Solubility Of Species Research Articles

Changes in Sb speciation with waterlogging of shooting range soils and impacts on plant uptake

A pot experiment was conducted to investigate the solubility and redox species of antimony (Sb) in a relocated shooting range soil and its uptake by Lolium perenne L. and Holcus lanatus L. under different water regimes. After 1-week waterlogging, the total Sb concentration in soil solution decreased from ∼110 μg L−1 to <20 μg L−1, and slowly increased over the following 4 weeks, with the dissolution of Fe and Mn (hydr)oxides. In this process, half of the Sb in soil solution was reduced to Sb(III), which greatly affected the plant uptake of Sb. Waterlogging increased shoot Sb concentrations of L. perenne by ∼10 fold but decreased uptake in H. lanatus by 80%. Results indicate that Sb might primarily be taken up as Sb(III) by L. perenne and as Sb(V) by H. lanatus. Temporary waterlogging of soil may increase the risk of trace elements entering the food chain.

Effects of cations and anions on iron and manganese sorption and desorption capacity in calcareous soils from Iran

This study investigated the effect of cations and anions on the sorption and desorption of iron (Fe) and manganese (Mn) in six surface calcareous soil samples from Western Iran. Six 10 mM electrolyte background solutions were used in the study, i.e., KCl, KNO3, KH2PO4, Ca(NO3)2, NaNO3, and NH4NO3. NH4NO3 and NaNO3 increased the soil retention of Fe and Mn, whereas Ca(NO3)2 decreased the soil retention of Fe and Mn. Iron and Mn sorption was decreased by NO3 − compared with H2PO4 − or Cl−. The Freundlich equation adequately described Fe and Mn adsorption, with all background electrolytes. The Freundlich distribution coefficient (K F) decreased in the order H2PO4 − > Cl− > NO3 − for Mn and H2PO4 − > NO3 − > Cl− for Fe. The highest sorption reversibility was for Fe and Mn in competition with a Ca2+ background, indicating the high mobility of these two cations. A MINTEQ speciation solubility model showed that Fe and Mn speciation was considerably affected by the electrolyte background used. Saturation indices indicated that all ion background solutions were saturated with respect to siderite and vivianite at low and high Fe concentrations. All ion background solutions were saturated with respect to MnCO3(am), MnHPO4, and rhodochrosite at low and high Mn concentrations. The hysteresis indices (HI) obtained for the different ion backgrounds were regressed on soil properties indicating that silt, clay, sand, and electrical conductivity (EC) were the most important soil properties influencing Fe adsorption, while cation exchange capacity (CEC), organic matter (OM), and Mn-DTPA affected Mn adsorption in these soils.

The influence of Cl concentration and pH on solubility and species of Zn and Pb in water-chloride fluids at T-P parameters of granitoidic magmas degassing

The study of concentrations and species of ore elements in the aqueous fluid phases separating from magmatic melts during their uprising to the surface and crystallization is important for understanding of a role of magmatic fluids in ore-forming systems formation. The purpose of this investigation is determination of solubility and possible species of zinc and lead in water-chloride fluids at Т–Р parameters of granitic magmas degassing. In this report the results of thermodynamic modeling of equilibrium relations of Zn and Pb complexes in water-chloride solutions depending on temperature (600–900С), pressure (0.7–5 kbar), composition and acidity of a fluid (NaCl, KCl, NaCl+HCl), and also initial concentration Zn and Pb in system in the form of ZnO(c), PbO(c) or ZnCl2, PbCl2 are presented. Modeling was conducted by means of program complex HCh [Shvarov, 1999] with use of thermodynamic information received by Shock model [Shock, 1997]. Values of free energy formations of solid phases are borrowed from bank of thermodynamic data of Holland and Powell [Holland, Powell, 1998]. In ZnO-NaCl-H2O system within studied Т–Р range at low chlorine concentrations (CCl 700C Pb(OH)3 is dominant complex within all investigated range of pressure and CCl.

Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths

This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fourth paper in our series of “Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems”. In our third paper, we demonstrated via speciation–solubility modeling that partial equilibrium between secondary minerals and aqueous solutions was not attained in feldspar hydrolysis batch reactors at 90–300 °C and that a strong coupling between dissolution and precipitation reactions follows as a consequence of the slower precipitation of secondary minerals ( Zhu and Lu, 2009). Here, we develop this concept further by using numerical reaction path models to elucidate how the dissolution and precipitation reactions are coupled. Modeling results show that a quasi-steady state was reached. At the quasi-steady state, dissolution reactions proceeded at rates that are orders of magnitude slower than the rates measured at far from equilibrium. The quasi-steady state is determined by the relative rate constants, and strongly influenced by the function of Gibbs free energy of reaction ( Δ G r ) in the rate laws. To explore the potential effects of fluid flow rates on the coupling of reactions, we extrapolate a batch system ( Ganor et al., 2007) to open systems and simulated one-dimensional reactive mass transport for oligoclase dissolution and kaolinite precipitation in homogeneous porous media. Different steady states were achieved at different locations along the one-dimensional domain. The time-space distribution and saturation indices (SI) at the steady states were a function of flow rates for a given kinetic model. Regardless of the differences in SI, the ratio between oligoclase dissolution rates and kaolinite precipitation rates remained 1.626, as in the batch system case ( Ganor et al., 2007). Therefore, our simulation results demonstrated coupling among dissolution, precipitation, and flow rates. Results reported in this communication lend support to our hypothesis that slow secondary mineral precipitation explains part of the well-known apparent discrepancy between lab measured and field estimated feldspar dissolution rates ( Zhu et al., 2004). Here we show how the slow secondary mineral precipitation provides a regulator to explain why the systems are held close to equilibrium and show how the most often-quoted “near equilibrium” explanation for an apparent field-lab discrepancy can work quantitatively. The substantiated hypothesis now offers the promise of reconciling part of the apparent field-lab discrepancy.

CHARACTERIZATION AND COMPARISON OF COLLAGENS EXTRACTED FROM THE DIGESTIVE TRACT AND SKIN OF A JAPANESE AMBERJACK SERIOLA QUINQUERADIATA

ABSTRACT Collagen was extracted from the digestive tract and skin of a Japanese amberjack (Seriola quinqueradiata) by acid extraction and limited pepsin digestion. The amounts of collagen solubilized from the digestive tract were smaller than those from the skin. Based on the solubility in NaCl solution, electrophoretic and peptide map patterns, and amino acid composition, the main digestive tract collagen was identified as type I, having characteristics different from those of the body wall collagen in cyclostome intestine. Further, the degree of hydroxylation of prolyl and lysyl residues in the type I collagen of the digestive tract is significantly higher than that of the skin. Collagen preparations from the digestive tract have a higher ratio of type V collagen than those from the skin. Hence, the digestive tract collagen differs from that in the skin in the degree or property of intermolecular crosslinking, posttranslational modification, and molecular species composition. PRACTICAL APPLICATIONS Partial hydrolyzate of gelatin, in other word collagen peptide, has gained popularity as a food ingredient, as it has been suggested to have health benefits, such as improvement of skin and joint conditions. Recently, attention toward collagen derived from marine origin such as fish skin increased because of the outbreak of bovine spongiform encephalopathy. Large amounts of the digestive tract, stomach, intestine and adhesion tissues are generated by fishery industries and most of them are by-products of low value. Although these organs are also rich in collagen, the collagen in fish digestive tract has not been characterized. The present study demonstrates that the collagen in digestive tract differs from the skin collagen in the solubility, posttranslational modification and molecular species composition. These facts suggest that modified collagen peptides might be obtained from the digestive tract.

Hydrogeochemical modeling of a thermal system and lessons learned for CO 2 geologic storage

Geological storage of carbon dioxide is presently considered to be one of the main strategies to mitigate the impact of the emissions of this gas on global warming. Among the various alternatives considered for CO 2 geological storage, one of the main geological candidates for hosting injected CO 2 in the long term are deep porous reservoir rock formations saturated with brackish or saline solutions. Although valuable information on the expected hydrogeochemical processes involved in the CO 2 storage in such deep saline aquifers can be obtained in laboratory or modeling studies, the only direct source of information about the long-term behavior of geological storages for CO 2 in deep aquifers is natural analogues. In this work, a classical and simple geochemical methodology is successfully applied to the study of the features and hydrogeochemical processes determining the evolution of a Spanish thermal system (the Alhama–Jaraba complex), which can be considered as a natural analogue for deep geological CO 2 storage in carbonate rocks. The geology, structure, depth and hydrogeochemistry of the Alhama–Jaraba thermal system are very similar to the expected features of a potential CO 2 reservoir in carbonate materials. The processes determining the hydrogeochemical evolution in the Alhama–Jaraba thermal system have been successfully identified and quantified with the assistance of ion–ion plots, speciation–solubility calculations and mass-balance calculations. Furthermore, the feasibility of the proposed conceptual hydrogeochemical model for this system has been verified by using reaction-path calculations. Mass-balance calculation results have indicated that the observed hydrogeochemical evolution between springs is mainly due to halite dissolution and dedolomitization triggered by gypsum or anhydrite dissolution. CO 2(g) mass transfer has been estimated to be negligible, which suggests that the main processes responsible for the variation in the TIC and the CO 2(g) pressure during deep circulation are dissolution and precipitation reactions for carbonate minerals. All the processes identified in the Alhama–Jaraba thermal system are relevant for the long-term evolution of a deep CO 2 storage site hosted by carbonate rocks. As shown in this study, the application of classical geochemical tools provides an excellent starting point for understanding the behavior of prospective storage systems. Moreover, the existence of dedolomitization is very relevant for the hydraulic properties of carbonate aquifers potentially used for CO 2 geological storage because of the effects on porosity and, therefore, permeability during the long-term evolution of such systems. Furthermore, dedolomitization may represent a mechanism of mineral trapping for CO 2 sequestration under certain conditions.

