Concomitant Increase In pH Research Articles

Mineralogical and Geochemical Evidence of Dissolution-Reprecipitation Controlled Hydrothermal Rare Earth Element Mineralization in the Amba Dongar Carbonatite Complex, Gujarat, Western India

Abstract The Amba Dongar carbonatite complex in western India comprises an inner ring of carbonatite breccia surrounded by a sövite ring dike. The various carbonatite units in the body include calcite carbonatite, alvikite, dolomite carbonatite, and ankerite carbonatite. The carbonate phases (calcite and ankerite) occur as phenocrysts, groundmass phases, fresh primary grains, and partially altered grains and/or pseudomorphs when hydrothermally overprinted. Rare earth element (REE) enrichment in the groundmass/altered calcite grains compared to the magmatic ones is ascribed to the presence of micron-sized REE phases. Fluorapatite and pyrochlore constitute important accessory phases that are altered to variable extents. Higher concentrations of Sr, Si, and REEs in fluorapatite are suggestive of a magmatic origin. Fresh pyrochlore preserves its magmatic composition, characterized by low A-site vacancy and high F in the Y-site, which on alteration becomes poorer in Na, Ca, and F and displays an increase in vacancy. The C-O isotope compositions of the carbonates also corroborate the extensive low-temperature hydrothermal alteration of the carbonatites. The REE mineralization is the result of interaction of the carbonatite with a sulfur-bearing, F-rich hydrothermal fluid that exsolved from late-stage carbonatitic magmas. The hydrothermal fluids caused dissolution of the primary carbonates and simultaneous precipitation of REEs and other high field strength element (HFSE)-bearing minerals. Complex spatial associations of the magmatic minerals with the REE fluorocarbonates, [synchysite-(Ce), parisite-(Ce), bastnäsite-(Ce)] and florencite-(Ce) point to the formation of these REE phases as a consequence of postmagmatic hydrothermal dissolution of the REEs from fluorapatite, pyrochlore, and carbonates. Ubiquitous association of fluorite and barite with REE minerals indicates transport of REEs as sulfate complexes in F-rich fluids. Precipitation of REE fluorocarbonates/florencite resulted from fluid-carbonate interaction, concomitant increase in pH, and decrease in temperature. Additionally, REE precipitation was aided and abetted by the removal of sulfur from the fluid by the precipitation of barite, which destabilized the REE sulfate complexes.

Heparin-Free Extracorporeal Life Support Using Tethered Liquid Perfluorocarbon: A Feasibility and Efficacy Study.

Coagulation management is the leading challenge during extracorporeal life support (ECLS) due to shear stress and foreign-surface-induced coagulation disturbance during circulation. A nonadhesive, liquid-infused coating called tethered liquid perfluorocarbon (TLP) was developed to prevent adhesion of blood on medical materials. We investigated the novel application of TLP to commercial ECLS circuits compared with standard heparin-coated circuits in vivo in anesthetized swine for 6 hours veno-venous ECLS (1 L/min blood flow) without systemic anticoagulation (n = 3/group). We hypothesized that TLP coating permits heparin-free circulation without untoward effects while reducing thrombus deposition compared with controls. Vital signs, respiration, gas transfer, coagulation, and histology were assessed. Scanning electron microscopy (SEM), elemental mapping, and digital imaging were used to assess thrombus deposition after circulation. There were no group differences in vitals, gas exchange, coagulation, and histology. In both groups, ECLS enabled a decrease in minute volume and end-tidal CO2, with concomitant increase in pH (p < 0.05). Scanning electron microscopy and digital imaging revealed significant thrombus on heparin-coated membranes, which was reduced or absent on TLP-coated materials. Tethered liquid perfluorocarbon permitted heparin-free ECLS without altering device performance and prevented thrombus deposition versus immobilized heparin. Pending multiday in vivo testing, TLP is a promising biomaterial solution to eliminate anticoagulation requirements during ECLS.

