Differences In Chloride Concentrations Research Articles

Research on the Macro-Cell Corrosion Behavior of Alloyed Corrosion-Resistant Steel for a Transmission Line Steel Structure under a Chloride Corrosion Environment

“The article investigates the macro-cell corrosion behavior and corrosion resistance when the alloyed steel and the carbon steel are used together because the traditional carbon steel is difficult to meet the corrosion resistance and durability of the steel structure of the transmission line in the marine environment.” In this paper, a new type of Cr-alloyed corrosion-resistant steel (00Cr10MoV) is used to partially replace carbon structural steel in order to meet the actual needs of corrosion resistance and service life improvement of steel structures for offshore transmission lines. It is important to systematically study the macro-cell corrosion behavior of combinations of the same type of steel and dissimilar steel, induced by the chloride concentration difference in simulated concrete solutions, and employ electrochemical testing methods to scientifically evaluate the corrosion resistance of steel after macro-cell corrosion. The aim is to study and evaluate the macro-cell corrosion behavior of alloyed corrosion-resistant steel and to lay a foundation for its combined use with carbon steel in a chloride corrosion environment to improve the overall corrosion resistance and service life. Under the same concentration difference, the macro-cell corrosion of the alloyed steel combination is milder compared with the carbon steel combination. The corrosion current of the alloyed steel combination at 29 times the concentration difference is only 1/10 of the carbon steel combination. Moreover, at 29 times the concentration difference, the macro-cell corrosion potential of dissimilar steel is only 1/6 of the combined potential of carbon steel combination under the same concentration difference, and the corrosion current is only 1/10 of that of the carbon steel combination.

Validating the use of lyophilized natural organic matter as background material in GAC rapid small-scale column tests

Utilities often test the effectiveness of different granular activated carbons (GACs) to determine which is most advantageous for their system. For surface water systems, in particular, the seasonal and annual variability of natural organic matter (NOM) in the source water makes it difficult to benchmark the effectiveness of GACs over multiple contract periods. This study produced stable, lyophilized NOM from the filtered water (FW), i.e., the influent to GAC contactors, which was then reconstituted (Recon) and tested against the FW itself in parallel rapid small-scale column tests (RSSCTs). The results demonstrated nearly identical NOM breakthrough profiles. RSSCTs conducted with both FW and Recon were shown to simulate the full-scale contactor performance well, while similar RSSCTs with regenerated GAC yielded a slightly earlier breakthrough, possibly due to the changes in GAC characteristics during regeneration and grinding. RSSCTs evaluating the removal of microcystin-LR (MC-LR) in the presence of background NOM contained in FW and Recon showed slightly different results, possibly due to the difference in chloride concentrations of these two waters. This work validates that reconstituted lyophilized NOM can be used as a source water surrogate for GAC evaluations when the constituent of interest is NOM, and potentially for other constituents depending upon the influence of additional inorganic constituents that were not evaluated as part of this study.

Assessment of river water infiltration conditions based on both chloride mass-balance and hydrogeological setting: the Krajkowo riverbank filtration site (Poland)

Abstract In the present work measurements of chloride concentrations were used to assess the variability of infiltration conditions and contributions of surface water and local groundwater to the discharge of wells at Krajkowo riverbank filtration site (western Poland). Tests were performed on samples from 26 wells located in a well gallery close to the River Warta. Due to higher chloride concentrations in river water in comparison with local groundwater, significant differences in concentrations in samples from individual wells were noted. In particular, lower chloride concentrations in 11 wells were recorded, which can be linked to the local occurrence of low-permeability deposits in the superficial zone; a locally higher degree of riverbed sediment clogging in the highly convex meandering zone, where strong erosion of the riverbed occurred, which in turn led to increased clogging; the occurrence of a more intensive groundwater inflow into the river valley due to water infiltration from a smaller river entering the River Warta valley, as well as unfavourable conditions for the infiltration of surface water to the lower part of the aquifer with a greater thickness. Differences in chloride concentrations observed were also used to quantify approximately river water contribution to the well production. The average contribution of the River Warta to the recharge of the entire well gallery was estimated at 59.8%.

