Artificial Soil Solution Research Articles

Corrosion of API 5L X60 Pipeline Steel in Soil and Surface Defects Detection by Ultrasonic Analysis

The corrosion steels phenomenon is one of the main problems in the oil industry, such as in buried transmission pipelines used for high gas pressure for long distances. Steels are protected from the external soil corrosion through a bituminous coating, whose action is coupled with a cathodic protection system, which aims to maintain steel in its protection field and thus to avoid any corrosion risk. However, steels in service may experience external surface defects like corrosion pitting and cracking due to electrochemical or mechanical interactions of bare steel with an aggressive soil solution after steel protection failure. These are concerning phenomena and are the major threats of the pipeline transmission system’s reliability and ecological safety. Corrosion mechanisms are varied and can be evaluated by different methods, such as electrochemical measurements, which are influenced by various factors like temperature, pH, soil characteristics, resistivity, water content, and as well mechanical stresses. Corrosion results from simulated artificial soil solutions showed that steel is sensitive to corrosion by soil. Surface defects detection was carried out using an ultrasonic non-destructive method such as C-Scan Emission testing and the time of flight diffraction technique (TOFD) ultrasonic non-contact testing method. After propagation of the ultrasonic waves, the diffracted ultrasonic reflected wave occurring at the edges of the defects appears due to the presence of a corrosion defect by generating defect echoes. The C-Scan ultrasonic image shows surface reflection, including corrosion defects on interfaces with varying acoustic impedances. The cross-transverse speed ultrasonic propagation through the plate including defect is modified, revealing more surface defects, and cross-transverse speed is shown to increase ultrasonic detection presents some advantages, such as precision and speed of detection without alteration to the structure. This method can be used in the industrial context as an intelligent industrial robotics technique.

Effect of AC interference on the corrosion behavior of cathodically protected mild steel in an artificial soil solution. Part I: Investigation on formed corrosion product layer

AbstractAC‐induced corrosion is a big threat even for cathodically protected pipelines nowadays. While this phenomenon was intensively investigated in the last decades, the corrosion mechanisms due to AC interference remain unclear. In the present work, investigations on the surface processes on cathodically protected mild steel during AC polarization have been performed. They utilized high‐speed potential measurements that have demonstrated the influence of the polarization parameters on the resulting alternating voltage. The corrosion product layer was characterized with scanning electron microscopy, electron probe microanalysis, and Raman spectroscopy, which clearly show the effect of the parameters of the applied alternating current on the surface under different cathodic protection (CP) conditions. It was demonstrated that the properties of the formed corrosion product layer, meaning the layer thickness, amount of oxygen, and so on, is not only dependent on the AC polarization parameters but also on the CP potential itself.

Modelling the removal and reversible immobilization of murine noroviruses in a Phaeozem under various contamination and rinsing conditions

Enteric viruses entering the soil with contaminated irrigation water can reach groundwater or be internalized in plants through their roots without being inactivated. Their fate in the soil depends on the virus, the soil and the soil solution. In order to write a mathematical model suitable for a Calcaric Phaeozem, we investigated the removal of murine norovirus and reversible immobilization in aggregate columns according to a saturation procedure, conditions between contamination and rinsing time, temperature and soil solution. Viruses were quantified before and after 0.45‐μm filtration with an RT‐qPCR (real‐time polymerase chain reaction). Experimental results supported a model that combined free and colloidal transport of viruses in mobile water, exchange of free viruses between mobile and immobile water, virus removal and reversible virus adsorptions on suspended colloids, the outer aggregate surface and the inner aggregate particles. For an artificial soil solution at 20°C, the fate of viruses in contaminations lasting 1 to 7 days followed by 7 hours of rinsing was described by combining 0.38 log10 daily removal and weak reversible immobilization using a Freundlich adsorption isotherm (kF = 1120, nF = 1.53), which explained why free viruses prevailed in mobile water. Partial drying without aggregate desaturation did not affect virus recovery. Magnesium cation enrichment induced geochemical changes that faded over time, resulting in up to ten times more viruses adsorbed on suspended colloids than free and enhanced adsorption on outer aggregate surfaces. Likewise, groundwater rich in Mg2+ slowed remobilization. The fate of murine norovirus within a Calcaric Phaeozem can be described by a model that takes into account geochemical fluctuations.Highlights How far does soil reduce the risk of noroviruses from irrigation reaching groundwater or roots? Virus removal over a 5‐day average residence time in Phaeozem is about two log10. Reversible virus immobilization is weak; Mg intake favours it, together with colloidal transport. Virus removal and reversible adsorption can be modelled for better assessment of contamination risk.