Increased soil pH and dissolved organic matter after a decade of organic fertilizer application mitigates copper and zinc availability despite contamination

Long-term organic fertilizer (OF) application on agricultural soils is known to induce soil Cu and Zn contamination, along with pH and organic matter changes, which in turn alter the soil Cu and Zn availability. Our study was aimed at assessing Cu and Zn availability in long-term OF-amended soils by distinguishing the importance of increased contamination levels versus pH and organic matter changes in soil. Seventy-four soil samples were collected over time from fields corresponding to three soil types upon which no, mineral, or organic fertilization had been applied over a decade, and thus exhibited a gradient of Cu and Zn contamination, pH, and organic matter concentration. Soil Cu and Zn contamination (i.e. total and DTPA-extractable Cu and Zn concentration), soil solution chemistry (i.e. pH and dissolved organic matter concentration and aromaticity) and Cu and Zn availability (i.e. total concentration and free ionic activity in solution and DGT-available concentration in soil) levels were measured. The Windermere humic aqueous model (WHAM) was used to estimate Zn2+ activity and dissolved organic matter (DOM) binding properties in soil solution. Regardless of the soil type, organic fertilization increased Cu and Zn contamination in soil, in addition to the pH and the DOM concentration, aromaticity and binding properties in soil solution. The pH increase prompted a decrease in the total Zn concentration and Zn2+ activity in soil solution. The concomitant pH increase and DOM concentration, aromaticity and binding properties boosted the total Cu concentration but decreased the Cu2+ activity in soil solution. DGT-available Cu and Zn varied very little between the three fertilization modalities. Our results suggest that pH and DOM changes were able to regulate Cu and Zn availability in long-term OF amended soils by exerting a protective effect that offset the concomitant increase in soil Cu and Zn contamination.

Widespread release of dissolved organic carbon from anoxic boreal lake sediments

Sediments in boreal lakes are important components of the carbon cycle because they receive and store large amounts of organic carbon (OC) and at the same time are a source of greenhouse gases. Under anoxic conditions, sediment OC can be lost through dissolution from the solid phase and subsequent diffusion to the water column. Although this process may have implications for sediment OC budgets, it has yet to be studied systematically. We combined laboratory sediment incubation experiments from 4 boreal lakes in central Sweden that differed widely in their biogeochemical conditions with data from the Swedish monitoring program covering >100 lakes to analyze the frequency of occurrence of sediment DOC loss in boreal lakes and identify lake characteristics and the conditions related to high DOC fluxes from anoxic sediments. We found DOC diffusion from anoxic sediments in all the anoxic sediment incubations but at different mean rates (0.7–3.7 mmol m−2 d−1). Similarly, 16 of 17 of the monitoring lakes that developed anoxic bottom water exhibited an increase in bottom-water DOC concentration, corresponding to a mean (and standard deviation) DOC diffusion flux from anoxic sediment of 11.1 (35.4) mmol m−2 d−1. The observed variability between lakes was related to particularly large DOC fluxes in humic-rich lakes, which we attribute to their low pH and high share of terrestrial OC favoring the formation of OC-iron aggregates. Accordingly, increasing pH might facilitate the dissolution of sediment OC because high dissolved OC fluxes from anoxic sediments were accompanied by high microbial iron and sulfate reduction, resulting in concomitant pH increase.

Micronutrient Availability from Steel Slag Amendment in Pine Bark Substrates

Steel slag is a byproduct of the steel industry that can be used as a liming agent, but also has a high mineral nutrient content. While micronutrients are present in steel slag, it is not known if the mineral form of the micronutrients would render them available for plant uptake. The objective of this research was to determine if steel slag could be used as the sole micronutrient source for container-grown nursery crops. Butterfly bush (Buddleja davidii ‘Pink Delight’) and rose (Rosa ‘Radrazz’) were grown in #3 (3 gal) containers in a base substrate composed of pine bark and peatmoss (80:20, by vol). The base substrate was amended with the following treatments: with a complete controlled release fertilizer (CRF) including micronutrients (C-control), a substrate amended with a different CRF containing only N, P, and K along with a granular micronutrient package (M-control), and three additional treatments amended with the CRF (N, P, and K only) and either 1.2, 2.4, or 4.8 kg·m−3 (2, 4, and 8 lb·yd−3) of steel slag. Plants were harvested at 2 and 4 months after potting (MAP). None of the plants displayed any sign of nutrient deficiency or toxicity throughout the experiment. However, plants grown in the substrate amended with the highest slag rate [4.8 kg·m−3 (8 lb·yd−3)] had lower shoot dry weight (SDW) than both control groups. Substrate pH increased with increasing slag rate, which may have affected micronutrient availability in those substrates. Among the micronutrients analyzed, only Copper (Cu) was consistently deficient in both the substrate and foliar tissue of slag-amended treatments. Steel slag either does not provide a sufficient quantity of Cu or the concomitant increase in pH with increasing rates of steel slag renders Cu unavailable for plant uptake. Steel slag should not be used as the sole source of micronutrients for shrubs grown in pine bark-based substrates.