Bayesian set pair analysis and machine learning based ensemble surrogates for optimal multi-aquifer system remediation design

Surrogate models are often adopted to substitute computationally intensive groundwater simulation models for aquifer management due to their high effectiveness and computing efficiency. However, solutions of using only one surrogate model are prone to large prediction uncertainty. This study compares individual surrogate models and an ensemble surrogate model in an optimal groundwater remediation design problem. Three machine learning based surrogate models (response surface regression model, artificial neural network and support vector machine) were developed to replace a high-fidelity solute transport model for predicting saltwater intrusion and assisting saltwater scavenging design. An optimal Latin hypercube design was employed to generate training and testing datasets. Set pair analysis was employed to construct a more reliable ensemble surrogate and to address prediction uncertainty arising from individual surrogate models. Bayesian set pair weights were derived by utilizing full information from both training and testing data and improved typical set pair weights. The individual and ensemble surrogate models were applied to the salinization remediation problem in the Baton Rouge area, southeast Louisiana. The optimal remediation design includes two conflicting objectives: minimizing total groundwater extraction from a horizontal scavenger well while maximizing chloride concentration difference to the MCL (maximum contamination level) at monitoring locations. NSGA-II (Non-dominated Sorting Genetic Algorithm II) was employed to solve the nonlinear optimization model and obtain Pareto-optimal pumping schedules. The optimal pumping schedules from ensemble surrogate models and individual surrogate models were verified by the solute transport model. The study found that Bayesian set pair analysis builds robust ensemble surrogates and accounts for model prediction uncertainty. The ensemble-surrogate-assisted optimization model provides stable and reliable solutions while considerably alleviating computational burden.

Simulating the Effects of Lake Wind Waves on Water and Solute Exchange across the Lakeshore Using Hydrus-2D

Wind waves, which frequently occur on large surface water bodies such as lakes, may temporarily alter flow patterns in a subsurface zone and the corresponding water and nutrient interactions between surface waters and shallow groundwaters. To better understand these processes, soil flume experiments were carried out to investigate wind wave-driven water and chloride interactions across the lake–groundwater interface, and the Hydrus-2D model was used to analyze and evaluate the observed experimental results. Two interaction cases between the lake and groundwater systems were considered: groundwater discharging into a lake (the GDL case), and lake water recharging groundwater (the LRG case). For comparison, no-wave conditions for both the GDL and LRG cases were also analyzed. The results revealed that, similarly to no-wave conditions, water and chloride exchange fluxes between the lake and groundwater systems under wave conditions occurred mainly within narrow bands near the intersection of the water level in the lake and the interface in both the GDL and LRG cases, and then exponentially decreased along the interface. Most water and chloride that infiltrated into the subsurface zone through the upper part of the interface during a wave crest returned to the lake through the lower part during a wave trough in both the GDL and LRG cases, creating local recirculation zones in the subsurface near the interface. Such recirculation produced a more frequent exchange of water and solute across the interface compared with those under no-wave conditions. During a one-day period after wind waves started, the total exchange fluxes of water and chloride to the lake decreased by 36.2% and 71.9%, respectively, compared to the no-wave conditions in the GDL case. In the LRG case, the total exchange water fluxes to the subsurface increased by 89.7%, while the total exchange chloride fluxes increased only slightly (4.5%) compared to the no-wave conditions due to the difference in chloride concentrations between the upper and lower parts of the interface. The sensitivity analysis revealed that the hydraulic conductivity of the lakeshore zone and the characteristics of the waves were important factors influencing water and chloride exchange between the lake and groundwater systems. The simulated results helped us to better understand water and solute interactions in the lake–groundwater system during windy periods.

Quantifying loading, toxic concentrations, and systemic persistence of chloride in a contemporary mixed-land-use watershed using an experimental watershed approach.