The Effect of Current Densities in Zinc Electroplating Process on Mild Steel for Soil Water Environment Application

For more environmental friendly study, commonly undesired natural process which is corrosion will present. Thus, in this century there is a serious effort in ongoing analysis in order to prevent this phenomenon occurring. The challenge of corrosion in manufacturing and domestic sector is enormous. Thus, corrosion can be defined as the deterioration and destruction of a material because of reaction with the environment. Replacing a corroded pipeline can cost about $643,000 per kilometer. The application of the traffic sign or a road sign that embedded in soil usually can withstand for two to three years until it will corrode and then fracture. The main objectives of this study is to increase the protection on the surface of the materials towards corrosion and to improve the appearance of the product or serves as an effective undercoat for paints which can reduce the cost of using expensive material by using the other method; electroplating process. The samples were plated with zinc at 2, 4 and 6 A/dm2 for 20 minutes for every sample. Then, the samples were immersed in the artificial soil solution for 30 days, then the testing to measure the corrosion rate, phase analysis, morphological analysis and hardness test were conducted. From all the tests, sample with 6 A/dm2 got the best results with 5.2059 mpy and 80.6 HV hardness strength. It is because by increasing the current density, the thickness will then increase the zinc plating will not easily peel off and attack by corrosive agent.

Development of online microdialysis-mass spectrometry for continuous minimally invasive measurement of soil solution dynamics

The rate that amino acids are removed from the soil solution is poorly known but vitally important. It is possible to determine the time course of soil solution concentrations by extracting soils at different time points after adding labelled compounds, but this approach either lacks sufficient temporal resolution or generates large number of samples that require subsequent offline analysis. The aim of this study was to develop online microdialysis-mass spectrometry to enable the minimally invasive measurement of the time-course of isotope labelled amino acid added to soil. The method was subsequently tested by examining the fate of isotope labelled L- and d-alanine added to sterile and non-sterile soils. One concern with application of microdialysis to soil is if calibrations are affected by inorganic ion composition of the perfusate and the external (soil) solution. Tests showed that the presence/absence of inorganic ions in perfusate and external solution did not affect dialysate concentrations, suggesting that perfusing with an artificial soil solution matching the inorganic ion composition of the external solution does not convey any benefits. Hence water was used as perfusate for development of online microdialysis-mass spectrometry. The online system took around one minute to equilibrate to step-changes in concentration and had detection limits around 0.5 μmol L−1 for alanine. Addition of isotope labelled alanine to soils led to an almost instantaneous increase and subsequent decrease in dialysate alanine concentration. With sterile soils there was a slow abiotic decrease in dialysate concentrations, presumably due to development of a depletion shell around the microdialysis probe and adsorption of alanine to the soil. For non-sterile soils there was an additional more rapid biotic decrease in dialysate concentrations that presumably reflected microbial uptake. For l-alanine added to non-sterile soil much of the compound was taken up before it reached the probe surface and concentrations decreased to below detection limits within 5–20 min. Thus microdialysis afforded a graphic illustration of the ephemeral nature of intact l-alanine in non-sterile soil, while parallel measurements showed that added d-alanine was removed from soil solution several times more slowly.

