Introducing TEX86 as a Water pH Proxy for Alkaline Lakes on the Tibetan Plateau

Science.gov (United States)

Wang, M.; Tian, Q.; Li, X.; Liang, J.; Yue, H.; Hou, J.

2017-12-01

Lake water pH represents one of the most important indicators for lake evolution and factors influencing the evolution of aquatic ecosystem, however, which is less studied on the Tibetan Plateau (TP). Applicability of diatom assemblages, an effective proxy of lake water pH variation in freshwater lakes, is highly limited on the TP because the widespread distribution of alkaline lakes is unfavorable for preservation of diatom shells. Glycerol dialkyl glycerol tetraethers (GDGTs) are a series of specific membrane lipids biosynthesized by archaea and bacteria, which appear to be a promising method to reflect lake water pH variation. Here we present the distribution of iGDGTs compounds in surface sediments across the TP to discuss the effect of various environmental factors on iGDGTs distribution. The results show that TEX86 is a promising proxy for lake water pH in high-elevation alkaline lakes, as water pH appears to be the most important factor to affect the cyclization of iGDGTs. We proposed the water pH calibration for lakes (salinitywater pH. The TEX86-derived pH at Bangong Co varied from 8.69 to 9.49 since the last 16 kyr BP, which is generally consistent with precipitation isotope variation that was reconstructed from leaf wax D/H ratios in the same sediment core, suggesting the lake water pH was mainly controlled by local hydrology. We believe that TEX86 will be able to infer past water pH of alkaline lakes over TP and could be a potentially useful tool for reconstructing pH in alkaline lakes worldwide after regional calibrated.

Biology and chemistry of tree Pennsylvania lakes: responses to acid precipitation. [Lepomis gibbosus; Lepomis machrochirous

Energy Technology Data Exchange (ETDEWEB)

Bradt, P.T.; Dudley, J.L.; Berg, M.B.; Barrasso, D.S.

1986-01-01

The biology and chemistry of three northeastern Pennsylvania lakes was studied from summer 1981 through summer 1983 to evaluate lakes with different sensitivities to acidification. At the acidifies lake (total alkalinity par. delta 0.0 ..mu..eq L/sup -1/) there were fewer phytoplankton and zooplankton species than at the moderately sensitive lakes. The most numerous plankton species in all three lakes are reportedly acid tolerant. Among the benthic macro- invertebrates (BMI) there were more acid tolerant Chironomidae at the acidified lake, but more acid intolerant Ephemeroptera and Mollusca and a higher wet weight at the least sensitive lake. There were no differences among the lakes' BMI mean total numbers or mean number of taxa. The fish community at the acidified lake was dominated by stunted Lepomis gibbosus, but L. machrochirous were most abundant in the other lakes. Principal component analysis suggested a shift in all three lakes over the sampling period toward combined lower pH, alkalinity, specific conductance, Ca, and Mg and higher Al and Mn. Such chemical changes have been associated with acidification. The rate and extent of acidification appeared to be controlled by geological and hydrological characteristics of the drainage basins.

Controls on the pH of hyper-saline lakes - A lesson from the Dead Sea

Science.gov (United States)

Golan, Rotem; Gavrieli, Ittai; Ganor, Jiwchar; Lazar, Boaz

2016-01-01

The pH of aqueous environments is determined by the dominant buffer systems of the water, defined operationally as total alkalinity (TA). The major buffer systems in the modern ocean are carbonic and boric acids of which the species bicarbonate, carbonate and borate make up about 77%, 19% and 4% of the TA, respectively. During the course of seawater evaporation (e.g. lagoons) the residual brine loses considerable portion of the dissolved inorganic carbon (DIC) and carbonate alkalinity (CA) already at the early stages of evaporation. DIC and CA decrease due to massive precipitation of CaCO3, while total boron (TB) increases conservatively, turning borate to the dominant alkalinity species in marine derived brines. In the present work we assess the apparent dissociation constant value of boric acid (KB‧) in saline and hypersaline waters, using the Dead Sea (DS) as a case study. We explain the DS low pH (∼6.3) and the effect of the boric and carbonic acid pK‧-s on the behavior of the brine's buffer system, including the pH increase that results from brine dilution. The KB‧ in DS was estimated from TB, TA, DIC and pH data measured in this study and early empirical data on artificial DS brines containing just carbonic acid. The KB‧ value was corroborated by Pitzer ion interaction model calculations using PHREEQC thermodynamic code applied to the chemical composition of the DS. Our results show that KB‧ increases considerably with the brine's ionic strength, reaching in the DS to a factor of 100 higher than in ;mean; seawater. Based on theoretical calculations and analyses of other natural brines it is suggested that brines' composition is a major factor in determining the KB‧ value and in turn the pH of such brines. We show that the higher the proportion of divalent cations in the brine the higher the dissociation constants of the weak acids (presumably due to formation of complexes). The low pH of the Dead Sea is accordingly explained by its extremely

pH dependent dissolution of sediment aluminum in six Danish lakes treated with aluminum

DEFF Research Database (Denmark)

Reitzel, Kasper; Jensen, Henning S.; Egemose, Sara

2013-01-01

The possible pH dependent dissolution of aluminum hydroxides (Al(OH)(3)) from lake sediments was studied in six lakes previously treated with Al to bind excess phosphorus (P). Surface sediment was suspended for 2 h in lake water of pH 7.5, 8.5, or 9.5 with resulting stepwise increments in dissolved...

Acid Rain, pH & Acidity: A Common Misinterpretation.

Science.gov (United States)

Clark, David B.; Thompson, Ronald E.

1989-01-01

Illustrates the basis for misleading statements about the relationship between pH and acid content in acid rain. Explains why pH cannot be used as a measure of acidity for rain or any other solution. Suggests that teachers present acidity and pH as two separate and distinct concepts. (RT)

Hydrogeochemical Processes Causing Persistent Low pH in Lakes within a Reclaimed Lignite Mine, East Texas

Science.gov (United States)

Paul, J. C.; Schwab, P.; Knappett, P.; Deng, Y.

2017-12-01

Surface water pH values ranging from 2.5 to 2.6 have been reported in three lakes at a reclaimed lignite mine located in the Wilcox Formation of East Texas (the site). Traditional neutralization processes using alkaline chemicals to neutralize the surface water were found to be temporary solutions at the site. Low pH conditions usually are caused by oxidation of pyritic materials in the original tailings, but that was not always apparent based on previous studies at this site. The objective of this study is to determine factors contributing to acid seepage to aid in developing pre- and post-mining strategies to mitigate persistent acidity in surface waters at this and other sites. Mineralogy, hydrogeology, and hydrogeochemical reactions were evaluated. A network of 30 wells was used to monitor the water table and chemistry of the shallow, unconfined aquifer surrounding the lakes. Pressure transducers were deployed in 18 of these wells and each of the lakes to measure high frequency water levels over approximately one year. These water levels were contoured to visualize changing hydraulic head over time and determine the correlation in time between ground water flow directions and local rainfall events. Boreholes at 15 of the monitoring wells were continuously cored, and samples were taken at selected depth intervals based on pH measurements. XRD, SEM, and TEM were used to determine the mineralogy of select soil samples. Ion chromatography was used to determine sulfate concentration, and ICP-MS was used to determine solute concentrations from water and digested soil samples. Framboidal and microcrystalline pyrite were identified in the vadose zone in silt and clay-sized fractions; these minerals have high surface area that is conducive to rapid oxidation and acidification as ground water permeates from the vadose into the saturated zone. Morphology in addition to quantity of weatherable pyrite plays a significant role in acidification. Computer models were used to

Chemical hazards from acid crater lakes

Science.gov (United States)

van Bergen, M. J.; Sumarti, S.; Heikens, A.; Bogaard, T. A.; Hartiyatun, S.

2003-04-01

Acid crater lakes, which are hosted by a considerable number of active volcanoes, form a potential threat for local ecosystems and human health, as they commonly contain large amounts of dissolved chemicals. Subsurface seepage or overflow can lead to severe deterioration of the water quality of rivers and wells, as observations around several of these volcanoes have shown. The Ijen crater lake in East Java (Indonesia) is a striking example, as this reservoir of hyperacid (pHfluoride-rich water is the source of a ca. 50 km long acid river that transports substantial quantities of potentially toxic elements. A downstream trend of increasing pH from fluoride levels pose some of the most severe environmental threats. Its concentration decreases from ca. 1300 mg/kg in the lake to ca. 10 mg/kg in a coastal area downstream, where virtually all of the river water is used for irrigating rice fields and other cropland. Apart from serious problems for agriculture, our survey of 55 drinking water wells in the irrigation area shows that 50% contain fluoride above the 1.5 ppm WHO limit, in line with the observation that dental fluorosis is widespread among the ca. 100,000 residents of the area. A conspicuous spatial correlation between fluoride concentrations and the irrigation system suggest that long-term (century) infiltration of irrigation water may have affected the quality of groundwater. Fluorosis is also a problem in some villages within the caldera, where well water sources may have a more direct subsurface connection with the lake system. From our observations we conclude that water-quality monitoring is especially needed for health reasons in volcanic areas where volatile elements, derived from passively degassing magma, are intercepted by (sub) surface water bodies.

Gas flushing through hyper-acidic crater lakes: the next steps within a reframed monitoring time window

Science.gov (United States)

Rouwet, Dmitri

2016-04-01

Tracking variations in the chemical composition, water temperature and pH of brines from peak-activity crater lakes is the most obvious way to forecast phreatic activity. Volcano monitoring intrinsically implies a time window of observation that should be synchronised with the kinetics of magmatic processes, such as degassing and magma intrusion. To decipher "how much time ago" a variation in degassing regime actually occurred before eventually being detected in a crater lake is key, and depends on the lake water residence time. The above reasoning assumes that gas is preserved as anions in the lake water (SO4, Cl, F anions), in other words, that scrubbing of acid gases is complete and irreversible. Less is true. Recent work has confirmed, by direct MultiGas measurement from evaporative plumes, that even the strongest acid in liquid medium (i.e. SO2) degasses from hyper-acidic crater lakes. The less strong acid HCl has long been recognised as being more volatile than hydrophyle in extremely acidic solutions (pH near 0), through a long-term steady increase in SO4/Cl ratios in the vigorously evaporating crater lake of Poás volcano. We now know that acidic gases flush through hyper-acidic crater lake brines, but we don't know to which extend (completely or partially?), and with which speed. The chemical composition hence only reflects a transient phase of the gas flushing through the lake. In terms of volcanic surveillance this brings the advantage that the monitoring time window is definitely shorter than defined by the water chemistry, but yet, we do not know how much shorter. Empirical experiments by Capaccioni et al. (in press) have tried to tackle this kinetic problem for HCl degassing from a "lab-lake" on the short-term (2 days). With this state of the art in mind, two new monitoring strategies can be proposed to seek for precursory signals of phreatic eruptions from crater lakes: (1) Tracking variations in gas compositions, fluxes and ratios between species in

Egg fatty acid composition from lake trout fed two Lake Michigan prey fish species.

Science.gov (United States)

Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.; Brown, S.B.

2009-01-01

We previously demonstrated that there were significant differences in the egg thiamine content in lake trout Salvelinus namaycush fed two Lake Michigan prey fish (alewife Alosa pseudoharengus and bloater Coregonus hoyi). Lake trout fed alewives produced eggs low in thiamine, but it was unknown whether the consumption of alewives affected other nutritionally important components. In this study we investigated the fatty acid composition of lake trout eggs when females were fed diets that resulted in different egg thiamine concentrations. For 2 years, adult lake trout were fed diets consisting of four combinations of captured alewives and bloaters (100% alewives; 65% alewives, 35% bloaters; 35% alewives, 65% bloaters; and 100% bloaters). The alewife fatty acid profile had higher concentrations of arachidonic acid and total omega-6 fatty acids than the bloater profile. The concentrations of four fatty acids (cis-13, 16-docosadienoic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) were higher in bloaters than in alewives. Although six fatty acid components were higher in lake trout eggs in 2001 than in 2000 and eight fatty acids were lower, diet had no effect on any fatty acid concentration measured in lake trout eggs in this study. Based on these results, it appears that egg fatty acid concentrations differ between years but that the egg fatty acid profile does not reflect the alewife-bloater mix in the diet of adults. The essential fatty acid content of lake trout eggs from females fed alewives and bloaters appears to be physiologically regulated and adequate to meet the requirements of developing embryos.

Primordial soup or vinaigrette: did the RNA world evolve at acidic pH?

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Bernhardt Harold S

2012-01-01

Full Text Available Abstract Background The RNA world concept has wide, though certainly not unanimous, support within the origin-of-life scientific community. One view is that life may have emerged as early as the Hadean Eon 4.3-3.8 billion years ago with an atmosphere of high CO2 producing an acidic ocean of the order of pH 3.5-6. Compatible with this scenario is the intriguing proposal that life arose within alkaline (pH 9-11 deep-sea hydrothermal vents like those of the 'Lost City', with the interface with the acidic ocean creating a proton gradient sufficient to drive the first metabolism. However, RNA is most stable at pH 4-5 and is unstable at alkaline pH, raising the possibility that RNA may have first arisen in the acidic ocean itself (possibly near an acidic hydrothermal vent, acidic volcanic lake or comet pond. As the Hadean Eon progressed, the ocean pH is inferred to have gradually risen to near neutral as atmospheric CO2 levels decreased. Presentation of the hypothesis We propose that RNA is well suited for a world evolving at acidic pH. This is supported by the enhanced stability at acidic pH of not only the RNA phosphodiester bond but also of the aminoacyl-(tRNA and peptide bonds. Examples of in vitro-selected ribozymes with activities at acid pH have recently been documented. The subsequent transition to a DNA genome could have been partly driven by the gradual rise in ocean pH, since DNA has greater stability than RNA at alkaline pH, but not at acidic pH. Testing the hypothesis We have proposed mechanisms for two key RNA world activities that are compatible with an acidic milieu: (i non-enzymatic RNA replication of a hemi-protonated cytosine-rich oligonucleotide, and (ii specific aminoacylation of tRNA/hairpins through triple helix interactions between the helical aminoacyl stem and a single-stranded aminoacylating ribozyme. Implications of the hypothesis Our hypothesis casts doubt on the hypothesis that RNA evolved in the vicinity of alkaline

Geographic distance and pH drive bacterial distribution in alkaline lake sediments across Tibetan Plateau

Science.gov (United States)

Xiong, Jinbo; Liu, Yongqin; Lin, Xiangui; Zhang, Huayong; Zeng, Jun; Hou, Juzhi; Yang, Yongping; Yao, Tandong; Knight, Rob; Chu, Haiyan

2012-01-01

Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4–1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r = 0.443, P = 0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments. PMID:22676420

The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

Science.gov (United States)

Schaefer, J.R.; Scott, W.E.; Evans, William C.; Jorgenson, J.; McGimsey, R.G.; Wang, B.

2008-01-01

A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing. In early May 2005, an estimated 3.8??106 m3 of sulfurous, clay-rich debris and acidic water, with an accompanying acidic aerosol component, exited the crater through a tunnel at the base of a glacier that breaches the south crater rim. Over 27 km downstream, the acidic waters of the flood inundated an important salmon spawning drainage, acidifying Mother Goose Lake from surface to depth (approximately 0.5 km3 in volume at a pH of 2.9 to 3.1), killing all aquatic life, and preventing the annual salmon run. Over 2 months later, crater lake water sampled 8 km downstream of the outlet after considerable dilution from glacial meltwater was a weak sulfuric acid solution (pH = 3.2, SO4 = 504 mg/L, Cl = 53.6 mg/L, and F = 7.92 mg/L). The acid flood waters caused severe vegetation damage, including plant death and leaf kill along the flood path. The crater lake drainage was accompanied by an ambioructic flow of acidic aerosols that followed the flood path, contributing to defoliation and necrotic leaf damage to vegetation in a 29 km2 area along and above affected streams, in areas to heights of over 150 m above stream level. Moss species killed in the event contained high levels of sulfur, indicating extremely elevated atmospheric sulfurcontent. The most abundant airborne phytotoxic constituent was likely sulfuric acid aerosols that were generated during the catastrophic partial crater lake drainage event. Two mechanisms of acidic aerosol formation are proposed: (1) generation of aerosol mist through turbulent flow of acidic water and (2) catastrophic gas exsolution. This previously undocumented phenomenon of simultaneous vegetationdamaging acidic aerosols accompanying drainage of an acidic crater

An overview of a uranium acidic mining lake (Caldas, Brazil): composition of the zooplankton community and limno-chemical aspects

Energy Technology Data Exchange (ETDEWEB)

Nascimento, H.; Ferrari, C.; Roque, C.V.; Nascimento, M.R. [Brazilian Nuclear Energy Commission/Pocos de Caldas Laboratory (Brazil); Wisniewski, M.J. [Alfenas Federal University/Limnology Laboratory (Brazil); Rodgher, S. [Universidade Estadual Paulista Julio de Mesquita Filho/Science and Technology Laboratory (Brazil)

2014-07-01

This research represents an attempt to fill a gap in the information on the zooplankton composition and limno-chemical aspects of the uranium pit lake (Osamu Utsumi Pit, Brazil), affected by acid mine drainage. In the present study water samples were collected three-monthly, for a period of one year (2008-2009). The water samples from the uranium pit lake showed moderately acidic pH values (3.6 to 4.1), high values of the electrical conductivity, sulfate, uranium, fluoride, zinc, manganese and aluminum concentrations. The Rotifera cephalodella sp., Keratella americana, K. cochlearis, Bdelloidea order and the Cladocera Bosminopsis deitersi, Bosmina sp., were registered in the samples from the uranium pit lake with ADM. Of the species registered the Bdelloidea order was the most important in terms of density (17,500 - 77,778 ind m{sup -3}), since it occurred throughout the whole sampling period. In this study, probably the combined effect of moderately acid pH values and other potentially co-stressors factors, for example the high concentrations of stable and radioactive chemical species, could have influenced this richness and also the composition of the zooplankton species in the water samples from the uranium pit lake. Document available in abstract form only. (authors)

Recently surveyed lakes in northern Manitoba and Saskatchewan, Canada: characteristics and critical loads of acidity

Directory of Open Access Journals (Sweden)

Isaac WONG

2010-08-01

Full Text Available Based on minimal information, lakes in the western Canadian provinces of Manitoba (MB and Saskatchewan (SK have long been considered unaffected by acid rain. However, emissions of acidifying pollutants from MB smelters and oil sand processing in Alberta (AB may pose a developing threat. Surveys of 347 lakes located on geologically sensitive terrain in northern MB and SK were conducted to assess their acidification sensitivity and status. The survey domain (~193,000 km2 contained 81,494 lakes ≥1 ha in area. Small lakes dominated the inventory in terms of numbers, and large lakes dominated in terms of area. Survey lakes were selected using a stratified-random sampling design in 10 sampling blocks within the overall survey domain. Few lakes had pH <6, and only three (all in SK were acidic, i.e., Gran Alkalinity (Alk <0 μeq L–1. A broad range in lake sensitivity was apparent, and very sensitive lakes (low specific conductance, base cations and Alk were present in all sampling blocks. Dissolved organic carbon (DOC was an important constituent of many lakes. Critical loads (CL of acidity calculated using the Steady-State Water Chemistry model (SSWC revealed extremely low 5th percentile values for every block (range 1.9 to 52.7 eq ha–1 y–1. Block CL exceedances calculated using estimated S and N deposition for 2002 ranged from 54.5 to 909 eq ha–1 y–1. The largest exceedances were for sampling blocks located near smelter sources or downwind of the oil sands. Lake chemistry revealed by our surveys was compared to others conducted both nearby and outside Canada.

Liming the acid lake Hovvatn, Norway: a whole-ecosystem study

Energy Technology Data Exchange (ETDEWEB)

Raddum, G G; Brettum, P; Matzow, D; Nilssen, J P; Skov, A; Sveaelv, T; Wright, R F

1986-12-01

Hovvatn, a 1 sq. km. chronically-acidified lake in southernmost Norway, was treated with 200 tonne of powdered limestone in March 1981. An additional 40 tonne were added to a 0.046 sq km pond (Pollen) draining into Hovvatn. The lakes were stocked with brown trout in June 1981 and in each subsequent year. At ice-out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5 (Pollen), Ca and alkalinity increased, and total Al decreased by 120 ..mu..g/l. None of the other major ions exhibited significant changes in concentration. Total organic C and P increased after liming. The phytoplankton community was dominated by chrysophytes and did not change significantly following liming. The zooplankton community was typical of acid lakes prior to liming. There was a clear succession in species dominance following treatment, although no new species immigrated to the lakes. Zoobenthos changed from a community characterized by low abundance and reduced number of species to increased abundance of oligochaetes, mayflies and chironomids. Hovvatn and Pollen were barren of fish prior to stocking. The stocked fish showed remarkably high growth rate during the first years. Liming apparently improved conditions for zoobenthos, enhancing the processing of fine detritus which in turn resulted in elevated levels of TOC and P in the lakewaters during the first year after liming. The oligotrophication process typical of acid lakes was temporarily reversed by liming. The interactions between groups of organisms in Hovvatn and Pollen indicates that many years are required before a new steady-state can be attained following liming. 61 references.

Methanogenesis in the sediment of the acidic Lake Caviahue in Argentina

Science.gov (United States)

Koschorreck, Matthias; Wendt-Potthoff, Katrin; Scharf, Burkhard; Richnow, Hans H.

2008-12-01

The biogeochemistry of methane in the sediments of Lake Caviahue was examined by geochemical analysis, microbial activity assays and isotopic analysis. The pH in the water column was 2.6 and increased up to a pH of 6 in the deeper sediment pore waters. The carbon isotope composition of CH 4 was between - 65 and - 70‰ which is indicative for the biological origin of the methane. The enrichment factor ɛ increased from - 46‰ in the upper sediment column to more than - 80 in the deeper sediment section suggesting a transition from acetoclastic methanogenesis to CO 2 reduction with depth. In the most acidic surface layer of the sediment (pH Copahue Volcano, supported high rates of sulfate reduction which probably raised the pH and created favorable conditions for methanogens in deeper sediment layers.

Acid loading test (pH)

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/003615.htm Acid loading test (pH) To use the sharing features on this page, please enable JavaScript. The acid loading test (pH) measures the ability of the ...

Light Rare Earth Elements enrichment in an acidic mine lake (Lusatia, Germany)

International Nuclear Information System (INIS)

Bozau, Elke; Leblanc, Marc; Seidel, Jean Luc; Staerk, Hans-Joachim

2004-01-01

The distribution of Rare Earth Elements (REE) was investigated in the acidic waters (lake and groundwater) of a lignite mining district (Germany). The Fe- and SO 4 -rich lake water (pH 2.7) displays high REE contents (e.g. La∼70 μg/l, Ce∼160 μg/l) and an enrichment of light REE (LREE) in the NASC normalised pattern. Considering the hydrodynamic model and geochemical data, the lake water composition may be calculated as a mixture of inflowing Quaternary and mining dump groundwaters. The groundwater of the dump aquifer is LREE enriched. Nevertheless, the leachates of dump sediments generally have low REE contents and display flat NASC normalised patterns. However, geochemical differences and REE pattern in undisturbed lignite (LREE enriched pattern and low water soluble REE contents) and the weathered lignite of the dumps (flat REE pattern and high water soluble REE contents) suggest that lignite is probably the main REE source rock for the lake water

Acid rain recovery may help to mitigate the impacts of climate change on thermally sensitive fish in lakes across eastern North America.

Science.gov (United States)

Warren, Dana R; Kraft, Clifford E; Josephson, Daniel C; Driscoll, Charles T

2017-06-01

From the 1970s to 1990s, more stringent air quality regulations were implemented across North America and Europe to reduce chemical emissions that contribute to acid rain. Surface water pH slowly increased during the following decades, but biological recovery lagged behind chemical recovery. Fortunately, this situation is changing. In the past few years, northeastern US fish populations have begun to recover in lakes that were historically incapable of sustaining wild fish due to acidic conditions. As lake ecosystems across the eastern United States recover from acid deposition, the stress to the most susceptible populations of native coldwater fish appears to be shifting from acidification effects to thermal impacts associated with changing climate. Extreme summer temperature events - which are expected to occur with increasing frequency in the coming century - can stress and ultimately kill native coldwater fish in lakes where thermal stratification is absent or highly limited. Based on data from northeastern North America, we argue that recovery from acid deposition has the potential to improve the resilience of coldwater fish populations in some lakes to impacts of climate change. This will occur as the amount of dissolved organic carbon (DOC) in the water increases with increasing lake pH. Increased DOC will reduce water clarity and lead to shallower and more persistent lake thermoclines that can provide larger areas of coldwater thermal refuge habitat. Recovery from acidification will not eliminate the threat of climate change to coldwater fish, but secondary effects of acid recovery may improve the resistance of coldwater fish populations in lakes to the effects of elevated summer temperatures in historically acidified ecosystems. This analysis highlights the importance of considering the legacy of past ecosystem impacts and how recovery or persistence of those effects may interact with climate change impacts on biota in the coming decades. © 2016 John

Inter- and intra-annual chemical variability during the ice-free season in lakes with different flushing rates and acid deposition histories.

Science.gov (United States)

Arnott, Shelley E; Dillon, Peter J; Somers, Keith; Keller, Bill

2003-01-01

Quantifying chemical variability in different lake types is important for the assessment of both chemical and biological responses to environmental change. For monitoring programs that emphasize a large number of lakes at the expense of frequent samples, high variability may influence how representative single samples are of the average conditions of individual lakes. Intensive temporal data from long-term research sites provide a unique opportunity to assess chemical variability in lakes with different characteristics. We compared the intra- and inter-annual variability of four acidification related variables (Gran alkalinity, pH, sulphate concentration, and total base cation concentration) in four lakes with different flushing rates and acid deposition histories. Variability was highest in lakes with high flushing rates and was not influenced by historic acid deposition in our study lakes. This has implications for the amount of effort required in monitoring programs. Lakes with high flushing rates will require more frequent sampling intervals than lakes with low flushing rates. Consideration of specific lake types should be included in the design of monitoring programs.

Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 280 000 years

Science.gov (United States)

Ajioka, T.; Yamamoto, M.; Takemura, K.; Hayashida, A.; Kitagawa, H.

2014-10-01

We generated a 280 000 yr record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores. Our aim was to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on orbital timescales. Because the water pH in Lake Biwa is determined by phosphorus and alkali cation inputs, the record of water pH should indicate the changes in precipitation and temperature in central Japan. Comparison with a pollen assemblage in a Lake Biwa core suggests that lake water pH was determined by summer temperature in the low-eccentricity period before 55 ka, while it was determined by summer precipitation in the high-eccentricity period after 55 ka. From 130 to 55 ka, the variation in lake pH (summer precipitation) lagged behind that in summer temperature by several thousand years. This perspective is consistent with the conclusions of previous studies (Igarashi and Oba, 2006; Yamamoto, 2009), in that the temperature variation preceded the precipitation variation in central Japan.

Acidic pit lakes. The legacy of coal and metal surface mines

Energy Technology Data Exchange (ETDEWEB)

Geller, Walter; Schultze, Martin [Helmholtz Centre for Environmental Research - UFZ, Magdeburg (Germany); Wolkersdorfer, Christian (eds.) [Cape Breton Univ., Sydney, NS (Canada). Industrial Research Chair in Mine Water Remediation and Management; International Mine Water Association, Wendelstein (Germany). General Secretary; Kleinmann, Robert

2013-07-01

This monograph provides an international perspective on pit lakes in post-mining landscapes, including the problem of geogenic acidification. Much has been learned during the last decade through research and practical experience on how to mitigate or remediate the environmental problems of acidic pit lakes. In the first part of the book, general scientific issues are presented in 21 contributions from the fields of geo-environmental science, water chemistry, lake physics, lake modeling, and on the peculiar biological features that occur in the extreme habitats of acidic pit lakes. Another chapter provides an overview of methods currently used to remediate acidic pit lakes and treat outflowing acidic water. The second part of the book is a collection of regional surveys of pit lake problems from three European countries and Australia, and case studies of various individual representative lakes. A final case study provides an innovative approach to assessing the economic value of new pit lakes and balancing the costs and benefits, a valuable tool for decision makers.

Geochemical processes assessed by Rare Earth Elements fractionation at “Laguna Verde” acidic-sulphate crater lake (Azufral volcano, Colombia)

International Nuclear Information System (INIS)

Inguaggiato, Claudio; Burbano, Viviana; Rouwet, Dmitri; Garzón, Gustavo

2017-01-01

The geochemical behaviour of major elements, Fe, Al, Mn, and Rare Earth Elements (REE) was investigated in the “Laguna Verde” acidic crater lake of Azufral volcano (Colombia). The cold lake water (T close to 10 °C) is sulphate-dominated, due to absorption and oxidation of H_2S (pH 2.1–2.7, Eh 196–260 mV), and Na-enriched (Total Dissolved Solids 0.79 g L"−"1). The total amount of REE dissolved in the lake ranges from 3.3 to 9.1 ppb. The REE patterns normalized to the local rocks show a Light Rare Earth Elements (LREE) depletion quite constant in the 15 samples. Similar patterns were already found in the acidic sulphate springs of Nevado del Ruiz volcano-hydrothermal system, caused by the precipitation of alunite and jarosite, absorbing LREE and hence removing them from solution. Alunite and jarosite minerals are not oversaturated at chemical-physical conditions within the lake itself, but alunite becomes oversaturated for temperatures above ≈100 °C, reigning in the underlying hydrothermal system. Water temperatures close to 75 °C were found in the northern part of the lake. Coupling the distribution of REE in lake water (LREE depleted) and the saturation indexes, we suggest that the distribution of REE in the lake water is the result of the alunite precipitation in the northern part of the lake and/or in the deeper hydrothermal system. The acidic hydrothermal fluids mobilize the REE with contents up to ≈5 orders of magnitude higher than seawater; acidic-hydrothermal systems, such as acidic crater lakes, can hence be considered potential REE “reservoirs”. - Highlights: • Acidic crater lakes can be considered potential Rare Earth Elements reservoirs. • Alunite precipitation removes Light Rare Earth Elements. • Rare Earth Elements identify geochemical processes in volcano-hydrothermal systems.

Parent Body Influences on Amino Acids in the Tagish Lake Meteorite

Science.gov (United States)

Glavin, D. P.; Callahan, M. P.; Dworkin, J. P.; Elsila, J. E.; Herd, C. D. K.

2010-01-01

The Tagish Lake meteorite is a primitive C2 carbonaceous chondrite with a mineralogy, oxygen isotope, and bulk chemical. However, in contrast to many CI and CM carbonaceous chondrites, the Tagish Lake meteorite was reported to have only trace levels of indigenous amino acids, with evidence for terrestrial L-amino acid contamination from the Tagish Lake meltwater. The lack of indigenous amino acids in Tagish Lake suggested that they were either destroyed during parent body alteration processes and/or the Tagish Lake meteorite originated on a chemically distinct parent body from CI and CM meteorites where formation of amino acids was less favorable. We recently measured the amino acid composition of three different lithologies (11h, 5b, and 11i) of pristine Tagish Lake meteorite fragments that represent a range of progressive aqueous alteration in order 11h amino acids found in hot-water extracts of the Tagish Lake fragments were determined by ultra performance liquid chromatography fluorescence detection and time of flight mass spectrometry coupled with OPA/NAC derivatization. Stable carbon isotope analyses of the most abundant amino acids in 11h were measured with gas chromatography coupled with quadrupole mass spectrometry and isotope ratio mass spectrometry.

Acidic deposition: State of science and technology. Report 11. Historical changes in surface-water acid-base chemistry in response to acidic deposition. Final report

International Nuclear Information System (INIS)

Sullivan, T.J.; Small, M.J.; Kingston, J.C.; Bernert, J.A.; Thomas, D.R.

1990-09-01

The objectives of the analyses reported in the State of Science report are to: identify the lake and stream populations in the United States that have experienced chronic changes in biologically significant constituents of surface water chemistry (e.g. pH, Al) in response to acidic deposition; quantify biologically meaningful historical changes in chronic surface water chemistry associated with acidic deposition, with emphasis on ANC, pH, and Al; estimate the proportion of lakes nor acidic that were not acidic in pre-industrial times; estimate the proportional response of each of the major chemical constituents that have changed in response to acidic deposition using a subset of statistically selected Adirondack lakes for which paleolimnological reconstructions of pre-industrial surface water chemistry have been performed; evaluate and improve, where appropriate and feasible, empirical models of predicting changes in ANC; and evaluate the response of seepage lakes to acidic deposition

Effects of experimental acidification on mobilisation of metals from sediments of limed and non-limed lakes

International Nuclear Information System (INIS)

Waellstedt, Teresia; Borg, Hans

2003-01-01

In order to study the influence of pH on the mobilisation of metals from lake sediments, intact sediment cores with overlying water were sampled from one lime treated lake and one acidified lake. The overlying water of two cores from each lake was successively acidified to pH 4.2 over a period of 3 months. In the acid treated samples from the limed lake, the initial concentrations of Al, Cd, Mn, Pb and Zn in the overlying water were generally lower and the final concentrations were higher than in the acid treated samples from the acidified lake. The labile inorganic fraction of Al (Al i ) was increasingly dominating as pH decreased. Redox potential and pH in the sediment indicated that the upper two centimetres were involved in the exchange reactions. The experiment showed that mobilisation of metals from sediments can occur and the results indicated that mobilisation could contribute to increased concentrations of metals in lake water during reacidification of formerly lime treated lakes. - Reacidification leads to mobilisation of metals from lake sediments

Volcanic nutrient inputs and trophic state of Lake Caviahue, Patagonia, Argentina

Science.gov (United States)

Pedrozo, Fernando L.; Temporetti, Pedro F.; Beamud, Guadalupe; Diaz, Mónica M.

2008-12-01

The strategies for eutrophication control, remediation, and policy management are often defined for neutral to alkaline freshwater systems, as they are most suitable for human use. The influence of nutrients on eutrophication in a naturally-acidic lake is poorly known. The main purpose of the present work is to evaluate the significance of volcanic nutrients in the control of the trophic state of the acidic Lake Caviahue, located at North Patagonia, Argentina. Acidic water systems were most studied on artificial acidified lakes, such as mining lakes in Germany or pit lakes in the United States. Lake Caviahue received a very high P load (42-192 ton P/yr) and low N load (14 ton N/yr), mainly as ammonium with quite low N:P ratios (Copahue volcano represents the main natural contribution of nutrients and acidity to the Lake Caviahue. The lake is oligotrophic in terms of CHLa. Neither the transparency nor the nutrient, dissolved or particulate, contents are to date representative of the trophic state of the lake. High P loads do not imply the eutrophication of the lake. We suggest that nitrogen and not phosphorus represents the key control nutrient in volcanically acidified lakes as TON was better related to CHLa observed (0.13-0.36 mg/m 3) in the lake. The pH increased around one unit (pH 2.0-3.0) during the last five years suggesting that the lake has not yet returned to a stable state.

Acid rain still plaguing lakes and loons

International Nuclear Information System (INIS)

Anon.

2000-01-01

Acid rain monitoring began more than two decades ago by Environment Canada and recent numbers indicate that acid levels in the inland waters barely respond to the reductions in sulphur dioxide (SO 2 ). Under the Canada-U.S. Air Quality Agreement, both countries have committed to reduce SO 2 emissions by 50 per cent over 1980 levels and to reduce nitrogen oxide emissions. Although Canada's goal for SO 2 reductions was achieved in 1994, the nitrogen oxide emissions remained relatively constant. A study of 152 lakes in southeastern Canada indicated that the lakes are only 41 per cent less acidic than they were 20 years ago. The area studied is more vulnerable since it received more acid rain than any other part of the country and the granite bedrock of the Canadian Shield shows a weakness in neutralizing ability. The acidification has caused declines in the populations of fish and invertebrate which loons rely on to survive. A volunteer-based program called Canadian Lakes Loon Survey supported by Environment Canada and other partners began annual monitoring of the breeding success of loons on about 800 lakes. The results showed a decline in the proportion of successful breeding between 1981 and 1997. The decline was more pronounced where the acid level was greatest. Near Sudbury, Ontario, where the emissions of SO 2 declined dramatically, invertebrates started reappearing and fish populations were successfully re-established

Influence of lake water pH and alkalinity on the distribution of coreand intact polar branched glycerol dialkyl glycerol tetraethers (GDGTs) in lakes

NARCIS (Netherlands)

Schoon, P.L.; de Kluijver, A.; Middelburg, J.J.; Downing, J.A.; Sinninghe Damsté, J.S.; Schouten, S.

2013-01-01

Branched glycerol dialkyl glycerol tetraethers (GDGTs) are bacterial membrane lipids, ubiquitously present in soils and peat bogs, as well as in rivers, lakes and lake sediments. Their distribution in soil is controlled mainly by pH and mean annual air temperature, but the controls on their

Spatial characterization of acid rain stress in Canadian Shield Lakes

Science.gov (United States)

Tanis, Fred J.

1987-01-01

The acidification of lake waters from airborne pollution is of continental proportions both in North America and Europe. A major concern of the acid rain problem is the cumulative ecosystem damage to lakes and forest. The number of lakes affected in northeastern U.S. and on the Canadian Shield is though to be enormous. How seasonal changes in lake transparency are related to annual acidic load was examined. The relationship between variations in lake acidification and ecophysical units was also examined. The utility of Thematic Mapper based observations to measure seasonal changes in the optical transparency in acid lakes was investigated. The potential for this optical response is related to a number of local ecophysical factors with bedrock geology being, perhaps, the most important. Other factors include sulfate deposition, vegetative cover, and terrain drainage/relief. The area of southern Ontario contains a wide variety of geologies from the most acid rain sensitive granite quartzite types to the least sensitive limestone dolomite sediments. Annual sulfate deposition ranges from 1.0 to 4.0 grams/sq m.

Carbon and nitrogen stable isotope ratios analysis of food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) in strongly acidic lake Katanuma

International Nuclear Information System (INIS)

Doi, Hideyuki; Kikuchi, Eisuke; Shikano, Shuichi

2001-01-01

The food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) were analyzed using carbon and nitrogen stable isotope ratios in Lake Katanuma. Lake Katanuma is a volcanic and strongly acidic lake (average pH 2.2). In Lake Katanuma, potential sources of diets for the chironomid larvae are limited including a benthic diatom (Pinnularia braunii), a phytoplankton (Chlamydomonas acidophila), sulfate oxidizing bacteria, and vascular plants supplied from vegetation surrounding the lake. Based on the average carbon and nitrogen isotope ratios among these potential sources and sediment, benthic diatoms were considered to be most probable food source of the chironomid larvae. δ 13 C values of the chironomid were significantly different among seasons and habitat depths, suggesting that diet of C. acerbiphilus changed seasonally and with habitat depth. (author)

Influence of lake water pH and alkalinity on the distribution of core and intact polar branched glycerol dialkyl glycerol tetraethers (GDGTs) in lakes

NARCIS (Netherlands)

Schoon, P.L.; de Kluijver, A.; Middelburg, J.J.; Downing, J.A.; Sinninghe Damsté, J.S.; Schouten, S.

2013-01-01

Branched glycerol dialkyl glycerol tetraethers (GDGTs) are bacterial membrane lipids, ubiquitously present in soils and peat bogs, as well as in rivers, lakes and lake sediments. Their distribution in soil is controlled mainly by pH and mean annual air temperature, but the controls on their

Fish populations in a large group of acid-stressed lakes

Energy Technology Data Exchange (ETDEWEB)

Harvey, H H

1975-01-01

The purpose of this study was to determine the effects of environmental stress on the number and diversity of fish species in a group of acid-stressed lakes. The study area was the La Cloche Mountains, a series of quartzite ridges covering 1,300 km/sup 2/ along the north shore of Georgian Bay and north channel of Lake Huron. Within these ridges are 173 lakes; 68 of the largest of these made up the study sample. The lakes of the La Cloche Mountains are undergoing rapid acidification. Coincident with this there has been the loss of sport fishes from several lakes. Lakes such as Nellie, Lumsden, O.S.A., Acid and Killarney supported good sport fisheries for the lake trout, (Salvelinus namaycush) for many years, but have ceased to do so in the last 5 to 15 years. Other sport fishes, notably the walleye (Stizostedion vitreum) and smallmouth bass (micropterus dolomieu) have disappeared from some of the La Cloche Lakes. Thus recreational fishing alone could not have been the cause of the change. Beamish (1974) recorded the extreme sparcity of the three remaining fish species in O.S.A. Lake. Many of the lakes of the La Cloche mountains are accessible only with difficulty and little or no information exists for these lakes prior to this study. This precluded simple comparison of these lakes before and during acidification. This lack of historic data determined in part the approach taken in this study; a comparison of the fish communities of a group of lakes differing in degree of acid stress.

Benthic fauna of 41 acid sensitive headwater lakes in north central Ontario. [Chironomidae salinarius; Chironomidae anthracinus; Tanytarsini

Energy Technology Data Exchange (ETDEWEB)

Dermott, R.; Kelso, J.R.M.; Douglas, A.