A nested-scale experimental watershed study was implemented to quantify loading and persistence of chloride in an urbanizing, mixed-land-use watershed. A Midwest USA (Missouri) watershed was partitioned into five sub-basins with contrasting dominant land use. Streamwater was tested for chloride concentration four days per week from October 2009 through May 2014 at each site. Monitoring sites included co-located gauging and climate stations recording variables at 30-minute intervals. Results indicate significant (p<0.01) differences in chloride concentrations and loading between sites. Loading consistently increased from the forested headwaters (average=507kgday-1) to primarily urban watershed terminus (average=7501kgday-1). Chloride concentrations were highest (average=83.9mgL-1) with the greatest frequency of acutely toxic conditions (i.e. 860mgL-1) mid-watershed. This finding is in-part attributable to the ratio of chloride application to streamflow volume (i.e. increasing flow volume with stream distance resulted in chloride dilution, offsetting increased percent urban land use with stream distance). Results highlight the important, yet often confounding, interactions between pollutant loading and flow dynamics. Chloride peaks occurred during late winter/early spring melting periods, implicating road salt application as the primary contributor to the chloride regime. Floodplain groundwater analysis indicated seasonal sink/source relationships between the stream and floodplain, which could contribute to chronic toxicity and persistent low Cl- concentrations in streamwater year-round. Results hold important implications for resource managers wishing to mitigate water quality and aquatic habitat degradation, and suggest important water quality limitations to stream restoration success in complex urban aquatic ecosystems.

Characteristics of Point Recharge in Karst Aquifers

Karstic groundwater basins are characterized by both point and diffuse recharge. This paper describes the hydrologic characteristics of point recharge and their influence on recharge estimation for four groundwater basins. Point recharge is highly transient and may occur in relatively short-time periods, yet is capable of recharging a large volume of water, even from a single extreme rainfall event. Preferential groundwater flows are observed in karst aquifers with local fresher water pockets of low salinity that develop around point recharge sources. Measurable fresh water plumes develop only when a large quantity of surface water enters the aquifer as a point recharge. In fresh water plumes, the difference in chloride concentrations in diffuse and point recharge zones decreases as the plumes become enriched through mixing. The relative contributions to total recharge from point sources using the measured gap between groundwater and rainwater chloride in the chloride vs. δ18O plot is not necessarily indicative of sinkholes not directly recharging the aquifer. In karst aquifers, recharge estimation methods based on groundwater age distribution; average annual rainfall and basin average chloride in the conventional chloride mass balance (CMB) method are questionable due to theoretical limitations and key assumptions of these methods not being met. In point recharge dominant groundwater basins, application of: watertable fluctuation, numerical groundwater modelling, Darcy flow calculation or water budget methods are more suitable for recharge estimation as they are independent of the particular mode of recharge. The duality of the recharge mechanism in karst aquifers suggests that modification to the CMB method may be required to include both point and diffuse recharge components.

Effects of dietary vegetal fatty acid and fat content on growth and acclimation to Caspian Sea water in Caspian brown trout (Salmo trutta caspius) parr

This study assessed the effects of dietary fat level and source on growth performance, and seawater acclimation of the Caspian brown trout. Tuna fish oil and a blend of canola and soybean oils (85:15) with different levels of fat (LF: 10% and HF: 20%) were made to produce four different diets. The diets were labeled accordingly: LFFO (low fat fish oil), LFVO (low fat vegetal oil), HFFO (high fat fish oil) and HFVO (high fat vegetable oil). Each diet was fed to Caspian brown trout parr (~10g) for 60days. Both diets with vegetable oil base and high dietary fat (i.e. 20%) improved the growth performance, only the fishes fed a LFFO diet gained significantly less weight than the ones fed the other diets (P<0.05). The seawater acclimation was assessed by a gill Na+K+-ATPase immunolocalization (chloride cells number, size and area ratio) and by measuring the concentrations of serum chloride, sodium, magnesium, cortisol and glucose before transferring the fishes to seawater as well as 5days later. The fish fed with the test diets had no significant difference in chloride concentration but magnesium concentration significantly increased in all treatments after the seawater transfer. Sodium concentration increased significantly (P<0.05) only in fish fed the LFFO diet after the seawater transfer. Nor was there any difference in the number of filament chloride cells, but the fish fed this LFFO diet showed low salt secretion ability in SW due to the smaller size and area ratio of the filament chloride cells. The cortisol increased significantly only with the HFVO treatment after transfer to seawater (P<0.05). This experiment provides evidence that, due to higher energy supply, favorable fatty acids for energy production and facilitating better acclimation of the fish to Caspian Sea water, a high dietary fat level with vegetable oil (HFVO) meet adequately the essential nutritional requirements of the Caspian brown trout parr.