Influence of Environmental Factors on Property of Passive Film Formed on X100 Pipeline Steel

Effect of temperature, pH and chloride ion concentration on the property of passive films formed on X100 pipeline steel were investigated in an artificial soil solution by polarization curves, electrochemical impedance spectroscopy (EIS) and capacitance measurements technique. The results polarization measurement showed that the range of passive potential and the corrosion resistance of the steel decreased with the increasing temperature from 20 to 60 ℃, the increasing Cl - concentration from 0.001 to 0.005 mol/L and the decreasing pH value from 10.84 to 9.27 re- spectively. EIS results displayed that the compactness of passive films decreased with the increas- ing temperature and Cl - concentration, and the decreasing pH respectively, while temperature exhib- ited the strongest effect among the three factors on the compactness of the passive films. The re- sults of capacitance measurement and theoretical calculation implied that the Cl

Retention and Dissolution of Engineered Silver Nanoparticles in Natural Soils

Soils are likely to be increasingly exposed to nanoparticles due to growing consumer use of nanoparticles. This has necessitated an investigation into the fate and bioavailability of nanoparticles in natural soils. However, the effect of soil properties on these processes are unknown. To find the dominant properties that determine AgNP retention in natural soils, nonequilibrium retention (Kr) values of polyvinylpyrrolidone (PVP) coated silver nanoparticles (AgNP) were obtained in suspensions of 16 soils having a wide range of physical and chemical properties. The AgNP dissolution was investigated using ultrafiltration, but could only be detected in six soils, possibly due to strong partitioning of dissolved Ag (median Kd 1791 L kg−1); a process that increased predominantly with the organic matter content of the soils. When corrected for partitioning, dissolution of AgNP was higher (median 26% of total Ag added as AgNP) in these six soils compared to dissolution in artificial soil solutions. The homocoagulation kinetics of AgNP as a function of increasing NaClO4 concentrations were studied at pH 4 and pH 8, showing that homocoagulation of AgNP is unlikely in the studied soil suspensions. Moreover, Kr values (median value 589 L kg−1) only correlated with the soil granulometric clay content and not with parameters that increase the homocoagulation rate, a correlation that suggests that negatively charged AgNP were adsorbed preferentially at positively charged surface sites of clay‐sized minerals. Adsorption of negatively charged engineered nanoparticles by Fe and Al oxides and mineral clay edges may thus be an important fate‐determining reaction in soils, and possibly also in aquatic systems.

Copper Toxicity to Bioluminescent Nitrosomonas europaea in Soil Is Explained by the Free Metal Ion Activity in Pore Water

The terrestrial biotic ligand model (BLM) for metal toxicity in soil postulates that metal toxicity depends on the free metal ion activity in solution and on ions competing for metal sorption to the biotic ligand. Unequivocal evidence for the BLM assumptions is most difficult to obtain for native soil microorganisms because the abiotic and biotic compartments cannot be experimentally separated. Here, we report copper (Cu) toxicity to a bioluminescent Nitrosomonas europaea reporter strain that was used in a solid phase-contact assay and in corresponding soil extracts and artificial soil solutions. The Cu(2+) ion activities that halve bioluminescence (EC50) in artificial solutions ranged 10(-5) to 10(-7) M and increased with increasing activities of H(+), Ca(2+) and Mg(2+) according to the BLM concept. The solution based Cu(2+) EC50 values of N. europaea in six contaminated soils ranged 2 × 10(-6) to 2 × 10(-9) M and these thresholds for both solid phase or soil extract based assays were well predicted by the ion competition model fitted to artificial solution data. In addition, solution based Cu(2+) EC50 of the solid phase-contact assay were never smaller than corresponding values in soil extracts suggesting no additional solid phase toxic route. By restricting the analysis to the same added species, we show that the Cu(2+) in solution represents the toxic species to this bacterium.

Investigations on the protection effect of filling materials for post‐tensioning systems under construction conditions

AbstractAbout the long‐term protection behaviour of corrosion protection materials (filling materials) for prestressed systems under critical environmental conditions is only little known. The corrosion protection effect is usually based on theoretical considerations and is proven by short‐term tests. The selection of the different products is mainly made according to economical or workability criteria. In a research project the barrier effect of different commercial corrosion protection materials (waxes as well as oil‐based greases) against water, their tendency for undercutting as well as their additional corrosion protection effect were investigated. The exposure tests were carried out with non‐stressed as well as stressed prestressing steel specimens which were subjected to critical conditions (condensed water, artificial soil solution, direct soil contact). Parallel to these long‐term exposure tests the applicability of different electrochemical techniques and their significance with respect to testing the corrosion protection ability and water absorption was evaluated. Within the project a suitable method for simple testing the performance of corrosion protection materials under real conditions was developed. By means of a small compact cell submicroscopical reactions of the used sensors could be measured. The high sensitivity of this measuring technique enables the detection of degradation processes at thin protection layers.