1986-01-01

The benthic fauna of 41 nonhumic, soft water lakes situated north of lakes Superior and Huron were sampled during 1980. The pH range of the lakes sampled was 4.6 to 7.7. The benthic infauna displayed regional differences in abundance and composition, with large variation with each district. Total abundance, biomass, and number of taxa were not correlated with lake pH or alkalinity. The Chironomidae displayed a slight change in percent composition of the major species with lower pH. The Tanytarsini and Chironomus Salinarius group decreased, while C. anthracinus group increased in relative abundance in those lakes with lower pH. Other factors appear to control the distribution of the various invertebrate orders, with depth and sediment nature being important variables.

Factors influencing mercury concentrations in walleyes in northern Wisconsin lakes

Science.gov (United States)

Wiener, J.G.; Martini, R.E.; Sheffy, T.B.; Glass, G.E.

1990-01-01

The authors examined relations between mercury concentrations in walleyes Stizostedion vitreum and the characteristics of clear-water Wisconsin lakes, which spanned a broad range of pH values (5.0-8.1) and acid- neutralizing capacities (-9 to 1,017 mu eq/L). Total concentrations of mercury in axial muscle tissue of walleyes (total length, 25-56 cm) varied from 0.12 to 1.74 mu g/g wet weight. Concentrations were greatest in fish from the eight lakes with pH less than 7.0; concentrations in these fish equaled or exceeded 0.5 mu g/g in 88% of the samples analyzed and 1.0 mu g/g in 44%. In the five lakes with pH of 7.0 and above, concentrations exceeded 0.5 mu g/g in only 1 of 21 walleyes. Multiple regression revealed that lake pH and total length of fish accounted for 69% of the variation in mercury concentration in walleyes. Regression models with total length and either waterborne calcium or acid-neutralizing capacity as independent variables accounted for 67% of the variation in concentration.

Potential Influence of Climate Change on the Acid-Sensitivity of High-Elevation Lakes in the Georgia Basin, British Columbia

Directory of Open Access Journals (Sweden)

Donna Strang

2015-01-01

Full Text Available Global climate models predict increased temperature and precipitation in the Georgia Basin, British Colmbia; however, little is known about the impacts on high-elevation regions. In the current study, fifty-four high-elevation lakes (754–2005 m a.s.l. were studied to investigate the potential influence of climate change on surface water acid-sensitivity. Redundancy analysis indicated that the concentration of nitrate, dissolved organic carbon, and associated metals was significantly influenced by climate parameters. Furthermore, these components differed significantly between biogeoclimatic zones. Modelled soil base cation weathering for a subset of the study lakes (n=11 was predicted to increase by 9% per 1°C increase in temperature. Changes in temperature and precipitation may potentially decrease the pH of surface waters owing to changes in anthropogenic deposition and organic acid production. In contrast, increased soil base cation weathering may increase the critical load (of acidity of high-elevation lakes. Ultimately, the determining factor will be whether enhanced base cation weathering is sufficient to buffer changes in natural and anthropogenic acidity. Mountain and high-elevation regions are considered early warning systems to climate change; as such, future monitoring is imperative to assess the potential ramifications of climate change on the hydrochemistry and acid-sensitivity of these surface waters.

How much acidification has occurred in Adirondack region lakes (New York, USA) since preindustrial times

International Nuclear Information System (INIS)

Cumming, B.F.; Smol, J.P.; Kingston, J.C.; Charles, D.F.; Birks, H.J.B.

1992-01-01

Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. The authors estimate that approximately 80% of the target population lakes with present-day measured pH = or < 5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in Al(sub m). Estimated changes in (DOC) were small and show no consistent pattern in the acidified lakes. The study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks

Carbon and nitrogen stable isotope ratios analysis of food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) in strongly acidic lake Katanuma

Energy Technology Data Exchange (ETDEWEB)

Doi, Hideyuki [Tohoku Univ., Sendai (Japan). Graduate School of Science; Kikuchi, Eisuke; Shikano, Shuichi

2001-12-01

The food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) were analyzed using carbon and nitrogen stable isotope ratios in Lake Katanuma. Lake Katanuma is a volcanic and strongly acidic lake (average pH 2.2). In Lake Katanuma, potential sources of diets for the chironomid larvae are limited including a benthic diatom (Pinnularia braunii), a phytoplankton (Chlamydomonas acidophila), sulfate oxidizing bacteria, and vascular plants supplied from vegetation surrounding the lake. Based on the average carbon and nitrogen isotope ratios among these potential sources and sediment, benthic diatoms were considered to be most probable food source of the chironomid larvae. {delta}{sup 13}C values of the chironomid were significantly different among seasons and habitat depths, suggesting that diet of C. acerbiphilus changed seasonally and with habitat depth. (author)

Effects of low pH on decomposition, primary production and nutrient recycling in the littoral zone. Effekter ev lav ph pa produksjon, nedbrytning og stoffkretslop i littoralsonen

Energy Technology Data Exchange (ETDEWEB)

Laake, M

1976-01-01

Field experiments were conducted in Tovdal, Southern Norway, to investigate the effects of low pH on decomposition, primary production and nutrient recycling in the littoral zone of softwater lakes. Sediment cores were incubated in throughflow boxes at pH 4, variable pH (4.5 to 5.6) and pH 6 at natural temperature conditions. One dark experiment with cores enriched with allochtonous material, and one natural light experiment with natural cores were conducted, lasting for 6 and 3 months respectively. The results show an overall reduction in decomposition with increasing acidity as measured by oxygen uptake and glucose turnover, although successions and adaptions occurred in enriched cores. Primary production of the flowering plant Lobelia dortmanna l. was inhibited at pH 4, while the acid conditions favoured epiphytic growth of the filamentous algae Mougeotia sp. turnover of phosphate reflected the activity of decomposers, while no pH-effect of phosphate uptake in plants was evident. Enriched cores developed heavy growth of ilamentous fungi at the surface, indicating a shift from bacterial to fungal decomposition with increasing acidity. More reduced conditions in sediments with increasing acidity were observed in some cases, which may be due to reduced oxygen diffusion through surface layers of gelatinous masses of fungi and bacteria. The results correlate very well with field observations of increased accumulation of organics and a reduction in macrophyte vegetation reported from Swedish lakes. It is concluded that the effects observed may have serious implications for the productivity in the littoral zone and in oligotrophic soft water lakes as a whole.

Low pH levels wipe out salmon and trout populations in southernmost Norway

Energy Technology Data Exchange (ETDEWEB)

Jensen, K W; Snekvik, E

1972-01-01

A gradual decrease in pH has been documented for many Scandinavian rivers and lakes and there is little doubt that the main cause is acid precipitation (1-4). Eggs, fry, and alevins of salmon and brown trout are more susceptible to acid water than are the older fish. A gradually increasing acidity of trout biotopes will cause a reduction in the natural reproduction rate of trout, because eggs and fry succumb, while the older individuals in the population survive, at least until the pH level sinks low enough to affect them, as well. A study of the present situation and examination of the available data show that the salmon populations in a number of rivers in southernmost Norway have been nearly wiped out by low pH values. During the last twenty to thirty years, low pH levels have eliminated the brown trout populations in a great number of lakes and rivers in Norway's southernmost districts. This alarming development is continuing.

Summit crater lake observations, and the location, chemistry, and pH of water samples near Mount Chiginagak volcano, Alaska: 2004-2012

Science.gov (United States)

Schaefer, Janet R.; Scott, William E.; Evans, William C.; Wang, Bronwen; McGimsey, Robert G.

2013-01-01

maximum depth of 45 m (resulting pH ~2.9), and preventing the annual salmon run in the King Salmon River. A simultaneous release of gas and acidic aerosols from the crater caused widespread vegetation damage along the flow path. Since 2005, we have been monitoring the crater lake water that continues to flow into Mother Goose Lake by collecting surface water samples for major cation and anion analysis, measuring surface-water pH of affected drainages, and photo-documenting the condition of the summit crater lake. This report describes water sampling locations, provides a table of chemistry and pH measurements, and documents the condition of the summit crater between 2004 and 2011. In September 2013, the report was updated with results of water-chemistry samples collected in 2011 and 2012, which were added as an addendum.

Forest blowdown and lake acidification

International Nuclear Information System (INIS)

Dobson, J.E.; Rush, R.M.; Peplies, R.W.

1990-01-01

The authors examine the role of forest blowdown in lake acidification. The approach combines geographic information systems (GIS) and digital remote sensing with traditional field methods. The methods of analysis consist of direct observation, interpretation of satellite imagery and aerial photographs, and statistical comparison of two geographical distributions-one representing forest blow-down and another representing lake chemistry. Spatial and temporal associations between surface water pH and landscape disturbance are strong and consistent in the Adirondack Mountains of New York. In 43 Adirondack Mountain watersheds, lake pH is associated with the percentage of the watershed area blown down and with hydrogen ion deposition (Spearman rank correlation coefficients of -0.67 and -0.73, respectively). Evidence of a temporal association is found at Big Moose Lake and Jerseyfield Lake in New York and the Lygners Vider Plateau of Sweden. They conclude that forest blowdown facilities the acidification of some lakes by altering hydrologic pathways so that waters (previously acidified by acid deposition and/or other sources) do not experience the neutralization normally available through contact with subsurface soils and bedrock. Increased pipeflow is suggested as a mechanism that may link the biogeochemical impacts of forest blowdown to lake chemistry

Assessment of lake sensitivity to acidic deposition in national parks of the Rocky Mountains

Science.gov (United States)

Nanus, L.; Williams, M.W.; Campbell, D.H.; Tonnessen, K.A.; Blett, T.; Clow, D.W.

2009-01-01

The sensitivity of high-elevation lakes to acidic deposition was evaluated in five national parks of the Rocky Mountains based on statistical relations between lake acid-neutralizing capacity concentrations and basin characteristics. Acid-neutralizing capacity (ANC) of 151 lakes sampled during synoptic surveys and basin-characteristic information derived from geographic information system (GIS) data sets were used to calibrate the statistical models. The explanatory basin variables that were considered included topographic parameters, bedrock type, and vegetation type. A logistic regression model was developed, and modeling results were cross-validated through lake sampling during fall 2004 at 58 lakes. The model was applied to lake basins greater than 1 ha in area in Glacier National Park (n = 244 lakes), Grand Teton National Park (n = 106 lakes), Great Sand Dunes National Park and Preserve (n = 11 lakes), Rocky Mountain National Park (n = 114 lakes), and Yellowstone National Park (n = 294 lakes). Lakes that had a high probability of having an ANC concentration 3000 m, with 80% of the catchment bedrock having low buffering capacity. The modeling results indicate that the most sensitive lakes are located in Rocky Mountain National Park and Grand Teton National Park. This technique for evaluating the lake sensitivity to acidic deposition is useful for designing long-term monitoring plans and is potentially transferable to other remote mountain areas of the United States and the world.

Effects of acidity and alkalinity on the stability of amidohydrolases in freshwater

Energy Technology Data Exchange (ETDEWEB)

Frankenberger, W.T. Jr.; Page, A.L.

1983-01-01

The influence of acidity and alkalinity on the enzymatic hydrolysis of amide-N in the aquatic system was investigated by determining the stability of L-asparaginase (EC (Enzyme Commission) 3.5.1.1), L-glutaminase (EC 3.5.1.2), and amidase (EC 3.5.1.4), and urease (EC 3.5.1.5) with respect to pH in three freshwater lakes. The water samples were first incubated at the indicated buffer pH (1-13) for 24 h; then each enzyme was assayed at its optimal pH (pH/sub opt/) under standardized conditions. L-Asparaginase retained essentially 100% of its activity within the pH range of 6-7 in Lake Evans and Lake Matthews, and 5-7 in Lake Perris. L-Glutaminase was active between pH 6 and 7 in the water samples surveyed. Amidase remained completely active at pH ranges of 4-8 in Lake Evans, 4-7 in Lake Matthews, and 5-8 in Lake Perris. Urease remained active over a broad pH range of 5-9 in Lake Evans, 5-8 in Lake Matthews, and 4-8 in Lake Perris. There was a progressive loss in enzyme activity below and above these pH ranges. The results suggest that the decline in aquatic amidohydrolase activities in relation to the pH-profile near their pH/sub opt/ was caused by a reversible reaction involving the ionization or deionization of functional groups of the active center of the protein, but under highly acidic or alkaline conditions (pH <4 to >9) the reduced activitiy appears to be due to irreversible inactivation of the enzyme.

Zooplankton community response to experimental acidification in boreal shield lakes with different ecological histories

Energy Technology Data Exchange (ETDEWEB)

Derry, A.M.; Arnott, S.E. [Queen' s Univ., Kingston, ON (Canada). Dept. of Biology

2007-06-15

This study investigated the adaptive response of crustacean zooplankton to widespread regional acidification at the Killarney Provincial Park in Ontario. Mesocosm experiments were conducted in 2 circumneutral lakes with different acidification histories. A reciprocal transplant field enclosure experiment was conducted to assess whether the zooplankton community within the acid-recovering boreal shield lake showed evidence of increased acid tolerance to historical acidification following a 6 year period in which the lake's pH was 6.0. The enclosures were filled with epilimnetic water from the lake. Zooplankton from other lakes in the area were used. Zooplankton and water samples were collected from the enclosures once a week. Shannon-Wiener indices, species richness, and total abundance of the zooplankton were calculated for each sample day. Repeated measures analyses of variance (RM-ANOVAs) were used to test for the effects of the incubation lake, the zooplankton source, and the pH. Species abundance data were log{sub 10} transformed to improve homogeneity of variances and normality. Principle components analysis was conducted on species abundances to infer the influence of treatments on zooplankton community composition. Zooplankton were also transferred from 1 lake to the other in order to determine if subtle differences in local water chemistry and food conditions were limiting the recovery of species in acid-recovering lakes. The study showed that 2 key species, H. gibberum and L. minutus, contributed to community-level differences to acid tolerance of zooplankton with different acidification histories. It was concluded that zooplankton with adaptable acid tolerances may monopolize resources in acidified and acid-recovering lakes, and may contribute to the delayed recolonization of other taxa. 62 refs., 3 tabs., 6 figs.

Geochemical behavior and dissolved species control in acid sand pit lakes, Sepetiba sedimentary basin, Rio de Janeiro, SE - Brazil

Science.gov (United States)

Marques, Eduardo D.; Sella, Sílvia M.; Bidone, Edison D.; Silva-Filho, Emmanoel V.

2010-12-01

This work shows the influence of pluvial waters on dissolved components and mineral equilibrium of four sand pit lakes, located in the Sepetiba sedimentary basin, SE Brazil. The sand mining activities promote sediment oxidation, lowering pH and increasing SO 4 contents. The relatively high acidity of these waters, similar to ore pit lakes environment and associated acid mine drainage, increases weathering rate, especially of silicate minerals, which produces high Al concentrations, the limiting factor for fish aquaculture. During the dry season, basic cations (Ca, Mg, K and Na), SiO 2 and Al show their higher values due to evapoconcentration and pH are buffered. In the beginning of the wet season, the dilution factor by rainwater increases SO 4 and decreases pH values. The aluminum monomeric forms (Al(OH) 2+ and Al(OH) 2+), the most toxic species for aquatic organisms, occur during the dry season, while AlSO 4+ species predominate during the wet season. Gibbsite, allophane, alunite and jurbanite are the reactive mineral phases indicated by PHREEQC modeling. During the dry season, hydroxialuminosilicate allophane is the main phase in equilibrium with the solution, while the sulphate salts alunite and jurbanite predominate in the rainy season due to the increasing of SO 4 values. Gibbsite is also in equilibrium with sand pit lakes waters, pointing out that hydrolysis reaction is a constant process in the system. Comparing to SiO 2, sulphate is the main Al retriever in the pit waters because the most samples (alunite and jurbanite) are in equilibrium with the solution in both seasons. This Al hydrochemical control allied to some precaution, like pH correction and fertilization of these waters, allows the conditions for fishpond culture. Equilibrium of the majority samples with kaolinite (Ca, Mg, Na diagrams) and primary minerals (K diagram) points to moderate weathering rate in sand pit sediments, which cannot be considered for the whole basin due to the anomalous

Decomposition of Alternative Chirality Amino Acids by Alkaliphilic Anaerobe from Owens Lake, California

Science.gov (United States)

Townsend, Alisa; Pikuta, Elena V.; Guisler, Melissa; Hoover, Richard B.

2009-01-01

The study of alkaliphilic microbial communities from anaerobic sediments of Owens and Mono Lakes in California led to the isolation of a bacterial strain capable of metabolizing amino acids with alternative chirality. According to the phylogenetic analysis, the anaerobic strain BK1 belongs to the genus Tindallia; however, despite the characteristics of other described species of this genus, the strain BK1 was able to grow on D-arginine and Dlysine. Cell morphology of this strain showed straight, motile, non-spore-forming rods with sizes 0.45 x 1.2-3 microns. Physiological characteristics of the strain showed that it is catalase negative, obligately anaerobic, mesophilic, and obligately alkaliphilic. This isolate is unable to grow at pH 7 and requires CO3 (2-) ions for growth. The strain has chemo-heterotrophic metabolism and is able to ferment various proteolysis products and some sugars. It plays the role of a primary anaerobe within the trophic chain of an anaerobic microbial community by the degradation of complex protein molecules to smaller and less energetic molecules. The new isolate requires NaCl for growth, and can grow within the range of 0.5-13 %, with the optimum at 1 % NaCl (w/v). The temperature range for the growth of the new isolate is 12-40 C with optimum at 35 C. The pH range for the growth of strain BK1 occurs between 7.8 and 11.0 with optimum at 9.5. This paper presents detailed physiological characteristics of the novel isolate from Owens Lake, a unique relic ecosystem of Astrobiological significance, and makes an accent on the ability of this strain to utilize L-amino acids.

Characteristics of fatty acid composition of Gammarus lacustris inhabiting lakes with and without fish.

Science.gov (United States)

Makhutova, O N; Sharapova, T A; Kalachova, G S; Shulepina, S P; Gladyshev, M I

2016-01-01

The effect of a biotic factor--the presence of predatory fish in water--on the composition and content of fatty acids in crustaceans was studied in the populations of the lake amphipod Gammarus lacustris from two lakes with fish and three lakes without fish. It was found that, at an overall increase in the quantity and quality of food resources (namely, increase in the content of eicosapentaenoic acid and docosahexaenoic acid (DHA) in the biomass), the relative rate of DHA accumulation in gammarids in the lakes without fish is higher than in the lake with fish.

Titratable acidity of beverages influences salivary pH recovery.

Science.gov (United States)

Tenuta, Livia Maria Andaló; Fernández, Constanza Estefany; Brandão, Ana Carolina Siqueira; Cury, Jaime Aparecido

2015-01-01

A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

Titratable acidity of beverages influences salivary pH recovery

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Livia Maria Andaló TENUTA

2015-01-01

Full Text Available A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively. Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

Acidic pH promotes intervertebral disc degeneration: Acid-sensing ion channel -3 as a potential therapeutic target.

Science.gov (United States)

Gilbert, Hamish T J; Hodson, Nathan; Baird, Pauline; Richardson, Stephen M; Hoyland, Judith A

2016-11-17

The aetiology of intervertebral disc (IVD) degeneration remains poorly understood. Painful IVD degeneration is associated with an acidic intradiscal pH but the response of NP cells to this aberrant microenvironmental factor remains to be fully characterised. The aim here was to address the hypothesis that acidic pH, similar to that found in degenerate IVDs, leads to the altered cell/functional phenotype observed during IVD degeneration, and to investigate the involvement of acid-sensing ion channel (ASIC) -3 in the response. Human NP cells were treated with a range of pH, from that of a non-degenerate (pH 7.4 and 7.1) through to mildly degenerate (pH 6.8) and severely degenerate IVD (pH 6.5 and 6.2). Increasing acidity of pH caused a decrease in cell proliferation and viability, a shift towards matrix catabolism and increased expression of proinflammatory cytokines and pain-related factors. Acidic pH resulted in an increase in ASIC-3 expression. Importantly, inhibition of ASIC-3 prevented the acidic pH induced proinflammatory and pain-related phenotype in NP cells. Acidic pH causes a catabolic and degenerate phenotype in NP cells which is inhibited by blocking ASIC-3 activity, suggesting that this may be a useful therapeutic target for treatment of IVD degeneration.

Geochemical characterization of acid mine lakes in northwest Turkey and their effect on the environment.

Science.gov (United States)

Yucel, Deniz Sanliyuksel; Baba, Alper

2013-04-01

Mining activity generates a large quantity of mine waste. The potential hazard of mine waste depends on the host mineral. The tendency of mine waste to produce acid mine drainage (AMD) containing potentially toxic metals depends on the amounts of sulfide, carbonate minerals, and trace-element concentrations found in ore deposits. The acid mine process is one of the most significant environmental challenges and a major source of water pollution worldwide. AMD and its effects were studied in northwest Turkey where there are several sedimentary and hydrothermal mineral deposits that have been economically extracted. The study area is located in Can county of Canakkale province. Canakkale contains marine, lagoon, and lake sediments precipitated with volcanoclastics that occurred as a result of volcanism, which was active during various periods from the Upper Eocene to Plio-Quaternary. Can county is rich in coal with a total lignite reserve >100 million tons and contains numerous mines that were operated by private companies and later abandoned without any remediation. As a result, human intervention in the natural structure and topography has resulted in large open pits and deterioration in these areas. Abandoned open pit mines typically fill with water from runoff and groundwater discharge, producing artificial lakes. Acid drainage waters from these mines have resulted in the degradation of surface-water quality around Can County. The average pH and electrical conductivity of acid mine lakes (AMLs) in this study were found to be 3.03 and 3831.33 μS cm(-1), respectively. Total iron (Fe) and aluminum (Al) levels were also found to be high (329.77 and 360.67 mg L(-1), respectively). The results show that the concentration of most elements, such as Fe and Al in particular, exceed national and international water-quality standards.

The influence of total organic carbon (TOC) on the relationship between acid neutralizing capacity (ANC) and fish status in Norwegian lakes.

Science.gov (United States)

Lydersen, Espen; Larssen, Thorjørn; Fjeld, Eirik

2004-06-29

Acid neutralizing capacity (ANC) is the parameter most commonly used as chemical indicator for fish response to acidification. Empirical relationships between fish status of surface waters and ANC have been documented earlier. ANC is commonly calculated as the difference between base cations ([BC]=[Ca2+]+[Mg2+]+[N+]+[K+]) and strong acid anions ([SAA]=[SO4(2)-]+[NO3-]+[Cl-]). This is a very robust calculation of ANC, because none of the parameters incorporated are affected by the partial pressure of CO2, in contrast to the remaining major ions in waters, pH ([H+]), aluminum ([Aln+]), alkalinity ([HCO3-/CO3(2)-]) and organic anions ([An-]). Here we propose a modified ANC calculation where the permanent anionic charge of the organic acids is assumed as a part of the strong acid anions. In many humic lakes, the weak organic acids are the predominant pH-buffering system. Because a significant amount of the weak organic acids have pK-values4.5). This means that they will be permanently present as anions, equal to the strong acid inorganic anions, SO4(2)-, NO3- and Cl-. In the literature, natural organic acids are often described as triprotic acids with a low pK1 value. Assuming a triprotic model, we suggest to add 1/3 of the organic acid charge density to the strong acid anions in the ANC calculation. The suggested organic acid adjusted ANC (ANC(OAA)), is then calculated as follows: ANC(OAA)=[BC]-([SAA]+1/3CD*TOC) where TOC is total organic carbon (mg C L(-1)), and CD=10.2 is charge density of the organic matter (microeq/mg C), based on literature data from Swedish lakes. ANC(OAA) gives significant lower values of ANC in order to achieve equal fish status compared with the traditional ANC calculation. Using ANC(OAA) the humic conditions in lakes are better taken into account. This may also help explain observations of higher ANC needed to have reproducing fish populations in lakes with higher TOC concentrations. Copryright 2003 Elsevier B.V.

Lake Lysevatten - A study of liming and reacidification effects in a forest lake ecosystem in southwestern Sweden

Energy Technology Data Exchange (ETDEWEB)

Andersson, B.I.; Hultberg, H.

1997-02-01

Long-term monitoring (1973 to 1987) of acidification and liming effects to a lake ecosystem is reported in this study. The liming intervention of Lake Lysevatten in spring 1974 resulted in neutralisation of lake water and positive alkalinity. Invasion and population expansion of new species started and proceeded for several years. Following the neutralisation Sphagnum was almost eradicated. The restocking with fish changed the predator-prey interactions, and the community composition gradually approached what would be expected to be within the normal range for an unacidified lake. Early signs of reacidification were: The appearance of filamentous algae; Decreased condition of Brown trout (Salmo trutta) caused by increased aluminium concentrations in connection with an acid event; Enhanced growth of Sphagnum surviving on profundal bottoms. Progressive reacidification to Ph 5.0 resulted in accelerated growth of Mougeotia reaching nuisance level. If implemented, liming should be prolonged by reinterventions before alkalinity and pH decrease to much. A stable circumneutral pH is a prerequisite to provide the timescale necessary for invasion and population growth of organisms with low dispersal capacity. Furthermore, the most sensitive organisms will be adversely affected already at pH-values around six. Extensive reacidification should by all means be prevented as development of a destabilized lake community could react rather unpredictably. 168 refs, 80 figs, 26 tabs

Metabolism of nonparticulate phosphorus in an acid bog lake

International Nuclear Information System (INIS)

Koenings, J.P.

1977-01-01

In North Gate Lake, an acid bog lake located on the northern Michigan-Wisconsin border, U.S.A., the algal nutrient inorganic phosphate (FRP) is not detectable by chemical means. Organic phosphorus (FUP) represents 100% of the detectable filterable phosphorus. The availability and cycling of this organic fraction are of considerable interest in regard to the primary productivity of this system. To clarify these relationships, the cycling of nonparticulate forms of phosphorus found in the epilimnion of this lake was studied

Metabolism of nonparticulate phosphorus in an acid bog lake

Energy Technology Data Exchange (ETDEWEB)

Koenings, J. P.

1977-01-01

In North Gate Lake, an acid bog lake located on the northern Michigan-Wisconsin border, U.S.A., the algal nutrient inorganic phosphate (FRP) is not detectable by chemical means. Organic phosphorus (FUP) represents 100% of the detectable filterable phosphorus. The availability and cycling of this organic fraction are of considerable interest in regard to the primary productivity of this system. To clarify these relationships, the cycling of nonparticulate forms of phosphorus found in the epilimnion of this lake was studied.

The evolution of a mining lake - From acidity to natural neutralization

Energy Technology Data Exchange (ETDEWEB)

Sienkiewicz, Elwira, E-mail: esienkie@twarda.pan.pl; Gąsiorowski, Michał, E-mail: mgasior@twarda.pan.pl

2016-07-01

Along the border of Poland and Germany (central Europe), many of the post-mining lakes have formed “an anthropogenic lake district”. This study presents the evolution of a mining lake ecosystem (TR-33) based on subfossil phyto- and zooplankton, isotopic data (δ{sup 13}C, δ{sup 15}N), elemental analyses of organic carbon and nitrogen (C/N ratio and TOC) and sedimentological analyses. Recently, lake TR-33 became completely neutralized from acidification and an increase in eutrophication began a few years ago. However, the lake has never been neutralized by humans; only natural processes have influenced the present water quality. From the beginning of the existence of the lake (1920s) to the present, we can distinguish four stages of lake development: 1) very shallow reservoir without typical lake sediments but with a sand layer containing fine lignite particles and very poor diatom and cladoceran communities; 2) very acidic, deeper water body with increasing frequencies of phyto- and zooplankton; 3) transitional period (rebuilding communities of diatoms and Cladocera), meaning a deep lake with benthic and planktonic fauna and flora with wide ecological tolerances; and 4) a shift to circumneutral conditions with an essential increase in planktonic taxa that prefer more fertile waters (eutrophication). In the case of lake TR-33, this process of natural neutralization lasted approximately 23 years. - Highlights: • Originally acid water lake had poor phyto- and zooplankton populations. • Process of natural neutralization lasted approximately 23 years. • Presently, lake's ecosystem is similar to other shallow lakes in the region. • Changes in the lake are representative for other mine lakes.

Neutralizing salivary pH by mouthwashes after an acidic challenge.

Science.gov (United States)

Dehghan, Mojdeh; Tantbirojn, Daranee; Kymer-Davis, Emily; Stewart, Colette W; Zhang, Yanhui H; Versluis, Antheunis; Garcia-Godoy, Franklin

2017-05-01

The aim of the present study was to test the neutralizing effect of mouthwashes on salivary pH after an acidic challenge. Twelve participants were recruited for three visits, one morning per week. Resting saliva was collected at baseline and after 2-min swishing with 20 mL orange juice as an acidic challenge. Participants then rinsed their mouth for 30 s with 20 mL water (control), an over-the-counter mouthwash (Listerine), or a two-step mouthwash, randomly assigned for each visit. Saliva was collected immediately, 15, and 45 min after rinsing. The pH values of the collected saliva were measured and analyzed with anova, followed by Student-Newman-Keuls post-hoc test (significance level: 0.05). Orange juice significantly lowered salivary pH. Immediately after rinsing, Listerine and water brought pH back to baseline values, with the pH significantly higher in the Listerine group. The two-step mouthwash raised pH significantly higher than Listerine and water, and higher than the baseline value. Salivary pH returned to baseline and was not significantly different among groups at 15 and 45 min post-rinsing. Mouth rinsing after an acidic challenge increased salivary pH. The tested mouthwashes raised pH higher than water. Mouthwashes with a neutralizing effect can potentially reduce tooth erosion from acid exposure. © 2015 Wiley Publishing Asia Pty Ltd.

Temporal and spatial variability of acid rock drainage in a rehabilitated coal mine, Wangaloa, South Otago, New Zealand

International Nuclear Information System (INIS)

Begbie, M.; Craw, D.; Rufaut, C.; Martin, C.

2007-01-01

The Wangaloa open cast coal mine ceased operations in 1989, with no restoration of the 252 ha site, and moderate acid rock drainage developed. A major rehabilitation programme was initiated in 2002 with removal of exotic vegetation, and extensive planting (>60,000) of native seedlings was begun in 2003. By 2006, most seedlings were thriving, and, combined with adventive exotic weeds, a 70% vegetation cover had been achieved. The site substrates were highly variable on the 10-100 m 2 scale, and have been characterised by paste pH (>700 measurements). In 2003, substrates had moderate acidity (pH 4.5 ± 0.9) with distinctly acid patches (pH down to 100 samples from 15 sites) were also highly variable spatially and temporally. Incoming stream and rainwater (pH 5-6) chemically interacted with acid substrates, especially waste rock piles that contain pyrite-bearing material, and evolved to lower pH (pH down to 3.4), sulfate-rich waters. A pit lake on the site receives most surface and groundwater runoff, and this lake, with a water residence time of 1-2 yr, controls the site discharge water quality. The lake pH varies on a monthly time-scale from 4.5 to 6.5, synchronised with pH variations in groundwater boreholes in waste rock. In addition, there has been a general increase in pH of the lake during rehabilitation from consistent pH 4.6-4.8 before rehabilitation to near pH 6 during rehabilitation. The sulfate/chloride ratio of lake water has decreased from 20 to <10 during rehabilitation as well. These changes in lake water composition from year to year may be a result of increased input of rainwater that has had less interaction with substrate than runoff water had before rehabilitation began. (author). 23 refs., 10 figs., 1 tab

Organic acid excretion in Penicillium ochrochloron increases with ambient pH

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Pamela eVrabl

2012-04-01

Full Text Available Despite being of high biotechnological relevance, many aspects of organic acid excretion in filamentous fungi like the influence of ambient pH are still insufficiently understood. While the excretion of an individual organic acid may peak at a certain pH value, the few available studies investigating a broader range of organic acids indicate that total organic acid excretion rises with increasing external pH.We hypothesized that this phenomenon might be a general response of filamentous fungi to increased ambient pH. If this is the case, the observation should be widely independent of the organism, growth conditions or experimental design and might therefore be a crucial key point in understanding the function and mechanisms of organic acid excretion in filamentous fungi.In this study we explored this hypothesis using ammonium limited chemostat cultivations (pH 2-7, and ammonium or phosphate limited bioreactor batch cultivations (pH 5 and 7. Two strains of Penicillium ochrochloron were investigated differing in the spectrum of excreted organic acids.Confirming our hypothesis, the main result demonstrated that organic acid excretion in P. ochrochloron was enhanced at high external pH levels compared to low pH levels independent of the tested strain, nutrient limitation and cultivation method. We discuss these findings against the background of three hypotheses explaining organic acid excretion in filamentous fungi, i.e. overflow metabolism, charge balance and aggressive acidification hypothesis.

Contemporaneous deposition of phyllosilicates and sulfates: Using Australian acidic saline lake deposits to describe geochemical variability on Mars

Science.gov (United States)

Baldridge, A.M.; Hook, S.J.; Crowley, J.K.; Marion, G.M.; Kargel, J.S.; Michalski, J.L.; Thomson, B.J.; de Souza, Filho C.R.; Bridges, N.T.; Brown, A.J.

2009-01-01

Studies of the origin of the Martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked, global-scale change in the Mars environment from circum-neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to Hesperian. However, terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation.Western Australian acidic playa lakes have large pH differences separated vertically and laterally by only a few tens of meters, demonstrating how highly variable chemistries can coexist over short distances in natural environments. We suggest diverse and variable Martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the Australian sites are analogs for regions where phyllosilicates and sulfates coexist on Mars. In these systems, Fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater, whereas aluminous phyllosilicates and sulfates represent near-surface evaporitic facies formed from more acidic brines. Copyright 2009 by the American Geophysical Union.

Experimental study of trace metal chemistry in soft-water lakes at different pH levels

Energy Technology Data Exchange (ETDEWEB)

Jackson, T A; Kipphut, G; Hesslein, R H; Schindler, D W

1980-03-01

The biogeochemistry of Hg, Zn, Co, Fe, Mn, Cr, V, Th, Ba, Cs, As, and Se in two soft-water lakes of the Canadian shield was investigated. The residence times of the radionuclides in the water were determined, and the partitioning of the nuclides among different metal-binding agents in the water and sediments was studied. Metals of high crystal field stabilization energy, high electronegativity, or small ionic radius were most readily scavenged by greater than 0.45 micrometer suspended particles and dispersed colloids in the water, disappeared most rapidly from the water column, and were preferentially accumulated by sedimentary binding agents, including organic substances. Hg was removed fairly rapidly from the water at pH 6.7-6.8 owing to its high electronegativity but was removed more slowly than any other metal at pH 5.1 owing to its large ionic radius. Acidification of lake water to pH 5.1 interfered with accumulation of Hg and other metals by organic ooze. Acidification also lowered the concentration of extractable colloidal phosphate in the ooze but had no effect on extractable orthophosphate content. 45 references, 10 figures, 4 tables.

Alteration of the phospho- or neutral lipid content and fatty acid composition in Listeria monocytogenes due to acid adaptation mechanisms for hydrochloric, acetic and lactic acids at pH 5.5 or benzoic acid at neutral pH.

Science.gov (United States)

Mastronicolis, Sofia K; Berberi, Anita; Diakogiannis, Ioannis; Petrova, Evanthia; Kiaki, Irene; Baltzi, Triantafillia; Xenikakis, Polydoros

2010-10-01

This study provides a first approach to observe the effects on Listeria monocytogenes of cellular exposure to acid stress at low or neutral pH, notably how phospho- or neutral lipids are involved in this mechanism, besides the fatty acid profile alteration. A thorough investigation of the composition of polar and neutral lipids from L. monocytogenes grown at pH 5.5 in presence of hydrochloric, acetic and lactic acids, or at neutral pH 7.3 in presence of benzoic acid, is described relative to cells grown in acid-free medium. The results showed that only low pH values enhance the antimicrobial activity of an acid. We suggest that, irrespective of pH, the acid adaptation response will lead to a similar alteration in fatty acid composition [decreasing the ratio of branched chain/saturated straight fatty acids of total lipids], mainly originating from the neutral lipid class of adapted cultures. Acid adaptation in L. monocytogenes was correlated with a decrease in total lipid phosphorus and, with the exception of cells adapted to benzoic acid, this change in the amount of phosphorus reflected a higher content of the neutral lipid class. Upon acetic or benzoic acid stress the lipid phosphorus proportion was analysed in the main phospholipids present: cardiolipin, phosphatidylglycerol, phosphoaminolipid and phosphatidylinositol. Interestingly only benzoic acid had a dramatic effect on the relative quantities of these four phospholipids.

Toxicity of acid mine pit lake water remediated with limestone and phosphorus

Energy Technology Data Exchange (ETDEWEB)

Neil, L.L.; McCullough, C.D.; Lund, M.A.; Evans, L.H.; Tsvetnenko, Y. [Edith Cowan University, Joondalup, WA (Australia)

2009-11-15

Pit lakes are increasingly common worldwide and have potential to provide many benefits. However, lake water toxicity may require remediation before beneficial end uses can be realised. Three treatments to remediate AMD (pH similar to 4.8) pit lake water containing elevated concentrations of Al and Zn from Collie, Western Australia were tested in mesocosms. Treatments were: (a) limestone neutralisation (L), (b) phosphorus amendment (P), and c) combined limestone neutralisation and phosphorus amendment (L+P). Laboratory bioassays with Ceriodaphnia cf. dubia, Chlorella protothecoides and Tetrahymena thermophila assessed remediation. Limestone neutralisation increased pH and reduced heavy metal concentrations by 98% (Al) to 14% (Mg), removing toxicity to the three test species within 2 months. Phosphorus amendment removed toxicity after 6 months of treatment. However, phosphorus amendment to prior limestone neutralisation failed to reduce toxicity more than limestone neutralisation alone. Low concentrations of both phosphorus and nitrogen appear to limit phytoplankton population growth in all treatments.

Toxicity of acid mine pit lake water remediated with limestone and phosphorus.

Science.gov (United States)

Neil, Luke L; McCullough, Clint D; Lund, Mark A; Evans, Louis H; Tsvetnenko, Yuri

2009-11-01

Pit lakes are increasingly common worldwide and have potential to provide many benefits. However, lake water toxicity may require remediation before beneficial end uses can be realised. Three treatments to remediate AMD (pH approximately 4.8) pit lake water containing elevated concentrations of Al and Zn from Collie, Western Australia were tested in mesocosms. Treatments were: (a) limestone neutralisation (L), (b) phosphorus amendment (P), and (c) combined limestone neutralisation and phosphorus amendment (L+P). Laboratory bioassays with Ceriodaphnia cf. dubia, Chlorella protothecoides and Tetrahymena thermophila assessed remediation. Limestone neutralisation increased pH and reduced heavy metal concentrations by 98% (Al) to 14% (Mg), removing toxicity to the three test species within 2 months. Phosphorus amendment removed toxicity after 6 months of treatment. However, phosphorus amendment to prior limestone neutralisation failed to reduce toxicity more than limestone neutralisation alone. Low concentrations of both phosphorus and nitrogen appear to limit phytoplankton population growth in all treatments.

Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 282 000 years

Science.gov (United States)

Ajioka, T.; Yamamoto, M.; Takemura, K.; Hayashida, A.

2014-03-01

We generated a 282 000-year record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on the orbital timescale. Because water pH in Lake Biwa is determined by phosphorus input driven by precipitation, the record of water pH should indicate changes in summer precipitation in central Japan. The estimated pH showed significant periodicity at 19 and 23 ka (precession) and at 41 ka (obliquity). The variation in the estimated pH agrees with variation in the pollen temperature index. This indicates synchronous variation in summer air temperature and precipitation in central Japan, which contradicts the conclusions of previous studies. The variation in estimated pH was also synchronous with the variation of oxygen isotopes in stalagmites in China, suggesting that East Asian summer monsoon precipitation was governed by Northern Hemisphere summer insolation on orbital timescales. However, the estimated winter temperatures were higher during interglacials and lower during glacials, showing an eccentricity cycle. This suggests that the temperature variation reflected winter monsoon variability.

Hydrology of the Goat Lake watershed, Snohomish County, Washington, 1982-87

Science.gov (United States)

Dion, N.P.; Ebbert, J.C.; Poole, J.E.; Peck, B.S.