Effect of pulp preconditioning on acidification, proteolysis, sugars and free fatty acids concentration during fermentation of cocoa (Theobroma cacao) beans

Changes in acidification, proteolysis, sugars and free fatty acids (FFAs) concentrations of Ghanaian cocoa beans as affected by pulp preconditioning (pod storage or PS) and fermentation were investigated. Non-volatile acidity, pH, proteolysis, sugars (total, reducing and non-reducing) and FFAs concentrations were analysed using standard methods. Increasing PS consistently decreased the non-volatile acidity with concomitant increase in pH during fermentation of the beans. Fermentation decreased the pH of the unstored beans from 6.7 to 4.9 within the first 4 days and then increased slightly again to 5.3 by the sixth day. Protein, total sugars and non-reducing sugars decreased significantly (p < 0.05) during fermentation, whereas reducing sugars and FFA increased. PS increased the FFA levels, reduced the protein content but did not have any effect on the sugars. The rate of total and non-reducing sugars degeneration with concomitant generation of reducing sugars in the cocoa beans was largely affected by fermentation than by PS.

Bioremediation of acid mine water utilising red mud and Desulfotomaculum nigrificans

The efficiency of red mud as an adsorbent for the removal of metal ions and sulphate from synthetic acid mine water was assessed. Almost complete removal of Fe–z (98%), Fe3+ (99%) and Cu2+ (97%) and a significant removal of Zn2+ (84%) was achieved from acid mine water at pH 2·3. However, only about 27% of sulphate reduction could be attained. A noteworthy feature was the concomitant increase in pH from 2·3 to 7·6 with the increase in red mud loading under appropriate conditions. The adsorption isotherms adhered to Freundlich and Langmuir relationships and were endothermic in nature. The free energy of the adsorption process was found to be negative attesting to the feasibility of the reaction. The adsorption kinetics followed the first order Lagergren rate equation. The filtrate obtained after treatment of red mud with synthetic acid mine water supplemented with carbon and nitrogen sources served as a successful growth medium for the sulphate reducing bacteria, namely Desulfotomaculum nigrificans (Dsm. nigrificans). Bacterial growth studies indicated that about 22, 41 and 52% of sulphate reduction could be achieved at initial pH values of 5, 6·1 and 7·2 respectively. The pretreatment of the acid mine water with red mud followed by bioremoval using Dsm. nigrificans resulted in about 27, 47 and 62% of sulphate removal at initial pH values of 5, 6·1 and 7·2 respectively, cumulatively by adsorption and bioreduction. The mechanisms of metal ion removal utilising red mud and sulphate reduction using Dsm. nigrificans are discussed.

Influence of microbial photosynthesis on tufa stromatolite formation and ambient water chemistry, SW Japan

Photosynthetic influences on tufa stromatolite formation and ambient water chemistry were investigated at two well-studied streams depositing tufa in Southwestern Japan (Shirokawa and Shimokuraida). The tufa stromatolites in both streams are composed of fine-grained calcite crystals showing annual lamination, and colonized by a number of filamentous cyanobacteria as well as non-phototrophic bacteria. Microelectrode measurements of pH, O 2, and Ca 2+ near the stromatolite surface (the diffusive boundary layer; DBL) revealed that the investigated tufa stromatolites are formed by photosynthesis-induced CaCO 3 precipitation (PCP): cyanobacterial photosynthesis induces calcite precipitation under light conditions, while respiration of cyanobacteria and non-phototrophic bacteria inhibits precipitation in the dark. The bulk water chemistry at the lower sites of the investigated streams showed the daytime decreases of Ca 2+ concentration and alkalinity that was expected for significant influence of PCP, while the other expected change, increased pH, was not observed. In order to examine this discrepancy, a novel approach using semi- in situ microelectrode measurements was applied to perform precise quantitative calculations. The calculation results demonstrated that the observed Ca 2+ concentration and alkalinity decreases were caused by PCP, and that the concomitant pH increase was expected to be under the detection level of a conventional pH meter. Although the amount of PCP is supposed to be significantly affected by light intensity, observations in Shimokuraida revealed that the amount of PCP on cloudy day nonetheless accounted for about 80% of that on sunny day. Despite the significant role of PCP for tufa stromatolite formation, PCP accounted for only about 10% of the precipitated calcite in the investigated streams, which indicates that tufa stromatolites, the characteristic deposits in the streams, are responsible for only a small portion of calcite precipitation, and the rest is considered to precipitate inorganically at biofilm-free substrates.

