Elevated pH Values Research Articles

Matrine, a novel autophagy inhibitor, blocks trafficking and the proteolytic activation of lysosomal proteases

Autophagy has been referred to as a double-edged sword in tumorigenesis and tumor progression. Emerging evidence suggests that pharmacological modulation of autophagy is a promising therapeutic strategy for cancer. However, few autophagy-modulating compounds are currently approved for clinical use in humans. Matrine is a natural compound extracted from traditional Chinese medicine that is widely used for treatment of a variety of diseases without any obvious side effects. Recently, matrine has been reported to induce autophagy and autophagic cell death in cancer cells, although the underlying mechanisms have yet to be elucidated. Here, we systematically examined the autophagic events induced by matrine in SGC7901 cells. The accumulation of autophagic vacuoles in matrine-treated cells was verified by the conversion of microtubule-associated protein light chain 3 as well as confocal and transmission electron microscopy. Furthermore, we demonstrated that matrine blocked autophagic degradation by impairing the activities of lysosomal proteases. Moreover, confocal microscopy and gradient ultracentrifugation revealed that the trafficking processes and proteolytic activation of cathepsins were inhibited by matrine. Using a pH sensor probe, we found elevated pH values in endosomes/lysosomes in response to matrine treatment. Therefore, matrine seems to be a novel autophagy inhibitor that can modulate the maturation process of lysosomal proteases.

The kinetics of process dependent ammonia inhibition of methanogenesis from acetic acid

Advanced anaerobic digestion processes aimed at improving the methanization of sewage sludge may be potentially impaired by the production of inhibitory compounds (e.g. free ammonia). The result of methanogenic inhibition is relatively high effluent concentrations of acetic acid and other soluble organics, as well as reduced methane yields. An extreme example of such an advanced process is the thermal hydrolytic pretreatment of sludge prior to high solids digestion (THD). Compared to a conventional mesophilic anaerobic digestion process (MAD), THD operates in a state of constant inhibition driven by high free ammonia concentrations, and elevated pH values. As such, previous investigations of the kinetics of methanogenesis from acetic acid under uninhibited conditions do not necessarily apply well to the modeling of extreme processes such as THD. By conducting batch ammonia toxicity assays using biomass from THD and MAD reactors, we compared the response of these communities over a broad range of ammonia inhibition. For both processes, increased inhibitor concentrations resulted in a reduction of biomass growth rate (rmax = μmax∙X) and a resulting decrease in the substrate half saturation coefficient (KS). These two parameters exhibited a high degree of correlation, suggesting that for a constant transport limited system, the KS was mostly a linear function of the growth rate. After correcting for reactor pH and temperature, we found that the THD and MAD biomass were both able to perform methanogenesis from acetate at high free ammonia concentrations (equivalent to 3–5 g/L total ammonia nitrogen), albeit at less than 30% of their respective maximum rates. The reduction in methane production was slightly less pronounced for the THD biomass than for MAD, suggesting that the long term exposure to ammonia had selected for a methanogenic pathway less dependent on those organisms most sensitive to ammonia inhibition (i.e. aceticlastic methanogens).

An assessment of heavy metal contamination in soils of fresh water aquifer system and evaluation of eco-toxicity by lithogenic implications

The chemistry of heavy metals in sediments with respect to bio-availability and chemical reactivity is regulated by pH, texture, and organic matter contents of the sediments and specific binding form and coupled reactivity of the metals within. To focus on the metal distribution (Fe, Mn, Pb, Cd, Zn, Co, Cu, and Cr) and behavior in a fresh water aquifer system along with the ecological toxicity parameters, a four-step sequential extraction method was applied on 18 Eastern Ghats' type sediments from fluorosis-hit Nayagarh district, India. Geo-accumulation index of metals in the sediments indicates that they are practically uncontaminated and/or less contaminated with and Fe, Mn, and Cu; contaminated to moderately contaminated with Pb, Zn, and Cr; and strongly contaminated with Cd. Rather, more than 80 % recovered Cd metal concentration in sediments constitute the labile fractions. Temporal clustering of metal fractions indicates transition metal fraction distribution claiming the sediment pH regulation. Similarly, base metal distribution accounts for organic carbon and soil conductivity due to their greater availability in exchangeable and sulfide fractions. Correlation analysis and factor analysis scores demonstrate lack of inter-relationship between transition group and base metal fractions. High fluoride concentration in ground water is associated with high sodium-bicarbonate-iron affinity with elevated pH values (i.e., >7.0) and high positive factor score with the total iron concentration in ground water.