1989-01-01

The Goat Lake watershed in Snohomish County, Washington, functions as an ' experimental watershed ' for long-term studies to determine the effects of acidic precipitation on water resources. Data have been collected there by the U.S. Geological Survey since 1982. The watershed is in a wilderness area of the Cascade Range and is downwind of an industrial and urban area that produces chemical compounds found in acidic precipitation. The lake is considered sensitive to acidic inputs from atmospheric deposition and streamflow. The mean annual discharge of the Goat Lake outflow is 35 cu ft/sec; precipitation on the watershed is calculated to be about 170 in/yr. The inflow to Goat Lake is sufficient to replace the entire contents of the lake basin on an average every 21.5 days, or 17 times/year. Water in Goat Lake, and that of the inlet and outlet, is of low ionic strength and of calcium-bicarbonate type. The lake, although considered oligotrophic, is sufficiently deep to stratify thermally, and summer dissolved-oxygen concentrations in the hypolimnion are depressed. Even though alkalinity and specific conductance at Goat Lake are in the range considered sensitive to acidic inputs , the pH of water in the lake has consistently ranged from 6.1 to 7.2, indicating that the lake is not acidified at this time. (USGS)

Adirondack lakes survey: An interpretive analysis of fish communities and water chemistry, 1984--1987

Energy Technology Data Exchange (ETDEWEB)

Baker, J.P. (Baker (Joan P.), Raleigh, NC (USA)); Gherini, S.A.; Munson, R.K. (Tetra Tech, Inc., Pasadena, CA (USA)); Christensen, S.W. (Oak Ridge National Lab., TN (USA)); Driscoll, C.T. (Syracuse Univ., NY (USA)); Gallagher, J. (Adirondack Lakes Survey Corp., Ray Brook, NY (USA)); Newton, R.M. (Smith Coll., Northampton, MA (USA)); Reckhow, K.H. (Duke Univ., Durham, NC (USA)); Schofield, C.L. (Co

1990-01-01

The Adirondack Lakes Survey Corporation (ALSC) was formed as a cooperative effort of the New York State Department of Environmental Conservation and the Empire State Electric Energy Research Corporation to better characterize the chemical and biological status of Adirondack lakes. Between 1984 and 1987, the ALSC surveyed 1469 lakes within the Adirondack ecological zone. As a follow-up to the survey, the ALSC sponsored a series of interpretive analyses of the ALSC data base. The primary objectives of these analyses were as follows: Evaluate the influence of mineral acids (from acidic deposition) and nonmineral acids (natural organic acids) on lake pH levels; classify Adirondack lakes according to lake and watershed features expected to influence their responsiveness to changes in acidic deposition; evaluate the sensitivity of Adirondack lakes to changes in environmental conditions, such as changes in mineral acids or dissolved organic carbon concentrations; identify lake characteristics important in explaining the observed present-day status of fish communities in Adirondack lakes, in particular the relative importance of lake acidity; evaluate changes that have occurred over time in Adirondack fish communities and probable causes for these trends by using the available historical data on fish communities in the Adirondacks and the ALSC data base; and determine the degree to which the existing fish resource might be at risk from continued acidic deposition, or might recover if acidity levels were reduced. The basic approach examined relationships observed in the ALSC data base among watershed characteristics, lake chemistry, and fish status. Individual reports are processed separately for the data bases.

Whole-lake algal responses to a century of acidic industrial deposition on the Canadian Shield

International Nuclear Information System (INIS)

Vinebrooke, R.D.; Dixit, S.S.; Graham, M.D.; Gunn, J.M.; Chen, Y.-W.; Belzile, N.

2002-01-01

A century of cultural acidification is hypothesized to have altered algal community structure in boreal lakes. To date, this hypothesis has remained untested because of both the lack of data predating the onset of industrial pollution and incomplete estimates of whole-lake algal community structure. High-pressure liquid chromatography (HPLC) of sedimentary pigments was used to quantify whole-lake algal responses to acid deposition in six boreal lakes located in Killarney Park, Ontario, Canada. Concomitant significant increases in chlorophyll and carotenoid concentrations, diatom-inferred lake acidity, and metal levels since 1900 suggested that algal abundances in four acidified lakes and one small, circumneutral lake were enhanced by aerial pollution. An alternate explanation is that increased acidity and underwater light availability in the acidified lakes shifted algal abundance towards phytobenthos and deepwater phytoplankton, whose pigment signatures were better preserved in the sediments. Taxonomically diagnostic pigment stratigraphies were consistent with shifts in algal community structure towards filamentous green phytobenthos and deepwater phytoflagellates in the acidified lakes. Our findings suggest that decades of aerial pollution have altered the base of foodwebs in boreal lakes, potentially rendering them less resilient to other environmental stressors. (author)

A novel acidic pH fluorescent probe based on a benzothiazole derivative

Science.gov (United States)

Ma, Qiujuan; Li, Xian; Feng, Suxiang; Liang, Beibei; Zhou, Tiqiang; Xu, Min; Ma, Zhuoyi

2017-04-01

A novel acidic pH fluorescent probe 1 based on a benzothiazole derivative has been designed, synthesized and developed. The linear response range covers the acidic pH range from 3.44 to 6.46, which is valuable for pH researches in acidic environment. The evaluated pKa value of the probe 1 is 4.23. The fluorescence enhancement of the studied probe 1 with an increase in hydrogen ions concentration is based on the hindering of enhanced photo-induced electron transfer (PET) process. Moreover, the pH sensor possesses a highly selective response to H+ in the presence of metal ions, anions and other bioactive small molecules which would be interfere with its fluorescent pH response. Furthermore, the probe 1 responds to acidic pH with short response time that was less than 1 min. The probe 1 has been successfully applied to confocal fluorescence imaging in live HeLa cells and can selectively stain lysosomes. All of such good properties prove it can be used to monitoring pH fluctuations in acidic environment with high sensitivity, pH dependence and short response time.

Composite Biofilms grown in Acidic Mining Lakes and assessed by Electron Microscopy and Molecular Techniques

International Nuclear Information System (INIS)

Luensdorf, Heinrich; Wenderoth, Dirk F.; Abraham, Wolf-Rainer

2002-01-01

Microbial consortia of composite biofilms, grown in surface water of acidicmining lakes near Lauchhammer, Germany, were investigated. The red-brown colored lake water was acidic (pH 2.5), had high concentrations of Fe(III), Al(III), and sulphate and low concentrations of dissolved organic matter. As a result the abundance of bacteria in the lake is with 10 4 cells mL -1 rather low. One input of organic material into the lake are autumnal leaves from trees, growing in the lakeside area. From aliquots of unfixed birch leave biofilms the 16S rRNA genes were amplified by PCR and community fingerprints were determined by single-strand conformation polymorphism (SSCP) analysis. Specific bands within the fingerprints were extracted from SSCP gels and sequenced for the taxonomical affiliation.These results were compared with those from the second type of biofilms which were grown on sterile substrata, floating submersed in surface waters of the lakes. By excising the bands from the gel and sequencing the individual bands bacterial taxa, common to both types of biofilms, were found but also some, which were only present in one type of biofilm. Ultrathin sectioned biofilms often showed bacteria associated with electron dense particles as main inorganic constituents. Elemental microanalysis by energy dispersive X-ray analysis (EDX) revealed them to contain iron, sulfur and oxygen as main elemental fractions and electron diffraction ring pattern analysis classified them to be schwertmannite. These bacteria and their interactions with each other as well as with the inorganic minerals formed in this lake generally is of great interest, in order to use these results for bioremediation applications

Trends in summer chemistry linked to productivity in lakes recovering from acid deposition in the Adirondack region of New York

Science.gov (United States)

Momen, B.; Lawrence, G.B.; Nierzwicki-Bauer, S. A.; Sutherland, J.W.; Eichler, L.W.; Harrison, J.P.; Boylen, C.W.

2006-01-01

The US Environmental Protection Agency established the Adirondack Effects Assessment Program (AEAP) to evaluate and monitor the status of biological communities in lakes in the Adirondack region of New York that have been adversely affected by acid deposition. This program includes chemical analysis of 30 lakes, sampled two to three times each summer. Results of trends analysis for lake chemistry and chlorophyll a (chlor a) are presented for 1994 to 2003, and a general comparison is made with recent results of the Adirondack Long-Term Monitoring (ALTM) Program, which included chemical analysis of all but two of these lakes (plus an additional 24 lakes) monthly, year-round for 1992-2004. Increases in pH were found in 25 of the 30 AEAP lakes (P level of P level of P level of P level of P level of P chemistry were similar to those of the ALTM Program, although decreases in SO 42- concentrations were more evident in the year-round ALTM record. Overall, the results suggest (a) a degree of chemical recovery from acidification during the summer, (b) an increase in phytoplankton productivity, and (c) a decreasing trend in NO 3- concentrations resulting from the increased productivity. ?? 2007 Springer Science+Business Media, Inc.

Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists.

Science.gov (United States)

Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun; Ezawa, Tatsuhiro

2016-01-01

Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0-7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils.

Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists

Science.gov (United States)

Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun

2016-01-01

Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0–7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils. PMID

Geochemistry of highly acidic mine water following disposal into a natural lake with carbonate bedrock

International Nuclear Information System (INIS)

Wisskirchen, Christian; Dold, Bernhard; Friese, Kurt; Spangenberg, Jorge E.; Morgenstern, Peter; Glaesser, Walter

2010-01-01

Research highlights: → Mean lake water element composition did not differ greatly from discharged AMD. → Most elements showed increasing concentrations from the surface to lake bottom. → Jarosite formed in the upper part, settled, and dissolved in the deeper part of the lake. → Elements migrated into the underlying carbonates in the sequence As 3 , 4330 mg/L Fe and 29,250 mg/L SO 4 . Mean trace element concentrations were 86.8 mg/L Cu, 493 mg/L Zn, 2.9 mg/L Pb and 48 mg/L As, which did not differ greatly from the discharged AMD. Most elements showed increasing concentrations from the surface to the lake bottom at a maximal depth of 41 m (e.g. from 3581 to 5433 mg/L Fe and 25,609 to 35,959 mg/L SO 4 ). The variations in the H and O isotope compositions and the element concentrations within the upper 10 m of the water column suggest mixing with recently discharged AMD, shallow groundwater and precipitation waters. Below 15 m a stagnant zone had developed. Gypsum (saturation index, SI ∼ 0.25) and anglesite (SI ∼ 0.1) were in equilibrium with lake water. Jarosite was oversaturated (SI ∼ 1.7) in the upper part of the water column, resulting in downward settling and re-dissolution in the lower part of the water column (SI ∼ -0.7). Accordingly, jarosite was only found in sediments from less than 7 m water depth. At the lake bottom, a layer of gel-like material (∼90 wt.% water) of pH ∼1 with a total organic C content of up to 4.40 wet wt.% originated from the kerosene discharge of the Cu-extraction plant and had contaminant element concentrations similar to the lake water. Below the organic layer followed a layer of gypsum with pH 1.5, which overlaid the dissolving carbonate sediments of pH 5.3-7. In these two layers the contaminant elements were enriched compared to lake water in the sequence As < Pb ∼ Cu < Cd < Zn = Mn with increasing depth. This sequence of enrichment was explained by the following processes: (i) adsorption of As on Fe

The role of pegmatites and acid fluids for REE/HFSE mobilization in the Strange Lake peralkaline granitic pluton, Canada

Science.gov (United States)

Gysi, A. P.; Williams-Jones, A.

2012-12-01

. We modeled the interaction of HF-NaCl and HF-HCl-NaCl fluids with a Strange Lake pegmatite at 400-250 °C to test different alteration scenarios. The simulations indicated that a stronger acid than HF is needed to shift the system towards fluid buffered pH values, which are required to remobilize the REE and Zr. Comparison of the field study with numerical simulation indicates that for the effective hydrothermal remobilization of REE/HFSE, the system needs a source of elevated acidity and high fluid/rock ratios. We propose a model in which the Strange Lake pegmatites were a source of acidic fluids and upon cooling were affected by autometasomatic alteration due to increased acidity of the fluids, creating pathways for REE/HFSE mobilization.

Removal of emerging perfluorooctanoic acid and perfluorooctane sulfonate contaminants from lake water.

Science.gov (United States)

Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Sarker, Dipok Chandra; Suja, Fatihah

2017-08-01

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the major polyfluoroalkyl substances (PFASs) contaminating global water environment. This study investigated the efficiency of granular activated carbon (GAC), ultrafiltration (UF) and nanofiltration (NF) treatment for removing PFOS and PFOA contaminants from lake water. NF gave greater removal of all contaminant types (in terms of organic matter, PFOS and PFOA) than GAC treatment which in turn was greater than UF treatment. The lower removal by UF was due to larger pore size of the membrane compared to the size of the target contaminants. For all treatment processes, lower pH (4) in the feedwater showed greater rejection of the organics and selected PFASs. This was likely due to increase in the electrostatic repulsion between solute and sorbent. It could be observed that on increasing the concentration of organics in the feed solution, the rejection of PFOA/PFOS decreased which was due to competition between organics and PFOS/PFOA for binding sites on the membrane/activated carbon surface. It was also noted that protein content led to greater influence for lower rejection of the PFOA/PFOS than carbohydrate or DOC content. This study demonstrated the potential use of membrane processes for removing emerging persistent organic pollutant removal from lake water.

Calcite growth-rate inhibition by fulvic acids isolated from Big Soda Lake, Nevada, USA, The Suwannee River, Georgia, USA and by polycarboxylic acids

Science.gov (United States)

Reddy, Michael M.; Leenheer, Jerry

2011-01-01

Calcite crystallization rates are characterized using a constant solution composition at 25°C, pH=8.5, and calcite supersaturation (Ω) of 4.5 in the absence and presence of fulvic acids isolated from Big Soda Lake, Nevada (BSLFA), and a fulvic acid from the Suwannee River, Georgia (SRFA). Rates are also measured in the presence and absence of low-molar mass, aliphatic-alicyclic polycarboxylic acids (PCA). BSLFA inhibits calcite crystal-growth rates with increasing BSLFA concentration, suggesting that BSLFA adsorbs at growth sites on the calcite crystal surface. Calcite growth morphology in the presence of BSLFA differed from growth in its absence, supporting an adsorption mechanism of calcite-growth inhibition by BSLFA. Calcite growth-rate inhibition by BSLFA is consistent with a model indicating that polycarboxylic acid molecules present in BSLFA adsorb at growth sites on the calcite crystal surface. In contrast to published results for an unfractionated SRFA, there is dramatic calcite growth inhibition (at a concentration of 1 mg/L) by a SRFA fraction eluted by pH 5 solution from XAD-8 resin, indicating that calcite growth-rate inhibition is related to specific SRFA component fractions. A cyclic PCA, 1, 2, 3, 4, 5, 6-cyclohexane hexacarboxylic acid (CHXHCA) is a strong calcite growth-rate inhibitor at concentrations less than 0.1 mg/L. Two other cyclic PCAs, 1, 1 cyclopentanedicarboxylic acid (CPDCA) and 1, 1 cyclobutanedicarboxylic acid (CBDCA) with the carboxylic acid groups attached to the same ring carbon atom, have no effect on calcite growth rates up to concentrations of 10 mg/L. Organic matter ad-sorbed from the air onto the seed crystals has no effect on the measured calcite crystal-growth rates.

Sensitivity to acidification of subalpine ponds and lakes in north-western Colorado

Science.gov (United States)

Campbell, D.H.; Muths, E.; Turk, J.T.; Corn, P.S.

2004-01-01

Although acidifying deposition in western North America is lower than in many parts of the world, many high-elevation ecosystems there are extremely sensitive to acidification. Previous studies determined that the Mount Zirkel Wilderness Area (MZWA) has the most acidic snowpack and aquatic ecosystems that are among the most sensitive in the region. In this study, spatial and temporal variability of ponds and lakes in and near the MZWA were examined to determine their sensitivity to acidification and the effects of acidic deposition during and after snowmelt. Within the areas identified as sensitive to acidification based on bedrock types, there was substantial variability in acid-neutralizing capacity (ANC), which was related to differences in hydrological flowpaths that control delivery of weathering products to surface waters. Geological and topographic maps were of limited use in predicting acid sensitivity because their spatial resolution was not fine enough to capture the variability of these attributes for lakes and ponds with small catchment areas. Many of the lakes are sensitive to acidification (summer and autumn ANC pH value was 5·4, and pH generally remained less than 6·0 throughout early summer in the most sensitive ponds, indicating that biological effects of acidification are possible at levels of atmospheric deposition that occurred during the study. The aquatic chemistry of lakes was dominated by atmospheric deposition and biogeochemical processes in soils and shallow ground water, whereas the aquatic chemistry of ponds was also affected by organic acids and biogeochemical processes in the water column and at the sediment–water interface. These results indicate that conceptual and mechanistic acidification models that have been developed for lakes and streams may be inadequate for predicting acidification in less-understood systems such as ponds.

A new fluorescent pH probe for extremely acidic conditions

Energy Technology Data Exchange (ETDEWEB)

Xu, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Jiang, Zheng [School of Life Science, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Xiao, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Bi, Fu-Zhen [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

2014-04-01

A new coumarin-based fluorescent probe can detect highly acidic conditions in both solution and bacteria with high selectivity and sensitivity. Highlights: • A new fluorescence probe for very low pH was synthesized and characterized. • The probe can monitor pH in solution and bacteria. • The two-step protonation of N atoms of the probe leads to fluorescence quenching. Abstract: A novel turn-off fluorescent probe based on coumarin and imidazole moiety for extremely acidic conditions was designed and developed. The probe with pK_a = 2.1 is able to respond to very low pH value (below 3.5) with high sensitivity relying on fluorescence quenching at 460 nm in fluorescence spectra or the ratios of absorbance maximum at 380 nm to that at 450 nm in UV–vis spectra. It can quantitatively detect pH value based on equilibrium equation, pH = pK_a -log[(I_x - I_b)/(I_a - I_x)]. It had very short response time that was less than 1 min, good reversibility and nearly no interference from common metal ions. Moreover, using ¹H NMR analysis and theoretical calculation of molecular orbital, we verified that a two-step protonation process of two N atoms of the probe leaded to photoinduced electron transfer (PET), which was actually the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. Furthermore, the probe was also applied to imaging strong acidity in bacteria, E.coli and had good effect. This work illustrates that the new probe could be a practical and ideal pH indicator for strongly acidic conditions with good biological significance.

Acidic pH sensing in the bacterial cytoplasm is required for Salmonella virulence.

Science.gov (United States)

Choi, Jeongjoon; Groisman, Eduardo A

2016-09-01

pH regulates gene expression, biochemical activities and cellular behaviors. A mildly acidic pH activates the master virulence regulatory system PhoP/PhoQ in the facultative intracellular pathogen Salmonella enterica serovar Typhimurium. The sensor PhoQ harbors an extracytoplasmic domain implicated in signal sensing, and a cytoplasmic domain controlling activation of the regulator PhoP. We now report that, surprisingly, a decrease in Salmonella's own cytoplasmic pH induces transcription of PhoP-activated genes even when the extracytoplasmic pH remains neutral. Amino acid substitutions in PhoQ's cytoplasmic domain hindered activation by acidic pH and attenuated virulence in mice, but did not abolish activation by low Mg(2+) or the antimicrobial peptide C18G. Conversely, removal of PhoQ's extracytoplasmic domains prevented the response to the latter PhoQ-activating signals but not to acidic pH. PhoP-dependent genes were minimally induced by acidic pH in the non-pathogenic species Salmonella bongori but were activated by low Mg(2+) and C18G as in pathogenic S. enterica. Our findings indicate that the sensor PhoQ enables S. enterica to respond to both host- and bacterial-derived signals that alter its cytoplasmic pH. © 2016 John Wiley & Sons Ltd.

Physicochemical studies on Uburu Salt Lake Ebonyi State-Nigeria.

Science.gov (United States)

Akubugwo, I E; Ofoegbu, C J; Ukwuoma, C U

2007-09-15

Physicochemical properties of soil (sediment) and water from Uburu salt lake were evaluated and compared with control soil and surface water from the same community. Results showed significant (p copper, lead and zinc in the lake water relative to the control. The values of these metals in the lake soil (sediments) however, were significantly (p potassium, nitrate, carbonate, sulphate and phosphate levels compared to the control. Significant (p < 0.05) changes were also noted in the lake soil's pH, exchangeable acidity, nitrogen, organic carbon, calcium and magnesium levels. Also the soil texture was affected relative to the control. In a number of cases, the values of the studied parameters were higher than the permissible WHO standards. In view of these findings, cautious use of the salt lake soil and water is advocated.

Hydrological evolution and chemical structure of a hyper-acidic spring-lake system on Whakaari/White Island, NZ

Science.gov (United States)

Christenson, B. W.; White, S.; Britten, K.; Scott, B. J.

2017-10-01

White Island has a long and varied history of acid spring discharge and shallow ephemeral lake formation on its main crater floor. In the 12 months prior to the onset of the 1976-2000 eruptive episode, mass discharge from the spring system increased ca. 10-fold, pointing to a strong coupling of the hydrothermal environment to the evolving magmatic system. Between 1976 and 1978, the formation of numerous eruption vents to 200 m depth in the Western Sub-crater abruptly changed the hydraulic gradients in the volcano, resulting in the reversal of groundwater flow in the massif towards the newly-formed crater(s). This affected not only the style of volcanic activity (leading to phreatic-phreatomagmatic-magmatic eruption cycles), but also led to the demise of the spring system, with discharge from the main crater declining by a factor > 100 by 1979. Eruptive activity ended shortly after a moderate Strombolian eruption in mid-2000, after which ephemeral lakes started to form in the eruption crater complex. Between 2003 and 2015 there were three complete lake filling and evaporative cycles, reflecting varying heat flow through the conduit system beneath the lake. Over these cycles, lake water concentrations of Cl and SO4 varied between ca. 35-150 and 5-45 g/L respectively, with pH values temporally ranging from + 1.5 to - 1. Springs appeared on the Main Crater floor in 2004, and their discharges varied with lake level, pointing to the lake level being a primary control over the piezometric surface in the crater area. Springs closest to the crater complex show direct evidence of crater lake water infiltration into the crater floor aquifer, whereas distal spring discharges show compositional variations reflecting vertical displacement of the interface between shallow, dilute condensate and underlying acidic brine fluids. Source components for the spring fluids include magmatic vapour, dissolved andesitic host rocks, seawater and meteoric water. Lake waters, on the other hand

Modeling aluminum-silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

Science.gov (United States)

Marion, G. M.; Crowley, J. K.; Thomson, B. J.; Kargel, J. S.; Bridges, N. T.; Hook, S. J.; Baldridge, A.; Brown, A. J.; Ribeiro da Luz, B.; de Souza Filho, C. R.

2009-06-01

Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid-salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na-K-Mg-Ca-Fe(II)-Fe(III)-Al-H-Cl-Br-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-Si-H 2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron precipitates such as jarosite and hematite. Differences include: (1) the dominance of NaCl in many WA lakes, versus the dominance of Fe-Mg-Ca-SO 4 in Meridiani Planum, (2) excessively low K + concentrations in Meridiani Planum due to jarosite precipitation, (3) higher acid production in the presence of high iron concentrations in Meridiani Planum, and probably lower rates of acid neutralization and hence, higher acidities on Mars owing to colder temperatures, and (4) lateral salt patterns in WA lakes. The WA playa lakes display significant lateral variations in mineralogy and water

Features of acid-saline systems of Southern Australia

International Nuclear Information System (INIS)

Dickson, Bruce L.; Giblin, Angela M.

2009-01-01

The discovery of layered, SO 4 -rich sediments on the Meridiani Planum on Mars has focused attention on understanding the formation of acid-saline lakes. Many salt lakes have formed in southern Australia where regional groundwaters are characterized by acidity and high salinity and show features that might be expected in the Meridiani sediments. Many (but not all) of the acid-saline Australian groundwaters are found where underlying Tertiary sediments are sulfide-rich. When waters from the formations come to the surface or interact with oxidised meteoric water, acid groundwaters result. In this paper examples of such waters around Lake Tyrrell, Victoria, and Lake Dey-Dey, South Australia, are reviewed. The acid-saline groundwaters typically have dissolved solids of 30-60 g/L and pH commonly 4 and MgSO 4 ) or differential separation of elements with differing solubility (K, Na, Ti, Cr). Thus, it is considered unlikely that groundwaters or evaporative salt-lake systems, as found on earth, were involved. Instead, these features point to a water-poor system with local alteration and very little mobilization of elements

Importance of different physiological groups of iron reducing microorganisms in an acidic mining lake remediation experiment.

Science.gov (United States)

Porsch, Katharina; Meier, Jutta; Kleinsteuber, Sabine; Wendt-Potthoff, Katrin

2009-05-01

Iron- and sulfate-reducing microorganisms play an important role for alkalinity-generating processes in mining lakes with low pH. In the acidic mining lake 111 in Lusatia, Germany, a passive in situ remediation method was tested in a large scale experiment, in which microbial iron and sulfate reduction are stimulated by addition of Carbokalk (a mixture of the nonsugar compounds of sugar beets and lime) and straw. The treated surface sediment consisted of three layers of different pH and geochemical composition. The top layer was acidic and rich in Fe(III), the second and third layer both showed moderately acidic to circum-neutral pH values, but only the second was rich in organics, strongly reduced and sulfidic. Aim of the study was to elucidate the relative importance of neutrophilic heterotrophic, acidophilic heterotrophic, and acidophilic autotrophic iron-reducing microorganisms in each of the three layers. In order to distinguish between them, the effect of their respective characteristic electron donors acetate, glucose, and elemental sulfur on potential iron reduction rates was investigated. Limitation of iron reduction by the availability of Fe(III) was revealed by the addition of Fe(OH)(3). The three groups of iron-reducing microorganisms were quantified by most probable number (MPN) technique and their community composition was analyzed by cloning and sequencing of 16S rRNA genes. In the acidic surface layer, none of the three electron donors stimulated iron reduction; acetate even had an inhibiting effect. In agreement with this, no decrease of the added electron donors was observed. Iron reduction rates were low in comparison to the other layers. Iron reduction in layers 2 and 3 was enhanced by glucose and acetate, accompanied by a decrease of these electron donors. Addition of elemental sulfur did not enhance iron reduction in either layer. Layer 2 exhibited the highest iron reduction rate (4.08 mmol dm(-3) d(-1)) and the highest cell numbers in MPN

Average rainwater pH, concepts of atmospheric acidity, and buffering in open systems

Energy Technology Data Exchange (ETDEWEB)

Liljestrand, H.M.

1985-01-01

The system of water equilibrated with a constant partial pressure of CO/sub 2/, as a reference point for pH acidity-alkalinity relationships, has nonvolatile acidity and alkalinity components as conservative quantities, but not (H/sup +/). Simple algorithms are presented for the determination of the average pH for combinations of samples both above and below pH 5.6. Averaging the nonconservative quantity (H/sup +/) yields erroneously low mean pH values. To extend the open CO/sub 2/ system to include other volatile atmospheric acids and bases distributed among the gas, liquid and particulate matter phases, a theoretical framework for atmospheric acidity is presented. Within certain oxidation-reduction limitations, the total atmospheric acidity (but not free acidity) is a conservative quantity. The concept of atmospheric acidity is applied to air-water systems approximating aerosols, fogwater, cloudwater and rainwater. The buffer intensity in hydrometers is described as a function of net strong acidity, partial pressures of acid and base gases and the water to air ratio. For high liquid to air volume ratios, the equilibrium partial pressures of trace acid and base gases are set by the pH or net acidity controlled by the nonvolatile acid and base concentrations. For low water to air volume ratios as well as stationary state systems such as precipitation scavenging with continuous emissions, the partial pressures of trace gases (NH/sub 3/, HCl, NHO/sub 3/, SO/sub 2/, and CH/sub 3/COOH) appear to be of greater or equal importance as carbonate species as buffers in the aqueous phase.

Average rainwater pH, concepts of atmospheric acidity, and buffering in open systems

Science.gov (United States)

Liljestrand, Howard M.

The system of water equilibrated with a constant partial pressure of CO 2, as a reference point for pH acidity-alkalinity relationships, has nonvolatile acidity and alkalinity components as conservative quantities, but not [H +]. Simple algorithms are presented for the determination of the average pH for combinations of samples both above and below pH 5.6. Averaging the nonconservative quantity [H +] yields erroneously low mean pH values. To extend the open CO 2 system to include other volatile atmospheric acids and bases distributed among the gas, liquid and particulate matter phases, a theoretical framework for atmospheric acidity is presented. Within certain oxidation-reduction limitations, the total atmospheric acidity (but not free acidity) is a conservative quantity. The concept of atmospheric acidity is applied to air-water systems approximating aerosols, fogwater, cloudwater and rainwater. The buffer intensity in hydrometeors is described as a function of net strong acidity, partial pressures of acid and base gases and the water to air ratio. For high liquid to air volume ratios, the equilibrium partial pressures of trace acid and base gases are set by the pH or net acidity controlled by the nonvolatile acid and base concentrations. For low water to air volume ratios as well as stationary state systems such as precipitation scavenging with continuous emissions, the partial pressures of trace gases (NH 3, HCl, HNO 3, SO 2 and CH 3COOH) appear to be of greater or equal importance as carbonate species as buffers in the aqueous phase.

Towards control of aggregational behaviour of alpha-lactalbumin at acidic pH.

Science.gov (United States)

Pedersen, Jane B; Fojan, Peter; Sorensen, John; Petersen, Steffen B

2006-07-01

alpha-Lactalbumin (alpha-La) undergoes considerable structural changes upon loss of bound Ca2+ at acidic pH, leaving alpha-La in a molten globule structure. Using fluorescence the present work provides more insight into the structural transition of alpha-La at acidic pH leading to protein aggregation, most likely caused by a combination of hydrophobic and electrostatic interactions. The rate of aggregation is determined by the protein concentration and temperature applied. Availability of Ca2+ stabilises the protein, and thus prevent aggregation at pH values as low as pH 2.9. In contrast, presence of Cu2+ induces a destabilisation of the protein, which can be explained by a binding to the Zn2+ binding site in alpha-La, possibly resulting in structural alterations of the protein. In general, presence of anions destabilize alpha-La at pH values below pI, with SO4(2-) exhibiting the strongest effect on the protein stability, thus correlating well with the Hofmeister series. At more acidic pH values far from pI, alpha-La becomes more stable towards ion induced aggregation, since higher ion activity is required to efficiently screen the charges on the protein surface. The results presented in this paper provide detailed knowledge on the external parameters leading to aggregation of alpha-La at acidic pH, thus permitting rational design of the aggregation process.

Mesocosm studies to assess acidity removal from acidic mine lakes through controlled eutrophication

International Nuclear Information System (INIS)

Fyson, A.; Nixdorf, B.; Kalin, M.; Steinberg, C.E.W.

1998-01-01

Flooded lignite pits (Tagebaurestseen) in Lusatia, Germany, are acidic (pH 2.5-4) with high concentrations of iron. Mesocosms (total volume 20 l) were set up with water and sediment from a Tagebaurestsee to assess the effects of phosphate and organic amendments under natural light and low temperature. Chemical and biological parameters were observed over a 9-month period. Phosphate rock addition resulted in sustained reduction in acidity in the water column and induced the growth of Chlamydomonas spp. (Chlorophyceae) near the water surface and Lepocinclis teres (Euglenophyceae) in a band above the sediment. Addition of potatoes to mesocosms resulted in the generation of near-anoxic conditions above the sediment, and phosphorus, ammonium and carbon (organic and inorganic) were released as the potatoes decomposed. A pH > 6 was attained with 5.1 g (dry weight) of potatoes and pH > 8 with 34 g (dry weight). In both mesocosms, more than 90% of total acidity was removed

Zooplankton community composition of high mountain lakes in the Tatra Mts., the Alps in North Tyrol, and Scotland: relationship to pH, depth, organic carbon, and chlorophyll-a concentration

Directory of Open Access Journals (Sweden)

Skála Ivan

2015-10-01

Full Text Available The European EMERGE (European Mountain lake Ecosystems: Regionalisation, diaGnostic & socio-economic Evaluation project was a survey of high mountain lakes (above treeline across Europe using unified methods of sampling and analysis. The sampling was carried out in summer or autumn 2000, and comprised biological samples, and samples for chemical analysis. Data from three lake districts are used in this paper: the Tatra Mts. in Slovakia and Poland (45 lakes, the Alps in Tyrol in Austria (22 lakes, and Scotland (30 lakes. As it is shown by multiple regression analysis, DTOC (dissolved or total organic carbon is the key variable for most groups of zooplankton. With increasing DTOC and mostly with chlorophyll-a decreasing, pH increasing and depth decreasing, macrofitrators with coarse filter meshes are replaced by microfiltrators with fine filter meshes. Higher DTOC may increase bacterioplankton production and advantage species able to consume bacteria (microfiltrators. Other zooplankton species also differ in their preference for DTOC, chlorophyll-a, pH and depth, but DTOC being positively correlated with chlorophyll-a and pH positively correlated with depth. It may be caused by their different preference for food quality in terms of C:P ratio.

Assessing diet compositions of Lake Ontario predators using fatty acid profiles of prey fishes

Science.gov (United States)

Happell, Austin; Pattridge, Robert; Rinchard, Jacques; Walsh, Maureen

2017-01-01

Fatty acid profiles are used in food web studies to assess trophic interactions between predator and prey. The present study provides the first comprehensive fatty acid dataset for important prey and predator species in Lake Ontario. Three major prey fish (alewife, rainbow smelt, and round goby) were collected at three sites along the southern shore of Lake Ontario during the spring and fall of 2013, and predator species were collected in similar locations during the summer of 2013. Fatty acid compositions were compared among all prey species, all predator species, and information from both predator and prey was used to infer foraging differences among predators. Seasonal differences in fatty acids were found within each prey species studied. Differences among prey species were greater than any spatio-temporal differences detected within species. Fatty acids of predators revealed species-specific differences that matched known foraging habits. Chinook and Coho salmon, which are known to select alewife as their dominant prey item, had relatively little variation in fatty acid profiles. Conversely, brown trout, lake trout, yellow perch and esocids had highly variable fatty acid profiles and likely highly variable diet compositions. In general, our data suggested three dominant foraging patterns: 1) diet composed of nearly exclusively alewife for Chinook and Coho Salmon; 2) a mixed diet of alewife and round goby for brown and lake trout, and both rock and smallmouth bass; 3) a diet that is likely comprised of forage fishes other than those included in our study for northern pike and chain pickerel.

Changes of organic acid exudation and rhizosphere pH in rice plants under chromium stress

International Nuclear Information System (INIS)

Zeng Fanrong; Chen Song; Miao Ying; Wu Feibo; Zhang Guoping

2008-01-01

The effect of chromium (Cr) stress on the changes of rhizosphere pH, organic acid exudation, and Cr accumulation in plants was studied using two rice genotypes differing in grain Cr accumulation. The results showed that rhizosphere pH increased with increasing level of Cr in the culture solution and with an extended time of Cr exposure. Among the six organic acids examined in this experiment, oxalic and malic acid contents were relatively higher, and had a significant positive correlation with the rhizosphere pH, indicating that they play an important role in changing rhizosphere pH. The Cr content in roots was significantly higher than that in stems and leaves. Cr accumulation in plants was significantly and positively correlated with rhizosphere pH, and the exudation of oxalic, malic and citric acids, suggesting that an increase in rhizosphere pH, and exudation of oxalic, malic and citric acid enhances Cr accumulation in rice plants. - Rhizosphere pH and organic acid exudation of rice roots are markedly affected by chromium level in culture solution

Oxidation in fish oil enriched mayonnaise : Ascorbic acid and low pH increase oxidative deterioration

DEFF Research Database (Denmark)

Jacobsen, Charlotte; Timm Heinrich, Maike; Meyer, Anne S.

2001-01-01

The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil- water interface into the aqueous phase at all pH levels......, but this effect of ascorbic acid was strongest at low pH (pH 3.8- 4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted...... oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced...

Influence of sodium chloride, pH, and lactic acid bacteria on anaerobic lactic acid utilization during fermented cucumber spoilage.

Science.gov (United States)

Johanningsmeier, Suzanne D; Franco, Wendy; Perez-Diaz, Ilenys; McFeeters, Roger F

2012-07-01

Cucumbers are preserved commercially by natural fermentations in 5% to 8% sodium chloride (NaCl) brines. Occasionally, fermented cucumbers spoil after the primary fermentation is complete. This spoilage has been characterized by decreases in lactic acid and a rise in brine pH caused by microbial instability. Objectives of this study were to determine the combined effects of NaCl and pH on fermented cucumber spoilage and to determine the ability of lactic acid bacteria (LAB) spoilage isolates to initiate lactic acid degradation in fermented cucumbers. Cucumbers fermented with 0%, 2%, 4%, and 6% NaCl were blended into slurries (FCS) and adjusted to pH 3.2, 3.8, 4.3, and 5.0 prior to centrifugation, sterile-filtration, and inoculation with spoilage organisms. Organic acids and pH were measured initially and after 3 wk, 2, 6, 12, and 18 mo anaerobic incubation at 25 °C. Anaerobic lactic acid degradation occurred in FCS at pH 3.8, 4.3, and 5.0 regardless of NaCl concentration. At pH 3.2, reduced NaCl concentrations resulted in increased susceptibility to spoilage, indicating that the pH limit for lactic acid utilization in reduced NaCl fermented cucumbers is 3.2 or lower. Over 18 mo incubation, only cucumbers fermented with 6% NaCl to pH 3.2 prevented anaerobic lactic acid degradation by spoilage bacteria. Among several LAB species isolated from fermented cucumber spoilage, Lactobacillus buchneri was unique in its ability to metabolize lactic acid in FCS with concurrent increases in acetic acid and 1,2-propanediol. Therefore, L. buchneri may be one of multiple organisms that contribute to development of fermented cucumber spoilage. Microbial spoilage of fermented cucumbers during bulk storage causes economic losses for producers. Current knowledge is insufficient to predict or control these losses. This study demonstrated that in the absence of oxygen, cucumbers fermented with 6% sodium chloride to pH 3.2 were not subject to spoilage. However, lactic acid was degraded

Hyperpolarized Amino Acid Derivatives as Multivalent Magnetic Resonance pH Sensor Molecules

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Christian Hundshammer

2018-02-01

Full Text Available pH is a tightly regulated physiological parameter that is often altered in diseased states like cancer. The development of biosensors that can be used to non-invasively image pH with hyperpolarized (HP magnetic resonance spectroscopic imaging has therefore recently gained tremendous interest. However, most of the known HP-sensors have only individually and not comprehensively been analyzed for their biocompatibility, their pH sensitivity under physiological conditions, and the effects of chemical derivatization on their logarithmic acid dissociation constant (pKa. Proteinogenic amino acids are biocompatible, can be hyperpolarized and have at least two pH sensitive moieties. However, they do not exhibit a pH sensitivity in the physiologically relevant pH range. Here, we developed a systematic approach to tailor the pKa of molecules using modifications of carbon chain length and derivatization rendering these molecules interesting for pH biosensing. Notably, we identified several derivatives such as [1-13C]serine amide and [1-13C]-2,3-diaminopropionic acid as novel pH sensors. They bear several spin-1/2 nuclei (13C, 15N, 31P with high sensitivity up to 4.8 ppm/pH and we show that 13C spins can be hyperpolarized with dissolution dynamic polarization (DNP. Our findings elucidate the molecular mechanisms of chemical shift pH sensors that might help to design tailored probes for specific pH in vivo imaging applications.

Hyperpolarized Amino Acid Derivatives as Multivalent Magnetic Resonance pH Sensor Molecules.

Science.gov (United States)

Hundshammer, Christian; Düwel, Stephan; Ruseckas, David; Topping, Geoffrey; Dzien, Piotr; Müller, Christoph; Feuerecker, Benedikt; Hövener, Jan B; Haase, Axel; Schwaiger, Markus; Glaser, Steffen J; Schilling, Franz

2018-02-15

pH is a tightly regulated physiological parameter that is often altered in diseased states like cancer. The development of biosensors that can be used to non-invasively image pH with hyperpolarized (HP) magnetic resonance spectroscopic imaging has therefore recently gained tremendous interest. However, most of the known HP-sensors have only individually and not comprehensively been analyzed for their biocompatibility, their pH sensitivity under physiological conditions, and the effects of chemical derivatization on their logarithmic acid dissociation constant (p K a ). Proteinogenic amino acids are biocompatible, can be hyperpolarized and have at least two pH sensitive moieties. However, they do not exhibit a pH sensitivity in the physiologically relevant pH range. Here, we developed a systematic approach to tailor the p K a of molecules using modifications of carbon chain length and derivatization rendering these molecules interesting for pH biosensing. Notably, we identified several derivatives such as [1- 13 C]serine amide and [1- 13 C]-2,3-diaminopropionic acid as novel pH sensors. They bear several spin-1/2 nuclei ( 13 C, 15 N, 31 P) with high sensitivity up to 4.8 ppm/pH and we show that 13 C spins can be hyperpolarized with dissolution dynamic polarization (DNP). Our findings elucidate the molecular mechanisms of chemical shift pH sensors that might help to design tailored probes for specific pH in vivo imaging applications.

Monascus ruber as cell factory for lactic acid production at low pH.

Science.gov (United States)

Weusthuis, Ruud A; Mars, Astrid E; Springer, Jan; Wolbert, Emil Jh; van der Wal, Hetty; de Vrije, Truus G; Levisson, Mark; Leprince, Audrey; Houweling-Tan, G Bwee; Pha Moers, Antoine; Hendriks, Sjon Na; Mendes, Odette; Griekspoor, Yvonne; Werten, Marc Wt; Schaap, Peter J; van der Oost, John; Eggink, Gerrit

2017-07-01

A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175g/l lactic acid at pH 2.8. Its genome and transcriptomes were sequenced and annotated. Genes encoding lactate dehydrogenase (LDH) were introduced to accomplish lactic acid production and two genes encoding pyruvate decarboxylase (PDC) were knocked out to subdue ethanol formation. The strain preferred lactic acid to glucose as carbon source, which hampered glucose consumption and therefore also lactic acid production. Lactic acid consumption was stopped by knocking out 4 cytochrome-dependent LDH (CLDH) genes, and evolutionary engineering was used to increase the glucose consumption rate. Application of this strain in a fed-batch fermentation resulted in a maximum lactic acid titer of 190g/l at pH 3.8 and 129g/l at pH 2.8, respectively 1.7 and 2.2 times higher than reported in literature before. Yield and productivity were on par with the best strains described in literature for lactic acid production at low pH. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Influence of pH on organic acid production by Clostridium sporogenes in test tube and fermentor cultures.