Stability of fatty acids in grass and maize silages after exposure to air during the feed out period

Lipids in forages are extensively hydrolysed in the silo with a concomitant increase in the level of free fatty acids (FFA). After opening of the silo, exposure of the FFA to air and light with, a concomitant increase in pH and microbial growth, could induce oxidization. The present study investigated the stability of FA in grass and maize silages exposed to air for 0, 12 and 24 h. Eight maize silages were selected with varying dry matter (DM) contents, being very wet, wet, normal and dry. In addition, eight grass silages were chosen on the basis of ammonia (NH 3) concentration and pH level. Grass and maize silages were sampled 8–10 weeks after ensiling and anaerobically transported to the lab in cooled plastic bags. After mixing, each sample was divided into three subsamples and exposed to air for 0, 12 or 24 h. Concentrations of individual FA were quantified by gas chromatography. Among the investigated silages, concentrations of total FA varied greatly and ranged from 16.4 to 23.9 and 9.5 to 21.6 g/kg DM in grass and maize silages, respectively. Exposure to air up to 24 h lowered ( P<0.01) the contents of linolenic acid (C18:3), linoleic acid (C18:2), oleic acid (C18:1) and total FA in maize silages. In grass silages, 24 h exposure to air decreased ( P<0.05) concentrations of C18:3, C18:2 and total FA ( P<0.01). In both grass and maize silages a decline in concentrations of major unsaturated FA (UFA) was associated with a concomitant increase ( P<0.01) in the proportion (g/g total FA) of palmitic acid (C16:0). The relative decrease in total FA after 24 h exposure to air was higher in maize silages with a high moisture content, and progressively decreased with increasing DM content. In contrast, pH and NH 3 levels of grass silages had no effect on the stability of FA during feed out. The present study demonstrates that extended exposure of silages to air during feeding increased the proportion (g/g total FA) of C16:0 and lowered the concentration of polyunsaturated FA.

Complex formation between polyacrylic acid and cationic/nonionic mixed micelles: effect of pH on electrostatic interaction and hydrogen bonding

The interaction of a weak polyacid, sodium polyacrylate (PAA), and cationic mixed micelles of n-hexadecyl trimethyl ammonium chloride/ n-dodecyl hexaoxyethylene glycol monoether (CTAC/C 12E 8) was studied by turbidimetric titrations at varying pH, in order to determine the effect of polymer charge. Electrostatically-driven complex formation is controlled by three variables: the polymer linear charge density ( ξ), the micelle surface charge density ( σ), and the ionic strength ( I) or the related Debye–Hückel parameter ( κ). In this system, the former two parameters depend, respectively, on α, the degree of ionization of the polymer carboxylic acid groups, and on Y, the micellar mole fraction of ionic surfactant. In 0.10 M salt, the critical mole fraction of CTAC corresponding to the onset of polymer-micelle complex formation, Y c, varies inversely with pH, as expected, in the range 0.80< α<1.0. At these pH's, Y c× α is constant as predicted by our previously proposed equation σ c× ξ× κ −1=constant, suggesting that the polymer-micelle interaction is predominantly controlled by electrostatic forces. However, at pH 4.0 ( α=0.10), Y c is much smaller than expected. Turbidimetric titration of PAA+C 12E 8 with HCl shows complex formation bellow pH 4.2 even in the absence of CTAC. The concomitant pH increase indicates that the interaction at low pH is dominated by hydrogen bonding. The contribution of H-bonding to PAA–CTAC/C 12E 8 complex formation at moderate pH is superimposed on the electrostatically controlled polymer-micelle interaction. An additional factor in PAA–CTAC/C 12E 8 complexation is the role of the PAA counterion. Comparison of PAA with poly(acrylamido-2-methylpropane sulfate) in NaCl and in tetramethylammonium chloride indicates that Na + binds to PAA at large α, reducing the effective polymer charge density.