Facile fabrication of flower-shaped Bi2WO6 superstructures and visible-light-driven photocatalytic performance

Flower-shaped porous Bi2WO6 superstructures assembled from squared nanoplates have been successfully fabricated by a facile hydrothermal method without any surfactants or additives. Parameter-dependent experiments show that the initial strong acidic condition of the hydrothermal precursor is essential for the construction of tiny nanoplates into hierarchical Bi2WO6 flowers. The sample exhibits improved visible-light-driven photocatalytic activity in the degradation of Rhodamine-B, compared with Bi2WO6 multilayered disks, isolated platelets prepared at elevated pH values and bulk Bi2WO6 obtained by solid state method, respectively. It is believed that the higher BET surface area and nano/mesopore structure can afford more reactive sites and abundant transport paths for the degradation reaction. Moreover, the sample shows excellent circulation stability, suggesting its potential application in dealing with enviromental pollutions.

Groundwater Evolution and Mineral Alteration Reactions in the Basaltic Rock Sequence of Mt. Wasserkuppe, Germany: A Case Study

Groundwater sampling was accomplished in the basaltic sequence of the Rhon mountain range, Germany, in order to investigate hydrochemical groundwater evolution and to delineate mineral alteration reactions involved in natural weathering. The hydrochemical compositions of near-surface groundwaters indicate a Ca/Mg–HCO3 type with near-neutral pH and evolve to a Na–HCO3 type with high pH at greater depth. Column experiments were performed with basaltic and phonolitic rock samples to determine individual mineral alteration reactions. The basic reactions could be related to the alteration of olivine, Ca-pyroxene, plagioclase, pyrrhotite, and feldspathoids under formation of secondary clay minerals (smectites, illite) and goethite. The mineral alteration reactions deduced from the leaching experiments by inverse modelling were found to be consistent with the mineral reactions associated with the natural groundwaters. The reactions calculated for groundwater evolution involve the alteration of primary and secondary minerals to produce low-T mineral phase. The conversion of secondary Na-beidellite to illite occurs at a later stage of groundwater evolution, reducing the concentrations of K+ and Mg2+. Near-surface groundwaters do not indicate significant cation exchange. Initial cation exchange requires elevated pH values, with Mg2+ removed from solution preferred to Ca2+. Na-alkalisation of the groundwaters at greater depth suggests the exchange of Na+ for Mg2+ and Ca2+ on Na-beidellite, supported by cation exchange on coatings of iron hydroxides as alteration products. Among the mature high-pH groundwater at greater depth, the dissolution of anorthite and albite has significant effect on groundwater composition.

Preliminary Evaluation of Glass Microfiber Filter Effects on the Chemistry of Synthetic Precipitation Leaching Procedure Extracts

The synthetic precipitation leaching procedure (SPLP) is commonly used to measure the potential for release of constituents from soils and wastes by natural precipitation. However, experience has shown that SPLP extract pH values obtained from commercial laboratories are often elevated beyond that expected based on sample mineralogy and sometimes exceed environmental standards. This study was conducted to examine the effects of glass microfiber filters (GMFs) on pH values and metal concentrations of SPLP extracts. In a control experiment, GMF filtration increased the pH of standard SPLP extraction fluids (Eastern extraction fluid, pH 4.2, and Western extraction fluid, pH 5.0) to approximately 10.0 in the first 100 mL of filtrate. Filtration using GMFs also produced substantial pH increases in SPLP extracts from a variety of geologic materials, although dissolved metal concentrations were less affected. Laboratory analysts should be conscious of artificially elevated pH values in SPLP extracts caused by GMF filtration and consider using techniques to minimize these effects, such as (1) prerinsing GMFs with deionized H2O and pH monitoring of the resulting filtrate prior to SPLP filtration and (2) filtering the maximum volume of SPLP extract practicable.