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Montville, T J; Parris, N; Conway, L K

1985-01-01

The influence of pH on the growth parameters of and the organic acids produced by Clostridium sporogenes 3121 cultured in test tubes and fermentors at 35 degrees C was examined. Specific growth rates in the fermentor maintained at a constant pH ranged from 0.20 h-1 at pH 5.00 to 0.86 h-1 at pH 6.50. Acetic acid was the primary organic acid in supernatants of 24-h cultures; total organic acid levels were 2.0 to 22.0 mumol/ml. Supernatants from pH 5.00 and 5.50 cultures had total organic acid levels less than one-third of those found at pH 6.00 to 7.00. The specific growth rates of the test tube cultures ranged from 0.51 h-1 at pH 5.00 to 0.95 h-1 at pH 6.50. The pH of the medium did not affect the average total organic acid content (51.5 mumol/ml) but did affect the distribution of the organic acids, which included formic, acetic, propionic, butyric, 3-(p-hydroxyphenyl)propionic, and 3-phenylpropionic acids. Butyric acid levels were lower, but formic and propionic acid levels were higher, at pH 5.00 than at other pHs. PMID:4004207

Influence of polysorbate 80 and cyclopropane fatty acid synthase activity on lactic acid production by Lactobacillus casei ATCC 334 at low pH.

Science.gov (United States)

Broadbent, J R; Oberg, T S; Hughes, J E; Ward, R E; Brighton, C; Welker, D L; Steele, J L

2014-03-01

Lactic acid is an important industrial chemical commonly produced through microbial fermentation. The efficiency of acid extraction is increased at or below the acid's pKa (pH 3.86), so there is interest in factors that allow for a reduced fermentation pH. We explored the role of cyclopropane synthase (Cfa) and polysorbate (Tween) 80 on acid production and membrane lipid composition in Lactobacillus casei ATCC 334 at low pH. Cells from wild-type and an ATCC 334 cfa knockout mutant were incubated in APT broth medium containing 3 % glucose plus 0.02 or 0.2 % Tween 80. The cultures were allowed to acidify the medium until it reached a target pH (4.5, 4.0, or 3.8), and then the pH was maintained by automatic addition of NH₄OH. Cells were collected at the midpoint of the fermentation for membrane lipid analysis, and media samples were analyzed for lactic and acetic acids when acid production had ceased. There were no significant differences in the quantity of lactic acid produced at different pH values by wild-type or mutant cells grown in APT, but the rate of acid production was reduced as pH declined. APT supplementation with 0.2 % Tween 80 significantly increased the amount of lactic acid produced by wild-type cells at pH 3.8, and the rate of acid production was modestly improved. This effect was not observed with the cfa mutant, which indicated Cfa activity and Tween 80 supplementation were each involved in the significant increase in lactic acid yield observed with wild-type L. casei at pH 3.8.

Amino acid composition reveals functional diversity of zooplankton in tropical lakes related to geography, taxonomy and productivity.

Science.gov (United States)

Aranguren-Riaño, Nelson J; Guisande, Cástor; Shurin, Jonathan B; Jones, Natalie T; Barreiro, Aldo; Duque, Santiago R

2018-04-16

Variation in resource use among species determines their potential for competition and co-existence, as well as their impact on ecosystem processes. Planktonic crustaceans consume a range of micro-organisms that vary among habitats and species, but these differences in resource consumption are difficult to characterize due to the small size of the organisms. Consumers acquire amino acids from their diet, and the composition of tissues reflects both the use of different resources and their assimilation in proteins. We examined the amino acid composition of common crustacean zooplankton from 14 tropical lakes in Colombia in three regions (the Amazon floodplain, the eastern range of the Andes, and the Caribbean coast). Amino acid composition varied significantly among taxonomic groups and the three regions. Functional richness in amino acid space was greatest in the Amazon, the most productive region, and tended to be positively related to lake trophic status, suggesting the niche breadth of the community could increase with ecosystem productivity. Functional evenness increased with lake trophic status, indicating that species were more regularly distributed within community-wide niche space in more productive lakes. These results show that zooplankton resource use in tropical lakes varies with both habitat and taxonomy, and that lake productivity may affect community functional diversity and the distribution of species within niche space.

Nutrient cycling and productivity of dystrophic lake-bog systems (Part A). Technical progress report, December 1, 1972--September 30, 1975

International Nuclear Information System (INIS)

Hooper, F.F.

1975-10-01

A sampler and an analytical and characterization scheme were developed to investigate the chemical and physical state of iron in a highly stained acid bog lake. Iron fractions were chemically separated by reactivity to bathophenanthroline (BPN) after specific digestion procedures. Physical separation involved anaerobic in situ filtration (450 nm), and in situ dialysis (4.8 nm). This resulted in three size classes: particulate, colloidal, and dissolved. Unlike pH 6-8 lakes, inorganic, nonreactive species of iron [e.g., Fe(OH) 3 ] represent minor amounts of the total iron in North Gate Lake. In situ radiochemical analyses revealed that colloidal sized reactive ferric iron predominates in the oxygenated epilimnion, while dialyzable or dissolved ferrous iron increases with depth. Unlike iron, organic matter is present in a nontransient colloidal state. In acid (pH 4-5) bog lakes ferric iron is not colloidal as an inorganic complex (OH - ), but colloidal as reactive Fe + 3 by complexation with the colloidal organic acids. After thermally induced mixing with anaerobic waters, ferric iron is reduced and dissolved. However, some of the BPN reactive iron remains colloidal suggesting the presence of a residual ferrous organic complex

UV absorption reveals mycosporine-like amino acids (MAAs in Tatra mountain lake phytoplankton

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Jerzy Dera

2013-08-01

Full Text Available Enhanced absorption of UV radiation, an effect characteristic of mycosporine-like amino acids (MAAs, is reported in samples of phytoplankton from six lakes in the Tatra Mountains National Park (Poland. It was demonstrated that the mass-specific UV absorption coefficients for the phytoplankton in these lakes increased with altitude above sea level. Based on a comparison with the phytoplankton of Alpine lakes, investigated earlier by other authors (cited in this paper, it may be inferred that the phytoplankton of Tatra mountain lakes produce MAAs, which protect plant cells from UV light, the intensity of which increases with altitude.

Intracellular pH Response to Weak Acid Stress in Individual Vegetative Bacillus subtilis Cells.

Science.gov (United States)

Pandey, Rachna; Vischer, Norbert O E; Smelt, Jan P P M; van Beilen, Johan W A; Ter Beek, Alexander; De Vos, Winnok H; Brul, Stanley; Manders, Erik M M

2016-11-01

Intracellular pH (pH i ) critically affects bacterial cell physiology. Hence, a variety of food preservation strategies are aimed at perturbing pH i homeostasis. Unfortunately, accurate pH i quantification with existing methods is suboptimal, since measurements are averages across populations of cells, not taking into account interindividual heterogeneity. Yet, physiological heterogeneity in isogenic populations is well known to be responsible for differences in growth and division kinetics of cells in response to external stressors. To assess in this context the behavior of intracellular acidity, we have developed a robust method to quantify pH i at single-cell levels in Bacillus subtilis Bacilli spoil food, cause disease, and are well known for their ability to form highly stress-resistant spores. Using an improved version of the genetically encoded ratiometric pHluorin (IpHluorin), we have quantified pH i in individual B. subtilis cells, cultured at an external pH of 6.4, in the absence or presence of weak acid stresses. In the presence of 3 mM potassium sorbate, a decrease in pH i and an increase in the generation time of growing cells were observed. Similar effects were observed when cells were stressed with 25 mM potassium acetate. Time-resolved analysis of individual bacteria in growing colonies shows that after a transient pH decrease, long-term pH evolution is highly cell dependent. The heterogeneity at the single-cell level shows the existence of subpopulations that might be more resistant and contribute to population survival. Our approach contributes to an understanding of pH i regulation in individual bacteria and may help scrutinizing effects of existing and novel food preservation strategies. This study shows how the physiological response to commonly used weak organic acid food preservatives, such as sorbic and acetic acids, can be measured at the single-cell level. These data are key to coupling often-observed single-cell heterogeneous growth

Environmental responsiveness of polygalacturonic acid-based multilayers to variation of pH.

Science.gov (United States)

Westwood, Marta; Noel, Timothy R; Parker, Roger

2011-02-14

The effect of pH on the stability of layer-by-layer deposited polygalacturonic acid (PGalA)-based multilayer films prepared with the polycations poly-L-lysine, chitosan, and lysozyme is studied. The response was characterized using a quartz crystal microbalance, dual polarization interferometry, and Fourier transform infrared spectroscopy which probe multilayer thickness, density, polymer mass (composition and speciation), and hydration. All multilayers showed irreversible changes in response to pH change becoming thinner due to the partial disassembly. Preferential loss of the polycation (50-80% w/w) and relative small losses of PGaLA (10-35% w/w) occurred. The charge density on the polycation has a strong influence on the response to the acid cycle. Most of the disassembly takes place at the pH lower that pK(a) of PGaLA, indicating that this factor was crucial in determining the stability of the films. The pH challenge also revealed a polycation-dependent shift to acid pH in the PGaLA pK(a).

Is Your Drinking Water Acidic? A Comparison of the Varied pH of Popular Bottled Waters.

Science.gov (United States)

Wright, Kellie F

2015-06-01

Dental professionals continually educate patients on the dangers of consuming acidic foods and beverages due to their potential to contribute to dental erosion and tooth decay. Excess acid in the diet can also lead to acidosis, which causes negative systemic side effects. However, water is not typically categorized as acidic. The purpose of this in-vitro study was to investigate the pH levels of several popular brands of bottled water and compare them to various other acidic beverages. Two different brands of marketed alkaline water (with a pH of 8.8 or higher) were also studied, tested for acidity and described. A pilot in-vitro study was conducted to determine the pH levels of a convenience sample of popular brands of bottled water, tap water and other known acidic beverages in comparison with the pH values reported on the respective manufacturers' website. Each beverage was tested in a laboratory using a calibrated Corning pH meter model 240, and waters were compared to the corresponding company's testified pH value. Waters were also compared and contrasted based on their process of purification. The data was then compiled and analyzed descriptively. The pH values for the tested beverages and bottled waters were found to be predominantly acidic. Ten out of the 14 beverages tested were acidic (pHwaters were neutral (pH=7) and 2 bottled waters were alkaline (pH>7). The majority of waters tested had a more acidic pH when tested in the lab than the value listed in their water quality reports. It is beneficial for the health care provider to be aware of the potential acidity of popular bottled drinking waters and educate patients accordingly. Copyright © 2015 The American Dental Hygienists’ Association.

Evaluation of the effects of water hardness and chemical pollutants on the zooplankton community in uranium mining lakes with acid mine drainage

Energy Technology Data Exchange (ETDEWEB)

Nascimento, H.; Ferrari, C.; Nascimento, M.R. [Brazilian Nulcear Energy Commission/Pocos de Caldas Laboratory (Brazil); Rodgher, S. [Universidade Estadual Paulista Julio de Mesquita Filho/Science and Technology Institute (Brazil); Wisniewski, M.J. [Alfenas Federal University/Limnology Laboratory (Brazil)

2014-07-01

Several mining lakes are characterized by the inorganic pollution of its waters, known as acid mine drainage (AMD). The current study was developed in order to evaluate the effect of water hardness and chemical pollutants on the richness and density of the zoo-planktonic community species. A seasonal study was conducted in a uranium mining lake affected by AMD. In environmental conditions of extremely high hardness water values (960.3 to 1284,9 mg/l), zoo-planktonic species have indicated resistance to the combined effect of elevated average concentrations of chemical pollutants such as Al (81.9 mg/l), Zn (15.5 mg/l), Mn (102.8 mg/l), U (2.9 mg/l) and low pH values (average = 3.8). Thus, in environments of extreme chemical conditions, such as a uranium mining lake affected by AMD, the hardness showed to be the best predictor of the zoo-planktonic community richness, indicating a protective effect of ions Ca{sup +2} over in special to Bosminopsis deitersi, Bosmina sp., Keratella americana and K. cochlearis. Document available in abstract form only. (authors)

Microenvironmental pH measurement during sodium naproxenate dissolution in acidic medium by UV/vis imaging

DEFF Research Database (Denmark)

Ostergaard, Jesper; Jensen, Henrik; Larsen, Susan W

2014-01-01

Variable dissolution from sodium salts of drugs containing a carboxylic acid group after passing the acidic environment of the stomach may affect oral bioavailability. The aim of the present proof of concept study was to investigate pH effects in relation to the dissolution of sodium naproxenate...... in 0.01M hydrochloric acid. For this purpose a UV/vis imaging-based approach capable of measuring microenvironmental pH in the vicinity of the solid drug compact as well as monitoring drug dissolution was developed. Using a pH indicating dye real-time spatially resolved measurement of pH was achieved....... Sodium naproxenate, can significantly alter the local pH of the dissolution medium, is eventually neutralized and precipitates as the acidic species naproxen. The developed approach is considered useful for detailed studies of pH dependent dissolution phenomena in dissolution testing....

The effect of pH on the toxicity of fatty acids and fatty acid amides to rainbow trout gill cells.

Science.gov (United States)

Bertin, Matthew J; Voronca, Delia C; Chapman, Robert W; Moeller, Peter D R

2014-01-01

Harmful algal blooms (HABs) expose aquatic organisms to multiple physical and chemical stressors during an acute time period. Algal toxins themselves may be altered by water chemistry parameters affecting their bioavailability and resultant toxicity. The purpose of this study was to determine the effects of two abiotic parameters (pH, inorganic metal salts) on the toxicity of fatty acid amides and fatty acids, two classes of lipids produced by harmful algae, including the golden alga, Prymnesium parvum, that are toxic to aquatic organisms. Rainbow trout gill cells were used as a model of the fish gill and exposed to single compounds and mixtures of compounds along with variations in pH level and concentration of inorganic metal salts. We employed artificial neural networks (ANNs) and standard ANOVA statistical analysis to examine and predict the effects of these abiotic parameters on the toxicity of fatty acid amides and fatty acids. Our results demonstrate that increasing pH levels increases the toxicity of fatty acid amides and inhibits the toxicity of fatty acids. This phenomenon is reversed at lower pH levels. Exposing gill cells to complex mixtures of chemical factors resulted in dramatic increases in toxicity compared to tests of single compounds for both the fatty acid amides and fatty acids. These findings highlight the potential of physicochemical factors to affect the toxicity of chemicals released during algal blooms and demonstrate drastic differences in the effect of pH on fatty acid amides and fatty acids. Published by Elsevier B.V.

pH and its frequency distribution patterns of Acid Precipitation in Japan

International Nuclear Information System (INIS)

Kitamura, Moritsugu; Katou, Takunori; Sekiguchi, Kyoichi

1991-01-01

The pH data was collected at the 29 stations in Phase-I study of Acid Precipitation Survey over Japan by Japan Environment Agency in terms of frequency distribution patterns. This study was undertaken from April 1984 to March 1988, which was the first survey of acid precipitation over Japan with identical sampling procedures and subsequent chemical analyses. While the annual mean pH at each station ranged from 4.4 to 5.5, the monthly mean varied more widely, from 4.0 to 7.1. Its frequency distribution pattern was obtained for each station, and further grouped into four classes: class I; a mode at the rank of pH 4.5∼4.9, class II; bimodes above and below this pH region, class III; a mode at a higher pH region, class IV; a mode at a lower pH region. The bimodal pattern was suggestive of precipitation with and without incorporation of significant amounts of basic aerosol of anthropogenic origin during descent of rain droplet. The patterns of the stations were also classified on a basis of summer-winter difference into another four classes. Winter pH values were appreciably lower than summer pHs in western parts of Japan and on Japan Sea coast, we attribute the winter pH to probable contribution of acidic pollutants transported by strong winter monsoon from Eurasian Continent. At most stations in northern and eastern Japan, the pH was higher in winter months reflecting more incorporation of basic materials, e.g., NH 4 + and Ca 2+ . (author)

Origin of middle rare earth element enrichments in acid waters of a Canadian high Arctic lake.

Science.gov (United States)

Johannesson, Kevin H.; Zhou, Xiaoping

1999-01-01

-Middle rare earth element (MREE) enriched rock-normalized rare earth element (REE) patterns of a dilute acidic lake (Colour Lake) in the Canadian High Arctic, were investigated by quantifying whole-rock REE concentrations of rock samples collected from the catchment basin, as well as determining the acid leachable REE fraction of these rocks. An aliquot of each rock sample was leached with 1 N HNO 3 to examine the readily leachable REE fraction of each rock, and an additional aliquot was leached with a 0.04 M NH 2OH · HCl in 25% (v/v) CH 3COOH solution, designed specifically to reduce Fe-Mn oxides/oxyhydroxides. Rare earth elements associated with the leachates that reacted with clastic sedimentary rock samples containing petrographically identifiable Fe-Mn oxide/oxyhydroxide cements and/or minerals/amorphous phases, exhibited whole-rock-normalized REE patterns similar to the lake waters, whereas whole-rock-normalized leachates from mafic igneous rocks and other clastic sedimentary rocks from the catchment basin differed substantially from the lake waters. The whole-rock, leachates, and lake water REE data support acid leaching or dissolution of MREE enriched Fe-Mn oxides/oxyhydroxides contained and identified within some of the catchment basin sedimentary rocks as the likely source of the unique lake water REE patterns. Solution complexation modelling of the REEs in the inflow streams and lake waters indicate that free metal ions (e.g., Ln 3+, where Ln = any REE) and sulfate complexes (LnSO 4+) are the dominant forms of dissolved REEs. Consequently, solution complexation reactions involving the REEs during weathering, transport to the lake, or within the lake, cannot be invoked to explain the MREE enrichments observed in the lake waters.

Seasonal dynamics and life histories of pelagic cladocerans (Crustacea; Cladocera in an acid boreal lake

Directory of Open Access Journals (Sweden)

Jens Petter NILSSEN

2011-02-01

Full Text Available In the surveyed anthropogenic acidified Lake Gjerstadvann with pH ≈ 5.2 situated in southern Norway, spatial and temporal distribution of three characteristic planktonic cladocerans inhabiting acidified boreal biotopes, Bosmina longispina, Holopedium gibberum, and Diaphanosoma brachyurum, were studied over a period of one year. The major pelagic predator was Eurasian perch, Perca fluviatilis. The local perch probably balanced the cladoceran community and facilitated co-existence of all three species of cladocerans by removing significant portions of B. longispina, which could also be the case in similar types of boreal lakes. Invertebrate predators such as the dipteran larvae Chaoborus flavicans and carnivorous copepods did not seem to influence the cladoceran community. B. longispina was perennial, whereas both H. gibberum and D. brachyurum were recorded only during the ice-free period. The life cycle of these free-living pelagic species ranged from 2-3 in D. brachyurum, 3 in H. gibberum to approximately 6 annual generations in B. longispina. Wintering took place as resting eggs in D. brachyurum and H. gibberum, while B. longispina produced resting eggs in addition to an active planktonic stay. The warm water tolerant D. brachyurum was mainly distributed above the thermocline, whereas H. gibberum also inhabited deeper strata, and B. longispina most vertical strata of the lake. Maximum seasonal clutch volume of B. longispina coincided in time with peak in food abundance and may be a useful parameter to identify planktonic food availability in such lakes. Knowledge of the autecology and life history of species is fundamental for understanding ecosystem stress, such as anthropogenic acidification and recovery through liming or by natural causes. Seasonal depth isoplots combined with life history studies of commonly co-occurring cladoceran species from natural acid and anthropogenic acidified lakes on the Northern Hemisphere seem to be uncommon

Polymethylene-interrupted fatty acids: Biomarkers for native and exotic mussels in the Laurentian Great Lakes

Science.gov (United States)

Mezek, Tadej; Sverko, Ed; Ruddy, Martina D.; Zaruk, Donna; Capretta, Alfredo; Hebert, Craig E.; Fisk, Aaron T.; McGoldrick, Daryl J.; Newton, Teresa J.; Sutton, Trent M.; Koops, Marten A.; Muir, Andrew M.; Johnson, Timothy B.; Ebener, Mark P.; Arts, Michael T.

2011-01-01

Freshwater organisms synthesize a wide variety of fatty acids (FAs); however, the ability to synthesize and/or subsequently modify a particular FA is not universal, making it possible to use certain FAs as biomarkers. Herein we document the occurrence of unusual FAs (polymethylene-interrupted fatty acids; PMI-FAs) in select freshwater organisms in the Laurentian Great Lakes. We did not detect PMI-FAs in: (a) natural seston from Lake Erie and Hamilton Harbor (Lake Ontario), (b) various species of laboratory-cultured algae including a green alga (Scenedesmus obliquus), two cyanobacteria (Aphanizomenon flos-aquae and Synechococystis sp.), two diatoms (Asterionella formosa, Diatoma elongatum) and a chrysophyte (Dinobryon cylindricum) or, (c) zooplankton (Daphnia spp., calanoid or cyclopoid copepods) from Lake Ontario, suggesting that PMI-FAs are not substantively incorporated into consumers at the phytoplankton–zooplankton interface. However, these unusual FAs comprised 4-6% of total fatty acids (on a dry tissue weight basis) of native fat mucket (Lampsilis siliquoidea) and plain pocketbook (L. cardium) mussels and in invasive zebra (Dreissena polymorpha) and quagga (D. bugensis) mussels. We were able to clearly partition Great Lakes' mussels into three separate groups (zebra, quagga, and native mussels) based solely on their PMI-FA profiles. We also provide evidence for the trophic transfer of PMI-FAs from mussels to various fishes in Lakes Ontario and Michigan, further underlining the potential usefulness of PMI-FAs for tracking the dietary contribution of mollusks in food web and contaminant-fate studies.

The effect of pH on the erosion of dentine and enamel by dietary acids in vitro.

Science.gov (United States)

West, N X; Hughes, J A; Addy, M

2001-09-01

The reported incidence of tooth erosion caused by acidic soft drinks has been increasingly documented. Citric and phosphoric acids are the two main dietary acids present in these soft drinks. Many variables need to be determined in order to assess risk factors for dental erosion caused by beverage consumption including pH, titratable acidity, pKa, buffering capacity, hence the aim of these in vitro investigations. Methodologies included profiling flat enamel and dentine samples (acidic solutions adjusted with alkali over the available pH range; citric, phosphoric and hydrochloric acid were adjusted with sodium hydroxide and citric acid with trisodium citrate. Tissue loss was calculated by profilometry. Results showed that under these conditions citric acid caused far more erosion over the pH range employed than phosphoric acid for both tissue types. Citric acid compared with hydrochloric acid highlighted dissolution and chelation effects. Phosphoric acid caused minimal erosion over pH 3 for enamel and pH 4 for dentine. These factors could be considered in order to reduce the erosivity of acidic soft drinks.

Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.

Science.gov (United States)

O'Hanlon, Deirdre E; Moench, Thomas R; Cone, Richard A

2013-01-01

Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.

NORM levels in Spanish pit lakes and their impact in neighboring environments

Energy Technology Data Exchange (ETDEWEB)

Manjon, G.; Galvan, J.A.; Mantero, J.; Diaz, I.; Garcia-Tenorio, R. [University of Seville (Spain)

2014-07-01

The Iberian Pyrite Belt (IPB) is a part of the South Zone of the Hercynian Iberian Massif (SW of Iberian Peninsula), being pyrite (FeS{sub 2}) the main mineral associated to this volcano-sedimentary complex. The intensive mining activities in the area, which started in the Roman Empire, have generated mine pits where underground and/or rainwater are stored. These stored waters have produced oxidation of pyrite and, consequently, the pH of pit water has become acid (pH around 2), causing the dissolution of metals and natural radionuclides. The main objective of this work is to show and discuss the levels found for different natural radionuclides (mainly uranium isotopes and daughters via α/γ spectrometry) in water samples and sediments collected from several mine pit lakes located in the south-west of Spain. The waters of the studied pit lakes can interact with the environment, and a fraction can be transferred to surrounding aquifers and even to the main river of the zone (the Odiel River). The waters of this river, when cross the mining area, show low pH values and high concentrations of U-isotopes due to acid mining drainage. Through the analysis of several isotope activity ratios, the presence of natural radionuclides in these pit lakes and its influence in the surrounding area and Odiel river will be additionally evaluated. Document available in abstract form only. (authors)

Differential gene expression in tomato fruit and Colletotrichum gloeosporioides during colonization of the RNAi-SlPH tomato line with reduced fruit acidity and higher pH.

Science.gov (United States)

Barad, Shiri; Sela, Noa; Dubey, Amit K; Kumar, Dilip; Luria, Neta; Ment, Dana; Cohen, Shahar; Schaffer, Arthur A; Prusky, Dov

2017-08-04

The destructive phytopathogen Colletotrichum gloeosporioides causes anthracnose disease in fruit. During host colonization, it secretes ammonia, which modulates environmental pH and regulates gene expression, contributing to pathogenicity. However, the effect of host pH environment on pathogen colonization has never been evaluated. Development of an isogenic tomato line with reduced expression of the gene for acidity, SlPH (Solyc10g074790.1.1), enabled this analysis. Total RNA from C. gloeosporioides colonizing wild-type (WT) and RNAi-SlPH tomato lines was sequenced and gene-expression patterns were compared. C. gloeosporioides inoculation of the RNAi-SlPH line with pH 5.96 compared to the WT line with pH 4.2 showed 30% higher colonization and reduced ammonia accumulation. Large-scale comparative transcriptome analysis of the colonized RNAi-SlPH and WT lines revealed their different mechanisms of colonization-pattern activation: whereas the WT tomato upregulated 13-LOX (lipoxygenase), jasmonic acid and glutamate biosynthesis pathways, it downregulated processes related to chlorogenic acid biosynthesis II, phenylpropanoid biosynthesis and hydroxycinnamic acid tyramine amide biosynthesis; the RNAi-SlPH line upregulated UDP-D-galacturonate biosynthesis I and free phenylpropanoid acid biosynthesis, but mainly downregulated pathways related to sugar metabolism, such as the glyoxylate cycle and L-arabinose degradation II. Comparison of C. gloeosporioides gene expression during colonization of the WT and RNAi-SlPH lines showed that the fungus upregulates ammonia and nitrogen transport and the gamma-aminobutyric acid metabolic process during colonization of the WT, while on the RNAi-SlPH tomato, it mainly upregulates the nitrate metabolic process. Modulation of tomato acidity and pH had significant phenotypic effects on C. gloeosporioides development. The fungus showed increased colonization on the neutral RNAi-SlPH fruit, and limited colonization on the WT acidic fruit

Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

Science.gov (United States)

Viala, Julie P M; Méresse, Stéphane; Pocachard, Bérengère; Guilhon, Aude-Agnès; Aussel, Laurent; Barras, Frédéric

2011-01-01

During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i) to survive an extreme acid shock, (ii) to grow at mild acidic pH and (iii) to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

Directory of Open Access Journals (Sweden)

Julie P M Viala

Full Text Available During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i to survive an extreme acid shock, (ii to grow at mild acidic pH and (iii to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

Effect of systemic pH on pHi and lactic acid generation in exhaustive forearm exercise

International Nuclear Information System (INIS)

Hood, V.L.; Schubert, C.; Keller, U.; Mueller, S.

1988-01-01

To investigate whether changes in systemic pH affect intracellular pH (pH i ), energy-rich phosphates, and lactic acid generation in muscle, eight normal volunteers performed exhaustive forearm exercise with arterial blood flow occluded for 2 min on three occasions. Subjects ingested 4 mmol/kg NH 4 Cl (acidosis; A) or NaHCO 3 (alkalosis; B) or nothing (control; C) 3 h before the exercise. Muscle pH i and phosphocreatine (PCr) content were measured with 31 P-nuclear magnetic resonance ( 31 P-NMR) spectroscopy during exercise and recovery. Lactate output during 0.5-7 min of recovery was calculated as deep venous-arterial concentration differences times forearm blood flow. Before exercise, blood pH and bicarbonate were lower in acidosis than alkalosis and intermediate in control. Lactic acid output during recovery was less with A than B and intermediate in C. PCr utilization and resynthesis were not affected by extracellular pH changes. pH i did not differ before exercise or at its end. Hence systemic acidosis inhibited and alkalosis stimulated lactic acid output. These findings suggest that systemic pH regulates cellular acid production, protecting muscle pH, at the expense of energy availability

Phytoplankton community responses to acidification of Lake 223, Experimental Lakes Area, Northwestern Ontario

Energy Technology Data Exchange (ETDEWEB)

Findlay, D.L.; Kasian, S.E.

1986-10-01

From 1976 to 1983 the pH of Lake 223 was artificially lowered by additions of H/sub 2/SO/sub 4/. From an initial level of 6.7, the pH was lowered at a rate of 0.5 pH units a year until it reached 5.0 and was held there for 3 yr. The decrease in pH caused major changes in the epilimnetic phytoplankton community in this lake. Biomass increased as pH decreased. Chlorophyte (Chlorella) abundance increased as pH decreased from 6.1 to 5.6 while Cyanophytes (Merismopedia and Chroococcus) and dinoflagellates (Gymnodinium and Peridinium) dominated once pH decreased below 5.6. Community diversities decreased because of these species shifts and a decrease in the number of species. The amount of edible biomass increased as the pH decreased from 6.7 to 5.6, then declined as pH decreased to 5.0. 25 refs.

Norm Levels in Mine Pit Lakes in South-Western Spain

International Nuclear Information System (INIS)

Manjón, G.; Galván, J.; Mantero, J.; Díaz, I.; García-Tenorio, R.

2015-01-01

Former mining activities in a pyritic area in south-western Spain have generated mine pits in which underground water and rainwater has accumulated. The accumulated waters have produced oxidation of the pyrite and, consequently, the pit water has become acidic, causing the dissolution of metals and radionuclides of natural origin. The paper discusses the activity concentration levels of uranium isotopes and other radionuclides in water samples and sediments collected from these mine pit lakes. Tributaries of the nearby Odiel River, when crossing the mining area, show low pH values and high concentrations of uranium isotopes due to acid mine drainage. Through the analysis of several isotope activity ratios, the presence of radionuclides in the pit lakes and the influence of these radionuclides on the surrounding area and the Odiel River are evaluated. (author)

Does road salting confound the recovery of the microcrustacean community in an acidified lake?

Science.gov (United States)

Jensen, Thomas Correll; Meland, Sondre; Schartau, Ann Kristin; Walseng, Bjørn

2014-04-15

Numerous boreal lakes across the Northern Hemisphere recovering from acidification are experiencing a simultaneous increase in chloride (Cl) concentrations from road salting. Increasing Cl may have profound effects on the lake ecosystem. We examine if an increase in Cl from road salting has modified the recovery of the microcrustacean community in an acidified boreal lake undergoing chemical recovery (study lake). Results from the study lake were compared with an acidified "reference lake". The community changed during the study period in the study lake mainly driven by the reduction in acidification pressure. Despite the community changes and an increase in species richness, the absence of several acid sensitive species, previously occurring in the lake, indicates a delayed biological recovery relative to the chemical recovery. Moreover, changes in occurrence of acid sensitive and acid tolerant species indicated that the biological recovery was slower in the study lake compared to the "reference". Although recurrent episodes of high aluminum and low pH and decreasing Ca are likely important factors for the delay, these do not explain, for instance, the shift from Cyclops scutifer to Bosmina longispina in the study lake. Although the contribution of Cl was not significant, the correlation between Cl and the variation in microcrustacean community was twice as high in the study lake compared to the "reference". We argue that small, sheltered forest lakes may be especially sensitive to increased Cl levels, through changes in pattern of stratification, thus providing a mechanism for the shift from C. scutifer to B. longispina. The reduction of the acidification pressure seems to override the Cl effects on microcrustaceans at low Cl levels in salt-affected lakes recovering from acidification. However, prognoses for growing traffic and increasing road salting raise concern for many recovering lakes located in proximity to roads and urbanized areas. Copyright © 2014

Hydrochloric acid leach of Agnew Lake uranium concentrate

International Nuclear Information System (INIS)

Haque, K.E.; Ipekoglue, B.

1981-10-01

Hydrochloric acid leaching was conducted on the radioactive mineral concentrate separated from the Agenw Lake uranium ore. Leach tests conducted at the optimum conditions (75 0 C; 36 hours; 66.0 Kg HCl/tonne; solid:liquid -1:1) resulted in the extraction of 87% uranium and 84% radium. The radionuclide level of the residue was U-0.016%, Th-0.24% and Ra-65 pCi/g solids. However to obtain a residue almost free of radium (i.e., Ra level at the detection limit: 4-6 pCi/g solids), the first stage leach residue was further treated with hydrochloric acid. The radium level in the best second stage leach residue was also above the target level. Therefore, multistage (3 or 4) hydrochloric acid and/or neutral chloride leaching is recommended to obtain tailings almost free of radionuclide

Acidic precipitation: considerations for an air-quality standard

Energy Technology Data Exchange (ETDEWEB)

Evans, L.S.; Hendrey, G.R.; Stensland, G.J.; Johnson, D.W.; Francis, A.J.

1980-01-01

Acidic precipitation, wet or frozen deposition with a hydrogen ion concentration greatern than 2.5 ..mu..eq l/sup -1/ is a significant air pollution problem in the United States. The chief anions accounting for the hydrogen ions in rainfall are nitrate and sulfate. Agricultural systems are more likely to derive net nutritional benefits from increasing inputs of acidic rain than are forest systems when soils alone are considered. Agricultural soils may benefit because of the high N and S requirements of agricultural plants. Detrimental effects to forest soils may result if atmospheric H/sup +/ inputs significantly add to or exceed H/sup +/ production by soils. Acidification of fresh waters of southern Scandinavia, southwestern Scotland, southeastern Canada, and northeastern United States is caused by acid deposition. Areas of these regions in which this acidification occurs have in common, highly acidic precipitation with volume weighted mean annual H/sup +/ concentrations of 25 ..mu..eq l/sup -1/ or higher and slow weathering granitic or precambrian bedrock with thin soils deficient in minerals which would provide buffer capacity. Biological effects of acidification of fresh waters are detectable below pH 6.0. As lake and stream pH levels decrease below pH. 6.0, many species of plants, invertebrates, and vertebrates are progressively eliminated. Generally, fisheries are impacted below pH 5.0 and are completely destroyed below pH 4.8. There are few studies that document effects of acidic precipitation on terrestrial vegetation to establish an air quality standard. It must be demonstrated that current levels of precipitation acidity alone significantly injure terrestrial vegetation. In terms of documented damanges, current research indicates that establishing a standard for precipitation for the volume weighted annual H/sup +/ concentration at 25 ..mu..eq l/sup -1/ may protect the most sensitive areas from permanent lake acidification.

Tale of two pit lakes: initial results of a three-year study of the Main Zone and Waterline pit lakes near Houston, British Columbia, Canada

Science.gov (United States)

Crusius, John; Pieters, R.; Leung, A.; Whittle, P.; Pedersen, T.; Lawrence, G.; McNee, J.J.

2003-01-01

Pit lakes are becoming increasingly common in North America as well as in the rest of the world. They are created as openpit mines fill passively with ground water and surface inflows on cessation of mining activity. In many instances, the water quality in these pit lakes does not meet regulatory requirements due to a number of influences. The most important are the oxidation of sulfide minerals and the associated release of acid and metals and the flushing of soluble metals during pit filling. Examples of pit lakes with severe water-quality problems include the Berkeley Pit lake (Butte, MT) and the Liberty Pit lake (Nevada), whose waters are characterized by a pH near 3 and Cu concentrations as high as ~150 mg/L (Miller et al., 1996; Davis and Eary, 1997). The importance of the problem can be seen in the fact that some of these sites in the United States are Superfund sites.

Lower pH values of weakly acidic refluxes as determinants of heartburn perception in gastroesophageal reflux disease patients with normal esophageal acid exposure.

Science.gov (United States)

de Bortoli, N; Martinucci, I; Savarino, E; Franchi, R; Bertani, L; Russo, S; Ceccarelli, L; Costa, F; Bellini, M; Blandizzi, C; Savarino, V; Marchi, S

2016-01-01

Multichannel impedance pH monitoring has shown that weakly acidic refluxes are able to generate heartburn. However, data on the role of different pH values, ranging between 4 and 7, in the generation of them are lacking. The aim of this study was to evaluate whether different pH values of weakly acidic refluxes play a differential role in provoking reflux symptoms in endoscopy-negative patients with physiological esophageal acid exposure time and positive symptom index and symptom association probability for weakly acidic refluxes. One hundred and forty-three consecutive patients with gastroesophageal reflux disease, nonresponders to proton pump inhibitors (PPIs), were allowed a washout from PPIs before undergoing: upper endoscopy, esophageal manometry, and multichannel impedance pH monitoring. In patients with both symptom index and symptom association probability positive for weakly acidic reflux, each weakly acidic reflux was evaluated considering exact pH value, extension, physical characteristics, and correlation with heartburn. Forty-five patients with normal acid exposure time and positive symptom association probability for weakly acidic reflux were identified. The number of refluxes not heartburn related was higher than those heartburn related. In all distal and proximal liquid refluxes, as well as in distal mixed refluxes, the mean pH value of reflux events associated with heartburn was significantly lower than that not associated. This condition was not confirmed for proximal mixed refluxes. Overall, a low pH of weakly acidic reflux represents a determinant factor in provoking heartburn. This observation contributes to better understand the pathophysiology of symptoms generated by weakly acidic refluxes, paving the way toward the search for different therapeutic approaches to this peculiar condition of esophageal hypersensitivity. © 2014 International Society for Diseases of the Esophagus.

Speciation of aluminium, arsenic and molybdenum in excessively limed lakes

International Nuclear Information System (INIS)

Sjoestedt, Carin; Waellstedt, Teresia; Gustafsson, Jon Petter; Borg, Hans

2009-01-01

The possible existence of the potentially toxic oxyanions of Al (Al(OH) 4 - ), As (HAsO 4 2- ), and Mo (MoO 4 2- ) was examined in excessively limed lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively limed lakes (pH 7.1-7.7) and one acidic lake (pH ∼ 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively limed lakes were to a large extent present in the dialysable fraction (> 79% and > 92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH) 4 - ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.

Influence of acidic pH on hydrogen and acetate production by an electrosynthetic microbiome.

Directory of Open Access Journals (Sweden)

Edward V LaBelle

Full Text Available Production of hydrogen and organic compounds by an electrosynthetic microbiome using electrodes and carbon dioxide as sole electron donor and carbon source, respectively, was examined after exposure to acidic pH (∼ 5. Hydrogen production by biocathodes poised at -600 mV vs. SHE increased >100-fold and acetate production ceased at acidic pH, but ∼ 5-15 mM (catholyte volume/day acetate and >1,000 mM/day hydrogen were attained at pH ∼ 6.5 following repeated exposure to acidic pH. Cyclic voltammetry revealed a 250 mV decrease in hydrogen overpotential and a maximum current density of 12.2 mA/cm2 at -765 mV (0.065 mA/cm2 sterile control at -800 mV by the Acetobacterium-dominated community. Supplying -800 mV to the microbiome after repeated exposure to acidic pH resulted in up to 2.6 kg/m3/day hydrogen (≈ 2.6 gallons gasoline equivalent, 0.7 kg/m3/day formate, and 3.1 kg/m3/day acetate ( = 4.7 kg CO2 captured.

Acidic Food pH Increases Palatability and Consumption and Extends Drosophila Lifespan.

Science.gov (United States)

Deshpande, Sonali A; Yamada, Ryuichi; Mak, Christine M; Hunter, Brooke; Soto Obando, Alina; Hoxha, Sany; Ja, William W

2015-12-01

Despite the prevalent use of Drosophila as a model in studies of nutrition, the effects of fundamental food properties, such as pH, on animal health and behavior are not well known. We examined the effect of food pH on adult Drosophila lifespan, feeding behavior, and microbiota composition and tested the hypothesis that pH-mediated changes in palatability and total consumption are required for modulating longevity. We measured the effect of buffered food (pH 5, 7, or 9) on male gustatory responses (proboscis extension), total food intake, and male and female lifespan. The effect of food pH on germfree male lifespan was also assessed. Changes in fly-associated microbial composition as a result of food pH were determined by 16S ribosomal RNA gene sequencing. Male gustatory responses, total consumption, and male and female longevity were additionally measured in the taste-defective Pox neuro (Poxn) mutant and its transgenic rescue control. An acidic diet increased Drosophila gustatory responses (40-230%) and food intake (5-50%) and extended survival (10-160% longer median lifespan) compared with flies on either neutral or alkaline pH food. Alkaline food pH shifted the composition of fly-associated bacteria and resulted in greater lifespan extension (260% longer median survival) after microbes were eliminated compared with flies on an acidic (50%) or neutral (130%) diet. However, germfree flies lived longer on an acidic diet (5-20% longer median lifespan) compared with those on either neutral or alkaline pH food. Gustatory responses, total consumption, and longevity were unaffected by food pH in Poxn mutant flies. Food pH can directly influence palatability and feeding behavior and affect parameters such as microbial growth to ultimately affect Drosophila lifespan. Fundamental food properties altered by dietary or drug interventions may therefore contribute to changes in animal physiology, metabolism, and survival. © 2015 American Society for Nutrition.