Arsenic Transformation by Azospirillum Brasilense Sp245 in Association with Wheat (Triticum Aestivum L.) Roots

The transformation of sodium arsenite and sodium arsenate by the rhizospheric nitrogen-fixing bacterium Azospirillum brasilense Sp245 in association with wheat (Triticum aestivum L. ‘Saratovskaya 29’) was studied. The effect produced by the A. brasilense strain on the morphological parameters of wheat in an As-polluted environment was examined. The plants were cultivated in a hydroponic system, with glass beads serving as a support for root growth. The plant-growth medium (an artificial soil solution) was deficient in P and Fe. The total initial As concentrations used were 75, 750, and 7500 µg l−1. The As compounds used contained sodium arsenate and sodium arsenite at an As(V):As(III) ratio of 1:3.6 (in terms of As) in all experiments. Inoculation of A. brasilense Sp245 led to a decrease in the overall root length and to the formation of lateral roots; both effects are possibly related to the bacteria’s ability to synthesize auxins. Inoculation also changed the As(V): As(III) ratio of the plant-growth medium. In all experiments, the concentration of As(V) in the nutrient medium increased relative to the initial one and was approximately 1.5-fold higher than that in the medium of uninoculated plants. This value slightly decreased (1.6 > 1.5 > 1.4) with increasing concentration of As in the medium. Azospirillum-inoculated plants accumulated less As than did the surface-sterilized uninoculated plants. This study shows that A. brasilense Sp245 in association with wheat changes the speciation, bioavailability, and plant uptake of As.

Root uptake of uranium by a higher plant model (Phaseolus vulgaris) - bioavailability from soil solution

Uranium behaviour in soils is controlled by actions and interactions between physico-chemical and biological processes that also determine its bioavailability. In soil solution, uranium (+VI) aqueous speciation undergoes tremendous changes mainly depending on pH, carbonates, phosphates and organic matter. In a first approach, plants (Phaseolus vulgaris) were grown using hydroponics to allow an easy control of the composition of the exposure media. The latter, here an artificial soil solution, was designed to control the uranium species in solution. A geochemical speciation code was used to perform the solution speciation calculations. On this theoretical basis, three domains were defined for short-duration well-defined laboratory experiments in simplified conditions: pH 4.9, 5.8 and 7 where predicted dominant species are uranyl ions, hydroxyl complexes and carbonates respectively. For these domains, the influence of plant growth stage on transfer was determined. The Free Ion Model (or its derivated the Biotic Ligand Model) was tested to determine if U uptake was governed by the free uranyl species or if other metal complexes could be assimilated. The effect of different variables on root assimilation efficiency and phytotoxicity was explored: presence of ligands such as phosphates or carbonates and competitive ions such as Ca2+ at the 3 pHs.

Precipitation of Carbonates by Bacteria from a Saline Soil, in Natural and Artificial Soil Extracts

The precipitation of carbonates by populations of bacteria from a saline soil cultivated in both solid and liquid culture media was studied. The soil was a Gley-Gypsic-Carbonated Solonchak from near an inland saltern in Granada, Spain. Two types of soil extract were prepared: 1:1 extract and saturation extract. The soil samples used for the bacteriological analysis were taken in situ from the A and C soil horizons. The culture media were made from (1) soil extract, (2) artificial soil solutions, and (3) artificial solutions of marine salts. The geochemical analysis of the solution was carried out using the program PHREEQC. Samples of purified bioliths were examined by X-ray diffraction and were observed with SEM. We found that the mineral precipitated from the natural and artificial soil extracts was calcite. Calcite was also found in the secondary accumulations of this soil. However in the media derived from marine salts, mixtures of calcite, magnesian calcite, and aragonite were precipitated, depending on the Mg2+ concentration, the [Mg]/[Ca] molar ratio, and the type of medium. The morphology of the minerals precipitated shows bacterial involvement in the process of pedogenic bioprecipitation. The precipitation studied could be regarded as a process of induced biomineralization.