Listeria bacteriophage peptidoglycan hydrolases feature high thermoresistance and reveal increased activity after divalent metal cation substitution

The ability of the bacteriophage-encoded peptidoglycan hydrolases (endolysins) to destroy Gram-positive bacteria from without makes these enzymes promising antimicrobials. Recombinant endolysins from Listeria monocytogenes phages have been shown to rapidly lyse and kill the pathogen in all environments. To determine optimum conditions regarding application of recombinant Listeria phage endolysins in food or production equipments, properties of different Listeria endolysins were studied. Optimum NaCl concentration for the amidase HPL511 was 200 nM and 300 mM for the peptidases HPL118, HPL500, and HPLP35. Unlike most other peptidoglycan hydrolases, all four enzymes exhibited highest activity at elevated pH values at around pH 8-9. Lytic activity was abolished by EDTA and could be restored by supplementation with various divalent metal cations, indicating their role in catalytic function. While substitution of the native Zn(2+) by Ca(2+) or Mn(2+) was most effective in case of HPL118, HPL500, and HPLP35, supplementation with Co(2+) and Mn(2+) resulted in an approximately 5-fold increase in HPL511 activity. Interestingly, the glutamate peptidases feature a conserved SxHxxGxAxD zinc-binding motif, which is not present in the amidases, although they also require centrally located divalent metals for activity. The endolysins HPL118, HPL511, and HPLP35 revealed a surprisingly high thermostability, with up to 35% activity remaining after 30 min incubation at 90°C. The available data suggest that denaturation at elevated temperatures is reversible and may be followed by rapid refolding into a functional state.

Construction of mixed micelle with cross-linked core and dual responsive shells

A core cross-linked (CCL) mixed micelle with dual responsive shells was constructed from two amphiphilic block copolymers poly(methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate)-b- poly(N-isopropylacrylamide) (P(MMA-co-MPMA)-b-PNIPAAm) and P(MMA-co-MPMA)-b-poly(2-(diethylamino)ethyl methacrylate) (P(MMA-co-MPMA)-b-PDEA) via a two-step process: cooperative aggregation of the two block copolymers into core-shell mixed micelles in acidic aqueous solution at room temperature followed by cross-linking of the hydrophobic core via an acid-catalyzed sol–gel process. The reversibly structural transformation of the core-shell mixed micelles into core-shell-corona (CSC) mixed micelles took place when subjected to elevated temperature or pH value, that is, high temperature resulted in the fabrication of CSC mixed micelle with shrunk PNIPAAm chains as the inner shell and stretched PDEA chains as the outer corona, and alkaline pH led to the formation of CSC mixed micelle with collapsed PDEA chains as the inner shell and extended PNIPAAm chains as the outer corona. Due to the existence of thermo- and pH- dually responsive shells, the structurally stable CCL mixed micelle may find practical applications in biomedical fields such as drug delivery and intelligent release.

Enteric-coated solid dosage forms containing sodium bicarbonate as a drug substance: an exception from the rule?