Practical methodology for the solubility speciation analysis of ambient dust deposits for heavy metals: application to a 6-month measurement campaign

A robust and accurate method for the quantitative determination of the water-soluble and water-insoluble, Ni, Cd, Pb and Zn contents of deposited ambient dust is presented. The extraction of the soluble metal phase from deposited ambient dust has been validated using commercially available ambient dust certified reference material. Results from a 6 month measurement campaign, from July to December 2004, are presented. Quantitative analysis of the two fractions, of different aqueous solubility (referred to here as ‘solubility speciation analysis’), within deposited ambient dust is reported for the first time. Additionally, the two Bergerhoff dust deposit gauges used in parallel to acquire the dust deposit samples have shown good inter-sampler comparability. The measured total deposition fluxes compare well with those previously reported in urban and semi-rural locations around the UK.

Development and Validation of a Phosphate Rock Decision Support System

Although some mathematical models exist to assist in deciding whether or not to apply phosphate rock (PR) to soils as a source of P, these models focused either on the use of highly soluble PR sources, mainly for pastures, or were too impractical for field use. There was, therefore, a need to develop a Phosphate Rock Decision Support System (PRDSS) with more comprehensive capabilities to predict the relative agronomic effectiveness (RAE) of PR with respect to water‐soluble phosphorus (WSP) fertilizers at field and farm level. The PRDSS includes PR sources varying widely in solubility and different crop species grown on variable soil properties and rainfall conditions. In this paper, we describe the development and use of the mathematical model, PRDSS, to estimate RAE of PR sources with respect to WSP fertilizers and to calculate a simple index to be used for preliminary economic comparison of these two types of P sources. The PRDSS is able to function with a minimum input of only soil pH, the name of the mine that is the source of the phosphate rock, and the species of crop to be grown. A more accurate prediction of RAE is obtained from the PRDSS when more detailed data describing the soil, crop, and weather are included as inputs.

Alteration of the Callovo-Oxfordian clay from Meuse-Haute Marne Underground Laboratory (France) by alkaline solution: II. Modelling of mineral reactions

One of the French options for the final disposal of high-level radioactive waste is a deep geological repository. The Callovo-Oxfordian formation in the Meuse and Haute-Marne (France) was proposed, by the French agency for the management of radioactive wastes (ANDRA), to be the site of a research laboratory in order to evaluate in situ the interaction between the host formation and the engineered barriers. In the previous experimental part, secondary minerals such as zeolites, tobermorite and katoite have been observed after the alteration of the Callovo-Oxfordian clay under alkaline conditions. Three different reactions of phyllosilicates alteration have been proposed as a function of both pH and chemical composition of the reacting solutions. The aim of this work was to simulate the reaction between the Callovo-Oxfordian clay and high-pH solutions in order to validate the proposed alteration reactions from experimental data. The thermodynamic modelling of stability relationships among minerals in the Callovo-Oxfordian clay was performed using the solution speciation solubility modelling code KINDIS at 120 °C for different chemical media (NaOH, KOH and Ca(OH) 2). Input data were the mineralogical composition of the <2 μm fraction of Callovo-Oxfordian clay at nearly the same burial depth of the underground laboratory construction as well as the neoformed minerals observed after the experimental alteration of this clay (zeolites and cement phases). In the NaOH and KOH runs, anacime, phillipsite and chabazite, respectively were the first stable minerals which appeared at the beginning of modelling. In the Ca(OH) 2 runs, oversaturated with respect to portlandite, katoite and then tobermorite were the first minerals occurring at the beginning of the alteration. Smectites and illites were undersaturated whatever the chemical composition. Both minerals and the interstratified illite-smectite were less stable in Ca(OH) 2 than in NaOH and KOH solutions. Concerning the secondary minerals, a discussion is developed in order to improve modelling and to predict the long term reactions between clays and alkaline solutions.

