop type on water and solute fluxes in deep vadose zone

AbstractSwitching crop type and consequently changing irrigation and fertilization regimes lead to alterations in deep percolation and solute concentrations of pore water. Herein, observations from the deep vadose zone and model simulations demonstrate the changes in water, chloride, and nitrate fluxes under a commercial greenhouse following the change from tomato to lettuce cropping. The site, located above a phreatic aquifer, was monitored for 5 years. A vadose‐zone monitoring system was implemented under the greenhouse and provided continuous data on both temporal variations in water content and chemical composition of the pore water at multiple depths in the deep vadose zone (up to 20 m). Following crop switching, a significant reduction in chloride concentration and dramatic increase in nitrate were observed across the unsaturated zone. The changes in chemical composition of the vadose‐zone pore water appeared as sequential breakthroughs across the unsaturated zone, initiating at land surface and propagating down toward the water table. Today, 3 years after switching the crops, penetration of the impact exceeds 10 m depth. Variations in the isotopic composition of nitrate (18O and 15N) in water samples obtained from the entire vadose zone clearly support a fast leaching process and mobilization of solutes across the unsaturated zone following the change in crop type. Water flow and chloride transport models were calibrated to observations acquired during an enhanced infiltration experiment. Forward simulation runs were performed with the calibrated models, constrained to tomato and lettuce cultivation regimes as surface boundary conditions. Predicted chloride and nitrate concentrations were in agreement with the observed concentrations. The simulated water drainage and nitrogen leaching implied that the observed changes are an outcome of recommended agricultural management practices.

A comparison of the efficacy of two strains of Bacillus subtilis and Pseudomonas fragii in the treatment of tannery wastewater

Tannery wastewater treatment using two isolated micro-organisms (Bacillus subtilis and Pseudomonas fragii) has been investigated in the present study. The growth patterns, pH normalisation and the abilities of these micro-organisms to reduce the concentrations of chemical oxygen demand (COD), total suspended solids (TSS) and chloride were studied using the shake flask apparatus. The specific growth rate and biomass concentration of B. subtilis and P. fragii were observed 0.138 h-1 and 3.01 mg/l and 0.051 h-1 and 2.34 mg/l, respectively, after 84 h. Both micro-organisms normalised pH of the wastewater. COD removal efficiency for B. subtilis was 87.6% while that of P. fragii was 85.2%. For TSS, B. subtilis caused a reduction of 91.7% (from 876 mg/l to 73 mg/l), while P. fragii reduced the solid concentration from 876 mg/l to 98 mg/l (88.8%). B. subtilis could only achieve 48.5% reduction in chloride concentration (from 127.08 mg/l to 65.39 mg/l compared to a reduction of 54.6% (from 127.08 mg/l to 57.72 mg/l) for P. fragii. From the results, it can be said that the bacteria present in tannery effluents have significant potential in treatment of tannery wastewater.

Investigations on the chloride migration in consequence of cathodic polarisation

AbstractAt the Institute for Building Materials Research (ibac) in Aachen and the Federal Institute for Materials Research and Testing (BAM) in Berlin a joint research project is currently running with the aim to develop a numerical model which describes cathodic protection (CP) of reinforced concrete. Special project focus is the CP of the rear reinforcement layer. The resulting model shall include the impact of chemical alterations at the steel surface and within the adjacent concrete on the polarisation behaviour of reinforcement, which are induced by long‐term application of CP. The investigations presented in this paper aim to clarify open aspects on the migration of chloride ions due to small electric fields as applied in CP of steel in reinforced concrete structures. A comparatively new method, laser induced breakdown spectroscopy (LIBS), was applied in order to determine chloride concentration profiles on laboratory specimens as one of several model parameters for a mathematical description of CP of the rear reinforcement of reinforced concrete structures. The paper concerns migration tests using non‐saturated specimens under laboratory conditions at constant voltage and the application of the experimental parameters on FEM‐calculations. The presented results suggest the conclusion that even comparably small electric fields, as applied in CP of steel in concrete, may lead to significant and sustainable reduction in chloride concentration at the surface of the reinforcement.