Measurement of pH, alkalinity and acidity in ultra-soft waters

African Journals Online (AJOL)

drinie

2001-10-04

Oct 4, 2001 ... A blend composed of the raw water, sodium chloride (to increase conductivity), and standard bicarbonate (to increase buffering capacity) was titrated with standard strong acid in two pH regions: 6.3 pH < 4.0. In both methods, total alkalinity was determined using the latter set of points, ...

Acidic deposition: State of science and technology. Report 10. Watershed and lake processes affecting surface-water acid-base chemistry. Final report

International Nuclear Information System (INIS)

Turner, R.S.; Cook, R.B.; Miegroet, H.V.; Johnson, D.W.; Elwood, J.W.

1990-09-01

The acid-base chemistry of surface waters is governed by the amount and chemistry of deposition and by the biogeochemical reactions that generate acidity or acid neutralizing capacity (ANC) along the hydrologic pathways that water follows through watersheds to streams and lakes. The amount of precipitation and it chemical loading depend on the area's climate and physiography, on it proximity to natural or industrial gaseous or particulate sources, and on local or regional air movements. Vegetation interacts with the atmosphere to enhance both wet and dry deposition of chemicals to a greater or lesser extent, depending on vegetation type. Vegetation naturally acidifies the environment in humid regions through processes of excess base cation uptake and generation of organic acids associated with many biological processes. Natural acid production and atmospheric deposition of acidic materials drive the acidification process. The lake or stream NAC represents a balance between the acidity-and ANC-generating processes that occur along different flow paths in the watershed and the relative importance of each flow path

The effects of extracellular pH and hydroxycinnamic acids influence the intracellular pH of Brettanomyces bruxellensis DSM 7001

DEFF Research Database (Denmark)

Campolongo, Simona; Siegumfeldt, Henrik; Aabo, Thomas Ask

2014-01-01

and intracellular pH changes in B. bruxellensis DSM 7001, in response to extracellular pH, as well as to the presence of an energy source and hydroxycinnamic acids, have been investigated in this paper by means of Fluorescent Ratio Imaging Microscopy (FRIM). The results show that B. bruxellensis DSM 7001 is able...

Acid skim milk gels: The gelation process as affected by preheated pH

NARCIS (Netherlands)

Lakemond, C.M.M.; Vliet, van T.

2008-01-01

The effect of preheating milk (10 min 80 [degree sign]C) at pH values from 6.20 to 6.90 on formation of acid skim milk gels was studied by dynamic oscillation measurements. Up to pH 6.65 a higher pH of heating (pHheating) resulted in a higher G'. Since below pH 4.9 the development of

Water-quality effects on Baker Lake of recent volcanic activity at Mount Baker, Washington

Science.gov (United States)

Bortleson, Gilbert Carl; Wilson, Reed T.; Foxworthy, B.L.

1976-01-01

Increased volcanic activity on Mount Baker, which began in March 1975, represents the greatest known activity of a Cascade Range volcano since eruptions at Lassen Peak, Calif. during 1914-17. Emissions of dust and increased emanations of steam, other gases, and heat from the Sherman Crater area of the mountain focused attention on the possibility of hazardous events, including lava flows, pyroclastic eruptions, avalanches, and mudflows. However, the greatest undesirable natural results that have been observed after one year of the increased activity are an increase in local atmospheric pollution and a decrease in the quality of some local water resources, including Baker Lake. Baker Lake, a hydropower reservoir behind Upper Baker Dam, supports a valuable fishery resource and also is used for recreation. The lake's feedwater is from Baker River and many smaller streams, some of which, like Boulder Creek, drain parts of Mount Baker. Boulder Creek receives water from Sherman Crater, and its channel is a likely route for avalanches or mudflows that might originate in the crater area. Boulder Creek drains only about 5 percent of the total drainage area of Baker Lake, but during 1975 carried sizeable but variable loads of acid and dissolved minerals into the lake. Sulfurous gases and the fumarole dust from Sherman Crater are the main sources for these materials, which are brought into upper Boulder Creek by meltwater from the crater. In September 1973, before the increased volcanic activity, Boulder Creek near the lake had a pH of 6.0-6.6; after the increase the pH ranged as low as about 3.5. Most nearby streams had pH values near 7. On April 29, in Boulder Creek the dissolved sulfate concentration was 6 to 29 times greater than in nearby creeks or in Baker River; total iron was 18-53 times greater than in nearby creeks; and other major dissolved constituents generally 2 to 7 times greater than in the other streams. The short-term effects on Baker Lake of the acidic

Pinatubo Lake Chemistry and Degassing 1991-2010

Science.gov (United States)

Schwandner, F. M.; Newhall, C. G.; Christenson, B. W.; Apfelbeck, C. A.; Arpa, M. C. B.; Vaquilar, R.; Bariso, E.

2016-12-01

We review the history of degassing, bathymetry and water chemistry of the crater lake of Mt. Pinatubo (Philippines) using data obtained during 1991-2001, and 2010. In late 1992, the initial small lake had a significant acid-sulfate component from a volcanic degassing through a hydrothermal system and the lake, and anhydrite dissolution. Subsequently, this component was "drowned" by rainfall (2-4 m/y), meteoric groundwater draining from the crater walls into the lake, and a few neutral chloride crater wall springs. Conductivity-Temperature-Depth (CTD) measurements in August 2000 found a strong inverted thermal gradient below 20m depth, reaching over 70°C at 50-60 m depth. By January 2001 the lake had homogenized and was much cooler (27°C at all depths), and it was again well-mixed and still cool when re-surveyed in June 2001 and November 2010. By 2010, the lake was well mixed, at neutral pH, with no significant vertical or horizontal structure. Bubbling of a predominantly carbon dioxide (CO2) gas phase persists throughout the lake's history, some from 1991-92 magma and some from degassing of the long-standing (pre-1991) hydrothermal system fed from a deeper magmatic or mantle source. Crater wall fumaroles emit boiling-point hydrothermal gases dominated by water, air, and CO2.

Decrease of intracellular pH as possible mechanism of embryotoxicity of glycol ether alkoxyacetic acid metabolites

International Nuclear Information System (INIS)

Louisse, Jochem; Bai Yanqing; Verwei, Miriam; Sandt, Johannes J.M. van de; Blaauboer, Bas J.; Rietjens, Ivonne M.C.M.

2010-01-01

Embryotoxicity of glycol ethers is caused by their alkoxyacetic acid metabolites, but the mechanism underlying the embryotoxicity of these acid metabolites is so far not known. The present study investigates a possible mechanism underlying the embryotoxicity of glycol ether alkoxyacetic acid metabolites using the methoxyacetic acid (MAA) metabolite of ethylene glycol monomethyl ether as the model compound. The results obtained demonstrate an MAA-induced decrease of the intracellular pH (pH i ) of embryonic BALB/c-3T3 cells as well as of embryonic stem (ES)-D3 cells, at concentrations that affect ES-D3 cell differentiation. These results suggest a mechanism for MAA-mediated embryotoxicity similar to the mechanism of embryotoxicity of the drugs valproic acid and acetazolamide (ACZ), known to decrease the pH i in vivo, and therefore used as positive controls. The embryotoxic alkoxyacetic acid metabolites ethoxyacetic acid, butoxyacetic acid and phenoxyacetic acid also caused an intracellular acidification of BALB/c-3T3 cells at concentrations that are known to inhibit ES-D3 cell differentiation. Two other embryotoxic compounds, all-trans-retinoic acid and 5-fluorouracil, did not decrease the pH i of embryonic cells at concentrations that affect ES-D3 cell differentiation, pointing at a different mechanism of embryotoxicity of these compounds. MAA and ACZ induced a concentration-dependent inhibition of ES-D3 cell differentiation, which was enhanced by amiloride, an inhibitor of the Na + /H + -antiporter, corroborating an important role of the pH i in the embryotoxic mechanism of both compounds. Together, the results presented indicate that a decrease of the pH i may be the mechanism of embryotoxicity of the alkoxyacetic acid metabolites of the glycol ethers.

Mode of de-esterification of alkaline and acidic pectin methyl esterases at different pH conditions.

Science.gov (United States)

Duvetter, Thomas; Fraeye, Ilse; Sila, Daniel N; Verlent, Isabel; Smout, Chantal; Hendrickx, Marc; Van Loey, Ann

2006-10-04

Highly esterified citrus pectin was de-esterified at pH 4.5 and 8.0 by a fungal pectin methyl esterase (PME) that was shown to have an acidic isoelectric pH (pI) and an acidic pH optimum and by a plant PME that was characterized by an alkaline pI and an alkaline pH optimum. Interchain and intrachain de-esterification patterns were studied by digestion of the pectin products with endo-polygalacturonase and subsequent analysis using size exclusion and anion-exchange chromatography. No effect of pH was observed on the de-esterification mode of either of the two enzymes. Acidic, fungal PME converted pectin according to a multiple-chain mechanism, with a limited degree of multiple attack at the intrachain level, both at pH 4.5 and at pH 8.0. A multiple-attack mechanism, with a high degree of multiple attack, was more appropriate to describe the action mode of alkaline, plant PME, both at pH 4.5 and at pH 8.0.

In-Lake Processes Offset Increased Terrestrial Inputs of Dissolved Organic Carbon and Color to Lakes

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Köhler, Stephan J.; Kothawala, Dolly; Futter, Martyn N.; Liungman, Olof; Tranvik, Lars

2013-01-01

Increased color in surface waters, or browning, can alter lake ecological function, lake thermal stratification and pose difficulties for drinking water treatment. Mechanisms suggested to cause browning include increased dissolved organic carbon (DOC) and iron concentrations, as well as a shift to more colored DOC. While browning of surface waters is widespread and well documented, little is known about why some lakes resist it. Here, we present a comprehensive study of Mälaren, the third largest lake in Sweden. In Mälaren, the vast majority of water and DOC enters a western lake basin, and after approximately 2.8 years, drains from an eastern basin. Despite 40 years of increased terrestrial inputs of colored substances to western lake basins, the eastern basin has resisted browning over this time period. Here we find the half-life of iron was far shorter (0.6 years) than colored organic matter (A420 ; 1.7 years) and DOC as a whole (6.1 years). We found changes in filtered iron concentrations relate strongly to the observed loss of color in the western basins. In addition, we observed a substantial shift from colored DOC of terrestrial origin, to less colored autochthonous sources, with a substantial decrease in aromaticity (-17%) across the lake. We suggest that rapid losses of iron and colored DOC caused the limited browning observed in eastern lake basins. Across a wider dataset of 69 Swedish lakes, we observed greatest browning in acidic lakes with shorter retention times (< 1.5 years). These findings suggest that water residence time, along with iron, pH and colored DOC may be of central importance when modeling and projecting changes in brownification on broader spatial scales. PMID:23976946

[Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

Science.gov (United States)

Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

2009-10-15

To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

Critical Loads of Acid Deposition for Wilderness Lakes in the Sierra Nevada (California) Estimated by the Steady-State Water Chemistry Model

Science.gov (United States)

Glenn D. Shaw; Ricardo Cisneros; Donald Schweizer; James O. Sickman; Mark E. Fenn

2014-01-01

Major ion chemistry (2000-2009) from 208 lakes (342 sample dates and 600 samples) in class I and II wilderness areas of the Sierra Nevada was used in the Steady-State Water Chemistry (SSWC) model to estimate critical loads for acid deposition and investigate the current vulnerability of high elevation lakes to acid deposition. The majority of the lakes were dilute (...

Enrichment of Non-Terrestrial L-Proteinogenic Amino Acids by Aqueous Alteration on the Tagish Lake Meteorite Parent Body

Science.gov (United States)

Glavin, Daniel P.; Elsila, Jamie E.; Burton, Aaron S.; Callahan, Michael P.; Dworkin, Jason P.; Herd, Christopher D. K.

2012-01-01

The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquid chromatography fluorescence detection time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. Large L-enantiomeric excesses (L(sub ee) approx. 43 to 59%) of the a-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another alpha-hydrogen protein amino acid, was found to be nearly racemic (D approx. L) using both techniques. Carbon isotope measurements of D- and L-aspartic acid and D- and L-alanine in Tagish Lake fall well outside of the terrestrial range and indicate that the measured aspartic acid enantioenrichment is indigenous to the meteorite. Alternate explanations for the Lexcesses of aspartic acid such as interference from other compounds present in the sample, analytical biases, or terrestrial amino acid contamination were investigated and rejected. These results can be explained by differences in the solid-solution phase behavior of aspartic acid, which can form conglomerate enantiopure solids during crystallization, and alanine, which can only form racemic crystals.

Seasonal quantitative dynamics and ecology of pelagic rotifers in an acidified boreal lake

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Svein Birger Wærvågen

2017-12-01

Full Text Available Lake Gjerstadvann is a dimictic, oligotrophic, slightly acidified boreal lake in southern Norway (northwest Europe. The planktonic rotifer community of this lake was studied quantitatively during one year in order to investigate the impacts of the local environment and biotic interactions on seasonal succession and habitat selection. Pure suspension feeders (mainly Keratella spp., Conochilus spp., and Kellicottia longispina together with raptorial graspers or specialised feeders (mainly Polyarthra spp. and Collotheca spp. dominated the rotifer community over prolonged periods, whereas carnivorous/omnivorous species (mainly Asplanchna priodonta were extremely uncommon. Low bicarbonate buffering capacity resulted in a distinctive seasonal oscillating pH between 5.0 and 5.6, defining a special acid-transition lake category. The pH values were highest in the productive period during summer, and lowest during ice break-up coinciding with the peak reactive aluminium concentrations of 250-300 mg L-1. As in typical Norwegian boreal perch lakes, the most abundant cladoceran was Bosmina longispina due to perch predation on the genus Daphnia. Rotifer community structure was significantly related to temperature and oxygen (P=0.001 and P=0.022, illustrating the important effects of the seasonal cycle and vertical density stratification. The most significant competition indicator species were B. longispina and Eudiaptomus gracilis (both with P=0.001. A variance partitioning indicated that 14% of the total community composition variance could only be explained by biotic interactions, while 19% of the variance could be attributed to environmental gradients. Of the variance, 23% could not be resolved between biotic interactions and environmental gradients, while a residual of 44% was not explainable by any of the variables. Acid conditions alone cannot account for all the observed changes in the rotifer community of this lake with low humic content, since

Isoelectric focusing of dansylated amino acids in immobilized pH gradients

Science.gov (United States)

Bianchi-Bosisio, Adriana; Righetti, Pier Giorgio; Egen, Ned B.; Bier, Milan

1986-01-01

The 21 free amino acids commonly encountered in proteins have been transformed into 'carrier ampholyte' species by reacting their primary amino groups with dansyl chloride. These derivatives can thus be focused in an immobilized pH gradient covering the pH interval 3.1 to 4.1, except for arginine, which still retains a pI of 8.8. Due to their inherent fluorescence, the dansyl derivatives are revealed in UV light, with a sensitivity of the order of 2-4 ng/sq mm. All nearest neighbors are separated except for the following couples: Asn-Gln, Gly-Thr, Val-Ile and Cys-Cys2, with a resolving power, in a Delta(pI) scale, of the order of 0.0018 pH units. Except for a few cases (notably the aromatic amino acids), the order of pI values is well correlated with the pK values of carboxyl groups, suggesting that the latter are not altered by dansylation. From the set of pK(COOH)-pI values of the different amino acids, the pK of the tertiary amino group in the dansyl label has been calculated to be 5.11 + or - 0.06. Knowing the pK of the amino-dansyl and the pI of the excess, free dansyl label (pI = 3.34), a pK of 1.57 is derived for its sulfonic acid group.

Initial pH of medium affects organic acids production but do not affect phosphate solubilization.

Science.gov (United States)

Marra, Leandro M; de Oliveira-Longatti, Silvia M; Soares, Cláudio R F S; de Lima, José M; Olivares, Fabio L; Moreira, Fatima M S

2015-06-01

The pH of the culture medium directly influences the growth of microorganisms and the chemical processes that they perform. The aim of this study was to assess the influence of the initial pH of the culture medium on the production of 11 low-molecular-weight organic acids and on the solubilization of calcium phosphate by bacteria in growth medium (NBRIP). The following strains isolated from cowpea nodules were studied: UFLA03-08 (Rhizobium tropici), UFLA03-09 (Acinetobacter sp.), UFLA03-10 (Paenibacillus kribbensis), UFLA03-106 (Paenibacillus kribbensis) and UFLA03-116 (Paenibacillus sp.). The strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 solubilized Ca3(PO4)2 in liquid medium regardless of the initial pH, although without a significant difference between the treatments. The production of organic acids by these strains was assessed for all of the initial pH values investigated, and differences between the treatments were observed. Strains UFLA03-09 and UFLA03-10 produced the same acids at different initial pH values in the culture medium. There was no correlation between phosphorus solubilized from Ca3(PO4)2 in NBRIP liquid medium and the concentration of total organic acids at the different initial pH values. Therefore, the initial pH of the culture medium influences the production of organic acids by the strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 but it does not affect calcium phosphate solubilization.

A single pH fluorescent probe for biosensing and imaging of extreme acidity and extreme alkalinity.

Science.gov (United States)

Chao, Jian-Bin; Wang, Hui-Juan; Zhang, Yong-Bin; Li, Zhi-Qing; Liu, Yu-Hong; Huo, Fang-Jun; Yin, Cai-Xia; Shi, Ya-Wei; Wang, Juan-Juan

2017-07-04

A simple tailor-made pH fluorescent probe 2-benzothiazole (N-ethylcarbazole-3-yl) hydrazone (Probe) is facilely synthesized by the condensation reaction of 2-hydrazinobenzothiazole with N-ethylcarbazole-3-formaldehyde, which is a useful fluorescent probe for monitoring extremely acidic and alkaline pH, quantitatively. The pH titrations indicate that Probe displays a remarkable emission enhancement with a pK a of 2.73 and responds linearly to minor pH fluctuations within the extremely acidic range of 2.21-3.30. Interestingly, Probe also exhibits strong pH-dependent characteristics with pK a 11.28 and linear response to extreme-alkalinity range of 10.41-12.43. In addition, Probe shows a large Stokes shift of 84 nm under extremely acidic and alkaline conditions, high selectivity, excellent sensitivity, good water-solubility and fine stability, all of which are favorable for intracellular pH imaging. The probe is further successfully applied to image extremely acidic and alkaline pH values fluctuations in E. coli cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Polyamine/salt-assembled microspheres coated with hyaluronic acid for targeting and pH sensing.

Science.gov (United States)

Zhang, Pan; Yang, Hui; Wang, Guojun; Tong, Weijun; Gao, Changyou

2016-06-01

The poly(allylamine hydrochloride)/trisodium citrate aggregates were fabricated and further covalently crosslinked via the coupling reaction of carboxylic sites on trisodium citrate with the amine groups on polyamine, onto which poly-L-lysine and hyaluronic acid were sequentially assembled, forming stable microspheres. The pH sensitive dye and pH insensitive dye were further labeled to enable the microspheres with pH sensing property. Moreover, these microspheres could be specifically targeted to HeLa tumor cells, since hyaluronic acid can specifically recognize and bind to CD44, a receptor overexpressed on many tumor cells. Quantitative pH measurement by confocal laser scanning microscopy demonstrated that the microspheres were internalized into HeLa cells, and accumulated in acidic compartments. By contrast, only a few microspheres were adhered on the NIH 3T3 cells surface. The microspheres with combined pH sensing property and targeting ability can enhance the insight understanding of the targeted drug vehicles trafficking after cellular internalization. Copyright © 2016 Elsevier B.V. All rights reserved.

Resistance of Streptococcus bovis to acetic acid at low pH: Relationship between intracellular pH and anion accumulation

Energy Technology Data Exchange (ETDEWEB)

Russell, J.B. (Cornell Univ., Ithaca, NY (USA))

1991-01-01

Streptococcus bovis JB1, an acid-tolerant ruminal bacterium, was able to grown at pHs from 6.7 to 4.5, and 100 mM acetate had little effect on growth rate or proton motive force across the cell membrane. When S. bovis was grown in glucose-limited chemostats at pH 5.2, the addition of sodium acetate (as much as 100 mM) had little effect on the production of bacterial protein. At higher concentrations of sodium acetate (100 to 360 mM), production of bacterial protein declined, but this decrease could largely be explained by a shift in fermentation products (acetate, formate, and ethanol production to lactate production) and a decline in ATP production (3 ATP per glucose versus 2 ATP per glucose). Y{sub ATP} (grams of cells per mole at ATP) was not decreased significantly even by high concentrations of acetate. Cultures supplemented with 100 mM sodium acetate took up ({sup 14}C)acetate and ({sup 14}C)benzoate in accordance with the Henderson-Hasselbalch equation and gave similar estimates of intracellular pH. As the extracellular pH declined, S. bovis allowed its intracellular pH to decrease and maintained a relatively constant pH gradient across the cell membrane (0.9 unit). The decrease in intracellular pH prevented S. bovis from accumulating large amounts of acetate anion. On the basis of these results it did not appear that acetate was acting as an uncoupler. The sensitivity of other bacteria to volatile fatty acids at low pH is explained most easily by a high transmembrane pH gradient and anion accumulation.

Resistance of Streptococcus bovis to acetic acid at low pH: Relationship between intracellular pH and anion accumulation

International Nuclear Information System (INIS)

Russell, J.B.

1991-01-01

Streptococcus bovis JB1, an acid-tolerant ruminal bacterium, was able to grown at pHs from 6.7 to 4.5, and 100 mM acetate had little effect on growth rate or proton motive force across the cell membrane. When S. bovis was grown in glucose-limited chemostats at pH 5.2, the addition of sodium acetate (as much as 100 mM) had little effect on the production of bacterial protein. At higher concentrations of sodium acetate (100 to 360 mM), production of bacterial protein declined, but this decrease could largely be explained by a shift in fermentation products (acetate, formate, and ethanol production to lactate production) and a decline in ATP production (3 ATP per glucose versus 2 ATP per glucose). Y ATP (grams of cells per mole at ATP) was not decreased significantly even by high concentrations of acetate. Cultures supplemented with 100 mM sodium acetate took up [ 14 C]acetate and [ 14 C]benzoate in accordance with the Henderson-Hasselbalch equation and gave similar estimates of intracellular pH. As the extracellular pH declined, S. bovis allowed its intracellular pH to decrease and maintained a relatively constant pH gradient across the cell membrane (0.9 unit). The decrease in intracellular pH prevented S. bovis from accumulating large amounts of acetate anion. On the basis of these results it did not appear that acetate was acting as an uncoupler. The sensitivity of other bacteria to volatile fatty acids at low pH is explained most easily by a high transmembrane pH gradient and anion accumulation

Acidic nanoparticles are trafficked to lysosomes and restore an acidic lysosomal pH and degradative function to compromised ARPE-19 cells.

Directory of Open Access Journals (Sweden)

Gabriel C Baltazar

Full Text Available Lysosomal enzymes function optimally in acidic environments, and elevation of lysosomal pH can impede their ability to degrade material delivered to lysosomes through autophagy or phagocytosis. We hypothesize that abnormal lysosomal pH is a key aspect in diseases of accumulation and that restoring lysosomal pH will improve cell function. The propensity of nanoparticles to end up in the lysosome makes them an ideal method of delivering drugs to lysosomes. This study asked whether acidic nanoparticles could traffic to lysosomes, lower lysosomal pH and enhance lysosomal degradation by the cultured human retinal pigmented epithelial cell line ARPE-19. Acidic nanoparticles composed of poly (DL-lactide-co-glycolide (PLGA 502 H, PLGA 503 H and poly (DL-lactide (PLA colocalized to lysosomes of ARPE-19 cells within 60 min. PLGA 503 H and PLA lowered lysosomal pH in cells compromised by the alkalinizing agent chloroquine when measured 1 hr. after treatment, with acidification still observed 12 days later. PLA enhanced binding of Bodipy-pepstatin-A to the active site of cathepsin D in compromised cells. PLA also reduced the cellular levels of opsin and the lipofuscin-like autofluorescence associated with photoreceptor outer segments. These observations suggest the acidification produced by the nanoparticles was functionally effective. In summary, acid nanoparticles lead to a rapid and sustained lowering of lysosomal pH and improved degradative activity.

pH and Titratable Acidity of different Cough Syrups in Nigeria ...

African Journals Online (AJOL)

Background: Cough linctuses are liquid oral medicines widely used in children to treat cough and related conditions. Some of their constituents are acidic and dental erosive. Objectives: This in vitro study aimed to evaluate the endogenous pH and titratable acidity of Nigerian cough syrups and also determine their erosive ...

Variations of thiaminase I activity pH dependencies among typical Great Lakes forage fish and Paenibacillus thiaminolyticus.

Science.gov (United States)

Zajicek, J.L.; Brown, L.; Brown, S.B.; Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.

2009-01-01

The source of thiaminase in the Great Lakes food web remains unknown. Biochemical characterization of the thiaminase I activities observed in forage fish was undertaken to provide insights into potential thiaminase sources and to optimize catalytic assay conditions. We measured the thiaminase I activities of crude extracts from five forage fish species and one strain of Paenibacillus thiaminolyticus over a range of pH values. The clupeids, alewife Alosa pseudoharengus and gizzard shad Dorosoma cepedianum, had very similar thiaminase I pH dependencies, with optimal activity ranges (> or = 90% of maximum activity) between pH 4.6 and 5.5. Rainbow smelt Osmerus mordax and spottail shiner Notropis hudsonius had optimal activity ranges between pH 5.5-6.6. The thiaminase I activity pH dependence profile of P. thiaminolyticus had an optimal activity range between pH 5.4 and 6.3, which was similar to the optimal range for rainbow smelt and spottail shiners. Incubation of P. thiaminolyticus extracts with extracts from bloater Coregonus hoyi (normally, bloaters have little or no detectable thiaminase I activity) did not significantly alter the pH dependence profile of P. thiaminolyticus-derived thiaminase I, such that it continued to resemble that of the rainbow smelt and spottail shiner, with an apparent optimal activity range between pH 5.7 and 6.6. These data are consistent with the hypothesis of a bacterial source for thiaminase I in the nonclupeid species of forage fish; however, the data also suggest different sources of thiaminase I enzymes in the clupeid species.

The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

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S. A. Watmough

2002-01-01

Full Text Available The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario. In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 μeq l-1. These calculations assume that extremely low calcium leaching losses (9–27 μeq l-1 from

Food selectivity of perch (Perca fluviatilis L. ) in acidified lakes on the west coast of Sweden

Energy Technology Data Exchange (ETDEWEB)

Andersson, B

1972-01-01

The objective of the present paper was to examine presumed changes in the food composition of perch in lakes subjected to recent acidification, which emanates from sulfuric acid in the precipitation. The material analyzed (825 preserved specimens from 49 different lakes) was collected by the Fishery Board. These lakes represent a great variability in terms of pH. The perch were divided into four size groups and the stomach contents of each specimen was analyzed qualitatively and quantitatively. The results indicate that fish, which make up the bulk of food for adult perch, are replaced by various invertebrates at a decreasing pH. With a moderate decrease the water hog-louse (Asellus aquaticus) appears of major importance, whereas its place is taken by Corixa bugs in the most acidified lakes. These latter invertebrates are normally absent in the food of adult perch. Also, plankton accounts for a substantial share of the stomach contents. The reasons for these changes are manifold, but two factors are primarily discussed in this paper, viz. the effect of the acidification on the prey populations and the elimination of certain species by selective predation in a normal lake.

ESTIMATION OF pH, TOTAL ACID AND ETHANOL CONTENT OF COMMERCIALLY AVAILABLE ALCOHOL-CONTAINING MOUTHWASHES AND ITS EFFECT ON SALIVARY pH

OpenAIRE

Rafi Shaik; Sharath Pocha Reddy; Sameeulla Shaik; Sarah Emerald Sheela Nemalladinne; Dandu Sivasai Prasad Reddy; Kotu Nagavenkata Sai Praveen

2017-01-01

BACKGROUND Use of mouthwash has become widespread as a part of routine oral hygiene. Mouthwashes may have deleterious effects on oral tissues because of its low pH, high acid content and use of ethanol as an antiseptic agent. MATERIALS AND METHODS A cross-sectional experimental study was conducted among 48 undergraduate dental students. Eight commercially available alcohol-containing mouthwashes, which are available in Indian market were selected for which the pH, total acid an...

Sensitive detection of strong acidic condition by a novel rhodamine-based fluorescent pH chemosensor.

Science.gov (United States)

Tan, Jia-Lian; Yang, Ting-Ting; Liu, Yu; Zhang, Xue; Cheng, Shu-Jin; Zuo, Hua; He, Huawei

2016-05-01

A novel rhodamine-based fluorescent pH probe responding to extremely low pH values has been synthesized and characterized. This probe showed an excellent photophysical response to pH on the basis that the colorless spirocyclic structure under basic conditions opened to a colored and highly fluorescent form under extreme acidity. The quantitative relationship between fluorescence intensity and pH value (1.75-2.62) was consistent with the equilibrium equation pH = pKa + log[(Imax - I)/(I - Imin)]. This sensitive pH probe was also characterized with good reversibility and no interaction with interfering metal ions, and was successfully applied to image Escherichia coli under strong acidity. Copyright © 2015 John Wiley & Sons, Ltd.

Periphyton changes over 20 years of chemical recovery of Lake Orta, Italy: differential response to perturbation of littoral and pelagic communities

OpenAIRE

Giuseppe MORABITO; Gabriele TARTARI; Rosario MOSELLO; Michèle DE SÈVE; Antonella CATTANEO

2011-01-01

Lake Orta, a large Italian subalpine lake, has a long history of industrial pollution by acid, ammonia, and metals. A whole-lake liming treatment in 1989-1990 led to a gradual increase in pH (from 4.4 to 7) and a concomitant decline in ammonia (from 2.5 to 0.05 mg L-1) and metal concentrations (e.g., copper: from 35 to 3 μg L-1). In this study, we examine the response of the littoral zone, in terms of chemistry and periphyton assemblages, to contamination and recovery of Lake Orta. We co...

Microbial Analysis of Australian Dry Lake Cores; Analogs For Biogeochemical Processes

Science.gov (United States)

Nguyen, A. V.; Baldridge, A. M.; Thomson, B. J.

2014-12-01

Lake Gilmore in Western Australia is an acidic ephemeral lake that is analogous to Martian geochemical processes represented by interbedded phyllosilicates and sulfates. These areas demonstrate remnants of a global-scale change on Mars during the late Noachian era from a neutral to alkaline pH to relatively lower pH in the Hesperian era that continues to persist today. The geochemistry of these areas could possibly be caused by small-scale changes such as microbial metabolism. Two approaches were used to determine the presence of microbes in the Australian dry lake cores: DNA analysis and lipid analysis. Detecting DNA or lipids in the cores will provide evidence of living or deceased organisms since they provide distinct markers for life. Basic DNA analysis consists of extraction, amplification through PCR, plasmid cloning, and DNA sequencing. Once the sequence of unknown DNA is known, an online program, BLAST, will be used to identify the microbes for further analysis. The lipid analysis approach consists of phospholipid fatty acid analysis that is done by Microbial ID, which will provide direct identification any microbes from the presence of lipids. Identified microbes are then compared to mineralogy results from the x-ray diffraction of the core samples to determine if the types of metabolic reactions are consistent with the variation in composition in these analog deposits. If so, it provides intriguing implications for the presence of life in similar Martian deposits.

Effecf of pH and some cations on activity of acid phosphatase secreted from Ustilago sp. isolated from acid sulphate soil

Directory of Open Access Journals (Sweden)

Chairatana Nilnond

2007-03-01

Full Text Available Acid phosphatase secreted from Ustilago sp. is able to hydrolyze organic phosphorus. These soil yeast microorganisms were isolated from rice roots grown in acid sulphate soil that generally contains highamount of aluminum (Al, iron (Fe and manganese (Mn ions. Therefore, the objectives of this study were to examine the effect of pH and some cations on acid phosphatase activity. Two isolates of Ustilago sp., AR101and AR102, were cultured in 100 mL of modified Pikovskaya's broth containing Na-phytate, pH 4, and acid phosphatase activity was determined at pH 2.0-7.0. Effect of Al, Fe, and Mn, including calcium (Ca ions,on growth of AR101 and AR102, secreted acid phosphatase activity, and the ability of acid phosphatase on the phosphorus release from Na-phytate by Ustilago sp. were investigated. It was found that the optimum pH for acid phosphatase activity was 3.5-4.5. The activity of acid phosphatase secreted from AR101 (3,690nmol min-1 mL-1 was remarkably higher than that from AR102 (956 nmol min-1 mL-1. Aluminum, iron, manganese and calcium ions in the medium did not affect the growth of either isolate. The activity of secretedacid phosphatase of AR101 was inhibited by Al and Ca ion, and synthesis of acid phosphatase of Ustilago sp. AR102 was possibly stimulated by Fe ion. Both AR101 and AR102 solubilized Na-phytate, resulting in therelease of P. However, some amount of released P was then precipitated with Al and Fe ions as the highly insoluble Fe- or Al- phosphate.

Acidic pH and divalent cation sensing by PhoQ are dispensable for systemic salmonellae virulence.

Science.gov (United States)

Hicks, Kevin G; Delbecq, Scott P; Sancho-Vaello, Enea; Blanc, Marie-Pierre; Dove, Katja K; Prost, Lynne R; Daley, Margaret E; Zeth, Kornelius; Klevit, Rachel E; Miller, Samuel I

2015-05-23

Salmonella PhoQ is a histidine kinase with a periplasmic sensor domain (PD) that promotes virulence by detecting the macrophage phagosome. PhoQ activity is repressed by divalent cations and induced in environments of acidic pH, limited divalent cations, and cationic antimicrobial peptides (CAMP). Previously, it was unclear which signals are sensed by salmonellae to promote PhoQ-mediated virulence. We defined conformational changes produced in the PhoQ PD on exposure to acidic pH that indicate structural flexibility is induced in α-helices 4 and 5, suggesting this region contributes to pH sensing. Therefore, we engineered a disulfide bond between W104C and A128C in the PhoQ PD that restrains conformational flexibility in α-helices 4 and 5. PhoQ(W104C-A128C) is responsive to CAMP, but is inhibited for activation by acidic pH and divalent cation limitation. phoQ(W104C-A128C) Salmonella enterica Typhimurium is virulent in mice, indicating that acidic pH and divalent cation sensing by PhoQ are dispensable for virulence.

A wireless pH sensor using magnetoelasticity for measurement of body fluid acidity.

Science.gov (United States)

Pang, Pengfei; Gao, Xianjuan; Xiao, Xilin; Yang, Wenyue; Cai, Qingyun; Yao, Shouzhuo

2007-04-01

The determination of body fluid acidity using a wireless magnetoelastic pH-sensitive sensor is described. The sensor was fabricated by casting a layer of pH-sensitive polymer on a magnetoelastic ribbon. In response to an externally applied time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic frequency that is inversely dependent upon the mass of the pH polymer film, which varies as the film swells and shrinks in response to pH. As the magnetoelastic sensor is magnetostrictive, the mechanical vibrations of the sensor launch magnetic flux that can be detected remotely using a pickup coil. The sensor can be used for direct measurements of body fluid acidity without a pretreatment of the sample by using a filtration membrane. A reversible and linear response was obtained between pH 5.0 and 8.0 with a measurement resolution of pH 0.1 and a slope of 0.2 kHz pH(-1). Since there are no physical connections between the sensor and the instrument, the sensor can be applied to in vivo and in situ monitoring of the physiological pH and its fluctuations.

Comparing the acidities of aqueous, frozen, and freeze-dried phosphate buffers: Is there a "pH memory" effect?

Science.gov (United States)

Vetráková, Ľubica; Vykoukal, Vít; Heger, Dominik

2017-09-15

The concept of "pH memory" has been established in the literature for the correlation between the pH of a pre-lyophilization solution and the ionization state of freeze-dried powder (lyophile). In this paper, the concept of "pH memory" is explored for the system of an aqueous solution, a frozen solution, and a lyophile. Sodium and potassium phosphate buffers in the pH range of 5-9 were frozen and lyophilized with sulfonephthalein indicators as acidity probes, and their Hammett acidity functions were compared to the initial pH of the aqueous solution. The results show that the acidities of the lyophiles are somewhat changed compared to the initial pHs, but the acidities in the frozen state differ more substantially. The Hammett acidity functions of the frozen buffers were found to be markedly dissimilar from the initial pH, especially in the sodium phosphate frozen at 233K, where an increase in the initial pH led to a decrease in the Hammett acidity function of the frozen state at a certain pH range. The large acidification observed after freezing the sodium phosphate buffer was not detected in the lyophiles after the sample had been dried; the phenomenon is explained considering the formed crystals analyzed by X-ray powder diffraction. The results suggest that monitoring the final acidity of a lyophile is not sufficient to predict all the acidity changes throughout the whole lyophilization process. The importance of well-controlled freezing and lyophilization conditions follows from the results of the research. Copyright © 2017 Elsevier B.V. All rights reserved.

THE IMPACT OF CONJUGATED LINOLEIC ACID ADDITION ON PH VALUE OF LONGISSIMUS DORSI MUSCLE

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Przemysław WASILEWSKI

2009-08-01

Full Text Available The subject of research was 60 crossbred gilts, divided into 6 groups, fed the fodder with addition of conjugated linoleic acid (CLA or sunflower oil (SFO in amount: 0.5; 1.0; and 2.0 %, respectively. Animals were slaughtered with the body weight ca. 95 kg. The aim of research was to determine pH value of loin meat tissue (Longissimus dorsi of right half-carcass in 45 minutes, 2, 3, 4, 5, 6 hours and 24 hours after slaughter. Results were statistically elaborated using one-way variance analysis. Longissimus dorsi muscle pH values measured 45 minutes after slaughter in case of all groups of pigs were in range from 6.34 up to 6.47, what shows good meat quality. The lowest pH1 (measured 45 minutes after slaughter had meat of fatteners where addition of 2 % sunflower oil was given into fodder and the highest value of this trait was in group of individuals where also was given sunflower oil in 1 % amount. Statistical significant differences in pH value measured in different time after slaughter i.e. after 45 minutes, 2, 3, 4, 6 and 24 hours between tested groups of pigs were not stated. The exception is the result of pH measurement 5 hours after slaughter. Statistical significant differences were between group of pigs getting 0.5 % addition of conjugated linoleic acid characterized by the highest pH value of meat and group of animals fed the fodder with 1 % addition of conjugated linoleic acid (P≤0.01. On the basis of the results obtained in presented paper may be stated that feeding pigs with addition of conjugated linoleic acid in amounts 0.5; 1.0 and 2.0 % did not impact negatively on meat quality defined by pH value.

Acidic pH retards the fibrillization of human islet amyloid polypeptide due to electrostatic repulsion of histidines

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Li, Yang; Xu, Weixin; Mu, Yuguang; Zhang, John Z. H.

2013-08-01

The human Islet Amyloid Polypeptide (hIAPP) is the major constituent of amyloid deposits in pancreatic islets of type-II diabetes. IAPP is secreted together with insulin from the acidic secretory granules at a low pH of approximately 5.5 to the extracellular environment at a neutral pH. The increased accumulation of extracellular hIAPP in diabetes indicates that changes in pH may promote amyloid formation. To gain insights and underlying mechanisms of the pH effect on hIAPP fibrillogenesis, all-atom molecular dynamics simulations in explicit solvent model were performed to study the structural properties of five hIAPP protofibrillar oligomers, under acidic and neutral pH, respectively. In consistent with experimental findings, simulation results show that acidic pH is not conducive to the structural stability of these oligomers. This provides a direct evidence for a recent experiment [L. Khemtemourian, E. Domenech, J. P. F. Doux, M. C. Koorengevel, and J. A. Killian, J. Am. Chem. Soc. 133, 15598 (2011)], 10.1021/ja205007j, which suggests that acidic pH inhibits the fibril formation of hIAPP. In addition, a complementary coarse-grained simulation shows the repulsive electrostatic interactions among charged His18 residues slow down the dimerization process of hIAPP by twofold. Besides, our all-atom simulations reveal acidic pH mainly affects the local structure around residue His18 by destroying the surrounding hydrogen-bonding network, due to the repulsive interactions between protonated interchain His18 residues at acidic pH. It is also disclosed that the local interactions nearby His18 operating between adjacent β-strands trigger the structural transition, which gives hints to the experimental findings that the rate of hIAPP fibril formation and the morphologies of the fibrillar structures are strongly pH-dependent.

Acidic precipitation. Volume 4: Soils, aquatic processes, and lake acidification. Advances in environmental science

Energy Technology Data Exchange (ETDEWEB)

Norton, S.A.; Lindberg, S.E.; Page, A.L. (eds.)

1990-01-01

Acidic precipitation and its effects have been the focus of intense research for over two decades. Recently, research has focused on a greater understanding of dose-response relationships between atmospheric loading of acidifying material and lake acidity. This volume of the subseries Acidic Precipitation emphasizes acid neutralizing processes and the capacity of terrestrial and aquatic systems to assimilate acidifying substances and, conversely, the ability of systems to recover after acid loading diminishes. Eight chapters have been processed separately for inclusion in the appropriate data bases.

Acid fluids from Copahue Volcano, Argentina, and their environmental effects

Science.gov (United States)

Varekamp, J. C.; Kading, T.