Sodium bicarbonate (sodium hydrogen carbonate) is used as an oral medication in disorders such as mild metabolic acidosis and chronic kidney disease. The two commercial products on the German market, bicaNorm and Nephrotrans, and also newly developed multiple-unit pellet formulations, have been characterized in these investigations by in-vitro methods like disintegration and dissolution testing. Both marketed products containing sodium bicarbonate are of sufficient pharmaceutical quality according to the European Pharmacopoeia. However, they and the novel pellet preparations showed different drug release at moderately elevated pH values. Early drug release may cause dose dumping in the stomach and adverse drug effects from the developed carbon dioxide. The soft capsule preparation (Nephrotrans) released the smallest amount of sodium bicarbonate at pH 1 and 4.5 of all formulations tested. It appeared that oral dosage formulations of sodium bicarbonate were an exception to the rule: the monolithic soft capsule seemed to be superior to an enteric-coated tablet as well as to multiple-unit pellet formulations from the biopharmaceutical point of view. Our results correspond with individual reports on adverse effects from patients treated with the sodium bicarbonate products.

Effects of Dietary Selenomethionine Supplementation on Growth Performance, Meat Quality and Antioxidant Property in Yellow Broilers

This study was conducted to investigate the effects of dietary selenomethionine (Se-Met) supplementation on growth performance, meat quality and antioxidant property in male broilers. A total of 800 43-day-old Lingnan yellow male broilers were randomly allotted to 5 dietary treatments with four replicates of 40 birds for a period of 3 weeks ad libitum. Final BW and weight gain of birds significantly increased by Se-Met supplementation at the 0.225 mg/kg level (P < 0.05). The addition of Se-Met significantly decreased drip loss, lightness value, and elevated pH value of meat (p < 0.05). Adding sodium selenite (SS) only increased pH value of meat (p < 0.05). In plasma, supplemental Se-Met at 0.225 mg/kg level increased total antioxidant capability (T-AOC), glutathione peroxidase (GPX), total superoxide dismutase (T-SOD), catalase (CAT) activities, glutathione (GSH) concentration (p < 0.05), and decreased malondialdehyde production (p < 0.05), compared with the control and broilers fed SS diet. In breast muscle, the addition of Se-Met significantly elevated T-AOC, GPX, T-SOD, CAT activities, contents of metallothionein and GSH (p < 0.05), and reduced carbonyl protein content (p < 0.05). While compared with broilers fed SS diet, supplemental 0.225 mg/kg Se-Met increased T-AOC, GPX, CAT activities, and GSH content (p < 0.05). Therefore, dietary Se-Met supplementation could improve growth performance and meat quality by enhancing antioxidative capacity in broilers compared with SS.

Physicochemical characterization of cement kiln dust for potential reuse in acidic wastewater treatment

Cement kiln dust (CKD) is a fine-grained material produced during the manufacture of cement. Current reuse options are limited and the bulk of CKD not reused in the cement manufacturing process is sent to landfills or stored on-site. Due to the calcium oxide (CaO) content of CKD, it has the potential to be used as a replacement for lime in treating acidic wastewaters such as acid rock drainage (ARD). This paper outlines the results of an examination of the physical and chemical properties of CKD samples collected from six cement plants. The CKD samples were analyzed for major oxides using X-ray diffraction (XRD), available lime, specific surface area, particle size, and morphology using scanning electron microscope (SEM) and compared with a commercial quicklime product. Conductivity, pH, and calcium concentrations of slaked CKD and quicklime solutions were used as indicators of reactivity of the CKD. Slaking of two of the CKD samples with the highest free lime contents (e.g., 34 and 37% free CaO) gave elevated pH values statistically comparable to those of the commercial quicklime sample that was characterized as having 87% available CaO. Acid neutralization trials indicate that even CKD samples with low free lime contents could be effective at neutralizing acidic wastewaters.