The solubility of alpha-synuclein in multiple system atrophy differs from that of dementia with Lewy bodies and Parkinson's disease.

Intracellular inclusions containing alpha-synuclein (alpha SN) are pathognomonic features of several neurodegenerative disorders. Inclusions occur in oligodendrocytes in multiple system atrophy (MSA) and in neurons in dementia with Lewy bodies (DLB) and Parkinson's disease (PD). In order to identify disease-associated changes of alpha SN, this study compared the levels, solubility and molecular weight species of alpha SN in brain homogenates from MSA, DLB, PD and normal aged controls. In DLB and PD, substantial amounts of detergent-soluble and detergent-insoluble alpha SN were detected compared with controls in grey matter homogenate. Compared with controls, MSA cases had significantly higher levels of alpha SN in the detergent-soluble fraction of brain samples from pons and white matter but detergent-insoluble alpha SN was not detected. There was an inverse correlation between buffered saline-soluble and detergent-soluble levels of alpha SN in individual MSA cases suggesting a transition towards insolubility in disease. The differences in solubility of alpha SN between grey and white matter in disease may result from different processing of alpha SN in neurons compared with oligodendrocytes. Highly insoluble alpha SN is not involved in the pathogenesis of MSA. It is therefore possible that buffered saline-soluble or detergent-soluble forms of alpha SN are involved in the pathogenesis of other alpha SN-related diseases.

Au-Sb association and fractionation in micro-disseminated gold deposits, southwestern Guizhou—geochemistry and thermodynamics

The dual geochemical character of paragenesis and fractionation between gold, arsenic and antimony in micro-disseminated gold deposits in southwestern Guizhou is discussed in terms of spatial distribution of independent deposits, lateral and vertical enrichment, mineralization stage and factor and correlation analyses. Thermodynamic calculations of solubility and speciation of gold and antimony minerals indicate that gold is transported in hydrothermal solution as Au(HS) - 2 and antimony is mainly as Sb (OH 0 3 ) although HSb 2 S - 4 may be of increasing importance in acid environment at low temperatures during the late stage of mineralization. Changes in physicochemical conditions hold the key to the association and fractionation between gold and antimony. Gold and antimony response differently to physicochemical variations because they are distinct from each other in soluble speciation and mineral solubility, leading to precipitation at different times and localities during hydrothermal evolution.

Measurements of Trace Metal (Fe, Cu, Mn, Cr) Oxidation States in Fog and Stratus Clouds

ABSTRACT The oxidation state of four transition metals (Fe, Mn, Cu, and Cr) in cloudwater has been investigated during several cloud events at Whiteface Mountain (NY), one cloud event at San Pedro Hill (CA), and one fog event at Bakers-field (CA). Samples were collected and immediately analyzed for the oxidation states of four transition metals: Fe(II) [44 measurements], Cu(I) [30 measurements], Mn(IV) [27 measurements], and Cr(III) [3 measurements]. Extreme care was taken to minimize contamination and interferences when measuring these oxidation states. Par-ticulate and dissolved concentrations of these metals were also determined. Other measurements performed—relevant to the redox chemistry of these metals—included pH, total elemental concentrations (Fe, Cu, Mn, Cr, Al, K, Ca, Na, and Mg), organic anions (formate, acetate, glyco-late, oxalate), inorganic anions (chloride, sulfate, nitrate, sulfite), cations (sodium, calcium, magnesium, potassium), peroxides, and formaldehyde. These measurements were then used in thermodynamic-speciation models to understand the speciation of ambient fog and cloudwater. From this analysis, two different cases were found for Fe(III)soluble speciation. Fe(III) was found to exist either as Fe(OH)2 + or Fe(Oxalate)2. However, an unidentified strong chelating ligand with Fe(III) was also suggested by the data. Cu(I) and Cu(II) were calculated to be predominantly Cu+ and Cu2+ (with less than 10% as Cu(II)-oxalate complexes). A chemical kinetic model was also used to investigate the transition-metal chemistry. The model results indicate that Fe(II) should be the predominant chemical form of Fe during daylight conditions. This prediction is in agreement with the field measurements in which the highest ratios of Fe(II)/Fe total were found in samples collected during the day. The model results also indicated that Fe(III) should be the predominant form of Fe during nighttime conditions, which is also in agreement with the field measurements. In the model, Cu(II) and Mn(II) were the predominant oxidation states during daylight and nighttime conditions with Cu(I) and Mn(III) increasing during daylight conditions. Mn(III) concentrations were never high enough to influence the redox chemistry of Cr. Overall, Cr(VI) in cloudwater is predicted to be reduced to Cr(III) if free S(IV) is present.