Nitrate and sulphate dynamics in peat subjected to different hydrological conditions: Batch experiments and field comparison

Summary Conservation of ecosystems that depend on water management and water quality has to be considered. We combined a field monitoring and batch experiments to better understand the impact of hydrological perturbations on peatland functioning. Factors influencing the dynamics of nitrate and sulphate concentration observed in two sites with different hydrological conditions in a south Normandy peatland were determined through the comparison of field and lab experiment. The effects of nitrate input, and oxic or anoxic conditions on nitrate and sulphate concentrations were investigated in bioreactors, using peat samples from field sites influenced by different hydrologic regimes. In this experiment, peat samples were subjected to similar conditions to address the effects of NO 3 - and O2 concentrations (chemical effects), and the effect of hydrologic regimes and peat soil moisture (physical effects) on nitrate and sulphate dynamics. Cl−, SO 4 2 - and NO 3 - were monitored for 215 h. Nitrate was significantly reduced in most experiments. A complete nitrate reduction after 215 h in soil under anoxic conditions was observed. A denitrification process was also found under aerobic conditions depending on the peat site sampling, i.e. depending on the hydrological conditions. This process was interpreted as a heterotrophic denitrification. Sulphate monitoring revealed that 400 mg L−1 were produced in peat from the peat site with high hydrologic fluxes under aerobic conditions. Clear differences in chloride concentration (deviance analysis, P

Comparison of solvent extraction and supported liquid membrane permeation using an ionic liquid for concentrating penicillin G

Room temperature ionic liquids are emerging as alternative solvents for volatile organic compounds conventionally used in liquid–liquid extraction and liquid membrane separation. In this study, imidazolium-based ionic liquids, the hexafluorophosphates of 1- n-butyl-, 1- n-hexyl- and 1 -n-octyl-3-methyl imidazolium, and trioctylmethylammonium chloride (TOMAC) were used as ionic liquids. First the distribution coefficient of penicillin G between the buffer solution and ionic liquids was measured. Although imidazolium-based ionic liquids can extract penicillin G from the buffer aqueous solution, the extent was much lower than using butyl acetate, the conventional organic solvent. While the distribution ratio with TOMAC was comparable to butyl acetate, it was difficult to strip penicillin G from the TOMAC phase. Therefore, ionic liquids were applied to the supported liquid membrane system. Penicillin G permeated through the supported liquid membrane with imidazolium-based ionic liquids but uphill transport driven by pH difference was not observed. Uphill transport was achieved by using TOMAC as a membrane solution and chloride concentration difference as a driving force of permeation.

Preferential Flow Estimates to an Agricultural Tile Drain with Implications for Glyphosate Transport

Agricultural subsurface drains, commonly referred to as tile drains, are potentially significant pathways for the movement of fertilizers and pesticides to streams and ditches in much of the Midwest. Preferential flow in the unsaturated zone provides a route for water and solutes to bypass the soil matrix and reach tile drains faster than predicted by traditional displacement theory. This paper uses chloride concentrations to estimate preferential flow contributions to a tile drain during two storms in May 2004. Chloride, a conservative anion, was selected as the tracer because of differences in chloride concentrations between the two sources of water to the tile drain, preferential and matrix flow. A strong correlation between specific conductance and chloride concentration provided a mechanism to estimate chloride concentrations in the tile drain throughout the storm hydrographs. A simple mixing analysis was used to identify the preferential flow component of the storm hydrograph. During two storms, preferential flow contributed 11 and 51% of total storm tile drain flow; the peak contributions, 40 and 81%, coincided with the peak tile drain flow. Positive relations between glyphosate [N-(phosphonomethyl)glycine] concentrations and preferential flow for the two storms suggest that preferential flow is an important transport pathway to the tile drain.