Expanding mesoporosity of triblock-copolymer-templated silica under weak synthesis acidity

With initial aging at low temperature for enough time, silicas with large mesoporosity were synthesized using triblock copolymer as template agent under weak acidities. SBA-15 with periodic mesostructure and short mesochannels could be synthesized at pH 2.5–3.0 within weak acidity range, and the surface areas, pore diameters and pore volumes reached up to ca. 1000 m 2/g, 8.8 nm and 2.0 cm 3/g, respectively, which were significantly higher than those of the conventional SBA-15 synthesized under strong acidities. Mesoporous silica with wormhole structure and abundant textural porosity was formed at pH ∼ 3.5. The increased hydrophobic volume of the copolymer micelles at elevated pH values was responsible for the enlargement of mesoporosity in the products. The materials synthesized under weak acidities showed lower hexagonal ordering in comparison to the general SBA-15 synthesized under strong acidities because the decreased hydronium ion concentration induced relatively weaker assembly forces during the synthesis. Nonetheless, the short mesochannels and large pore diameter in the products might be beneficial to some applications in which fast diffusion of molecules is required.

Down-Regulation of Hypoxia-Inducible Factor-1α by Hyperbaric Oxygen Attenuates the Severity of Acute Pancreatitis in Rats

This study investigated the role of hypoxia-inducible factor 1alpha (HIF-1alpha) in acute pancreatitis (AP) and whether HIF-1alpha is involved in the therapeutic effects of hyperbaric oxygen (HBO) on AP. Thirty Wistar rats with taurocholate-induced AP were randomly assigned to 3 groups (each group had 10 rats) receiving oxygen, HBO, or no therapeutic treatment 4 hours after induction. Ten healthy sham-operated rats also served as controls. The arterial oxygen saturation, PaO2, pH, lactate dehydrogenase in the arterial sera, and amylase and tumor necrosis factor alpha in the venous sera were measured 6 hours after induction. Pancreatic tissues were subjected to histopathologic analysis, immunohistochemical and Western-blotted analyses of HIF-1alpha and vascular endothelial growth factor, and measuring of myeloperoxidase activity. The HBO therapy attenuated the severity of acute pancreatitis; reduced histopathologic scores, dry weight-wet weight ratio of pancreatic tissues, and levels of amylase and lactate dehydrogenase; and elevated blood arterial oxygen saturation, PaO2, and pH values. The HBO therapy inhibited AP-induced up-regulation of HIF-1alpha and its downstream effector vascular endothelial growth factor and the production of tumor necrosis factor alpha and myeloperoxidase activity. Hypoxia-inducible factor 1alpha plays a key role in the pathogenesis of AP, and the ability to down-regulate the expression of HIF-1alpha may partially explain the therapeutic effect of HBO on AP.

Solid phase extraction of Co ions using l-tyrosine immobilized on multiwall carbon nanotubes

A study was performed to assess the performance of aminoacids immobilized on carbon nanotubes (CNTs) for their employment as a sorbent for solid phase extraction systems. An immobilization method is introduced and the aminoacid l -tyrosine was chosen as a case study. A spectrophotometric study revealed the amount of aminoacid immobilizated on CNTs surface, and it turned to be of 3174 μmol of l -tyr g −1. The material was tested for Co retention using a minicolumn inserted in a flow system. At pH 7.0, the amount of Co retained by the column was of 37.58 ± 3.06 μmol Co g −1 of CNTs. A 10% (v/v) HNO 3 solution was chosen as eluent. The pH study revealed that Co binding increased at elevated pH values. The calculation of the mol ratio (moles of Co bound at pH 9 to moles of l -tyr) turned to be 3:1. The retention capacity was compared to other bivalent cations and showed the following tendency: Cu 2+ > Ni 2+ > Zn 2+ ≫ Co 2+. The analytical performance was evaluated and an enrichment factor of 180 was obtained when 10 mL of 11.37 μg L −1 Co solution was loaded onto the column at pH 9.0; reaching a limit of detection (LoD) of 50 ng L −1. The proposed system was successfully applied to Co determination in QC-LL2 standard reference material (metals in natural water).