2010-12-01

The acid hydrothermal system of Copahue volcano (province of Neuquen, Argentina) consists of a crater lake, acid hot springs (both with pH values of Copahue erupted in 2000, and the hydrothermal dissolved element fluxes peaked at that time. Since 2001, the K and Al fluxes have decreased notably as a result of alunite saturation within the hydrothermal system, whereas over the last few years redissolution of that alunite has led to increases in K and Al discharges. The fluxes of Mg and Fe have remained high over time, while the overall system has become more dilute since 2000. Once the distal downstream system reached pH values of 2.9-3.2, the mineral Schwertmannite started to precipitate through a bacterially mediated pathway. The precipitation front gradually moved upstream with ongoing dilution, and reached the exit of Lake Caviahue in 2009. The lake bottom waters were already saturated with the mineral at that time, and if this trend continues, the currently clear blue lake may turn into a bright yellow-brown mass of Schwertmannite over the next few years. Schwertmannite is common in acid mine drainage fluids but has not often been described from volcanic environments. It strongly adsorbs oxyanions (or structurally incorporates them) and the precipitates contain up to 6000 ppm P, 1100 ppm V and 1000 ppm As. The Schwertmannite appears to convert to goethite-like minerals over time, although the exact stoichiometry has been difficult to constrain (variable mixtures of FeOOH and Fe8O8(OH)6SO4 nH2O). The oxyanions appear to remain in the mineral mix during aging. If Lake Caviahue becomes a focus of Schwertmannite deposition, the precipitates will scavenge As, P and V from the watercolumn and deposit those on the lake bottom. The lake ecosystem will then die back because of P limitation. Subsequent acidification of the lake during renewed volcanic activity may then lead to dissolution of these precipitates, with large releases of both the nutrient P and the toxin As

Growth of Avena Coleoptiles and pH Drop of Protoplast Suspensions Induced by Chlorinated Indoleacetic Acids

DEFF Research Database (Denmark)

Engvild, Kjeld Christensen; Doll, Hans; Böttger, M.

1978-01-01

-auxins. Some of the derivatives were compared for their effect on pH decline in stem protoplast suspensions of Helianthus annuus L. and Pisum sativum L. The change of pH occurs without a lag period or with only a very short one. Derivatives which are very active in the Avena straight growth assay cause......Several indoleacetic acids, substituted in the benzene ring, were compared in the Avena straight growth bioassay. 4-Chloroindoleacetic acid, a naturally occurring plant hormone, is one of the strongest hormones in this bioassay. With an optimum at 10-6 mol l-1, it is more active than indoleacetic...... a larger pH decline than indoleacetic acid, while inactive derivatives cause effectively no pH decline....

Ionoregulatory and toxicological responses of stonefly nymphs (Plecoptera) to acidic and alkaline pH

Energy Technology Data Exchange (ETDEWEB)

Lechleitner, R.A.; Cherry, D.S.; Cairns, J. Jr.; Stetler, D.A.

1985-03-01

The acute toxicities of acidic and alkaline pH to nymphs of the stoneflies Pteronarcys dorsata, P. proteus, and Tallaperla maria were determined in 96-hr static bioassays. The acidic and alkaline 96-hr LC/sub 50/ values were 2.8 to 3.3 and 12.1 to 10.3, respectively. Exposure to pH 3.0 for 72 hr or longer caused a significant loss of sodium from nymphs of P. proteus. Morphological changes, including distension of cuticular disk and increased number of vesicles, were observed in gill tissue from nymphs of P. dorsata exposed to pH 2.5 for 9 hr while minor changes were observed in nymphs exposed to pH 4.0 for 96 hr. Changes in gill tissue ultrastructure included an increase in number of vesicles and a decrease in number and size of mitochondria in nymphs exposed to alkaline pH of 11.75.

The pH ruler: a Java applet for developing interactive exercises on acids and bases.

Science.gov (United States)

Barrette-Ng, Isabelle H

2011-07-01

In introductory biochemistry courses, it is often a struggle to teach the basic concepts of acid-base chemistry in a manner that is relevant to biological systems. To help students gain a more intuitive and visual understanding of abstract acid-base concepts, a simple graphical construct called the pH ruler Java applet was developed. The applet allows students to visualize the abundance of different protonation states of diprotic and triprotic amino acids at different pH values. Using the applet, the student can drag a widget on a slider bar to change the pH and observe in real time changes in the abundance of different ionization states of this amino acid. This tool provides a means for developing more complex inquiry-based, active-learning exercises to teach more advanced topics of biochemistry, such as protein purification, protein structure and enzyme mechanism.

Geochemical evolution of the acid crater lake of Poas volcano (Costa Rica): Insights into volcanic-hydrothermal processes

NARCIS (Netherlands)

Martínez Cruz, María

2008-01-01

This thesis describes the evolution of Laguna Caliente, an acid crater lake at the summit of Po:is, a persistently active volcano in central Costa Rica. The appearance, volume, temperature and chemical composition of the lake have continuously changed over the entire known period of its

Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

Science.gov (United States)

Kitadai, Norio

2017-03-01

Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg 2+ ) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu 2+ ) are therefore not beneficial places for peptide bond formation on the primitive

Kinetics of salivary pH after acidic beverage intake by patients undergoing orthodontic treatment.

Science.gov (United States)

Turssi, Cecilia P; Silva, Carolina S; Bridi, Enrico C; Amaral, Flavia Lb; Franca, Fabiana Mg; Basting, Roberta T

2015-01-01

The saliva of patients undergoing orthodontic treatment with fixed appliances can potentially present a delay in the diluting, clearing, and buffering of dietary acids due to an increased number of retention areas. The aim of this clinical trial was to compare salivary pH kinetics of patients with and without orthodontic treatment, following the intake of an acidic beverage. Twenty participants undergoing orthodontic treatment and 20 control counterparts had their saliva assessed for flow rate, pH, and buffering capacity. There was no significant difference between salivary parameters in participants with or without an orthodontic appliance. Salivary pH recovery following acidic beverage intake was slower in the orthodontic subjects compared to controls. Patients with fixed orthodontic appliances, therefore, seem to be at higher risk of dental erosion, suggesting that dietary advice and preventive care need to be implemented during orthodontic treatment.

Photodegradation of bisphenol A in simulated lake water containing algae, humic acid and ferric ions

International Nuclear Information System (INIS)

Peng Zhang'e; Wu Feng; Deng Nansheng

2006-01-01

The photodegradation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in simulated lake water containing algae, humic acid and Fe 3+ ions was investigated. Algae, humic acid and Fe 3+ ions enhanced the photodegradation of BPA. Photodegradation efficiency of BPA was 36% after 4 h irradiation in the presence of 6.5 x 10 9 cells L -1 raw Chlorella vulgaris, 4 mg L -1 humic acid and 20 μmol L -1 Fe 3+ . The photodegradation efficiency of BPA was higher in the presence of algae treated with ultrasonic than that without ultrasonic. The photodegradation efficiency of BPA in the water only containing algae treated with ultrasonic was 37% after 4 h irradiation. The algae treated with heating can also enhance the photodegradation of BPA. This work helps environmental scientists to understand the photochemical behavior of BPA in lake water. - Algae, humic acid and ferric ions can induce the photodegradation of bisphenol A in an aqueous environment

Photodegradation of bisphenol A in simulated lake water containing algae, humic acid and ferric ions

Energy Technology Data Exchange (ETDEWEB)

Peng Zhang' e [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: zhepeng@126.com; Wu Feng [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: fengwu@whu.edu.cn; Deng Nansheng [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: nsdengwhu@163.com

2006-12-15

The photodegradation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in simulated lake water containing algae, humic acid and Fe{sup 3+} ions was investigated. Algae, humic acid and Fe{sup 3+} ions enhanced the photodegradation of BPA. Photodegradation efficiency of BPA was 36% after 4 h irradiation in the presence of 6.5 x 10{sup 9} cells L{sup -1} raw Chlorella vulgaris, 4 mg L{sup -1} humic acid and 20 {mu}mol L{sup -1} Fe{sup 3+}. The photodegradation efficiency of BPA was higher in the presence of algae treated with ultrasonic than that without ultrasonic. The photodegradation efficiency of BPA in the water only containing algae treated with ultrasonic was 37% after 4 h irradiation. The algae treated with heating can also enhance the photodegradation of BPA. This work helps environmental scientists to understand the photochemical behavior of BPA in lake water. - Algae, humic acid and ferric ions can induce the photodegradation of bisphenol A in an aqueous environment.

Effects of acetic acid and arginine on pH elevation and growth of Bacillus licheniformis in an acidified cucumber juice medium.

Science.gov (United States)

Yang, Zhenquan; Meng, Xia; Breidt, Frederick; Dean, Lisa L; Arritt, Fletcher M

2015-04-01

Bacillus licheniformis has been shown to cause pH elevation in tomato products having an initial pH below 4.6 and metabiotic effects that can lead to the growth of pathogenic bacteria. Because of this, the organism poses a potential risk to acidified vegetable products; however, little is known about the growth and metabolism of this organism in these products. To clarify the mechanisms of pH change and growth of B. licheniformis in vegetable broth under acidic conditions, a cucumber juice medium representative of a noninhibitory vegetable broth was used to monitor changes in pH, cell growth, and catabolism of sugars and amino acids. For initial pH values between pH 4.1 to 6.0, pH changes resulted from both fermentation of sugar (lowering pH) and ammonia production (raising pH). An initial pH elevation occurred, with starting pH values of pH 4.1 to 4.9 under both aerobic and anaerobic conditions, and was apparently mediated by the arginine deiminase reaction of B. licheniformis. This initial pH elevation was prevented if 5 mM or greater acetic acid was present in the brine at the same pH. In laboratory media, under favorable conditions for growth, data indicated that growth of the organism was inhibited at pH 4.6 with protonated acetic acid concentrations of 10 to 20 mM, corresponding to 25 to 50 mM total acetic acid; however, growth inhibition required greater than 300 mM citric acid (10-fold excess of the amount in processed tomato products) products under similar conditions. The data indicate that growth and pH increase by B. licheniformis may be inhibited by the acetic acid present in most commercial acidified vegetable products but not by the citric acid in many tomato products.

Estimated net acid excretion inversely correlates with urine pH in vegans, lacto-ovo vegetarians, and omnivores.

Science.gov (United States)

Ausman, Lynne M; Oliver, Lauren M; Goldin, Barry R; Woods, Margo N; Gorbach, Sherwood L; Dwyer, Johanna T

2008-09-01

Diet affects urine pH and acid-base balance. Both excess acid/alkaline ash (EAA) and estimated net acid excretion (NAE) calculations have been used to estimate the effects of diet on urine pH. This study's goal was to determine if free-living vegans, lacto-ovo vegetarians, and omnivores have increasingly acidic urine, and to assess the ability of EAA and estimated NAE calculations to predict urine pH. This study used a cross-sectional design. This study assessed urine samples of 10 vegan, 16 lacto-ovo vegetarian, and 16 healthy omnivorous women in the Boston metropolitan area. Six 3-day food records from each dietary group were analyzed for EAA content and estimated NAE, and correlations with measured urine pH were calculated. The mean (+/- SD) urine pH was 6.15 +/- 0.40 for vegans, 5.90 +/- 0.36 for lacto-ovo vegetarians, and 5.74 +/- 0.21 for omnivores (analysis of variance, P = .013). Calculated EAA values were not significantly different among the three groups, whereas mean estimated NAE values were significantly different: 17.3 +/- 14.5 mEq/day for vegans, 31.3 +/- 8.5 mEq/day for lacto-ovo vegetarians, and 42.6 +/- 13.2 mEq/day for omnivores (analysis of variance, P = .01). The average deattenuated correlation between urine pH and EAA was 0.333; this value was -0.768 for estimated NAE and urine pH, with a regression equation of pH = 6.33 - 0.014 NAE (P = .02, r = -0.54). Habitual diet and estimated NAE calculations indicate the probable ranking of urine pH by dietary groups, and may be used to determine the likely acid-base status of an individual; EAA calculations were not predictive of urine pH.

Ecotechnological water quality control in acidic mining lakes. Part 2. Primary production and respiration; Oekotechnologische Steuerung der Gewaesserguete in sauren Tagebauseen. Teil 2. Primaerproduktion und Respiration

Energy Technology Data Exchange (ETDEWEB)

Uhlmann, W. [Inst. fuer Wasser und Boden, Dresden (Germany); Nixdorf, B. [Brandenburgisch-Technische Univ., Fakultaet fuer Umweltwissenschaften, Lehrstuhl fuer Gewaesserschutz, Bad Saarow (Germany)

2002-07-01

The necessity of neutralizing acidic mining lakes is obvious if the water is to be used in reservoirs (Lohsa II) or for other purposes such as balancing the water budget, fishing or recreation or to be discharged into river systems. Flushing of mining lakes with alkaline surface water from rivers is the moist common method to stabilize the lake structures and to neutralize acidic water. This method is limited in lakes without river coupling or with a high re-acidification potential. The present contribution demonstrates the possibility of biogenic alkalinity production in acidic mining lakes focusing on the main biological processes of primary production and respiration. The influence of biogenic matter transformation on water chemistry in acidic mining lakes is analyzed. Calculation of the extent of aerobic and anaerobic decay of organic matter will be a necessary prerequisite for sustainable sulfate reduction. (orig.)

Putrescine biosynthesis in Lactococcus lactis is transcriptionally activated at acidic pH and counteracts acidification of the cytosol.

Science.gov (United States)

Del Rio, Beatriz; Linares, Daniel; Ladero, Victor; Redruello, Begoña; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A

2016-11-07

Lactococcus lactis subsp. cremoris CECT 8666 is a lactic acid bacterium that synthesizes the biogenic amine putrescine from agmatine via the agmatine deiminase (AGDI) pathway. The AGDI genes cluster includes aguR. This encodes a transmembrane protein that functions as a one-component signal transduction system, the job of which is to sense the agmatine concentration of the medium and accordingly regulate the transcription of the catabolic operon aguBDAC. The latter encodes the proteins necessary for agmatine uptake and its conversion into putrescine. This work reports the effect of extracellular pH on putrescine biosynthesis and on the genetic regulation of the AGDI pathway. Increased putrescine biosynthesis was detected at acidic pH (pH5) compared to neutral pH. Acidic pH induced the transcription of the catabolic operon via the activation of the aguBDAC promoter PaguB. However, the external pH had no significant effect on the activity of the aguR promoter PaguR, or on the transcription of the aguR gene. The transcriptional activation of the AGDI pathway was also found to require a lower agmatine concentration at pH5 than at neutral pH. Finally, the following of the AGDI pathway counteracted the acidification of the cytoplasm under acidic external conditions, suggesting it to provide protection against acid stress. Copyright © 2016 Elsevier B.V. All rights reserved.

Anti-biofilm potential of phenolic acids: the influence of environmental pH and intrinsic physico-chemical properties.

Science.gov (United States)

Silva, Sara; Costa, Eduardo M; Horta, Bruno; Calhau, Conceição; Morais, Rui M; Pintado, M Manuela

2016-09-13

Phenolic acids are a particular group of small phenolic compounds which have exhibited some anti-biofilm activity, although the link between their activity and their intrinsic pH is not clear. Therefore, the present work examined the anti-biofilm activity (inhibition of biomass and metabolic activity) of phenolic acids in relation to the environmental pH, as well as other physico-chemical properties. The results indicate that, while Escherichia coli was not inhibited by the phenolic acids, both methicillin resistant Staphylococcus aureus and methicillin resistant Staphylococcus epidermidis were susceptible to the action of all phenolic acids, with the pH playing a relevant role in the activity: a neutral pH favored MRSE inhibition, while acidic conditions favored MRSA inhibition. Some links between molecular polarity and size were associated only with their potential as metabolic inhibitors, with the overall interactions hinting at a membrane-based mechanism for MRSA and a cytoplasmic effect for MRSE.

Microbial Diversity and Its Relationship to Physicochemical Characteristics of the Water in Two Extreme Acidic Pit Lakes from the Iberian Pyrite Belt (SW Spain.

Directory of Open Access Journals (Sweden)

Esther Santofimia

Full Text Available The Iberian Pyrite Belt (IPB hosts one of the world's largest accumulations of acidic mine wastes and pit lakes. The mineralogical and textural characteristics of the IPB ores have favored the oxidation and dissolution of metallic sulfides, mainly pyrite, and the subsequent formation of acidic mining drainages. This work reports the physical properties, hydrogeochemical characteristics, and microbial diversity of two pit lakes located in the IPB. Both pit lakes are acidic and showed high concentrations of sulfate and dissolved metals. Concentrations of sulfate and heavy metals were higher in the Nuestra Señora del Carmen lake (NSC by one order of magnitude than in the Concepción (CN lake. The hydrochemical characteristics of NSC were typical of acid mine waters and can be compared with other acidic environments. When compared to other IPB acidic pit lakes, the superficial water of CN is more diluted than that of any of the others due, probably, to the strong influence of runoff water. Both pit lakes showed chemical and thermal stratification with well defined chemoclines. One particular characteristic of NSC is that it has developed a chemocline very close to the surface (2 m depth. Microbial community composition of the water column was analyzed by 16S and 18S rRNA gene cloning and sequencing. The microorganisms detected in NSC were characteristic of acid mine drainage (AMD, including iron oxidizing bacteria (Leptospirillum, Acidithiobacillus ferrooxidans and facultative iron reducing bacteria and archaea (Acidithiobacillus ferrooxidans, Acidiphilium, Actinobacteria, Acidimicrobiales, Ferroplasma detected in the bottom layer. Diversity in CN was higher than in NSC. Microorganisms known from AMD systems (Acidiphilium, Acidobacteria and Ferrovum and microorganisms never reported from AMD systems were identified. Taking into consideration the hydrochemical characteristics of these pit lakes and the spatial distribution of the identified

Evaluation of glutamic acid and glycine as sources of nonessential amino acids for lake trout (Salvelinus namaycush) and rainbow trout (Salmo gairdnerii)

Science.gov (United States)

Hughes, S.G.

1985-01-01

1. A semi-purified test diet which contained either glutamic acid or glycine as the major source of nonessential amino acids (NEAA) was fed to lake and rainbow trout.2. Trout fed the diet containing glutamic acid consistently showed better growth and feed conversion efficiencies than those fed the diets containing glycine.3. The data indicate that these trout utilize glutamic acid more efficiently than glycine when no other major sources of NEAA are present.

Sediment deposition and sources into a Mississippi River floodplain lake; Catahoula Lake, Louisiana

Science.gov (United States)

Latuso, Karen D.; Keim, Richard F.; King, Sammy L.; Weindorf, David C.; DeLaune, Ronald D.

2017-01-01

Floodplain lakes are important wetlands on many lowland floodplains of the world but depressional floodplain lakes are rare in the Mississippi River Alluvial Valley. One of the largest is Catahoula Lake, which has existed with seasonally fluctuating water levels for several thousand years but is now in an increasingly hydrologically altered floodplain. Woody vegetation has been encroaching into the lake bed and the rate of this expansion has increased since major human hydrologic modifications, such as channelization, levee construction, and dredging for improvement of navigation, but it remains unknown what role those modifications may have played in altering lake sedimentation processes. Profiles of thirteen 137Cs sediment cores indicate sedimentation has been about 0.26 cm y− 1 over the past 60 years and has been near this rate since land use changes began about 200 years ago (210Pb, and 14C in Tedford, 2009). Carbon sequestration was low (10.4 g m− 2 y− 1), likely because annual drying promotes mineralization and export. Elemental composition (high Zr and Ti and low Ca and K) and low pH of recent (sediments suggest Gulf Coastal Plain origin, but below the recent sediment deposits, 51% of sediment profiles showed influence of Mississippi River alluvium, rich in base cations such as K+, Ca2 +, and Mg2 +. The recent shift to dominance of Coastal Plain sediments on the lake-bed surface suggests hydrologic modification has disconnected the lake from sediment-bearing flows from the Mississippi River. Compared to its condition prior to hydrologic alterations that intensified in the 1930s, Catahoula Lake is about 15 cm shallower and surficial sediments are more acidic. Although these results are not sufficient to attribute ecological changes directly to sedimentological changes, it is likely the altered sedimentary and hydrologic environment is contributing to the increased dominance of woody vegetation.

[Analysis of tartrazine aluminum lake and sunset yellow aluminum lake in foods by capillary zone electrophoresis].

Science.gov (United States)

Zhang, Yiding; Chang, Cuilan; Guo, Qilei; Cao, Hong; Bai, Yu; Liu, Huwei

2014-04-01

A novel analytical method for tartrazine aluminum lake and sunset yellow aluminum lake using capillary zone electrophoresis (CZE) was studied. The pigments contained in the color lakes were successfully separated from the aluminum matrix in the pre-treatment process, which included the following steps: dissolve the color lakes in 0.1 mol/L H2SO4, adjust the pH of the solution to 5.0, then mix it with the solution of EDTA x 2Na and heat it in a water bath, then use polyamide powder as the stationary phase of solid phase extraction to separate the pigments from the solution, and finally elute the pigments with 0.1 mol/L NaOH. The CZE conditions systematically optimized for tartrazine aluminum lake were: 48.50 cm of a fused silica capillary with 40.00 cm effective length and 50 microm i. d., the temperature controlled at 20.0 degrees C, 29.0 kV applied, HPO4(2-)-PO4(3-) (0.015 mol/L, pH 11.45) solution as running buffer, detection at 263 nm. The conditions for sunset yellow aluminum lake were: the same capillary and temperature, 25.0 kV applied, HPO4(2-)-PO4(3-) (0.025 mol/L, pH 11.45) solution as running buffer, detection at 240 nm. The limits of detection were 0.26 mg/L and 0.27 mg/L, and the linear ranges were 0.53-1.3 x 10(2) mg/L and 0.54-1.4 x 10(2) mg/L for tartrazine aluminum lake and sunset yellow aluminum lake, respectively. The RSDs were 4.3% and 5.7% (run to run, n = 6), 5.6% and 6.0% (day to day, n = 6) for tartrazine aluminum lake and sunset yellow aluminum lake, respectively. Further developments for this method could make it a routinely used method analyzing color lakes in foods.

Inter-annual variations in water yield to lakes in northeastern Alberta: implications for estimating critical loads of acidity

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Roderick HAZEWINKEL

2010-08-01

Full Text Available Stable isotopes of water were applied to estimate water yield to fifty lakes in northeastern Alberta as part of an acid sensitivity study underway since 2002 in the Athabasca Oil Sands Region (AOSR. Herein, we apply site-specific water yields for each lake to calculate critical loads of acidity using water chemistry data and a steady-state water chemistry model. The main goal of this research was to improve site-specific critical load estimates and to understand the sensitivity to hydrologic variability across a Boreal Plains region under significant oil sands development pressure. Overall, catchment water yields were found to vary significantly over the seven year monitoring period, with distinct variations among lakes and between different regions, overprinted by inter-annual climate-driven shifts. Analysis of critical load estimates based on site-specific water yields suggests that caution must be applied to establish hydrologic conditions and define extremes at specific sites in order to protect more sensitive ecosystems. In general, lakes with low (high water yield tended to be more (less acid sensitive but were typically less (more affected by interannual hydrological variations. While it has been customary to use long-term water yields to define a static critical load for lakes, we find that spatial and temporal variability in water yield may limit effectiveness of this type of assessment in areas of the Boreal Plain characterized by heterogeneous runoff and without a long-term lake-gauging network. Implications for predicting acidification risk are discussed for the AOSR.

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

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Musa Ahmad

2017-11-01

Full Text Available An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

pH studies in the synthesis of amino acid coated hydrophilic MNPs

Science.gov (United States)

Saxena, Namita; Dube, Charu Lata

2018-04-01

Magnetic iron oxide nanoparticles magnetite and maghemite (MNPs) are specially useful in various fields like biomedical, waste disposal, catalysis etc. because of their biocompatibility and magnetic properties. They can be manipulated by applying magnetic field and hence their easier separation, wider applications and unending scope in the field of research. They are inherently hydrophobic, and aggregate easily mainly due to magnetic and nanosize effects. The present work reports the synthesis of hydrophilic, stably dispersed MNPs coated by different amino acids at different pH values. Lower concentration of amino acids, 1/3 (moles by moles) of Iron salts concentration was used in the study. Crystallites were found to be approximately 6-7 nm in size, as determined by XRD and also found to have good magnetization values in VSM studies. The effects of coating are mainly studied by FTIR and TG. Higher/lower pH values have been studied for better coating, and it is observed that higher pH is more helpful in getting better results, on bare MNPs synthesized under a pH of approximately 13.3. The effects of net charge on coating efficiency were also studied.

Sulfate Reduction at Low Ph To Remediate Acid Mine Drainage

NARCIS (Netherlands)

Sánchez-Andrea, I.; Sanz, J.L.; Bijmans, M.F.M.; Stams, A.J.M.

2014-01-01

Industrial activities and the natural oxidation of metallic sulfide-ores produce sulfate-rich waters with low pH and high heavy metals content, generally termed acid mine drainage (AMD). This is of great environmental concern as some heavy metals are highly toxic. Within a number of possibilities,

Behaviour of lactose with the presence of lactic acid and Ca as affected by pH.

Science.gov (United States)

Chandrapala, Jayani; Gauthier, Claire; Vasiljevic, Todor

2017-11-01

Contradictory statements about the effects of pH change on crystallisation behaviour of lactose exist in the literature. Considering the importance of addressing the processability issue of acid whey, a systematic study is required to establish lactose crystallisation behaviour in the presence of LA and Ca at concentrations present in real acid whey waste streams emphasising impact of pH. Structural modifications of lactose were evident at elevated, more neutral pH in the presence of 1% w/w LA and 0·12% w/w Ca. These structural changes led to changes in the anomeric equilibrium of lactose, which manipulated the water-lactose behaviour and increased the crystallinity. Therefore, altering pH to 6·5 may be the solution to proper industrial processing of acid whey, enhancing the ability of lactose to crystallise properly.

Deletion of the pH sensor GPR4 decreases renal acid excretion.

Science.gov (United States)

Sun, Xuming; Yang, Li V; Tiegs, Brian C; Arend, Lois J; McGraw, Dennis W; Penn, Raymond B; Petrovic, Snezana

2010-10-01

Proton receptors are G protein-coupled receptors that accept protons as ligands and function as pH sensors. One of the proton receptors, GPR4, is relatively abundant in the kidney, but its potential role in acid-base homeostasis is unknown. In this study, we examined the distribution of GPR4 in the kidney, its function in kidney epithelial cells, and the effects of its deletion on acid-base homeostasis. We observed GPR4 expression in the kidney cortex, in the outer and inner medulla, in isolated kidney collecting ducts, and in cultured outer and inner medullary collecting duct cells (mOMCD1 and mIMCD3). Cultured mOMCD1 cells exhibited pH-dependent accumulation of intracellular cAMP, characteristic of GPR4 activation; GPR4 knockdown attenuated this accumulation. In vivo, deletion of GPR4 decreased net acid secretion by the kidney and resulted in a nongap metabolic acidosis, indicating that GPR4 is required to maintain acid-base homeostasis. Collectively, these findings suggest that GPR4 is a pH sensor with an important role in regulating acid secretion in the kidney collecting duct.

Lake Orta chemical status 25 years after liming: problems solved and emerging critical issues

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Michela Rogora

2016-04-01

Full Text Available Lake Orta, located in Piedmont, northwestern Italy, has been severely affected by industrial pollution since the 1930s. A successful liming intervention, performed in 1988-1990, returned pH levels in the lake to neutrality, and accelerated the reduction of aqueous trace metal concentrations. In this paper, we present an update knowledge of the chemical status of Lake Orta, focusing on the data collected from 1990 to 2014. In this period we sampled the lake at its deepest point (Qualba station, on a monthly (1990-2000 or seasonal (since 2001 basis. Samples were collected at nine depths through the water column, and analyzed for pH, conductivity, alkalinity, major ions, nutrients, and trace metals. Collectively, these data allowed us to evaluate the long-term response of the lake to the restoration treatment, with particular regard to its acid-base status; they also provided insights into emerging or potential critical issues, including eutrophication and re-suspension of trace metals that still linger in the lake. Furthermore, the evaluation of the present chemical condition of the lake is a precondition for any successive restoration measure, such as fish introduction. The recent data confirmed the lake’s water quality has recovered, i.e. returned to a pre-pollution chemical state. Lake water values of pH and concentrations of ammonium, sulphate and base cations have stabilized. Alkalinity and nitrate concentrations are also expected to reach stable level in the next few years. Levels of nitrate, reactive silica, and phosphorus compounds are now regulated by algal uptake, providing indirect evidence of a partial biological recovery. For instance, both the inter-annual average decline and the reappearance of a seasonal signal in silica confirmed the presence of a stable diatom community. The lake is presently oligotrophic, and concentrations of both N and P compounds are steady and low throughout the year. However, a monthly check of nutrient

Long-term adaptation of Daphnia to toxic environment in Lake Orta: the effects of short-term exposure to copper and acidification

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Marina MANCA

2010-08-01

Full Text Available Because of its 80-year history of heavy pollution and re-colonization, Lake Orta provides a good opportunity for investigating the response of zooplankton organisms to heavy metals and acidification as well as the mechanisms involved. After the recent establishment of Daphnia galeata Sars, and the detection of an extremely low clonal diversity of Lake Orta population, we carried out a study to investigate the lethal tolerance to ionic copper, as well as to acidity, and the impact of newborn Daphnia exposure to sublethal concentrations of copper for their later development and reproduction. We conducted acute toxicity tests to estimate the EC50 for ionic copper and tolerance to low pH, as well as life table experiments. Tolerance to ionic copper was high, three times that reported in literature. An increased mortality soon after exposure to low pH confirmed a high sensitivity to acidity and explained the success of the species in Lake Orta only after pH recovery. An analysis of reproductive and demographic parameters revealed that D. galeata Sars was stressed at concentrations of ionic copper only twice higher than those presently recorded in the lake (i.e., ca 3 μg L-1. An increased cumulative number of eggs produced by each female were in fact counterbalanced by an increasing abortion rate, which resulted in an unaltered or lower intrinsic rate of population increase. Our results are likely due to the strong selective pressure, more than physiological processes (acclimation, in a polluted area in which only specific adapted clones are able to grow, confirming the results previously obtained on Lake Orta's D. obtusa Kurz population. The reproductive response and the relatively low within treatment variability suggest that clone specificity, rather than physiological acclimation, was the driving force. The low variability confirmed results previously obtained from life tables experiments on Lake Orta's D. obtusa clone. Overall, our results

Lake Granbury and Lake Whitney Assessment Initiative Final Scientific/Technical Report Summary

Energy Technology Data Exchange (ETDEWEB)

Harris, B. L. [Texas AgriLife Research, College Station, TX (United States); Roelke, Daniel [Texas AgriLife Research, College Station, TX (United States); Brooks, Bryan [Texas AgriLife Research, College Station, TX (United States); Grover, James [Texas AgriLife Research, College Station, TX (United States)

2010-10-11

blooms. Our numerical modeling results support the idea that cyanobacteria, through allelopathy, control the timing of golden algae blooms in Lake Granbury. The in-lake experiments in Lake Whitney and Lake Waco also revealed that as golden algae blooms develop, there are natural enemies (a species of rotifer, and a virus) that help slow the population growth. Again, better characterization of these organisms is a high priority as it may be key to managing golden algae blooms. Our laboratory and in-lake experiments and field monitoring have shown that nutrient additions will remove toxicity and prevent golden algae from blooming. In fact, other algae displace the golden algae after nutrient additions. Additions of ammonia are particularly effective, even at low doses (much lower than what is employed in fish hatchery ponds). Application of ammonia in limited areas of lakes, such as in coves, should be explored as a management option. The laboratory experiments and field monitoring also show that the potency of toxins produced by P. parvum is greatly reduced when water pH is lower, closer to neutral levels. Application of mild acid to limited areas of lakes (but not to a level where acidic conditions are created), such as in coves, should be explored as a management option. Finally, our field monitoring and mathematical modeling revealed that flushing/dilution at high enough levels could prevent P. parvum from forming blooms and/or terminate existing blooms. This technique could work using deeper waters within a lake to flush the surface waters of limited areas of the same lakes, such as in coves and should be explored as a management option. In this way, water releases from upstream reservoirs would not be necessary and there would be no addition of nutrients in the lake.

Concentration of total protein and degree of acidity (pH of saliva when fasting and after breakfasting

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Gemella Nur Illahi

2016-04-01

Full Text Available Background: While fasting, the mouth does not work to eat and drink so that the salivary glands become less active so saliva production decreased and there was a change in eating timewhich is relation to the mastication process that impact on changes in the degree of acidity (pH Objectives: To determine the concentration of total protein and the degree of acidity (pH of saliva when fasting and after breakfasting. Materials and Methods: The study was observational analytic design with longitudinal (follow up study conducted in the Hj. Halima Dg. Sikati Dental Hospital inKandea in July 2015, the sampling method was purposive sampling. Population was 35 clinical students at the Department of Dental Public Health, Faculty of Dentistry Hasanuddin University with a total sample of 16 students who fit the criteria of the study subjects. To calculate the total protein of saliva concentration using Kyltecautoanalyzerand pH meter to measure the acidity of saliva. Data was analyzed was using SPSS version 17.0 (paired t-test, p <0.05. Results: The mean of total protein (% while fasting by 0135% ± 0.026 and the mean total protein (% after breakfasting at 0.179% ± 0.035, while the average degree of acidity (pH during fasting at 7.26 ± 0:24 and the average degree of acidity (pH after breakfasting at 7.66 ± 0.23 with p-value (0.000. Conclusions: An increase in the total protein concentration and acidity (pH after breakfasting.

Effects Of pH, Temperature And Salinity In Growth And Organic Acid Production Of Lactic Acid Bacteria Isolated From Penaeid Shrimp Intestine

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Subagiyo Subagiyo

2015-12-01

Full Text Available Bakteri asam laktat telah lama dikembangkan sebagai probiotik. Penentuan kondisi lingkungan yang optimum untuk pertumbuhan sel serta asam organik memberikan gambaran aktivitas optimum untuk kinerja probiotik baik dalam sistem fisiologi inang maupun dalam sistem bioproses untuk produksi sel dan metabolit. Penelitian ini bertujuan untuk mengetahui pengaruh faktor lingkungan (pH, suhu dan salinitas terhadap pertumbuhan dan produksi total asam organik tiga isolat bakteri asam laktat yang telah diseleksi dari intestinum udang penaeid. Eksperimen menggunakan  medium deMan, Rogosa and Sharpe (MRS cair. Perlakuan pH awal meliputi  nilai pH 4, 5 dan 6. Perlakuan suhu meliputi suhu 25, 30 dan 35OC serta perlakuan salinitas  meliputi salinitas 0,75 %, 1,5 % dan 3 %.  Setiap interval 6 jam dilakukan pengambilan sampel kultur bakteri dan penghitungan pertumbuhan berdasarkan perubahan optical density (pada panjang gelombang 600 nm sedangkan produksi asam laktat dianalisis dengan metode titrimetrik menggunakan NaOH 1 N sebagai larutan titrasinya. Berdasarkan hasil penelitian disimpulkan bahwa suhu, pH awal dan salinitas berpengaruh terhadap pertumbuhan dan produksi asam organik. Nilai kondisi lingkungan terbaik untuk pertumbuhan dapat berbeda dengan nilai terbaik untuk produksi asam organic. Hal ini ditunjukan oleh nilai laju pertumbuhan dan produksi asam laktat tertinggi dari tiga isolat uji terjadi pada suhu, pH awal dan salinitas yang berbeda.  Isolat L12 tumbuh optimum pada suhu 30oC, pH awal 6 dan salinitas 0,75%. Isolat L14 tumbuh optimum pada suhu 30oC, pH awal 6 dan salinitas 1.5%. Isolat L 21 tumbuh optimum pada suhu 30 oC, pH awal 6 dan salinitas 1.5%. Kata kunci: bakteri asam laktat, suhu, pH, salinitas, asamorganik, pertumbuhan, Lactic acid bacteria are widely distributed in intestinal tracts of various animals where they live as normal flora.Strains of lactic acid bacteria are the most common microbes employed as probiotics, The optimum

pH-, Lactic Acid-, and Non-Lactic Acid-Dependent Activities of Probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium

OpenAIRE

Fayol-Messaoudi, Domitille; Berger, Cédric N.; Coconnier-Polter, Marie-Hélène; Liévin-Le Moal, Vanessa; Servin, Alain L.

2005-01-01

The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacill...

Recovery of carboxylic acids at pH greater than pK_a

Energy Technology Data Exchange (ETDEWEB)

Tung, Lisa A. [Univ. of California, Berkeley, CA (United States)

1993-08-01

Economics of producing carboxylic acids by fermentation is often dominated, not by the fermentation cost, but by the cost of recovering and purifying the acids from dilute aqueous solutions. Experiments were performed to measure uptakes of lactic and succinic acids as functions of pH by basic polymeric sorbents; sorbent regeneration was also tested. Performance at pH > pK_a and regenerability depend on sorbent basicity; apparent pK_a and monomer pK{sub a} can be used to predict sorbent performance. Two basic amine extractants, Alamine 336 and Amberlite LA-2, in were also studied; they are able to sustain capacity to higher pH in diluents that stabilize the acid-amine complex through H bonding. Secondary amines perform better than tert-amines in diluents that solvate the additional proton. Competitive sulfate and phosphate, an interference in fermentation, are taken up by sorbents more strongly than by extractants. The third step in the proposed fermentation process, the cracking of the trimethylammonium (TMA) carboxylate, was also examined. Because lactic acid is more soluble and tends to self-esterify, simple thermal cracking does not remove all TMA; a more promising approach is to esterify the TMA lactate by reaction with an alcohol.

Salt lakes of Western Australia - Natural abiotic formation of volatile organic compounds

Science.gov (United States)

Krause, T.; Studenroth, S.; Mulder, I.; Tubbesing, C.; Kotte, K.; Ofner, J.; Junkermann, W.; Schöler, H. F.

2012-04-01

Western Australia is a semi-/arid region that is heavily influenced by global climate change and agricultural land use. The area is known for its many ephemeral saline and hypersaline lakes with a wide range of hydrogeochemical parameters that have gradually changed over the last fifty years. Historically, the region was covered by eucalyptus trees and shrubs, but was cleared mainly within 10 years after WWII to make room for wheat and live stock. After the clearance of the deep rooted native plants the groundwater started to rise, bringing increased amounts of dissolved salts and minerals to the surface and discharging them into streams and lakes. Thus most of Western Australia is influenced by secondary salinisation (soil salting) [1]. Another problem is that the discharged minerals affect the pH of ground and surface water, which ranges from acidic to slightly basic. During the 2011 campaign surface water was measured with a pH between 2.5 and 7.1. Another phenomenon in Western Australia is the decrease of rainfall over the last decades assumed to be linked to the secondary salinisation. The rising saline and mineral rich groundwater increases the biotical and abiotical activity of the salt lakes. Halogenated and non-halogenated volatile organic compounds emitted from those lakes undergo fast oxidation and chemical reactions to form small particles modifying cloud microphysics and thus suppressing rain events [2]. Our objective is to gain a better understanding of this extreme environment with its hypersaline acidic lakes with regard to the potential abiotic formation of volatile organic compounds and its impact on the local climate. In spring 2011 fifty-three sediment samples from ten salt lakes in the Lake King region where taken, freeze-dried and ground. In order to simulate the abiotic formation of volatile organic compounds the soil samples were resuspended with water in gas-tight headspace vials. The headspace was measured using a purge and trap GC

Mine waters: Acidic to circumneutral

Science.gov (United States)

Nordstrom, D. Kirk

2011-01-01

Acid mine waters, often containing toxic concentrations of Fe, Al, Cu, Zn, Cd, Pb, Ni, Co, and Cr, can be produced from the mining of coal and metallic deposits. Values of pH for acid mine waters can range from –3.5 to 5, but even circumneutral (pH ≈ 7) mine waters can have high concentrations of As, Sb, Mo, U, and F. When mine waters are discharged into streams, lakes, and the oceans, serious degradation of water quality and injury to aquatic life can ensue, especially when tailings impoundments break suddenly. The main acid-producing process is the exposure of pyrite to air and water, which promotes oxidative dissolution, a reaction catalyzed by microbes. Current and future mining should plan for the prevention and remediation of these contaminant discharges by the application of hydrogeochemical principles and available technologies, which might include remining and recycling of waste materials.