Functional Expression of the Na-K-2Cl Cotransporter NKCC2 in Mammalian Cells Fails to Confirm the Dominant-negative Effect of the AF Splice Variant

The renal bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is the major salt transport pathway in the apical membrane of the mammalian thick ascending limb. It is differentially spliced and the three major variants (A, B, and F) differ in their localization and transport characteristics. Most knowledge about its regulation comes from experiments in Xenopus oocytes as NKCC2 proved difficult to functionally express in a mammalian system. Here we report the cloning and functional expression of untagged and unmodified versions of the major splice variants from ferret kidney (fNKCC2A, -B, and -F) in human embryonic kidney (HEK) 293 cells. Many NKCC2 antibodies used in this study detected high molecular weight forms of the transfected proteins, probably NKCC2 dimers, but not the monomers. Interestingly, monomers were strongly detected by phosphospecific antibodies directed against phosphopeptides in the regulatory N terminus. Bumetanide-sensitive 86Rb uptake was significantly higher in transfected HEK-293 cells and could be stimulated by incubating cells in a medium containing a low chloride concentration prior the uptake measurements. fNKCC2 was less sensitive to the reduction in chloride concentration than NKCC1. Using HEK-293 cells stably expressing fNKCC2A we also show that co-expression of variant NKCC2AF does not have the dominant-negative effect on NKCC2A activity that was seen in Xenopus oocytes, nor is it trafficked to the cell surface. In addition, fNKCC2AF is neither complex glycosylated nor phosphorylated in its N terminus regulatory region like other variants.

Myocardial Protection With the Use of L-arginine and N-α-acetyl-histidine

Effective myocardial preservation is an important condition for cardiac surgery, especially in heart transplantation with long ischemia times. During ischemia and reperfusion, myocardial function is altered by cold-induced ischemic injury. Cold-induced ischemic injury is triggered by cold storage and the amino acid histidine, a main component of the storage solution histidine-tryptophan-ketoglutarate (HTK). Cold-induced ischemic injury generates free oxygen radicals in an iron-dependent way. We investigated the efficacy of new modifications with the addition of L-arginine and N-alpha-acetyl-histidine to the well-established HTK solution (Custodiol) using a rat heart transplant model. Heterotopic transplantation was performed in Lewis rats (n = 20). After 1 hour of ischemic preservation and 1 hour of reperfusion, we assessed myocardial function and energy charge potential. The modifications of HTK solution included the addition of L-arginine, partial replacement of histidine with acetyl-histidine, and reduction of chloride concentration (HTK-1). In a second group, Custodiol served as the control. After 1 hour of reperfusion, left ventricular systolic pressure (106 +/- 33 vs 69 +/- 9 mm Hg; P < .05) and minimum rate of pressure development (dP/dt) (-1388 +/- 627 vs -735 +/- 219 mm Hg/s; P < .05) were significantly higher among the HTK-1 group compared with the control group. Energy charge potential did not differ significantly between the groups. This study showed that the novel modified HTK-1 solution improved myocardial contractility and relaxation after heart transplantation.

Amnioexchange for the Treatment of Gastroschisis – An in vitro Study to Determine the Volume and Number of Exchanges Needed

Objective: Intestinal damage of neonates with gastroschisis is thought to be attributed to prolonged exposure to the toxic environment of the amniotic fluid. Amnioexchange/infusion has been a proposed method to improve bowel quality. The aim of the current study was to design an in vitro model to determine the volume and number of amnioexchanges needed to achieve a predetermined reduction in a solute contained within the original concentration of amniotic fluid. Methods: We used a predetermined volume of normal saline to serve as the model for the amniotic cavity and the chloride anion as the surrogate for the noxious agent. Volumes of 250, 500, and 750 ml were used to represent the amniotic volume at different gestational ages. We performed a series of exchanges based on our calculated formula for each respective volume. The Student t test was used to calculate the differences between our expected and observed mean chloride concentrations (p < 0.05 = significance). Results: The mean baseline chloride concentration was 100 mmol/l for each volume. Our formula overestimated the number of exchanges needed to reach a 75% reduction in chloride concentration for each volume, but this was not statistically significantly different from the observed number of exchanges (p < 0.05). Conclusion: Our formula required a correction factor of 3 or 4 fewer exchanges to obtain the desired 75% reduction in chloride concentration. It may be useful when investigations to study amnioexchange are undertaken for the treatment of fetuses with gastroschisis.

Elemental content of airway surface liquid from infants with cystic fibrosis.