Removal of Dissolved Heavy Metals from Acid Rock Drainage Using Iron Metal

The chemical and microbial activity of corroding iron metal is examined in the acid rock drainage (ARD) resulting from pyrite oxidation to determine the effectiveness in neutralizing the ARD and reducing the load of dissolved heavy metals. ARD from Berkeley Pit, MT, is treated with iron in batch reactors and columns containing iron granules. Iron, in acidic solution, hydrolyzes water producing hydride and hydroxide ion resulting in a concomitant increase in pH and decrease in redox potential. The dissolved metals in ARD are removed by several mechanisms. Copper and cadmium cement onto the surface of the iron as zerovalent metals. Hydroxide forming metals such as aluminum, zinc, and nickel form complexes with iron and other metals precipitating from solution as the pH rises. Metalloids such as arsenic and antimony coprecipitate with iron. As metals precipitate from solution, various other mechanisms including coprecipitation, sorption, and ion exchange also enhance removal of metals from solution. Corroding iron also creates a reducing environment supportive for sulfate reducing bacteria (SRB) growth. Increases in SRB populations of 5000-fold are observed in iron metal treated ARD solutions. Although this biological process is slow, sulfidogenesis is an additional pathway to further stabilize heavy metal precipitates.

The roles of temperature, pH and mosquito factors as triggers of male and female gametogenesis of Plasmodium berghei in vitro.

Developmentally arrested malarial gametocytes undergo gamete formation in the mosquito midgut immediately after ingestion of the infected bloodmeal. In the rodent malaria parasite Plasmodium berghei male gametogenesis (exflagellation) can be induced in vitro by a temperature decrease (from 39 degrees C in the vertebrate host to 20 degrees C) and a concomitant pH increase (from 7.3 in mouse blood to 8.0). We report the presence of additional Gametocyte Activating Factor(s) (GAF) present in Anopheles stephensi tissue extracts, which induce both male and female gametogenesis at the otherwise nonpermissive pH of 7.3 in vitro but are unable to overcome the low temperature requirement. All constituent cellular events of microgametogeneis studied here are induced by the same triggers in vitro. A temperature decrease is also required for exflagellation in the mosquito midgut. The possible role of GAF as a second obligatory natural trigger of gametogenesis is discussed.

An Alternate Technique of Ammoniation by Ensiling Straw with Urea to Minimize Loss of Added Nitrogen

Mandal, A., Sil, B., Santra, A., Kamra, D.N. and Pathak, N.N. 1997. An alternate technique of ammoniation by ensiling straw with urea to minimize loss of added nitrogen. J. Appl. Anim. Res., 11: 195–200. Two laboratory experiments were conducted on urea ensiling of straw to minimize the loss of added nitrogen and the level of urea in glass jars. Wheat straw at different layers was treated as: lower layer (5 or 4% urea), middle layer (2.5 or 2% urea) and upper layer with either sulphuric acid (4% w/w of straw), molasses (10% w/w of straw) or green maize chaff to constitute about 80% of pre mix. The moisture content was about 50 per cent in straw of all layers except green maize containing layer (29.8 or 28.6%). The glass jars kept at room temperature were opened after 21 days. The CP content increased in upper layer with concomitant increase in pH in all the layers. The results of the experiment indicate that loss of urea can be minimized during urea ammoniation if the upper layers of straw are treated with acids, molasses or green forages, but there was no improvement in in sacco degradability of wheat straw.