Chemical and isotopic constraints on water/rock interactions at the Lost City hydrothermal field, 30°N Mid-Atlantic Ridge

Low temperature vent fluids (<91 °C) issuing from the ultramafic-hosted hydrothermal system at Lost City, 30°N Mid-Atlantic Ridge, are enriched in dissolved volatiles (H 2,CH 4) while attaining elevated pH values, indicative of the serpentization processes that govern water/rock interactions deep in the oceanic crust. Here, we present a series of theoretical models to evaluate the extent of hydrothermal alteration and assess the effect of cooling on the systematics of pH-controlled B aqueous species. Peridotite-seawater equilibria calculations indicate that the mineral assemblage composed of diopside, brucite and chrysotile likely dictates fluid pH at moderate temperature serpentinization processes (<300 °C), by imposing constraints on the aCa ++/ a 2H + ratios and the activity of dissolved SiO 2. Based on Sr abundances and the 87Sr/ 86Sr isotope ratios of vent fluids reported from Lost City, estimated water/rock mass ratios (w/r = 2–4) are consistent with published models involving dissolved CO 2 and alkane concentrations. Combining the reported δ 18O values of vent fluids (0.7‰) with such w/r mass ratios, allows us to bracket subseafloor reaction temperatures in the vicinity of 250 °C. These estimates are in agreement with previous theoretical studies supporting extensive conductive heat loss within the upflow zones. Experimental studies on peridotite-seawater alteration suggest that fluid pH increases during cooling which then rapidly enhances boron removal from solution and incorporation into secondary phases, providing an explanation for the highly depleted dissolved boron concentrations measured in the low temperature but alkaline Lost City vent fluids. Finally, to account for the depleted 11B composition (δ 11B ∼25–30‰) of vent fluids relative to seawater, isotopic fractionation between tetrahedrally coordinated aqueous boron species with BO 3-bearing mineral sites (e.g. in calcite, brucite) is proposed.

Ozonation of oxytetracycline and toxicological assessment of its oxidation by-products

Antibiotic formulation effluents are well known for their difficult elimination by traditional bio-treatment methods and their important contribution to environmental pollution due to its fluctuating and recalcitrant nature. In the present study the effect of ozonation on the degradation of oxytetracycline (OTC) aqueous solution (100 mg l −1) at different pH values (3, 7 and 11) was investigated. Ozone (11 mg l −1 corresponds the concentration of ozone in gas phase) was chosen considering its rapid reaction and decomposition rate. The concentration of oxytetracycline, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and BOD 5/COD ratio were the parameters to evaluate the efficiency of the ozonation process. In addition, the toxic potential of the OTC degradation was investigated by the bioluminescence test using the LUMIStox 300 instrument and results were expressed as the percentage inhibition of the luminescence of the marine bacteria Vibrio fischeri. The results demonstrate that ozonation as a partial step of a combined treatment concept is a potential technique for biodegradability enhancement of effluents from pharmaceutical industries containing high concentration of oxytetracycline provided that the appropriate ozonation period is selected. At pH 11 and after 60 min of ozonation of oxytetracycline aqueous solutions (100 and 200 mg l −1) the BOD 5/COD ratios were 0.69 and 0.52, respectively. It was also shown that COD removal rates increase with increasing pH as a consequence of enhanced ozone decomposition rates at elevated pH values. The results of bioluminescence data indicate that first by-products after partial ozonation (5–30 min) of OTC were more toxic than the parent compound.

Silicate HinderingIn SituFormed Ferric Hydroxide Precipitation: Inhibiting Arsenic Removal from Water

The effects and dominant mechanism of silicate hindering arsenic removal with in situ formed ferric hydroxides were investigated. Zeta potential analysis showed that 10 mg/L silicate as Si obviously decreased ζ potential from −11.9 mV (pH 8.61) to −29.9 mV (pH 8.84) for ferric hydroxides; more significant effects was observed at higher pH levels. Photometric dispersion analysis indicated that silicate apparently hindered ferric hydroxides precipitation and aggregation, with more apparent influence at elevated pH values. Furthermore, in high pH ranges silicate led to filtered iron concentration increase. These adverse effects resulted in a significant decrease of arsenic removal with in situ formed ferric hydroxides, especially in higher pH ranges. Sequential filtration analysis showed the presence of aqueous arsenic species in liquid phase, demonstrating that silicate increasing repulsive charges between ferric precipitates and decreasing surface sites available for arsenic, rather than contributing to the formation of tiny ferric colloids with adsorbed arsenic, was more significant in silicate hindering arsenic removal by ferric hydroxides.