Chloride Ion Barrier Properties of Small Electric Fields in the Protection of Steel in Concrete

Abstract Analysis of the Nernst-Plank relation suggested that a relatively small voltage drop would maintain a significant chloride concentration difference across an ideal electrolyte. This effect was used as the basis for a possible criterion for the protection of steel in concrete in which the chloride concentration at the steel is maintained at a level below that necessary to cause passive film breakdown. The applicability of ideal solution theory to the electrolyte in a porous cement matrix was investigated by driving chloride ions against a concentration gradient across a cement mortar disc using a small applied potential difference. Results indicated the potential difference was an effective barrier to chloride ions and that the theory presented can be used in the design of an active chloride barrier. This protective effect can be monitored by determining the voltage drop through the concrete between an installed anode and the protected steel. However, caution should be exercised when dealing with ...

Poly(4-vinylpyridine-co-styrene) membranes do not show facilitated transport

Membranes of a copolymer of vinylpyridine and styrene are more permeable to hydrogen chloride dissolved in water than to other dissolved salts. The hydrogen chloride flux varies linearly with the hydrogen chloride concentration difference across the membrane, which is inconsistent with facilitated diffusion. The membrane apparently operates by a diffusion-solubility mechanism, with a diffusion coefficient around 2.2 × 10 −10cm 2/sec and a partition coefficient of 450. Earlier claims of facilitated diffusion in this solid membrane probably result from artifacts like lag times and like chemical degradation of the membrane, though they may also result from relaxation of copolymer chains.

Leukotriene A 4 hydrolase: an anion activated peptidase

The peptidase activity of leukotriene A 4 hydrolase purified from human leukocytes has been characterized, utilizing synthetic amides as substrates. The enzyme was stimulated by several monovalent anions. Thiocyanate ions were most effective followed by chloride and bromide ions. In phosphate buffer alone the peptidase activity towards alanine-4-nitroanilide was barely detectable and addition of 100 mM NaCl increased the specific activity more than 20-fold. Increasing the concentration of NaCl (or NaSCN) did not significantly affect the apparent K m for the substrate alanine-4-nitroanilide, but resulted in a dose dependent increase of V max . The stimulatory effect of these anions on the reaction velocities appeared to obey saturation kinetics and thus indicated the presence of an anion binding site. Apparent affinity constants for chloride and thiocyanate ions were calculated to 100 and 50 mM, respectively. In contrast to the effect on the peptidase activity, no chloride-stimulation could be detected of the epoxide hydrolase activity of this enzyme, i.e., the conversion of leukotriene A 4 into leukotriene B 4. In conclusion, the results indicate that under physiological conditions, chloride ions may selectively stimulate the peptidase activity of LTA 4 hydrolase. Also, the differences in chloride concentrations between cellular compartments suggest that a possible proteolytic function of the enzyme may be limited to the extracellular space.

Calcifediol antagonizes PTH action on water and phosphate absorption in rabbit pars recta.

Reports of the effects of calcifediol (25-hydroxycholecalciferol) on phosphate excretion, alone or with parathyroid hormone (PTH), or with adenosine 3',5'-cyclic monophosphate (cAMP), have been conflicting. The purpose of this investigation was to examine the effects on fluid and phosphate transport by the rabbit pars recta of calcifediol alone or with PTH. In tubule segments obtained from rabbits fed a normal diet, the addition of 10 or 30 nM calcifediol to the bath did not alter fluid absorption (Jv) or lumen-to-bath phosphate flux (JPil----b). However, pharmacological concentrations did inhibit Jv by 20.9 +/- 5.6% (100 nM, P less than 0.02) and 37.9 +/- 9.4% (1.0 microM, P less than 0.01) and JPil----b by 18.5 +/- 6.6% (100 nM, P less than 0.05) and 40.5 +/- 8.6% (1.0 microM, P less than 0.01). In the presence of 30 nM, 100 nM, or 1.0 microM calcifediol, neither 0.25 nor 1.0 U/ml PTH inhibited JPil----b. A modest decline in Jv did occur with 1.0 U/ml PTH in the presence of 30 nM and 100 nM calcifediol. Unlike calcifediol, when 10 nM calcitriol (1,25-dihydroxycholecalciferol) was present in the bath, 0.2 U/ml PTH significantly depressed Jv and JPil----b. To investigate the mechanism of action of high calcifediol concentration, measurement of the collected minus perfused tubule fluid chloride concentration difference was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Chloride Corrosion Threshold in Concrete