Thermodynamic zonation in the black shale facies based on iron-manganese-vanadium content

The black shale facies contains several discrete chemical groupings of Mn, Fe and V in visually similar rocks. These groups are related to four thermodynamic zones based on changing p E and pH, are identified from a collection of ∼200 Paleozoic and Mesozoic finely-laminated, low-calcic ([Ca] < 0.4%) black shales. The low-calcic nature of this data set permits the simplifying assumption that CaCO 3 is not present as a significant complication factor. The relative variations in the concentrations of Mn and Fe can be used as indicators of p EpH conditions. In Group 1 (oxic conditions: high p E), Mn and Fe occur as Mn(III,IV)- and Fe(III)-oxides, and appear in relatively high concentrations (average concentrations 1,300 and 56,000 ppm, respectively). In Group 2 (anoxic: nitrate-reducing to sulfate-reducing at intermediate pH), Mn is reduced to Mn 2+ as is evidenced by low Mn concentration (310 ppm average); in Group 2, Fe remains bound in oxides or sulfides with concentrations comparable to those in Group 1 (52,000 ppm). In Group 3, both Mn and Fe are reduced and relatively soluble, reflecting anoxic, but non-sulfate reducing, p E at intermediate to low pH. This solubility, and Mn and Fe species instability, is shown in lower average concentrations 170 and 23,000 ppm, respectively, in Group- 3 sediments. Group- 4 black shales have V concentrations > 300 ppm, averaging 1500 ppm and indicating deposition under conditions of high organic preservation. Mn and Fe concentrations are low — the Mn concentration is <260 ppm and averages 80 ppm; Fe is <36,000 and averages 19,000 ppm. The high V concentration with the relatively low Mn and Fe content suggests low pH and possible methanogenesis at low p E. This study demonstrates the wide variety of black shale depositional environments from oxic to methanic. Accordingly, black shales cannot all be assigned to anoxic, sulfidic environments without additional chemical analysis and interpretation.

Physical and chemical controls (fO2,T,pH) of the opposite behaviour of U and Sn-W as examplified by hydrothermal deposits in France and Great-Britain, and solubility data

The aim of this paper is to determine the physical and chemical parameters which control the opposite behaviour of uranium and tin-tungsten between 300° and 500 °C. In uranium deposits, fO2 and fS2 of mineralizing fluids are higher than values fixed by the pyrite-hematite-magnetite triple point, as shown by uraninite-hematite and/or pyrite mineral association. The stability of quartz-K feldspar-muscovite paragenesis in the wall-rocks of hydrothermal U deposits indicates weakly acid pH. By contrast, in the Sn-W occurrences from the French Southern Massif Central, the fO2 of mineralizing fluids is between Ni-NiO and Q-F-M buffers as shown by CO2-CH4-H2O-NaCl bearing fluid inclusions. The pH of these fluids is weakly acid to weakly basic as shown by the stability of muscovite in presence or absence of quartz and/or feldspar. Sn-W mineralizing fluids from Cornwall are by contrast purely aqueous and acid, as indicated by the mineral assemblage muscovite-quartz which is typical of greisens. Experimental data on UO2, SnO2, FeWO4, CaWO4 solubility and metal species in fluids show that fO2 &gt; H-M are required for uranium transport whereas fO2 ≤ Ni-NiO favours Sn transport. The fluid oxidation state has no direct influence on the transport and deposition of tungsten. The fO2 control on the hydrothermal transport properties of these three metals is related on the one hand to the fluid and rock composition, and on the other hand to the minimal 320 °C temperature required for homogeneous equilibria in the C-O-H system to control the oxidation state at low values. At high temperatures, Sn, Fe and Ca chloride complexes are more stable than carbonate and phosphate uranium complexes ; this is attributable to their structure and to the dielectric content of the fluid. The presence of dissolved gases at high concentration, which are produced by devolatilization reactions at high temperatures, is emphasized since they lower the dielectric constant of the fluid which enhances the stability of chloride complexes. All these results show that temperature and fO2 account for the opposite behaviour of uranium and tin-tungsten in hydrothermal systems between 300° to 500 °C.