We tested the hypothesis that airway surface liquid (ASL) electrolyte composition is altered in infants with cystic fibrosis (CF) and that the presence of airway inflammation affects ASL composition. We measured the tracheal ASL sodium and chloride concentration and examined bronchoalveolar lavage (BAL) fluid cytology, interleukin-8 (IL-8) concentrations, and quantitative bacterial culture in 19 infants and young children with CF. Seven infants undergoing bronchoscopy for the evaluation of stridor served as non-CF controls. In addition, we measured nasal ASL sodium and chloride concentrations from 10 young adults with CF and from 10 control subjects. On the basis of the BAL findings, the infants with CF were divided into three groups: one with little evidence of pulmonary inflammation (CF-NI, n = 5); one with obvious pulmonary inflammation (CF-I, n = 7); and an intermediate group (CF-MI, n = 7). We found the ASL sodium was not different among any of the four groups (means mM +/- SE, 85 +/- 10 controls; 78 +/- 16 CF-NI; 83 +/- 9 CF-MI, 84 +/- 9 CF-I). In contrast the ASL chloride was lower in the CF-NI group when compared with control subjects (108 +/- 5 control subjects; 77 +/- 7 CF-NI, p < 0.01). In the CF-I and CF-MI groups, the ASL chloride concentrations were of intermediate values (CF-I 95 +/- 10 mM; CF-MI 96 +/- 9 mM) and not significantly different from controls. Results from the nasal ASL analysis showed no significant differences in sodium and chloride concentrations in the CF group compared with control subjects. These results suggest that the primary abnormality of ASL composition is a reduction in chloride concentration. ASL composition appears to be affected by the presence of airway inflammation.

Evaluation of moisture flux from chloride data in desert soils

Chloride concentration data from ten soil profiles in a 40 km 2 area of the Chihuahuan Desert of Texas were used to assess chloride mass balance methods of evaluating moisture flux. The relative importance of advective and diffusive transport mechanisms was determined. Moisture fluxes were calculated from measured chloride concentrations on the basis of a steady-state flow model. To evaluate controls on unsaturated flow, moisture fluxes from this study were compared with those from other regions. The chloride profiles displayed large variations in concentrations and had: (1) low chloride concentrations (⩽ 100 g m −3) near land surface; (2) maximum chloride concentrations (1900–9300 g m −3) at depths of from 1.3 to 4.6 m; (3) gradually decreasing chloride concentrations with depth below the peak. Steep concentration gradients (up to 12 000 g m −3 m −1), characteristic of chloride profiles in these desert soils, indicate a potential for molecular diffusion; however, low moisture contents (⩽ 0.1 m 3 m −3) in the zone of steep concentration gradients resulted in diffusive fluxes that were two to three orders of magnitude lower than the advective fluxes; therefore, diffusive fluxes were neglected in flux calculations. Because the chloride accession rate was assumed to be constant throughout the study area, calculated moisture fluxes are inversely proportional to chloride concentrations in the soil water. Highest moisture fluxes (up to 6 mm year −1) were calculated near land surface and are related to chloride leaching as a result of precipitation. Within the upper meter of the unsaturated zone, soil moisture fluxes decreased sharply to 0.1 mm year −1 as most of the water evapotranspired in this zone. Soil moisture fluxes decreased to a minimum at the chloride peak and then increased gradually as chloride concentrations decreased with depth below the peak. Reductions in chloride concentrations below the peak are attributed to differences in moisture fluxes as a result of paleoclimatic variations. Comparisons of chloride profiles from different regions indicate that geomorphic setting plays a major role in controlling moisture flux in the unsaturated zone.

Chloride Requirements of Lactating Dairy Cattle

Chloride is the third most abundant mineral element in milk and the most common anion in the extracellular body fluids of mammals (Coppock and Fettman, 1977). An early study at Cornell found that cows fed a low chloride diet, containing .18% chloride, had lower chloride excretion in urine and feces (Coppock et al., 1979). Significant reductions in chloride concentrations of blood plasma, urine, saliva and synovial fluids were reported in young calves fed a diet containing .038% chloride (Burkhalter et al., 1979; Burkhalter et al., 1980; and Neathery et al., 1981). A trial was designed to examine the potential affects of a chloride deficiency in dairy cows (Fettman et al., 1984b, I 984c). Diets were formulated containing either . 1 (low), .27 (medium) or .45 (high) % chloride on a dry matter basis. No differences in dry matter intake, milk production or body weight changes were detected between the medium and high diets (Fettman et al., 1984b, 1984c). However, significant decreases in these three measures were noted for cows on the low chloride diet. Cows on the medium and high chloride diets did not differ in the metabolic parameters monitored. The results of this study indicate that a dietary chloride content of . l % is too low for early lactation dairy cows. It would appear that a dietary chloride level of .25 to .3% on a dry matter basis should be used in practical ration formulation.