Determination of critical pH and Al concentration of acidic Ultisols for wheat and canola crops

Science.gov (United States)

Abdulaha-Al Baquy, M.; Li, Jiu-Yu; Xu, Chen-Yang; Mehmood, Khalid; Xu, Ren-Kou

2017-02-01

Soil acidity has become a principal constraint in dry land crop production systems of acidic Ultisols in tropical and subtropical regions of southern China, where winter wheat and canola are cultivated as important rotational crops. There is little information on the determination of critical soil pH as well as aluminium (Al) concentration for wheat and canola crops. The objective of this study is to determine the critical soil pH and exchangeable aluminium concentration (AlKCl) for wheat and canola production. Two pot cultures with two Ultisols from Hunan and Anhui (SE China) were conducted for wheat and canola crops in a controlled growth chamber. Aluminium sulfate (Al2(SO4)3) and hydrated lime (Ca(OH)2) were used to obtain the target soil pH levels from 3.7 (Hunan) and 3.97 (Anhui) to 6.5. Plant height, shoot dry weight, root dry weight, and chlorophyll content (SPAD value) of wheat and canola were adversely affected by soil acidity in both locations. The critical soil pH and AlKCl of the Ultisol from Hunan for wheat were 5.29 and 0.56 cmol kg-1, respectively. At Anhui, the threshold soil pH and AlKCl for wheat were 4.66 and 1.72 cmol kg-1, respectively. On the other hand, the critical soil pH for canola was 5.65 and 4.87 for the Ultisols from Hunan and Anhui, respectively. The critical soil exchangeable Al for canola cannot be determined from the experiment of this study. The results suggested that the critical soil pH and AlKCl varied between different locations for the same variety of crop, due to the different soil types and their other soil chemical properties. The critical soil pH for canola was higher than that for wheat for both Ultisols, and thus canola was more sensitive to soil acidity. Therefore, we recommend that liming should be undertaken to increase soil pH if it falls below these critical soil pH levels for wheat and canola production.

Intracellular product recycling in high succinic acid producing yeast at low pH

NARCIS (Netherlands)

Wahl, S.A.; Bernal Martinez, C.; Zhao, Zheng; van Gulik, W.M.; Jansen, Mickel L.A.

2017-01-01

Background: The metabolic engineering of Saccharomyces cerevisiae for the production of succinic acid has progressed dramatically, and a series of high-producing hosts are available. At low cultivation pH and high titers, the product transport can become bidirectional, i.e. the acid is reentering

Viability of Lactic Acid Bacteria Isolated from Kombucha Tea Against Low pH and Bile Salt

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Ni Nyoman Puspawati

2016-03-01

Full Text Available Kombucha tea is a functional drink fermented by various types of microbes. Kombucha tea is also a source of lactic acid bacteria that can maintain the balance of the microflora of the digestive tract which can improve the health of the human body. Lactic acid bacteria can act as a probiotic if it is able to survive to the human gastrointestinal tract, where in order to reach the digestive tract, lactic acid bacteria has to be resistant to the low pH in the stomach and bile salts. The purpose of this study was to determine the level of resistance of lactic acid bacteria in kombucha tea against low pH and bile salts. This study uses 20 isolates, each of these isolates were tested to the resistance of low pH 2.0 and 0.5 % bile salts with incubation time of 4 hours. The results indicated that from 20 isolates of lactic acid bacteria that were obtained from kombucha tea, 15 isolates were resistant to low pH and 13 isolates were resistant to bile salts. The isolates have a huge potential to be developed as a probiotic candidate that can contribute greatly to the health of the digestive tract.

Protein Complexation and pH Dependent Release Using Boronic Acid Containing PEG-Polypeptide Copolymers.

Science.gov (United States)

Negri, Graciela E; Deming, Timothy J

2017-01-01

New poly(L-lysine)-b-poly(ethylene glycol) copolypeptides have been prepared, where the side-chain amine groups of lysine residues are modified to contain ortho-amine substituted phenylboronic acid, i.e., Wulff-type phenylboronic acid (WBA), groups to improve their pH responsive, carbohydrate binding properties. These block copolymers form nanoscale complexes with glycosylated proteins that are stable at physiological pH, yet dissociate and release the glycoproteins under acidic conditions, similar to those found in endosomal and lysosomal compartments within cells. These results suggest that WBA modified polypeptide copolymers are promising for further development as degradable carriers for intracellular protein delivery. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The pH profile for acid-induced elongation of coleoptile and epicotyl sections is consistent with the acid-growth theory

Science.gov (United States)

Cleland, R. E.; Buckley, G.; Nowbar, S.; Lew, N. M.; Stinemetz, C.; Evans, M. L.; Rayle, D. L.

1991-01-01

The acid-growth theory predicts that a solution with a pH identical to that of the apoplast of auxin-treated tissues (4.5.-5.0) should induce elongation at a rate comparable to that of auxin. Different pH profiles for elongation have been obtained, however, depending on the type of pretreatment between harvest of the sections and the start of the pH-incubations. To determine the acid sensitivity under in vivo conditions, oat (Avena sativa L.) coleoptile, maize (Zea mays L.) coleoptile and pea (Pisum sativum L.) epicotyl sections were abraded so that exogenous buffers could penetrate the free space, and placed in buffered solutions of pH 3.5-6.5 without any preincubation. The extension, without auxin, was measured over the first 3 h. Experiments conducted in three laboratories produced similar results. For all three species, sections placed in buffer without pretreatment elongated at least threefold faster at pH 5.0 than at 6.0 or 6.5, and the rate elongation at pH 5.0 was comparable to that induced by auxin. Pretreatment of abraded sections with pH-6.5 buffer or distilled water adjusted to pH 6.5 or above gave similar results. We conclude that the pH present in the apoplast of auxin-treated coleoptile and stems is sufficiently low to account for the initial growth response to auxin.

Thermal resistance parameters of acid-adapted and unadapted Escherichia coli O157:H7 in apple-carrot juice blends: effect of organic acids and pH.

Science.gov (United States)

Usaga, Jessie; Worobo, Randy W; Padilla-Zakour, Olga I

2014-04-01

Numerous outbreaks involving fresh juices contaminated with Escherichia coli O157:H7 have occurred in the United States and around the world, raising concern for the safety of these products. Until now, only a few studies regarding the thermal tolerance of this pathogen in acidic juices over a wide range of pH values have been published. Therefore, the effect of varying the pH with different organic acids on the thermal inactivation of non-acid-adapted and acid-adapted E. coli O157:H7 (strain C7927) was determined. The decimal reduction times (D-values) and the change in temperature required for the thermal destruction curve to traverse 1 log cycle (z-values) were calculated for non-acid-adapted E. coli in an apple-carrot juice blend (80:20) adjusted to three pH values (3.3, 3.5, and 3.7) by the addition of lactic, malic, or acetic acid and at a pH of 4.5 adjusted with NaOH. Thermal parameters were also determined for acid-adapted cells in juices acidified with malic acid. The effect of the soluble solids content on the thermal tolerance was studied in samples with a pH of 3.7 at 9.4 to 11.5 °Brix. The D-values were determined at 54, 56, and 58 °C, and trials were conducted in triplicate. Non-acid-adapted E. coli exhibited the highest thermal tolerance at pH 4.5 (D-value at 54 °C [D54 °C] of 20 ± 4 min and z-value of 6.2 °C), although on average, the D-values increased significantly (P 0.01). The data from this study will be useful for establishing critical limits for safe thermal processing of pH-controlled juices and similar products.

Effect of acid rain pH on leaching behavior of cement stabilized lead-contaminated soil.

Science.gov (United States)

Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Liu, Zhao-Peng; Jin, Fei

2014-04-30

Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of the Microbial Diversity and Abundance Between the Freshwater Land-Locked Lakes of Schirmacher Oasis and the Perennially Ice-Covered Lake Untersee in East Antarctica

Science.gov (United States)

Huang, Jonathan; Hoover, Richard B.; Swain, Ashit; Murdock, Chris; Bej, Asim K.

2010-01-01

Extreme conditions such as low temperature, dryness, and constant UV-radiation in terrestrial Antarctica are limiting factors of the survival of microbial populations. The objective of this study was to investigate the microbial diversity and enumeration between the open water lakes of Schirmacher Oasis and the permanently ice-covered Lake Untersee. The lakes in Schirmacher Oasis possessed abundant and diverse group of microorganisms compared to the Lake Untersee. Furthermore, the microbial diversity between two lakes in Schirmacher Oasis (Lake L27C and L47) was compared by culture-based molecular approach. It was determined that L27Chad a richer microbial diversity representing 5 different phyla and 7 different genera. In contrast L47 consisted of 4 different phyla and 6 different genera. The difference in microbial community could be due to the wide range of pH between L27C (pH 9.1) and L47 (pH 5.7). Most of the microbes isolated from these lakes consisted of adaptive biological pigmentation. Characterization of the microbial community found in the freshwater lakes of East Antarctica is important because it gives a further glimpse into the adaptation and survival strategies found in extreme conditions.

Continuous water-quality monitoring to improve lake management at Lake Mattamuskeet National Wildlife Refuge

Science.gov (United States)

Michelle Moorman; Tom Augspurger

2016-01-01

The U.S. Fish and Wildlife Service has partnered with U.S. Geological Survey to establish 2 continuous water-quality monitoring stations at Lake Mattamuskeet. Stations on the east and west side of the lake measure water level, clarity, dissolved oxygen, pH, temperature, salinity, and conductivity.

The acid tolerance response and pH adaptation of Enterococcus faecalis in extract of lime Citrus aurantiifolia from Aceh Indonesia.

Science.gov (United States)

Mubarak, Zaki; Soraya, Cut

2018-01-01

Background:  The objective of the present study was to evaluate the acid tolerance response and pH adaptation when Enterococcus faecalis interacted with extract of lime ( Citrus aurant iifolia ). Methods : We used E. faecalis ATCC 29212 and lime extract from Aceh, Indonesia. The microbe was analyzed for its pH adaptation, acid tolerance response, and adhesion assay using a light microscope with a magnification of x1000. Further, statistical tests were performed to analyze both correlation and significance of the acid tolerance and pH adaptation as well as the interaction activity. Results : E. faecalis was able to adapt to a very acidic environment (pH 2.9), which was characterized by an increase in its pH (reaching 4.2) at all concentrations of the lime extract (p lime extract based on spectrophotometric data (595 nm) (p lime extract was relatively stable within 6 up to 12 hours (p 0.05) based on the mass profiles of its interaction activity. Conclusions : E. faecalis can adapt to acidic environments (pH 2.9-4.2); it is also able to tolerate acid generated by Citrus auranti ifolia extract, revealing a stable interaction in the first 6-12 hours.

Growth of aspergillus terreus and the production of itaconic acid in batch and continuous cultures. The influence of pH

Energy Technology Data Exchange (ETDEWEB)

Rychtera, M.; Wase, J.D.A.

1981-01-01

Aspergillus terreus (NRRL 1960) was cultivated in batch and in continuous single-stage culture. The influence of pH on the growth of the organism, on the formation of itaconic acid and on the kinetics of fermentation was studied under phosphate limitation, both at controlled ph values and also when the pH was allowed to decrease in a natural way. In the pH range 1.7-3.5, the ratio of undissociated:half-dissociated acid varied from 190:1 to 1.5:1. The amount of completely dissociated acid may be regarded as negligible. In batch systems operated without pH control, an initial pH of 3.1 proved to be the most effective. Product formation under such conditions started at a point where the exponential growth phase commenced and was described by a zero-order equation. The maximum itaconic acid production rate was shifted behind maximum growth rate. The continuous single-stage system was first order with respect to product formation. At pH greater than 3.1, a number of aberrant and pellet forms of the mould occurred, resulting in decreased acid production. (Refs. 41).

Impact of acid precipitation on freshwater ecosystems in Norway

Energy Technology Data Exchange (ETDEWEB)

Wright, R F; Dale, T; Gjessing, E T; Hendrey, G R; Henriksen, A; J Hannesen, M; Muniz, I P

1975-01-01

Precipitation in southern Norway contains large amounts of H/sup +/, SO/sub 4//sup 2 -/, and NO/sub 3//sup -/ ions, along with heavy metals such as Cu, Zn, Cd, and Pb. These pollutants are transported over long distances to Scandinavia and are deposited in precipitation and dry-fallout. Large areas of southern Norway have been adversely affected by acid precipitation. The pH of many lakes is below 5.0 and sulfate, rather than bicarbonate, is the major anion. Lakes in these areas are particularly vulnerable to acid precipitation because their watersheds are underlain by highly resistant bedrock with low calcium and magnesium contents. The effects of the increasing acidity of freshwater ecosystems involve interference at every trophic level. Biological surveys indicate that low pH-values inhibit the decomposition of allochthonous organic matter, decrease the species number of phyto- and zooplankton and benthic invertebrates, and promote the growth of benthic mosses. Fish populations have been severely affected - the salmon have been eliminated from many rivers, and hundreds of lakes have lost their sport fisheries.

Hydrothermal carbonization (HTC) of wheat straw: influence of feedwater pH prepared by acetic acid and potassium hydroxide.

Science.gov (United States)

Reza, M Toufiq; Rottler, Erwin; Herklotz, Laureen; Wirth, Benjamin

2015-04-01

In this study, influence of feedwater pH (2-12) was studied for hydrothermal carbonization (HTC) of wheat straw at 200 and 260°C. Acetic acid and KOH were used as acidic and basic medium, respectively. Hydrochars were characterized by elemental and fiber analyses, SEM, surface area, pore volume and size, and ATR-FTIR, while HTC process liquids were analyzed by HPLC and GC. Both hydrochar and HTC process liquid qualities vary with feedwater pH. At acidic pH, cellulose and elemental carbon increase in hydrochar, while hemicellulose and pseudo-lignin decrease. Hydrochars produced at pH 2 feedwater has 2.7 times larger surface area than that produced at pH 12. It also has the largest pore volume (1.1 × 10(-1) ml g(-1)) and pore size (20.2 nm). Organic acids were increasing, while sugars were decreasing in case of basic feedwater, however, phenolic compounds were present only at 260°C and their concentrations were increasing in basic feedwater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Seasonal variations in water quality of an oxbow lake in response to multiple short-time pulses of flooding (Jataí Ecological Station--Mogi-Guaçu River, Luiz Antonio, SP-Brazil).

Science.gov (United States)

Krusche, A V; Mozeto, A A

1999-01-01

Mogi-Guaçu River is a six-order floodplain river in the upper Paraná River Basin, Southern Brazil. Its yearly discharge varies from a minimum of 100 m3.s-1 to a maximum of 600 m3.s-1. Diogo Lake is a shallow lake located at its floodplain within the Jataí Ecological Station (Luiz Antonio, São Paulo State) and is connected throughout the year to the river through a narrow and shallow channel. The main finding of this study is that the river hidrology controls the annual variations in lake hydrochemistry through a series of hydraulic effects related to oscillations in river discharge. Lake water quality is a resultant of differential contribution from local and regional watersheds. During the low water period, lake water quality is determined by inputs from Cafundó Creek, which drains the local watershed into the lake. Raising the river level during the rain season results in the damming of lake and culminates with the entrance of river waters into the plain. The geochemistry of waters in this system is determined by weathering of sandstones with basalt intrusions. Waters are acidic (river pH = 6.00 to 7.02 and stream-lake pH = 5.15 to 6.7) and dominant cations are Na+ and K+. Major anions are almost exclusively represented by bicarbonate and an unknown concentration of organic acid anions. The overall ionic load of these soft waters in the system is therefore very low.

Sulfate reduction at low pH to remediate acid mine drainage

International Nuclear Information System (INIS)

Sánchez-Andrea, Irene; Sanz, Jose Luis; Bijmans, Martijn F.M.; Stams, Alfons J.M.

2014-01-01

Highlights: • Acid mine drainage (AMD) is an important environmental concern. • Remediation through biological sulfate reduction and metal recovery can be applied for AMD. • Microbial community composition has a major impact on the performance of bioreactors to treat AMD. • Acidophilic SRB are strongly influenced by proton, sulfide and organic acids concentration. - Abstract: Industrial activities and the natural oxidation of metallic sulfide-ores produce sulfate-rich waters with low pH and high heavy metals content, generally termed acid mine drainage (AMD). This is of great environmental concern as some heavy metals are highly toxic. Within a number of possibilities, biological treatment applying sulfate-reducing bacteria (SRB) is an attractive option to treat AMD and to recover metals. The process produces alkalinity, neutralizing the AMD simultaneously. The sulfide that is produced reacts with the metal in solution and precipitates them as metal sulfides. Here, important factors for biotechnological application of SRB such as the inocula, the pH of the process, the substrates and the reactor design are discussed. Microbial communities of sulfidogenic reactors treating AMD which comprise fermentative-, acetogenic- and SRB as well as methanogenic archaea are reviewed

Sulfate reduction at low pH to remediate acid mine drainage

Energy Technology Data Exchange (ETDEWEB)

Sánchez-Andrea, Irene, E-mail: irene.sanchezandrea@wur.nl [Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen (Netherlands); Sanz, Jose Luis [Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Bijmans, Martijn F.M. [Wetsus, Centre of Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden (Netherlands); Stams, Alfons J.M. [Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen (Netherlands); IBB – Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, 4710-057 Braga (Portugal)

2014-03-01

Highlights: • Acid mine drainage (AMD) is an important environmental concern. • Remediation through biological sulfate reduction and metal recovery can be applied for AMD. • Microbial community composition has a major impact on the performance of bioreactors to treat AMD. • Acidophilic SRB are strongly influenced by proton, sulfide and organic acids concentration. - Abstract: Industrial activities and the natural oxidation of metallic sulfide-ores produce sulfate-rich waters with low pH and high heavy metals content, generally termed acid mine drainage (AMD). This is of great environmental concern as some heavy metals are highly toxic. Within a number of possibilities, biological treatment applying sulfate-reducing bacteria (SRB) is an attractive option to treat AMD and to recover metals. The process produces alkalinity, neutralizing the AMD simultaneously. The sulfide that is produced reacts with the metal in solution and precipitates them as metal sulfides. Here, important factors for biotechnological application of SRB such as the inocula, the pH of the process, the substrates and the reactor design are discussed. Microbial communities of sulfidogenic reactors treating AMD which comprise fermentative-, acetogenic- and SRB as well as methanogenic archaea are reviewed.

Conformational changes in human serum albumin studied by fluorescence and absorption spectroscopy. Distance measurements as a function of pH and fatty acids

DEFF Research Database (Denmark)

Honoré, B; Pedersen, A O

1989-01-01

pH- and fatty acid-induced conformational changes in human serum albumin were investigated by fluorescence-energy transfer, determining the distance between Trp-214 and bound bilirubin at 25 degrees C. This distance changes significantly with the pH, being 2.52 +/- 0.01 nm at pH 6, 2.31 +/- 0.04 nm...... at pH 9, 2.13 +/- 0.07 nm at pH 11.0 and 2.77 nm at pH 11.9. The influence of different fatty acids on the distance was also determined. At pH 7.4 medium-chain fatty acids seem to increase this distance, whereas long-chain fatty acids, at low concentrations, decrease the distance between the two...... chromophores. The contraction of the protein carrying long-chain saturated fatty acids is even more pronounced at pH 9. Udgivelsesdato: 1989-Feb-15...

Acidification in Three Lake District Tarns: Historical Iong term trends and modelled future behaviour under changing sulphate and nitrate deposition

Directory of Open Access Journals (Sweden)

P. G. Whitchead

1997-01-01

Full Text Available Three upland Lake District Tarns, Scoat, Greendale and Burnmoor, have been evaluated using MAGIC (Model of Acidification of Groundwater In Catchments to reconstruct past, present and future chemical behaviour. The modelled historical changes in acidity are compared with palaeoecological estimation of pH to demonstrate model validity. Chemistry as simulated for all anions and cations and two of the three lakes are shown to have undergone significant acidification. The effects of changing atmospheric pollution levels on lake chemistry is evaluated and 80-90% sulphur reduction levels are required to achieve zero alkalinity. The impacts of increased nitrogen deposition are assessed and are shown to further delay reversibility.

Conditions affecting the release of phosphorus from surface lake sediments.

Science.gov (United States)

Christophoridis, Christophoros; Fytianos, Konstantinos

2006-01-01

Laboratory studies were conducted to determine the effect of pH and redox conditions, as well as the effect of Fe, Mn, Ca, Al, and organic matter, on the release of ortho-phosphates in lake sediments taken from Lakes Koronia and Volvi (Northern Greece). Results were evaluated in combination with experiments to determine P fractionation in the sediment. The study revealed the major effect of redox potential and pH on the release of P from lake sediments. Both lakes showed increased release rates under reductive conditions and high pH values. The fractionation experiments revealed increased mobility of the reductive P fraction as well as of the NaOH-P fraction, indicating participation of both fractions in the overall release of sediment-bound P, depending on the prevailing environmental conditions. The results were assessed in combination with the release patterns of Fe, Mn, Ca, Al, and organic matter, enabling the identification of more specific processes of P release for each lake. The basic release patterns included the redox induced reductive dissolution of P-bearing metal oxides and the competitive exchange of phosphate anions with OH- at high pH values. The formation of an oxidized surface microlayer under oxic conditions acted as a protective film, preventing further P release from the sediments of Lake Volvi, while sediments from Lake Koronia exhibited a continuous and increased tendency to release P under various physicochemical conditions, acting as a constant source of internal P loading.

Bioremediation of Acidic and Metalliferous Drainage (AMD) through organic carbon amendment by municipal sewage and green waste.

Science.gov (United States)

McCullough, Clint D; Lund, Mark A

2011-10-01

Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource in hot arid regions. However, pit lake water is often characterised by low pH with high dissolved metal concentrations resulting from Acidic and Metalliferous Drainage (AMD). Addition of organic matter to pit lakes to enhance microbial sulphate reduction is a potential cost effective remediation strategy. However, cost and availability of suitable organic substrates are often limiting. Nevertheless, large quantities of sewage and green waste (organic garden waste) are often available at mine sites from nearby service towns. We treated AMD pit lake water (pH 2.4) from tropical, North Queensland, Australia, with primary-treated sewage sludge, green waste, and a mixture of sewage and green waste (1:1) in a controlled microcosm experiment (4.5 L). Treatments were assessed at two different rates of organic loading of 16:1 and 32:1 pit water:organic matter by mass. Combined green waste and sewage treatment was the optimal treatment with water pH increased to 5.5 in only 145 days with decreases of dissolved metal concentrations. Results indicated that green waste was a key component in the pH increase and concomitant heavy metal removal. Water quality remediation was primarily due to microbially-mediated sulphate reduction. The net result of this process was removal of sulphate and metal solutes to sediment mainly as monosulfides. During the treatment process NH(3) and H(2)S gases were produced, albeit at below concentrations of concern. Total coliforms were abundant in all green waste-treatments, however, faecal coliforms were absent from all treatments. This study demonstrates addition of low-grade organic materials has promise for bioremediation of acidic waters and warrants further experimental investigation into feasibility at higher scales of application such as pit lakes. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

New Amino-Acid-Based β-Phosphorylated Nitroxides for Probing Acidic pH in Biological Systems by EPR Spectroscopy.

Science.gov (United States)

Thétiot-Laurent, Sophie; Gosset, Gaëlle; Clément, Jean-Louis; Cassien, Mathieu; Mercier, Anne; Siri, Didier; Gaudel-Siri, Anouk; Rockenbauer, Antal; Culcasi, Marcel; Pietri, Sylvia

2017-02-01

There is increasing interest in measuring pH in biological samples by using nitroxides with pH-dependent electron paramagnetic resonance (EPR) spectra. Aiming to improve the spectral sensitivity (Δa X ) of these probes (i.e., the difference between the EPR hyperfine splitting (hfs) in their protonated and unprotonated forms), we characterized a series of novel linear α-carboxy, α'-diethoxyphosphoryl nitroxides constructed on an amino acid core and featuring an (α or α')-C-H bond. In buffer, the three main hfs (a N , a H , and a P ) of their EPR spectra vary reversibly with pH and, from a P or a H titration curves, a two- to fourfold increase in sensitivity was achieved compared to reference imidazoline or imidazolidine nitroxides. The crystallized carboxylate 10 b (pK a ≈3.6), which demonstrated low cytotoxicity and good resistance to bioreduction, was applied to probe stomach acidity in rats. The results pave the way to a novel generation of highly sensitive EPR pH markers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Change of physical and chemical parameters of fulvic acids at different pH of the system

Science.gov (United States)

Dinu, Marina; Kremleva, Tatyana

2017-04-01

Organic substances of humic nature significantly change physicochemical properties at different pH of natural waters. As a consequence, a large number of consecutive and parallel reactions in the structure of organic polymers, and reacting with inorganic anions. The main indicators of changes in the properties of organic acids in natural systems are changes in their IR spectra, changes in the colloid stability (the zeta potential) as well as in the molecular weight and emission spectra (fluorescence emission spectra). The aim of our study was to evaluate of changing in physical and chemical properties of the fulvic acid from soil/water samples in the natural areas of European Russia and Western Siberia (the steppe and the northern taiga zones) at different pH (from 8 to 1.5). Changes in absorption bands of fulvic acid caused by both COOH groups and amino groups with varying degrees of protonation were found. Consequently, we can assume that in an electric field fulvic acid change the sign of their charge at depending on pH. During the lowering of the pH intensity of C-O bands generally decreases, while in the region 1590 cm-1 disappears. In turn, the band at 1700 cm-1 is the most intense; it could mean a complete protonation of the carboxyl groups. According to our data, the values of zeta potential changes depending on pH of the system. The zeta potential becomes more negative with increasing pH and it may be due to ionization of oxygen groups of fulvic acid. For the colloidal polymer systems the value of the zeta potential is strongly negative (less than -20 mV) and strongly positive (over 20 mV) characterize the system as the most stable. Our experimental data for the study of the zeta potential of fulvic acids extracted from the soils and waters of different climatic zones show zonal influence of the qualitative characteristics of organic substances on the surface charge of the high-molecular micelle of fulvic acids. It was found that fulvic acids extracted

Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

Science.gov (United States)

Chung-Yun Hse

2009-01-01

To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

Dynamics of fatty acid vesicles in response to pH stimuli

DEFF Research Database (Denmark)

Ikari, Keita; Sakuma, Yuka; Jimbo, Takehiro

2015-01-01

We investigate the dynamics of decanoic acid/decanoate (DA) vesicles in response to pH stimuli. Two types of dynamic processes induced by the micro injection of NaOH solutions are sequentially observed: deformations and topological transitions. In the deformation stage, DA vesicles show a series...

Determination of the titratable acidity and the pH of wine based on potentiometric flow injection analysis.

Science.gov (United States)

Vahl, Katja; Kahlert, Heike; von Mühlen, Lisandro; Albrecht, Anja; Meyer, Gabriele; Behnert, Jürgen

2013-07-15

A FIA system using a pH-sensitive detector based on a graphite/quinhydrone/silicone composite electrode was applied to determine sequentially the titratable acidity and the pH of wine, as well as the sum of calcium and magnesium ions. For all measurements the same FIA configuration was used employing different carrier solutions. The results for the determination of acidity and pH are in good agreement with those obtained by classical potentiometric titrations and by pH measurements using a conventional glass electrode. The standard deviation was less than 1.5% for both kinds of measurements and the sample volume was 150 μL. The method allows about 40 determinations of titratable acidity per hour and 30 pH measurements per hour. The titration method can be adjusted to the legal requirements in USA and Europe. Copyright © 2013 Elsevier B.V. All rights reserved.

Indications of human activity from amino acid and amino sugar analyses on Holocene sediments from lake Lonar, central India

Science.gov (United States)

Menzel, P.; Gaye, B.; Wiesner, M.; Prasad, S.; Basavaiah, N.; Stebich, M.; Anoop, A.; Riedel, N.; Brauer, A.

2012-04-01

The DFG funded HIMPAC (Himalaya: Modern and Past Climates) programme aims to reconstruct Holocene Indian Monsoon climate using a multi-proxy and multi-archive approach. First investigations made on sediments from a ca. 10 m long core covering the whole Holocene taken from the lake Lonar in central India's state Maharashtra, Buldhana District, serve to identify changes in sedimentation, lake chemistry, local vegetation and regional to supra-regional climate patterns. Lake Lonar occupies the floor of an impact crater that formed on the ~ 65 Ma old basalt flows of the Deccan Traps. It covers an area of ca. 1 km2 and is situated in India's core monsoon area. The modern lake has a maximum depth of about 5 m, is highly alkaline, and hyposaline, grouped in the Na-Cl-CO3 subtype of saline lakes. No out-flowing stream is present and only three small streams feed the lake, resulting in a lake level highly sensitive to precipitation and evaporation. The lake is eutrophic and stratified throughout most of the year with sub- to anoxic waters below 2 m depth. In this study the core sediments were analysed for their total amino acid (AA) and amino sugar (AS) content, the amino acid bound C and N percentage of organic C and total N in the sediment and the distribution of individual amino acids. The results roughly show three zones within the core separated by distinct changes in their AA content and distribution. (i) The bottom part of the core from ca. 12000 cal a BP to 11400 cal a BP with very low AA and AS percentage indicating high lithogenic contribution, most probably related to dry conditions. (ii) From 11400 cal a BP to 1200 cal a BP the sediments show moderate AA and AS percentages and low values for the ratios of proteinogenic AAs to their non-proteinogenic degradation products (e.g. ASP/β-ALA; GLU/γ-ABA). (iii) The top part of the core (land use. This hypothesis is corroborated by the dating of more than 10 temple ruins surrounding the lake, which were built in the 12

Cation effects on phosphatidic acid monolayers at various pH conditions.

Science.gov (United States)

Zhang, Ting; Cathcart, Matthew G; Vidalis, Andrew S; Allen, Heather C

2016-10-01

The impact of pH and cations on phase behavior, stability, and surface morphology for dipalmitoylphosphatidic acid (DPPA) monolayers was investigated. At pHCations are found to expand and stabilize the monolayer in the following order of increasing magnitude at pH 5.6: Na + >K + ∼Mg 2+ >Ca 2+ . Additionally, cation complexation is tied to the pH and protonation state of DPPA, which are the primary factors controlling the monolayer surface behavior. The binding affinity of cations to the headgroup and thus deprotonation capability of the cation, ranked in the order of Ca 2+ >Mg 2+ >Na + >K + , is found to be well explained by the law of matching water affinities. Nucleation of surface 3D lipid structures is observed from Ca 2+ , Mg 2+ , and Na + , but not from K + , consistent with the lowest binding affinity of K + . Unraveling cation and pH effects on DPPA monolayers is useful in further understanding the surface properties of complex systems such as organic-coated marine aerosols where organic films are directly influenced by the pH and ionic composition of the underlying aqueous phase. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

pH buffering capacity of acid soils from tropical and subtropical regions of China as influenced by incorporation of crop straw biochars

Energy Technology Data Exchange (ETDEWEB)

Xu, Ren-kou; Zhao, An-zhen; Yuan, Jin-hua; Jiang, Jun [Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture

2012-04-15

Purpose: The key factors influencing pH buffering capacity of acid soils from tropical and subtropical regions, and effects of soil evolution and incorporation of biochars on pH buffering capacity were investigated to develop suitable methods to increase pH buffering capacity of acid soils. Materials and methods: A total of 24 acid soils collected from southern China were used. The pH buffering capacity was determined using acid-base titration. The values of pH buffering capacity were obtained from the slope of titration curves of acid or alkali additions plotted against pH in the pH range 4.0-7.0. Two biochars were prepared from straws of peanut and canola using a low temperature pyrolysis method. After incubation of three acid soils, pH buffering capacity was then determined. Results and discussion: pH buffering capacity had a range of 9.1-32.1 mmol kg{sup -1} pH{sup -1} for 18 acid soils from tropical and subtropical regions of China. The pH buffering capacity was highly correlated (R{sup 2} = 0.707) with soil cation exchange capacity (CEC) measured with ammonium acetate method at pH 7.0 and decreased with soil evolution due to the decreased CEC. Incorporation of biochars at rates equivalent to 72 and 120 t ha{sup -1} increased soil pH buffering capacity due to the CEC contained in the biochars. Incorporation of peanut straw char which itself contained more CEC and alkalinity induced more increase in soil CEC, and thus greater increase in pH buffering capacity compared with canola straw char. At 5% of peanut straw char added, soil CEC increased by 80.2%, 51.3%, and 82.8% for Ultisol from Liuzhou, Oxisol from Chengmai and Ultisol from Kunlun, respectively, and by 19.8%, 19.6%, and 32.8% with 5% of canola straw char added, respectively; and correspondingly for these soils, the pH buffering capacity increased by 73.6%, 92.0%, and 123.2% with peanut straw char added; and by 31.3%, 25.6%, and 52.3% with canola straw char added, respectively. Protonation

Effects of pH, titratable acidity and calcium concentration of non ...

African Journals Online (AJOL)

It has also been reported that experimental addition of calcium in beverages can reduce the progression of erosion. This study was carried out to investigate effects the of pH, titratable acidity and calcium concentration of non alcoholic carbonated beverages on enamel erosion of extracted human premolar teeth. Method: ...

Esophageal pH monitoring

Science.gov (United States)

pH monitoring - esophageal; Esophageal acidity test ... Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus. It also checks how well the acid is cleared downward into the ...

A pH dependent Raman and surface enhanced Raman spectroscopic studies of citrazinic acid aided by theoretical calculations

Science.gov (United States)

Sarkar, Sougata; Chowdhury, Joydeep; Dutta, Soumen; Pal, Tarasankar

2016-12-01

A pH dependent normal Raman scattering (NRS) and surface enhanced Raman scattering (SERS) spectral patterns of citrazinic acid (CZA), a biologically important molecule, have been investigated. The acid, with different pKa values ( 4 and 11) for the two different functional groups (-COOH and -OH groups), shows interesting range of color changes (yellow at pH 14 and brown at pH 2) with the variation in solution pH. Thus, depending upon the pH of the medium, CZA molecule can exist in various protonated and/or deprotonated forms. Here we have prescribed the existence different possible forms of CZA at different pH (Forms ;C;, ;H; and ;Dprot; at pH 14 and Forms ;A;, ;D;, and ;P; at pH 2 respectively). The NRS spectra of these solutions and their respective SERS spectra over gold nanoparticles were recorded. The spectra clearly differ in their spectral profiles. For example the SERS spectra recorded with the CZA solution at pH 2 shows blue shift for different bands compared to its NRS window e.g. 406 to 450 cm- 1, 616 to 632 cm- 1, 1332 to 1343 cm- 1 etc. Again, the most enhanced peak at 1548 cm- 1 in NRS while in the SERS window this appears at 1580 cm- 1. Similar observation was also made for CZA at pH 14. For example, the 423 cm- 1 band in the NRS profile experience a blue shift and appears at 447 cm- 1 in the SERS spectrum as well as other bands at 850, 1067 and 1214 cm- 1 in the SERS window are markedly enhanced. It is also worth noting that the SERS spectra at the different pH also differ from each other. These spectral differences indicate the existence of various adsorptive forms of the CZA molecule depending upon the pH of the solution. Therefore based on the experimental findings we propose different possible molecular forms of CZA at different pH (acidic and alkaline) conditions. For example forms 'A', 'D' and 'P' existing in acidic pH (pH 2) and three other deprotonated forms 'C', 'H' and 'Dprot' in alkaline pH (pH 14). The DFT calculations for these

Accessible reactive surface area and abiotic redox reactivity of iron oxyhydroxides in acidic brines

Science.gov (United States)

Strehlau, Jennifer H.; Toner, Brandy M.; Arnold, William A.; Penn, R. Lee

2017-01-01

The reactivity of iron oxyhydroxide nanoparticles in low pH and high ionic strength solutions was quantified to assess abiotic contributions to oxidation-reduction chemistry in acidic brine environments, such as mine groundwater seepage, lakes in Western Australia, and acid mine drainage settings, which are of global interest for their environmental impacts and unique geomicrobiology. Factors expected to influence accessible and reactive surface area, including Fe(II) adsorption and aggregate size, were measured as a function of pH and CaCl2 concentration and related to the kinetics of redox reactions in aqueous suspensions of synthetic goethite (α-FeOOH), akaganeite (β-FeOOH), and ferrihydrite (Fe10O14(OH)2) nanoparticles. Aqueous conditions and iron oxyhydroxides were chosen based on characterization of natural iron-rich mine microbial mats located in Soudan Underground Mine State Park, Minnesota, USA. Quinone species were used as redox sensors because they are well-defined probes and are present in natural organic matter. Fe(II) adsorption to the iron oxyhydroxide mineral surfaces from aqueous solution was measurable only at pH values above 4 and either decreased or was not affected by CaCl2 concentration. Concentrations at or above 0.020 M CaCl2 in acetate buffer (pH 4.5) induced particle aggregation. Assessment of Fe(II) adsorption and particle aggregation in acidic brine suggested that accessible reactive surface area may be limited in acidic brines. This was supported by observations of decreasing benzoquinone reduction rate by adsorbed Fe(II) at high CaCl2 concentration. In contrast, the hydroquinone oxidation rate increased at high CaCl2 concentrations, which may be due to suppressed adsorption of Fe(II) generated by the reaction. Results suggest that iron geochemical cycling in acidic brine environments will be substantially different than for iron oxyhydroxides in low-saline waters with circumneutral pH. These findings have implications for acidic

Studies on mountain streams in the English lake district I. PH, calcium and the distribution of invertebrates in the River Duddon

Energy Technology Data Exchange (ETDEWEB)

Sutcliffe, D.W.; Carrick, T.R.

1973-01-01

The River Duddon and its tributaries rarely exceed pH 7.0. There are three types of acid regime; pH>5.7 and pH<5.7 independent of season or rainfall, and fluctuating acidity with pH<5.7 in winter and wet periods, pH>5.7 in summer or dry periods. PH in the River Duddon fluctuates for most of its length. Ph>5.7 is characteristic of tributaries in the lower drainage basin, but pH<5.7 occurs in the headwaters of two of these tributaries. With five exceptions, pH<5.7 or fluctuating pH are characteristic of tributaries in the upper drainage basin. A very close relationship exists between the pH regime of stream water and the benthis cauna. Apart from oligochaetes and flatworms, streams with pH<5.7 or fluctuating pH are characterized by thirteen common or abundant taxa; six plecoptera, four trichoptera and three diptera. These taxa are also common in streams with pH>5.7 but in addition these streams contain ephemeroptera, the trichopterans wormaldia and hydropsyche, the mollusc Ancylus and the amphipod gammarus. It is concluded that the calcium concentration is less important than the pH-bicarbonate concentrations in limiting the qualitative distribution of benthic invertebrates. The limiting effect of pH<5.7 on an extensive range of taxa in the duddon also occurs in other areas. The affected taxa are generally herbivores. It is suggested that in the case of insects the limiting effects of low pH may indirectly operate through changes in food supply.

Use of D(acid)-, D(bile)-, z(acid)-, and z(bile)-values in evaluating Bifidobacteria with regard to stomach pH and bile salt sensitivity.

Science.gov (United States)

Jia, Li; Shigwedha, Nditange; Mwandemele, Osmund D

2010-01-01

The survival of bifidobacteria in simulated conditions of the gastrointestinal (GI) tract was studied based on the D- and z-value concept. Some Bifidobacterium spp. are probiotics that improve microbial balance in the human GI tract. Because they are sensitive to low pH and bile salt concentrations, their viability in the GI tract is limited. The D- and z-value approach was therefore adopted as a result of observing constant log-cell reduction (90%) when Bifidobacterium spp. were exposed to these 2 different stressing factors. Survivals of one strain each or 4 species of Bifidobacterium was studied at pH between 3.0 and 4.5 and in ox-bile between 0.15% and 0.60% for times up to 41 h. From the D(acid)- and D(bile)-values, the order of resistance to acid and bile was B. bifidum > B. infantis > B. longum > B. adolescentis. While the former 3 strains retained high cell viability at pH 3.5 (>5.5 log CFU/mL after 5 h) and at elevated bile salt concentration of 0.6% (>4.5 log CFU/mL after 3 h), B. adolescentis was less resistant (pH units and 0.40% to 0.49%, respectively. The results suggest that the D(acid)-, D(bile)-, z(acid)-, and z(bile)-value approach could be more appropriate than the screening and selection method in evaluating survival of probiotic bacteria, and in measuring their tolerance or resistance to gastric acidity and the associated bile salt concentration in the small intestine. The evaluation of the tolerance of bifidobacteria to bile salts and low pH has been made possible by use of D- and z-value concept. The calculated z(acid)- and z(bile)-values were all fairly similar for the strains used and suggest the effect of increasing the bile salt concentration or decreasing the pH on the D(acid)- and D(bile)-values. This approach would be useful for predicting the suitability of bifidobacteria and other lactic acid bacteria (LAB) as probiotics for use in real-life situations.

A proposed relationship between pH and ascorbic acid content of ...

African Journals Online (AJOL)

A relationship between the ascorbic acid content of fresh squeezed juice of orange, lemon, grape and lime and the pH was presented. The relationship established were statistically compared with those obtained by the 2,6 dichlorophenol indophenol titration method. It was shown that they do not differ significantly (p≥0.05) ...

Mapping of short term acidification with help of biological pH indicators

Energy Technology Data Exchange (ETDEWEB)

Engblom, E.; Lindell, P.E.

1984-01-01

We have examined the acifification situation in the Swedish mountain ranges with the help of empiricaly and experimentally determined tolerance limits for aquatic organisms. The result show that there is damage due to acidification in the Swedish mountain area. In the Fulufjaell nature reserv in the southern region in the benthic fauna has been dominated for the past 10 years by acid-tolerant species such as Leptophlebia vespertina, L. marginata, Ameleteus inopinatus, Baetis rhodani and Ephemerella aurivillii (Ephemeroptera), and Nemoura cinerea (Plecoptera). The absence of sensitive species indicates that that the pH in streams has often been below 5.0. In the Lake Torroen area in the central mountain region, the acid-sensitiv species Baetis lapponicus (Ephemeroptera) and Philopotamus montanus (Trichoptera), which had been common in 1971, were absent in 1983. The species composition in 1971 indicates that the pH had not previously dropped below 5.5. Judging by the changes in the species composition of the benthic fauna after 1971, however, the pH has been well below 5.0 in many streams. In the Vindelfjaell nature reserve in the northern region those species present in 1961-66 were still represented in 1983 and were dominated by Baetis lapponicus. The high frequency of sensitive species indicates that the pH in streams has normally been above 6.0.