A preliminary study of a biosensor based on flow injection of the recognition element

A biosensor based on flow injection of the recognition element has been developed. As a model a pH-transducer was used, and urease was chosen as the recognition element. The pH-transducer was immersed in an internal flow-through chamber which was in contact with the sample solution via a semi-permeable membrane. The recognition element, urease, was injected into the buffer solution passing through the biosensor. The enzyme catalysed the hydrolysis of urea and the concomitant increase in pH was recorded. The biosensor response time was about three minutes at a constant flow rate of 0·05 ml/min. The linear range of the calibration curve of the biosensor was 0–5 mM. The observed detection limit was approximately 0.1 mM. The sample throughput was 6–12 per hour. The pH-response of the biosensor, for a sample solution containing urea (3·26 mM), showed a reproducibility (r.s.d) of 28% ( n = 5) and a repeatability (r.s.d.) of 8% ( n = 5). Operation at elevated temperatures (up to 50°C) was demonstrated. The presence of glucose (28 mM), acetone (6·7 mM), citric acid (0·2 mM) or sodium acetate (0·6 mM) in the sample solution did not interfere with the sensor response. A lowering of the biosensor response which was observed in the presence of copper ions (due to urease inhibition) could be completely eliminated by adding EDTA to the urease solution. Thus, this work demonstrates a new type of biosensors, based on SIRE-technology (Sensors with Injectable Recognition Elements), which show high accuracy and stability, quick response and high sample throughput. These features suggest the suitability of the system for automation. Such sensors should readily be combined with other enzymes or enzyme systems. The enzyme (urease) cost per analysis (injection) for the biosensor was estimated to be approximately US$0·02. This could be substantially reduced by further optimisation and miniaturisation.

Effects of temperature and concomitant change in pH on muscle

Contractile performance decreases with a decrease in temperature and increases with an increase in pH. In general, a decrease in ambient temperature is associated with an increase of the pH of the intracellular and extracellular fluids of ectotherms. Thus the concomitant increase in pH will to some extent counteract the effect of the decrease in temperature. We review the magnitude of this effect and show that it is modest for force (24%) but is small or negligible for speed or for variables involving time. Experiments with skinned fibers yield similar results to those with intact fibers. We argue that one important effect of the concomitant increase in pH is that it causes an increase in calcium sensitivity and that there may be a considerable metabolic saving associated with releasing less calcium at lower temperatures.

A geochemical model for sulfide paragenesis and zoning in the CuFeAsS system (Tsumeb, South West Africa/Namibia)

The Cu-bearing hypogene mineralization at Tsumeb, South West Africa/Namibia, is interpreted to have resulted from the interaction of hot circulating Cu-rich saline solutions and host dolomites. Fluids attending formation of the main sulfide stage were warm (210–280°C) and moderately saline (6–12 wt.% NaCl equivalent). Phase relations within the CuFeAsS system suggest that the observed paragenetic sequence (chalcopyrite → bornite → chalcocite → enargite → tennantite) is consistent with a model calling for successive introduction of a single Cu-rich solution into a host dolomite. The Cu and As content of the solution decreased as it passed through the permeable dolomite precipitating CuAs-sulfides and sulfosalts. A concomitant increase in pH created by the dissolution and buffering effect of dolomite produced sufficient changes in the fluid chemistry to shift the stable sulfide mineral assemblage.

Calcium, Magnesium, and Potassium Saturation Ratios in Two Soils and Their Effects Upon Yields and Nutrient Contents of German Millet and Alfalfa

AbstractA greenhouse study involving sequential cropping of two soils of differing cation exchange capacities (CEC) with five Ca‐Mg saturation ratios at two K levels was conducted. German millet (one cutting, Setaria italica, German) followed by alfalfa (five cuttings, Medicago sativa, Saranac) was grown with Mg‐Ca saturations varied from Mg 5%–Ca 75% to Mg 25%–Ca 55% at two K levels.German millet yields were not affected by treatment of either soil. Similarly, alfalfa yields were not affected in the above range of Ca‐Mg saturations. However, an apparent Mg response occurred when alfalfa yields were more than doubled by increasing initial Mg and Ca saturations from 3 and 18% to 5 and 75%, respectively (concomitant pH increase from 5.4 to 6.8).Magnesium contents of plant tissue increased with increased Mg saturation, but soil K depressed the Mg content of the tissues more per equivalent than soil Mg increased it. The results indicate that for most conditions, 6–10% Mg saturation (high to low soil CEC) would likely be adequate for maximum yields of crops, although 12–15% may be indicated for supplying adequate Mg when grasses are to be grown for use as the main dietary constituent of ruminants.Exchangeable Mg and Ca contents in the soils after cropping plus amounts removed by cropping were less than the initial contents in one soil and were more than the initial contents in the other. Evidently some type of fixation mechanism tied up Mg and Ca in the former while solubilization of residual lime released them in the latter.