Diurnal courses of ammonium net uptake by the roots of adult beech (Fagus sylvatica) and spruce (Picea abies) trees

Differences in ammonium net uptake by the roots of beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst) trees between day and night were examined during the growing seasons in 1995 and 1996 using the depletion technique. In addition, diurnal courses of ammonium net uptake of both species were analysed in five sets of uptake experiments in May and September 1997 and were related (1) to the content of carbohydrates, organic acids and total soluble non protein N (TSNN) in the fine roots, and (2) to xylem flow densities and soil temperature. During the growing seasons 1995 and 1996, ammonium net uptake of beech was significantly lower during the night than during the day at 5 of 8 dates of measurement. On average, uptake rates during the night amounted to 50% of the uptake rates during the day. In spruce, the mean values of ammonium net uptake rates determined were similar between day and night during both growing seasons. In beech, the assessment of diurnal courses showed highest ammonium uptake rates during noon and in the afternoon and minima at midnight. In May 1997, comparable, but less pronounced diurnal patterns of ammonium uptake were observed in spruce, whereas in September 1997, ammonium uptake by spruce was constant during the day. Since no distinct differences in carbohydrate and organic acid contents in fine roots were observed during the diurnal courses and since the addition of sucrose into the artificial soil solutions root tips were exposed to did not alter ammonium uptake, depression of uptake by C- and/or energy limitation during night could be excluded. The TSNN contents in the fine roots of beech (May and September 1997) and spruce (May 1997) showed a diurnal pattern inverse to ammonium uptake. It is concluded that the enrichment of TSNN compounds during night that is apparently caused by a reduction of xylem transport is responsible for the down-regulation of ammonium net-uptake.

Toxicological response of a bioluminescent microbial assay to Zn, Pb and Cu in an artificial soil solution: relationship with total metal concentrations and free ion activities

The relationship between toxicological response and both total concentrations and free ion activities of Pb, Cu and Zn in an artificial soil solution has been investigated using lux-marked Escherichia coli HB101 (pUCD607) as a bioassay. SO 4 2− (as K 2SO 4) was added as an inorganic complexing agent up to 0.01 M representing the range of ionic strengths found in soil solutions and giving a wide range of free metal ion activities. EC 50 values expressed in terms of concentration, varied significantly with K 2SO 4 molarity for all metals. However, when EC 50 values were expressed in terms of free ion activity they were not significantly different for Pb and Zn, supporting the free ion activity model. Conversely, EC 50 values expressed as free Cu activity did vary significantly with K 2SO 4 molarity, possibly due to a greater degree of adsorption of Cu onto inactive sites on the cell surfaces than for Zn and Pb. Linear regression analysis of bioluminescence on free ion activity revealed significant correlations for each metal above the toxicity threshold. In conclusion, lux-marked E. coli is suitable for investigating the toxicity of metal ions and complexes in non saline systems although cell surface adsorption effects could be important for some metals, e.g. Cu.

Cation exchange capacity variations in acidic forest soils from Sutton, Québec, Canada

Abstract Single values of the cation exchange capacity (CEC) are widely used in modeling soil solution chemistry in soil and water ecosystems. Our aim was to determine the CEC as a function of pH and ionic strength in an acidic forest soil. We examined the cation exchange of two Humo‐Ferric Podzols (Haplorthods) equilibrated with artificial soil solutions of different concentrations. Aliquots of acid (HC1) or base (NaOH) were added to generate a pH range of 3 to 6. The CEC, determined by displacement with BaCl2 showed little or no increase with increasing pH and a definite increase with lower pH. This anomalous behavior was attributed to the precipitation of aluminum (Al) at high pH and to its dissolution at low pH.

Cation selectivity coefficient variations in acidic forest soils from Sutton, Québec

Single values of the Vanselow, Gaines-Thomas or Gapon selectivity coefficients have been used to model cation exchange in terrestrial ecosystems; however, selectivity coefficients that do not vary as a function of pH and ionic strength have questionable validity. We examined cation exchange in two Humo-Ferric Podzols (Haplorthods) equilibrated with artificial soil solutions with two different ionic strengths in the pH range 3–6. The resulting selectivity coefficients varied by several orders of magnitude. These variations could not be fitted to regressions using the pH and ionic strength of the solutions. Estimating the cation concentrations using fixed values for selectivity coefficients within the chemical composition range of the soils studied would generate modelling errors of up to four orders of magnitude. An equation proposed by McBride and Bloom, relating the amount of an ion in solution to its relative abundance on the exchange complex was more easily fitted. This adsorption equation can be modelled using a regression of pH and ionic strength. Single regression equations are presented for Ca, Mg, K and Al that are capable of estimating the coefficients for two sites and two different soil horizons.