Influence of temperature and pH on the quality of metastable iron phases produced in zinc-rich solutions

The hydrolysis of ferric iron at elevated temperatures and pH values between 1.5 and 3.5 was characterized by determining the stability regions for schwertmannite, 6-line ferrihydrite and 2-line ferrihydrite, and linking them to the supersaturation levels present during their formation. It was shown that most industrial iron removal processes are operated above the metastability limit. However, stagewise precipitation of iron, even above the metastability limit, yielded better quality precipitates. Furthermore, careful selection and control of pH and temperature are required to improve product quality expressed in terms of the solids impurity content, dry solids density, particle size and the particle number density.

Mineralogical and geochemical patterns of urban surface soils, the example of Pforzheim, Germany

This study presents a combined geochemical and mineralogical survey of urban surface soils. Many studies on urban soils are restricted to purely chemical surveys in order to investigate soil pollution caused by anthropogenic activities such as traffic, heating, industrial processing, waste disposal and many more. In environmental studies, chemical elements are often distinguished as lithogenic and anthropogenic elements. As a novel contribution to those studies, the authors combined the analysis of a broad set of chemical elements with the analysis of the main mineralogical phases. The semi-quantification of mineralogical phases supported the assignment of groups of chemical elements to lithogenic or anthropogenic origin. Minerals are important sinks for toxic elements. Thus, knowledge about their distribution in soils is crucial for the assessment of the environmental hazards due to pollution of urban soils. In Pforzheim, surface soils (0–5 cm depth) from various land use types (forest, agriculture, urban green space, settlement areas of various site densities) overlying different geological units (clastic and chemical sediments) were investigated. Urban surface soils of Pforzheim reflect to a considerable degree the mineral and chemical composition of parent rocks. Irrespective of the parent rocks, elevated concentrations of heavy metals (Zn, Cu, Pb, Sn, Ag) were found in soils throughout the whole inner urban settlement area of Pforzheim indicating pollution. These pollutants will tend to accumulate in inner urban surface soils according to the available adsorption capacity, which is normally higher in soils overlying limestone than in soils overlying sandstone. However, inner urban surface soils overlying sandstone show elevated concentrations of carbonates, phyllo-silicates and Fe and elevated pH values compared with forest soils overlying sandstone. Thus, in comparison to forest soils overlying sandstones, inner urban soils overlying sandstone affected by pollution concurrently possess elevated concentrations of mineral phases typically providing relatively high adsorption capacities for heavy metals.

Membrane Potentials Across Hybrid Charged Mosaic Membrane in Organic Solutions

Membrane potentials across hybrid charged mosaic membrane in organic solutions were measured. Equilibrium swelling degree (SD) and fixed charge density in both organic solutions and water were also determined. Ethylene glycol, ethanol, n-propanol and glycerol were used as organic solutes; meanwhile 0.001mol-dm −3 aqueous KCl solution was utilized as a strong electrolyte to measure the electrical difference. Equilibrium swelling degree indicated that it could be affected by the density of organic solutes; while it enhanced with the increasing density of these solutes. The measurement of fixed charge density showed that the membrane had the maximal absolute value in water among these solvents whether for cationic or anionic groups; the difference of dielectric constant between the water and the organic solutes might be responsible for these change trends. It was confirmed that membrane potentials increased with both the increasing concentration of the organic solutions and the elevated pH values. These results demonstrated that the characteristics of the hybrid charged mosaic membrane could be highly impacted by the properties of the organic solutes. A theoretical model for charged membranes in ternary ion systems of weak electrolyte can be used to explain the above-mentioned phenomena.