Chloride ions can destroy the passivity of reinforcing steel in concrete and corrosion is likely to procede if moisture and oxygen availability are such as to support corrosion. Chloride may be introduced from different sources such as admixtures containing chloride, chloride bearing aggregates, or deicing salt solution permeating through hardened concrete. In this study, concrete slabs containing either single steel rods or electrically connected steel were subjected to various outdoor and indoor exposure conditions. It was found that corrosion rates of the single steel increased with increasing chloride content. The chloride corrosion threshold limit was between about 0.2% and 0.4% calcium chloride dihydrate by mass of cement (0.014% and 0.022% soluble chloride ion by mass of concrete) depending on the test method. Macrocell corrosion rate with electrically coupled steel was influenced greatly by the differential concentration of chloride ions in anode and cathode regions; large differences in chloride concentration resulted in a high corrosion rate. (Author/TRRL)

Some aspects of proximal tubular sodium chloride reabsorption in Necturus kidney

Some aspects of proximal tubular sodium chloride reabsorption in Necturus kidney. Renal tubular reabsorption of fluid and sodium was measured by clearance methods in the doubly perfused Necturus kidney in which the bicarbonate concentration was varied between 0 and 60 mEq/liter. The effects of Damox (2.2 times 10-3M), ocubain (10-5M) and ethacrynic acid (10-4M) and of acidosis were also investigated. In addition to clearance experiments, stationary microperfusion experiments were carried out on promimal tubules to measure volume flow and steady-state sodium and chloride concentration differences across the tubular epithelium. In some experiments, the transepithelial electrical potential difference was also measured using an axial electrode system. The following results were obtained: 1) Bicarbonate is not essential to the operation of renal tubular fluid and sodium transport. 2) Total renal and proximal tubular fluid and sodium transport are partially inhibited by Diamox, ouabian and ethacrynic acid. 3) The proximal tubule maintains a significant transepithelial sodium and chloride concentration difference and a significant electrical potential difference (lumen-negative) in the presence of a poorly permeant nonelectrolyte. The direction and magnitude of the electrical polarization fully accounts for the observed chloride concentration difference. The data support the thesis that sodium chloride transport accross the proximal tubular epithelium takes place by active sodium transport and electically coupled passive chloride reabsorption. Important species differences with respect to mammalian transport mechanisms are discussed.

Lack of relationship of potential difference to fluid absorption in the proximal renal tubule

Fluid absorption by isolated perfused rabbit proximal convoluted tubules is accompanied by an electrical potential difference (PD), negative in the lumen, when the tubule is bathed by rabbit serum and perfused with an ultrafitrate of that serum. In contrast the PD is positive when the perfusate composition approximates that of fluid in the late proximal tubule in vivo, which lacks glucose, amino acids and bicarbonate. The principal purpose of the present studies was to investigate the characteristics of fluid absorption under these conditions. Proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro. When the PD was positive, the mean net fluid absorption was 81 nl mm minus 1 min minus 1. The positive PD is caused by a chloride concentration difference across the tubule epithelium (higher in the lumen than in the bath). Elimination of the chloride concentration difference by replacing the bicarbonate in the bath as well as in the perfusate with chloride caused the PD to fall to zero without a significant change in the rate of fluid absorption. Therefore, neither the positive PD nor the chloride concentration difference is significantly related to the fluid absorption. Ouabain inhibited fluid absorption under all of the above conditions, making it likely that the fluid absorption is due to active sodium transport. Although the results are consistent with the generally accepted view that active sodium transport is a major driving force for fluid absorption, the mechanism of anion (chloride) transport is uncertain owing to the lack of correlation between fluid absorption and the transepithelial PD.