A new method for determining mineral weathering rates in soils

Abstract A new procedure based on measuring the amounts of H+ consumed when a pulse of acidic artificial soil solution is passed through a soil column was used to determine mineral weathering rates of a soil (Humo‐Ferric Podzol) from Roundtop Mountain near Sutton, Quebec. The method allows for quantification of H+ consumption due to weathering and H+ consumption due to cation exchange. Initial experiments yield a soil mineral weathering rate of 0.263 kmol ha‐1 yr‐1. This value is well within the range of results obtained by other workers in similar ecosystems. Multiple soil samples can be analysed in a relatively short time, allowing for better quantification of vertical and horizontal variation of H+ consumption within a site.

Sulfur and Nitrogen Requirements of Sugarcane1

AbstractThe internal S requirement of sugarcane (Saccharum officinarum L.) is not well defined and there are no published data on the external SO4‐S requirements. The objectives of this study was to provide this kind of information, and to provide data on sulfur distribution and N:S ratios in sugarcane.Sugarcane was grown in solution cultures and in potted soil material which provided several concentrations and ratios of NO3 and SO4 in solution. External S and N requirements were estimated from plots of yield vs. SO4 or NO3 concentrations in solution cultures and in artificial soil solutions. The external S requirement at age 35 days was about 9 ppm. After 70 days the requirement was about 5 ppm when N was adequately supplied. The external NO3 requirement was about 50 ppm N. The internal S requirement for early growth was 0.36% S in the whole plant and 0.24% for leaf blades 3 through 6. When plants were 70 days old, 0.10% S in leaf blades or 0.08% S in leaf sheaths was sufficient. Sulfur‐deficient, field‐grown sugarcane 18 months old contained 0.075% S in leaves 3 through 6 and 0.072% S in the corresponding leaf sheaths. Sulfur fertilized sugar cane contained 0.138% and 0.232% for the same tissues. Ratios N:S differed for various tissues of the same plant. Distribution of S in the plant may be a valuable tool for assessing the S status of sugarcane. When S is deficient, old leaf blades contain more S than corresponding leaf sheaths, and blades and sheaths of leaves 3 to 6 contain about equal concentrations of S. Good S nutrition was associated with an elevated concentration of S in leaf sheaths as compared with leaf blades.

Chlamydospores and survival in soil fungi.

MANY of the fungi found in soil are centred around particles of organic debris1,2, and from these food bases the fungi may spread into the soil matrix to a greater or lesser extent3. It is not known how far the fungi in the soil are dependent upon the undissolved organic matter or to what degree the nutrients in the soil solution support their growth. The work described in this communication forms part of an investigation into this question. The dilute solutions in which the fungi were grown were based on the formula given by Erikson4. To this inorganic artificial soil solution dextrose was added to give solutions varying from 0.005 gm./l. to 0.02 gm./l., so that the solutions might simulate a considerable range of true soil solutions. A 0.2-ml. drop of the dilute nutrient solution was placed on the surface of a clean microscope slide resting on a bent glass support in a Petri dish, the base of which contained 5 ml. sterile distilled water. A loopful, containing 20–25 conidia, of a washed spore suspension of the fungus under test was added to the culture drop, and the dishes incubated on the laboratory bench at 17.0–24.4° C. Microscopic observation of the subsequent development was made over a period of fourteen days, after staining with acid fuchsin/lactophenol. Botrytis cinerea Pers., Mycogone perniciosa Magn., Trichoderma viride Pers. ex. Fr., Trichothecium roseum Link., Fusarium oxysporum Schl. var. cubense (E. F. Sm.) Wollenweber and Reinking, and Stemphylium sarcinaeforme (Cav.) Wilts, were the fungi used.