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acid-base equilibria and pH buffers.

Science.gov (United States)

Persat, Alexandre; Chambers, Robert D; Santiago, Juan G

2009-09-07

We review fundamental and applied acid-base equilibrium chemistry useful to microfluidic electrokinetics. We present elements of acid-base equilibrium reactions and derive rules for pH calculation for simple buffers. We also present a general formulation to calculate pH of more complex, arbitrary mixtures of electrolytes, and discuss the effects of ionic strength and temperature on pH calculation. More practically, we offer advice on buffer preparation and on buffer reporting. We also discuss "real world" buffers and likely contamination sources. In particular, we discuss the effects of atmospheric carbon dioxide on buffer systems, namely, the increase in ionic strength and acidification of typical electrokinetic device buffers. In Part II of this two-paper series, we discuss the coupling of acid-base equilibria with electrolyte dynamics and electrochemistry in typical microfluidic electrokinetic systems.

Water Quality Conditions in Upper Klamath and Agency Lakes, Oregon, 2006

Science.gov (United States)

Lindenberg, Mary K.; Hoilman, Gene; Wood, Tamara M.

2008-01-01

The U.S. Geological Survey Upper Klamath Lake water quality monitoring program gathered information from multiparameter continuous water quality monitors, physical water samples, dissolved oxygen production and consumption experiments, and meteorological stations during the June-October 2006 field season. The 2006 study area included Agency Lake and all of Upper Klamath Lake. Seasonal patterns in water quality were similar to those observed in 2005, the first year of the monitoring program, and were closely related to bloom dynamics of the cyanobacterium (blue-green alga) Aphanizomenon flos-aquae (AFA) in the two lakes. High dissolved oxygen and pH conditions in both lakes before the bloom declined in July, which coincided with seasonal high temperatures and resulted in seasonal lows in dissolved oxygen and decreased pH. Dissolved oxygen and pH in Upper Klamath and Agency Lakes increased again after the bloom recovered. Seasonal low dissolved oxygen and decreased pH coincided with seasonal highs in ammonia and orthophosphate concentrations. Seasonal maximum daily average temperatures were higher and minimum dissolved oxygen concentrations were lower in 2006 than in 2005. Conditions potentially harmful to fish were influenced by seasonal patterns in bloom dynamics and bathymetry. Potentially harmful low dissolved oxygen and high un-ionized ammonia concentrations occurred mostly at the deepest sites in the Upper Klamath Lake during late July, coincident with a bloom decline. Potentially harmful pH conditions occurred mostly at sites outside the deepest parts of the lake in July and September, coincident with a heavy bloom. Instances of possible gas bubble formation, inferred from dissolved oxygen data, were estimated to occur frequently in shallow areas of Upper Klamath and Agency Lakes simultaneously with potentially harmful pH conditions. Comparison of the data from monitors in nearshore areas and monitors near the surface of the water column in the open waters of

Evolution of alkaline lakes - Lake Van case study

Science.gov (United States)

Tillman Meyer, Felix; Viehberg, Finn; Bahroun, Sonya; Wolf, Annabel; Immenhauser, Adrian; Kwiecien, Ola

2017-04-01

Lake Van in Eastern Anatolia (Turkey) is the largest terminal soda lake on Earth. The lake sedimentary profile covers ca. 600 ka (Stockhecke et al. 2014) Based on lithological changes, the presence of freshwater microfossils and close-to-freshwater pH value in the pore water, members of ICDP PALEOVAN concluded that Lake Van might have started as an open lake. Here we show paleontological and geochemical evidence in favour of this idea and constrain the time, when Lake Van likely transformed into a closed lake. Additionally we provide the first conceptual model of how this closure may have happened. Our archives of choice are inorganic and biogenic carbonates, separated by wet sieving. We identified microfossil assemblages (fraction > 125 µm) and performed high-resolution oxygen isotope (delta18O) and elemental (Mg/Ca, Sr/Ca) analyses of the fraction plants growing in the photic zone as food supply. These two aspects point to an increasing salinity in a shallowing lake. The delta18O values of inorganic carbonates are relatively low during the initial phase of Lake Van and increase abruptly (ca. 7‰) after 530 ka BP. At approximately the same time combination of Sr/Ca and Mg/Ca data suggest first occurrence of aragonite. Again, these findings suggest geochemical changes of the lake water concurrent with transition documented by microfossils. Comparison between Lake Van and Lake Ohrid (Lacey et al. 2016) delta18O data, precludes regional climate change (e.g.: increased evaporation) as the main driver of observed changes. With no evidence for increased volcanic or tectonic activity (e.g.: tephra layers, deformation structures, slumping) in the Lake Van sedimentary profile around 530 ka, it seems unlikely that a pyroclastic flow blocked the outflow of the lake. Alternatively, a portion of inflow has been diverged which might have caused a change in the hydrological balance and lake level falling below its outlet. However, as no geomorphological data confirming this

Dendritic Zinc Growth in Acid Electrolyte: Effect of the pH

Science.gov (United States)

Bengoa, Leandro N.; Pary, Paola; Seré, Pablo R.; Conconi, M. Susana; Egli, Walter A.

2018-03-01

In this paper, dendritic growth at the edges of electrogalvanized steel strip has been studied using a specially designed rotating washer electrode which simulates the fluid dynamic conditions and the current density distribution at the steel strip edge found in a production line. The effect of electrolyte pH and current density on dendritic growth in an acidic zinc plating bath (ZnSO4 and H2SO4) was addressed. The temperature was kept constant at 60 °C. Solution pH was adjusted to 1, 2 or 3 using different amounts of H2SO4. In addition, the influence of temperature on the pH of the solution was determined. The current density was set at 40 or 60 A/dm2, similar to that used in the industry. Deposits were characterized using SEM and XRD. The results showed that pH strongly affects dendrites shape, length and texture. Furthermore, the morphology of dendrites at the washer edge and of deposits on the flat portion of the washer changed considerably as solution pH was increased from 1 to 3. It was found that the morphology of dendrites at the washer edge stems from the morphology of the deposit on its flat portion, which in turn determines their shape.

Copper availability and bioavailability are controlled by rhizosphere pH in rape grown in an acidic Cu-contaminated soil

International Nuclear Information System (INIS)

Chaignon, Valerie; Quesnoit, Marie; Hinsinger, Philippe

2009-01-01

We evaluated how root-induced changes in rhizosphere pH varied and interacted with Cu availability and bioavailability in an acidic soil. Rape was grown on a Cu-contaminated acidic soil, which had been limed at 10 rates. Soil Cu bioavailability was not influenced by liming. However, liming significantly decreased CaCl 2 -extracted Cu for pH between 3.7 and 5.1. Little effect was found for pH above 5.1. For soil pH 2 -Cu contents were smaller in rhizosphere than uncropped soil. Rhizosphere alkalisation occurred at pH 2 -Cu in the rhizosphere at low pH and the absence of pH dependency of Cu bioavailability to rape. In addition, apoplastic Cu in roots increased with increasing soil pH, most probably as a result of increased dissociation and affinity of cell wall compounds for Cu. - Root-induced increase in pH reduces Cu availability in the rhizosphere and Cu bioavailability to rape.

Distribution of acidic and neutral drugs in surface waters near sewage treatment plants in the lower Great Lakes, Canada.

Science.gov (United States)

Metcalfe, Chris D; Miao, Xiu-Sheng; Koenig, Brenda G; Struger, John

2003-12-01

Prescription and nonprescription drugs have been detected in rivers and streams in Europe and the United States. Sewage treatment plants (STPs) are an important source of these contaminants, but few data exist on the spatial distribution of drugs in surface waters near STPs. Samples of surface water were collected in the summer and fall of 2000 at open-water sites in the lower Great Lakes (Lake Ontario and Lake Erie), at sites near the two STPs for the city of Windsor (ON, Canada), and at sites in Hamilton Harbour (ON, Canada), an embayment of western Lake Ontario that receives discharges from several STPs. In a follow-up study in the summer of 2002, samples of surface water and final effluent from adjacent STPs were collected from sites in Hamilton Harbour and Windsor. In addition, surface water and STP effluent samples were collected in Peterborough (ON, Canada). All samples of surface water and STP effluents were analyzed for selected acidic and neutral drugs. In the survey of Hamilton Harbour and Windsor conducted in 2000, acidic drugs and the antiepileptic drug carbamazepine were detected at ng/L concentrations at sites that were up to 500 m away from the STP, but the hydrological conditions of the receiving waters strongly influenced the spatial distribution of these compounds. Drugs were not detected at open-water locations in western Lake Erie or in the Niagara River near the municipality of Niagara-on-the-Lake (ON, Canada). However, clofibric acid, ketoprofen, fenoprofen, and carbamazepine were detected in samples collected in the summer of 2000 at sites in Lake Ontario and at a site in the Niagara River (Fort Erie, ON, Canada) that were relatively remote from STP discharges. Follow-up studies in the summer of 2002 indicated that concentrations of acidic and neutral drugs in surface waters near the point of sewage discharge into the Little River (ON, Canada) STP were approximately equal to the concentrations in the final effluent from the STP. Caffeine and

Aerosol pH buffering in the southeastern US: Fine particles remain highly acidic despite large reductions in sulfate

Science.gov (United States)

Weber, R. J.; Guo, H.; Russell, A. G.; Nenes, A.

2015-12-01

pH is a critical aerosol property that impacts many atmospheric processes, including biogenic secondary organic aerosol formation, gas-particle phase partitioning, and mineral dust or redox metal mobilization. Particle pH has also been linked to adverse health effects. Using a comprehensive data set from the Southern Oxidant and Aerosol Study (SOAS) as the basis for thermodynamic modeling, we have shown that particles are currently highly acidic in the southeastern US, with pH between 0 and 2. Sulfate and ammonium are the main acid-base components that determine particle pH in this region, however they have different sources and their concentrations are changing. Over 15 years of network data show that sulfur dioxide emission reductions have resulted in a roughly 70 percent decrease in sulfate, whereas ammonia emissions, mainly link to agricultural activities, have been largely steady, as have gas phase ammonia concentrations. This has led to the view that particles are becoming more neutralized. However, sensitivity analysis, based on thermodynamic modeling, to changing sulfate concentrations indicates that particles have remained highly acidic over the past decade, despite the large reductions in sulfate. Furthermore, anticipated continued reductions of sulfate and relatively constant ammonia emissions into the future will not significantly change particle pH until sulfate drops to clean continental background levels. The result reshapes our expectation of future particle pH and implies that atmospheric processes and adverse health effects linked to particle acidity will remain unchanged for some time into the future.

Evaluation of different approaches to quantify strong organic acidity and acid-base buffering of organic-rich surface waters in Sweden.

Science.gov (United States)

Köhler, Stephan; Hruska, Jakub; Jönsson, Jörgen; Lövgren, Lars; Lofts, Stephen

2002-11-01

The role of organic acids in buffering pH in surface waters has been studied using a small brownwater stream (26mg L(-1) TOC) draining a forested catchment in Northern Sweden. Under the conditions of elevated pressure of CO2 stream field pH was changed between 3.5 and 6.1 during the acidification and alkalinization experiment. Acid-base characteristics of the natural organic matter were also determined using a high precision potentiometric method for a concentrated sample from the same stream. We compared the predictions from the Windermere Humic Aqueous Model (WHAM Model V), a model derived from the potentiometric titration (diprotic/monoprotic acid model) and a previously derived triprotic acid model which only uses alkalinity and TOC as input variables. The predicted buffering characteristics of all three models are very similar in the pH range 4.5-7 which suggests that during routine analysis alkalinity and TOC are sufficient to give a good estimate of organic acid anion charge contribution in a large range of surface waters. A slightly adjusted version of WHAM V successfully describes the organic charge contribution in a large number of sampled surface water lakes, which were previously used to calibrate the triprotic model.

Contributions of Cell Metabolism and H+ Diffusion to the Acidic pH of Tumors

Directory of Open Access Journals (Sweden)

Paul A. Schornack

2003-03-01

Full Text Available The tumor microenvironment is hypoxic and acidic. These conditions have a significant impact on tumor progression and response to therapies. There is strong evidence that tumor hypoxia results from inefficient perfusion due to a chaotic vasculature. Consequently, some tumor regions are well oxygenated and others are hypoxic. It is commonly believed that hypoxic regions are acidic due to a stimulation of glycolysis through hypoxia, yet this is not yet demonstrated. The current study investigates the causes of tumor acidity by determining acid production rates and the mechanism of diffusion for H+ equivalents through model systems. Two breast cancer cell lines were investigated with divergent metabolic profiles: nonmetastatic MCF-7/s and highly metastatic MDA-mb-435 cells. Glycolysis and acid production are inhibited by oxygen in MCF-7/s cells, but not in MDA-mb-435 cells. Tumors of MDAmb-435 cells are significantly more acidic than are tumors of MCF-7/s cells, suggesting that tumor acidity is primarily caused by endogenous metabolism, not the lack of oxygen. Metabolically produced protons are shown to diffuse in association with mobile buffers, in concordance with previous studies. The metabolic and diffusion data were analyzed using a reaction-diffusion model to demonstrate that the consequent pH profiles conform well to measured pH values for tumors of these two cell lines.

Determination of free acid in high level liquid wastes by means of fixed pH value

International Nuclear Information System (INIS)

Li Jifu; Duan Shirong; Wu Xi; Yu Xueren

1991-01-01

For the determination of free acid in high level liquid wastes, 8% potassium oxalate solution with pH 6.50 as a complex agent of hydrolizable ion is added to 1 AW and the solution is titrated with standard sodium hydroxide to reach the original pH value. The quantity of free acid is calculated by standard sodium hydroxide consumed. This method is simple, rapid and accurate. The relative error of analysis is less than ±4%. The average percentage of recovery is 99.6-101.0%

Copper availability and bioavailability are controlled by rhizosphere pH in rape grown in an acidic Cu-contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Chaignon, Valerie; Quesnoit, Marie [INRA, UMR 1222 Eco and Sols Ecologie fonctionnelle and Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Hinsinger, Philippe, E-mail: philippe.hinsinger@supagro.inra.f [INRA, UMR 1222 Eco and Sols Ecologie fonctionnelle and Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France)

2009-12-15

We evaluated how root-induced changes in rhizosphere pH varied and interacted with Cu availability and bioavailability in an acidic soil. Rape was grown on a Cu-contaminated acidic soil, which had been limed at 10 rates. Soil Cu bioavailability was not influenced by liming. However, liming significantly decreased CaCl{sub 2}-extracted Cu for pH between 3.7 and 5.1. Little effect was found for pH above 5.1. For soil pH < 4.4, CaCl{sub 2}-Cu contents were smaller in rhizosphere than uncropped soil. Rhizosphere alkalisation occurred at pH < 4.8, while acidification occurred at greater pH. This explained the changes of CaCl{sub 2}-Cu in the rhizosphere at low pH and the absence of pH dependency of Cu bioavailability to rape. In addition, apoplastic Cu in roots increased with increasing soil pH, most probably as a result of increased dissociation and affinity of cell wall compounds for Cu. - Root-induced increase in pH reduces Cu availability in the rhizosphere and Cu bioavailability to rape.

Siderite formation in mining lakes. Sanitation strategy for the Spreetal Nordost lake; Sideritbildung in Tagebaurestseen. Moegliche Sanierungsstrategie des Restlochs Spreetal Nordost

Energy Technology Data Exchange (ETDEWEB)

Unger, Y.; Wolkersdorfer, C. [Technische Univ. Bergakademie Freiberg (Germany)

2006-07-01

The treatment of acid mine lakes is a worldwide problem. In this study, it will be investigated since the sludge from acid mine drainage (AMD) treatment plants combined with carbon dioxide injections may improve the water quality in such pit lakes. Simultaneously, the emissions of carbon dioxide into the atmosphere may be reduced. The CO{sub 2} will be sequestered in the lake sediments as siderite (FeCO{sub 3}). The acid mine lake Spreetal-Nordost (Lusatia/Germany) was chosen as a test site. Since 1998 iron hydroxide sludge from an AMD treatment plant was deposited into the lake. In preliminary tests the feasibility of this treatment scheme will be investigated. (orig.)

Biomass and species structure of the phytoplankton of an high mountain lake (Lake Paione Superiore, Central Alps, Italy

Directory of Open Access Journals (Sweden)

Roberta BETTINETTI

1999-08-01

Full Text Available In the framework of the EU MOLAR Project on “Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change” a three whole-year study (1996-1998 on the composition and dynamics of phytoplankton community of the high mountain lake, acid sensitive Lago Paione Superiore (LPS was carried out. The data were analyzed and compared with those gathered during the years 1991-1993. The phytoplankton was made up by nanoplanktonic unicellular algae, the only exception being the colonial Dinobryon sertularia. Just four species, belonging to Chrysophyceae (Chromulina sp., Dinobryon sertularia and Mallomonas alveolata and to Dinophyceae (Gymnodinium sp. were important as biomass and density, and they were always present throughout the year. The prevalence of potentially mixotrophic species suggests an adaptive strategy to the low environmental concentrations of inorganic carbon and phosphorus. The seasonal variations of the total biomass were similar to those observed in the previous years. The total number of species has increased; this could be related with the recent increase of the pH and of the alkalinity.

Direct Measurement of pH in Individual Particles via Raman Microspectroscopy and Variation in Acidity with Relative Humidity.

Science.gov (United States)

Rindelaub, Joel D; Craig, Rebecca L; Nandy, Lucy; Bondy, Amy L; Dutcher, Cari S; Shepson, Paul B; Ault, Andrew P

2016-02-18

Atmospheric aerosol acidity is an important characteristic of aqueous particles, which has been linked to the formation of secondary organic aerosol by catalyzing reactions of oxidized organic compounds that have partitioned to the particle phase. However, aerosol acidity is difficult to measure and traditionally estimated using indirect methods or assumptions based on composition. Ongoing disagreements between experiments and thermodynamic models of particle acidity necessitate improved fundamental understanding of pH and ion behavior in high ionic strength atmospheric particles. Herein, Raman microspectroscopy was used to determine the pH of individual particles (H2SO4+MgSO4) based on sulfate and bisulfate concentrations determined from νs(SO4(2-)) and νs(HSO4(-)), the acid dissociation constant, and activity coefficients from extended Debye-Hückel calculations. Shifts in pH and peak positions of νs(SO4(2-)) and νs(HSO4(-)) were observed as a function of relative humidity. These results indicate the potential for direct spectroscopic determination of pH in individual particles and the need to improve fundamental understanding of ion behavior in atmospheric particles.

A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH.

Science.gov (United States)

Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

2015-06-05

Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (K(a)=3582.88 M(-1)) and selectivity for fructose over glucose at pH=7.4. The sensor 1 showed a linear response toward d-fructose in the concentrations ranging from 2.5×10(-5) to 4×10(-4) mol L(-1) with the detection limit of 1.3×10(-5) mol L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Reconstructing pre-acidification pH for an acidified Scottish loch: A comparison of palaeolimnological and modelling approaches

International Nuclear Information System (INIS)

Battarbee, R.W.; Monteith, D.T.; Juggins, S.; Evans, C.D.; Jenkins, A.; Simpson, G.L.

2005-01-01

We reconstruct the pre-acidification pH of the Round Loch of Glenhead for 1800 AD using three diatom-pH transfer functions and a diatom-cladocera modern analogue technique (MAT), and compare these palaeo-data with hindcast data for the loch using the dynamic catchment acidification model MAGIC. We assess the accuracy of the transfer functions by comparing pH inferences from contemporary sediment and sediment trap diatom samples from the lake with measured pH from the UK Acid Waters Monitoring Network. The results from the transfer functions estimate the pH in 1800 to have been between 5.5. and 5.7, the MAT approach estimates pH at 5.8 and the MAGIC hindcast (for 1850) is pH 6.1. Whilst we have no independent method of assessing which of these values is most accurate, the disagreement between the two approaches indicates that further work is needed to resolve the discrepancies. - Methods of reconstructing pre-acidification pH for an acidified Scottish loch compared

Amphibian recovery after a decrease in acidic precipitation.

Science.gov (United States)

Dolmen, Dag; Finstad, Anders Gravbrøt; Skei, Jon Kristian

2018-04-01

We here report the first sign of amphibian recovery after a strong decline due to acidic precipitation over many decades and peaking around 1980-90. In 2010, the pH level of ponds and small lakes in two heavily acidified areas in southwestern Scandinavia (Aust-Agder and Østfold in Norway) had risen significantly at an (arithmetic) average of 0.14 since 1988-89. Parallel with the general rise in pH, amphibians (Rana temporaria, R. arvalis, Bufo bufo, Lissotriton vulgaris, and Triturus cristatus) had become significantly more common: the frequency of amphibian localities rose from 33% to 49% (n = 115), and the average number of amphibian species per locality had risen from 0.51 to 0.88. In two other (reference) areas, one with better buffering capacity (Telemark, n = 21) and the other with much less input of acidic precipitation (Nord-Trøndelag, n = 106), there were no significant changes in pH or amphibians.

Chlorine-assisted leaching of Key Lake uranium ore

International Nuclear Information System (INIS)

Haque, K.E.

1981-04-01

Bench-scale chlorine-assisted leach tests were conducted on the Key Lake uranium ore. Leach tests conducted at 80 0 C on a slurry containing 50% solids during 10 hours of agitation gave the maximum extraction of uranium - 96% and radium-226 - 91%. Chlorine was added at 23.0 Kg Cl 2 /tonne of ore to maintain the leach slurry pH in the range of 1.5-1.0. To obtain residue almost free of radionuclides, hydrochloric acid leaches were conducted on the first stage leach residues. The second stage leach residue still was found to contain uranium - 0.0076% and radium-226 - 200 pCi/g of solids

Use of cation selective membrane and acid addition for PH control in two-dimensional electrokinetic remediation of copper

Energy Technology Data Exchange (ETDEWEB)

Chan, M.S.M.; Lynch, R.J. [Cambridge Univ., Engineering Dept. (United Kingdom); Ilett, D.J. [AEA Technology, Harwell, Oxfordshire (United Kingdom)

2001-07-01

The feasibility of using a combination of a cation selective membrane and acid addition for pH control in electrokinetic remediation to toxic and heavy metals from low-permeability soil has been investigated. The high pH generated during the remediation process, as a result of surplus OH{sup -} ions, may cause metal ions to precipitate as hydroxides at or near the cathodes. This region of high pH is known to be associated with high electrical resistance, which limits the remediation efficiency by inhibiting current flow through the soil. One way to control pH is by adding acid to neutralize the OH{sup -} ions. However, preliminary work showed that addition of acid to the cathodic region was not effective in preventing the spread of the alkaline zone from cathodes toward anodes. Precipitates were formed before metal ions reached the cathodic region. Therefore, another method of pH control was investigated, using a cation selective membrane to enhance the electrokinetic process. The membrane was placed in front of the cathodes to contain the OH{sup -} ions generated, and confine the precipitates of metal hydroxide to a small cathodic region. The clean-up of a contaminated site was modelled in a rectangular tank, using silt as the low permeability soul and copper to simulate the contamination. The objective was to redistribute the contaminant so as to concentrate it into a small area. Three experiments were performed with the following methods of pH control: (1) acid addition, (2) use of a cation selective membrane and (3) a combination of acid addition and a cation selective membrane. Using the combined approach, it was found that 75% of the target clean-up section (bounded by the cation selective membrane and the anodes) had more than 40% of the initial copper removed. The general efficiency of remediation increased in the following order. (orig.)

Pit lake lime dosing: Assessment of the performance of the treatment based on a high-spatial resolution AUV survey

Science.gov (United States)

Delgado, Jordi; García-Morrondo, David; Cereijo-Arango, José Luis; Muñoz-Ibáñez, Andrea; Grande-García, Elisa; Rodríguez-Cedrún, Borja; Juncosa-Rivera, Ricardo

2016-04-01

The acidity of mine waters is typically corrected with passive (where possible) and/or active (i.e. chemical additions) systems. In the case of active treatments, lime dosing is a widespread technique due to the relatively ease of implementation and reduced operational costs. While neutralization of acidic waters is routinely performed in circulating water treatment facilities this is not so simple in open waters (e.g. pit lakes) because an efficient treatment requires the adequate distribution of the alkaline reagents throughout the volume of interest. To cope with this problem, a number of technical approaches have been proposed including active stirring (bubbling, etc.), surface spread diffusion, etc. In the early times of flooding of the Meirama mine, managers considered the necessity of lime dosing to correct the initially acidic mine waters. However, lake evolution proved that liming was not necessary and it was desirable to allow a reasonably unmanned evolution of the reclaimed system. In order to ensure that the lime dosing system is in good operative conditions in case of necessity, according to a prescribed time schedule to time mine managers put it in operation. That give us the opportunity to perform a large-scale "tracer" experiment useful to test the efficiency of wet lime dosing in a large water body. Dry lime, which is kept in a storage silo, is directly dosed over the channel of a small stream discharging in the lake. Therefore, stream water becomes saturated with lime and a pH of approximately 12.3. Stream water flows in cascade to the lake so that a certain potential and kinetic energy transfer is delivered to the lake. That promotes currents that enhance the re-distribution of the alkalinity load. In order to check for the distribution of alkaline water in the top body of the lake, an autonomous underwater vehicle (Yellow Spring Instruments Inc. EcoMapper AUV) was used. This device allows for the high- frequency simultaneous measurement of a

Novel pH responsive polymethacrylic acid-chitosan-polyethylene glycol nanoparticles for oral peptide delivery.

Science.gov (United States)

Sajeesh, S; Sharma, Chandra P

2006-02-01

In present study, novel pH sensitive polymethacrylic acid-chitosan-polyethylene glycol (PCP) nanoparticles were prepared under mild aqueous conditions via polyelectrolyte complexation. Free radical polymerization of methacrylic acid (MAA) was carried out in presence of chitosan (CS) and polyethylene glycol (PEG) using a water-soluble initiator and particles were obtained spontaneously during polymerization without using organic solvents or surfactants/steric stabilizers. Dried particles were analyzed by scanning electron microscopy (SEM) and particles dispersed in phosphate buffer (pH 7.0) were visualized under transmission electron microscope (TEM). SEM studies indicated that PCP particles have an aggregated and irregular morphology, however, TEM revealed that these aggregated particles were composed of smaller fragments with size less than 1 micron. Insulin and bovine serum albumin (BSA) as model proteins were incorporated into the nanoparticles by diffusion filling method and their in vitro release characteristics were evaluated at pH 1.2 and 7.4. PCP nanoparticles exhibited good protein encapsulation efficiency and pH responsive release profile was observed under in vitro conditions. Trypsin inhibitory effect of these PCP nanoparticles was studied using casein substrate and these particles displayed lesser inhibitory effect than reference polymer carbopol. Preliminary investigation suggests that these particles can serve as good candidate for oral peptide delivery. Copyright 2005 Wiley Periodicals, Inc.

Stability of poly(N-isopropylacrylamide-co-acrylic acid polymer microgels under various conditions of temperature, pH and salt concentration

Directory of Open Access Journals (Sweden)

Zahoor H. Farooqi

2017-03-01

Full Text Available This research article describes the colloidal stability of poly(N-isopropylacrylamide-co-acrylic acid [P(NIPAM-co-AAc] polymer microgels with different acrylic acid contents in aqueous medium under various conditions of temperature, pH and sodium chloride concentrations. Three samples of multi-responsive P(NIPAM-co-AAc polymer microgels were synthesized using different amounts of acrylic acid by free radical emulsion polymerization. Dynamic laser light scattering was used to investigate the responsive behavior and stability of the prepared microgels under various conditions of pH, temperature and ionic strength. The microgels were found to be stable at all pH values above the pKa value of acrylic acid moiety in the temperature range from 15 to 60 °C in the presence and absence of sodium chloride. Increase in temperature, salt concentration and decrease in pH causes aggregation and decreases the stability of microgels due to the decrease in hydrophilicity.

Multimedia fate modeling of perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) in the shallow lake Chaohu, China

NARCIS (Netherlands)

Kong, X.; Liu, W.; He, W.; Xu, F.; Koelmans, Albert A; Mooij, W.M.

2018-01-01

Freshwater shallow lake ecosystems provide valuable ecological services to human beings. However, these systems are subject to severe contamination from anthropogenic sources. Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS),

A mathematical model of pH, based on the total stoichiometric concentration of acids, bases and ampholytes dissolved in water.

Science.gov (United States)

Mioni, Roberto; Mioni, Giuseppe

2015-10-01

In chemistry and in acid-base physiology, the Henderson-Hasselbalch equation plays a pivotal role in studying the behaviour of the buffer solutions. However, it seems that the general function to calculate the valence of acids, bases and ampholytes, N = f(pH), at any pH, has only been provided by Kildeberg. This equation can be applied to strong acids and bases, pluriprotic weak acids, bases and ampholytes, with an arbitrary number of acid strength constants, pKA, including water. By differentiating this function with respect to pH, we obtain the general equation for the buffer value. In addition, by integrating the titration curve, TA, proposed by Kildeberg, and calculating its Legendre transform, we obtain the Gibbs free energy of pH (or pOH)-dependent titratable acid. Starting from the law of electroneutrality and applying suitable simplifications, it is possible to calculate the pH of the buffer solutions by numerical methods, available in software packages such as Excel. The concept of buffer capacity has also been clarified by Urbansky, but, at variance with our approach, not in an organic manner. In fact, for each set of monobasic, dibasic, tribasic acids, etc., various equations are presented which independently fit each individual acid-base category. Consequently, with the increase in acid groups (pKA), the equations become more and more difficult, both in practice and in theory. Some examples are proposed to highlight the boundary that exists between acid-base physiology and the thermodynamic concepts of energy, chemical potential, amount of substance and acid resistance.

Acidez potencial pelo método do pH SMP no Estado do Amazonas Potential acidity by pH SMP method in Amazonas State, Brazil

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Adônis Moreira

2004-01-01

Full Text Available O objetivo deste trabalho foi definir um modelo matemático que estime o H+Al a partir do pH SMP medido em água e em solução de CaCl2 0,01 mol L-1 nas condições edafoclimáticas locais. Foram utilizadas 246 amostras de solo provenientes de diversas localidades. Mesmo apresentando menor coeficiente da correlação (r = 0,89*, a equação H+Al = 30,646 - 3,848pH SMP obtida em H2O foi mais eficiente que a obtida em solução CaCl2 (H+Al = 30,155 - 3,834pH SMP, r = 0,91*, a qual subestima os valores da acidez potencial.The objective of this work was to determine a mathematic model that estimates the potential acidity with pH SMP measured in water and in solution of CaCl2 0.01 mol L-1. Two hundred and forty six soil samples from several localities were utilized. Despite presenting a lower correlation coefficient (r = 0.89*, the equation H+Al = 30.646 - 3.848pH SMP, obtained in H2O, was more efficient than in the CaCl2 solution (H+Al = 30.155 -3.834pH SMP, r = 0.91*, since this last one underestimates the values of the potential acidity.

Thermodynamic Solubility Profile of Carbamazepine-Cinnamic Acid Cocrystal at Different pH.

Science.gov (United States)

Keramatnia, Fatemeh; Shayanfar, Ali; Jouyban, Abolghasem

2015-08-01

Pharmaceutical cocrystal formation is a direct way to dramatically influence physicochemical properties of drug substances, especially their solubility and dissolution rate. Because of their instability in the solution, thermodynamic solubility of cocrystals could not be determined in the common way like other compounds; therefore, the thermodynamic solubility is calculated through concentration of their components in the eutectic point. The objective of this study is to investigate the effect of an ionizable coformer in cocrystal with a nonionizable drug at different pH. Carbamazepine (CBZ), a nonionizable drug with cinnamic acid (CIN), which is an acidic coformer, was selected to prepare CBZ-CIN cocrystal and its thermodynamic solubility was studied in pH range 2-7. Instead of HPLC that is a costly and time-consuming method, a chemometric-based approach, net analyte signal standard addition method, was selected for simultaneous determination of CBZ and CIN in solution. The result showed that, as pH increases, CIN ionization leads to change in CBZ-CIN cocrystal solubility and stability in solution. In addition, the results of this study indicated that there is no significant difference between intrinsic solubility of CBZ and cocrystal despite the higher ideal solubility of cocrystal. This verifies that ideal solubility is not good parameter to predict cocrystal solubility. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Seasonal variation in plasma nonesterified fatty acids of Lake Sturgeon (Acipenser fulvescens) in the vicinity of hydroelectric facilities

International Nuclear Information System (INIS)

McKinley, R.S.; Power, G.; Singer, T.D.; Ballantyne, J.S.

1993-01-01

To establish the effects of hydroelectric generation on the health of lake sturgeon (Acipenser fulvescens), seasonal variations in plasma nonesterified fatty acids (NEFAs) upstream and downstream from hydroelectric stations were measured over a 2-y period. Plasma NEFA profiles were also compared up- and downstream of the stations for differences in utilization of individual NEFA species as substrates for lipid oxidation. Significantly higher levels of total plasma NEFA were found in lake sturgeon upstream (2355 ± 395.9 nmole/ml) compared with those downstream (798 ± 133.5 nmole/ml) of the generating stations during the spring. The NEFA profiles for several key fatty acid species differed significantly among seasons up- and downstream of the facilities. In particular, during spring and summer, the levels of oleic acid (18:1n9) were highest upstream of the stations and levels of a polyunsaturated fatty acid, docosahexaenoic acid (22:6n3), were higher below rather than above the stations. The differences in plasma NEFA concentration may be attributed to altered nutritional status due to the varying flow regime located downstream of the hydroelectric stations. 33 refs., 4 figs., 1 tab

Mechanisms of intragastric pH sensing.

Science.gov (United States)

Goo, Tyralee; Akiba, Yasutada; Kaunitz, Jonathan D

2010-12-01

Luminal amino acids and lack of luminal acidity as a result of acid neutralization by intragastric foodstuffs are powerful signals for acid secretion. Although the hormonal and neural pathways underlying this regulatory mechanism are well understood, the nature of the gastric luminal pH sensor has been enigmatic. In clinical studies, high pH, tryptic peptides, and luminal divalent metals (Ca(2+) and Mg(2+)) increase gastrin release and acid production. The calcium-sensing receptor (CaSR), first described in the parathyroid gland but expressed on gastric G cells, is a logical candidate for the gastric acid sensor. Because CaSR ligands include amino acids and divalent metals, and because extracellular pH affects ligand binding in the pH range of the gastric content, its pH, metal, and nutrient-sensing functions are consistent with physiologic observations. The CaSR is thus an attractive candidate for the gastric luminal sensor that is part of the neuroendocrine negative regulatory loop for acid secretion.

Inhibitors of acid secretion can benefit gastric wound repair independent of luminal pH effects on the site of damage

Science.gov (United States)

Demitrack, Elise S; Aihara, Eitaro; Kenny, Susan; Varro, Andrea; Montrose, Marshall H

2012-01-01

Background and aims The authors’ goal was to measure pH at the gastric surface (pHo) to understand how acid secretion affects the repair of microscopic injury to the gastric epithelium. Methods Microscopic gastric damage was induced by laser light, during confocal/two-photon imaging of pH-sensitive dyes (Cl-NERF, BCECF) that were superfused over the mucosal surface of the exposed gastric corpus of anaesthetised mice. The progression of repair was measured in parallel with pHo. Experimental conditions included varying pH of luminal superfusates, and using omeprazole (60 mg/kg ip) or famotidine (30 mg/kg ip) to inhibit acid secretion. Results Similar rates of epithelial repair and resting pHo values (~pH 4) were reported in the presence of luminal pH 3 or pH 5. Epithelial repair was unreliable at luminal pH 2 and pHo was lower (2.5±0.2, P pH 3). Epithelial repair was slower at luminal pH 7 and pHo was higher (6.4±0.1, PpH 3 or pH 7, omeprazole reduced maximal damage size and accelerated epithelial repair, although only at pH 3 did omeprazole further increase surface pH above the level caused by imposed damage. At luminal pH 7, famotidine also reduced maximal damage size and accelerated epithelial repair. Neither famotidine nor omeprazole raised plasma gastrin levels during the time course of the experiments. Conclusions Epithelial repair in vivo is affected by luminal pH variation, but the beneficial effects of acutely blocking acid secretion extend beyond simply raising luminal and/or surface pH. PMID:21997560

Aquatic macrophyte richness in Danish lakes in relation to alkalinity, transparency, and lake area

DEFF Research Database (Denmark)

Vestergaard, Ole Skafte; Sand-Jensen, Kaj

2000-01-01

We examined the relationship between environmental factors and the richness of submerged macrophytes species in 73 Danish lakes, which are mainly small, shallow, and have mesotrophic to hypertrophic conditions. We found that mean species richness per lake was only 4.5 in acid lakes of low...... alkalinity but 12.3 in lakes of high alkalinity due to a greater occurrence of the species-rich group of elodeids. Mean species richness per lake also increased significantly with increasing Secchi depth. No significant relationship between species richness and lake surface area was observed among the entire...... group of lakes or a subset of eutrophic lakes, as the growth of submerged macrophytes in large lakes may be restricted by wave action in shallow water and light restriction in deep water. In contrast, macrophyte species richness increased with lake surface area in transparent lakes, presumably due...

[Effects of soil pH on the competitive uptake of amino acids by maize and microorganisms].

Science.gov (United States)

Ma, Qing Xu; Wang, Jun; Cao, Xiao Chuang; Sun, Yan; Sun, Tao; Wu, Liang Huan

2017-07-18

Organic nitrogen can play an important role in plant growth, and soil pH changed greatly due to the over-use of chemical fertilizers, but the effects of soil pH on the competitive uptake of amino acids by plants and rhizosphere microorganisms are lack of detailed research. To study the effects of soil pH on the uptake of amino acids by maize and soil microorganisms, two soils from Hangzhou and Tieling were selected, and the soil pH was changed by the electrokinesis, then the 15 N-labeled glycine was injected to the centrifuge tube with a short-term uptake of 4 h. Soil pH had a significant effect on the shoot and root biomass, and the optimal pH for maize shoot growth was 6.48 for Hangzhou red soil, while it was 7.65 for Tieling brown soil. For Hangzhou soil, the 15 N abundance of maize shoots under pH=6.48 was significantly higher than under other treatments, and the uptake amount of 15 N-glycine was also much higher. However, the 15 N abundance of maize shoots and roots under pH=7.65 Tieling soil was significantly lower than it under pH=5.78, but the uptake amount of 15 N-glycine under pH=7.65 was much higher. The microbial biomass C was much higher in pH=6.48 Hangzhou soil, while it was much lower in pH=7.65 Tieling soil. According to the results of root uptake, root to shoot transportation, and the competition with microorganisms, we suggested that although facing the fierce competition with microorganisms, the maize grown in pH=6.48 Hangzhou soil increased the uptake of glycine by increasing its root uptake and root to shoot transportation. While in pH=7.65 Tieling soil, the activity of microorganisms was decreased, which decreased the competition with maize for glycine, and increased the uptake of glycine by maize.

Acidic pH reduces VEGF-mediated endothelial cell responses by downregulation of VEGFR-2; relevance for anti-angiogenic therapies.

Science.gov (United States)

Faes, Seraina; Uldry, Emilie; Planche, Anne; Santoro, Tania; Pythoud, Catherine; Demartines, Nicolas; Dormond, Olivier

2016-12-27

Anti-angiogenic treatments targeting the vascular endothelial growth factor or its receptors have shown clinical benefits. However, impact on long-term survival remains limited. Solid tumors display an acidic microenvironment that profoundly influences their biology. Consequences of acidity on endothelial cells and anti-angiogenic therapies remain poorly characterized and hence are the focus of this study. We found that exposing endothelial cells to acidic extracellular pH resulted in reduced cell proliferation and migration. Also, whereas VEGF increased endothelial cell proliferation and survival at pH 7.4, it had no effect at pH 6.4. Furthermore, in acidic conditions, stimulation of endothelial cells with VEGF did not result in activation of downstream signaling pathways such as AKT. At a molecular level, acidity significantly decreased the expression of VEGFR-2 by endothelial cells. Consequently, anti-angiogenic therapies that target VEGFR-2 such as sunitinib and sorafenib failed to block endothelial cell proliferation in acidic conditions. In vivo, neutralizing tumor acidity with sodium bicarbonate increased the percentage of endothelial cells expressing VEGFR-2 in tumor xenografts. Furthermore, combining sodium bicarbonate with sunitinib provided stronger anti-cancer activity than either treatment alone. Histological analysis showed that sunitinib had a stronger anti-angiogenic effect when combined with sodium bicarbonate. Overall, our results show that endothelial cells prosper independently of VEGF in acidic conditions partly as a consequence of decreased VEGFR-2 expression. They further suggest that strategies aiming to raise intratumoral pH can improve the efficacy of anti-VEGF treatments.

Fatty acid composition of fish species with different feeding habits from an Arctic Lake.

Science.gov (United States)

Gladyshev, M I; Sushchik, N N; Glushchenko, L A; Zadelenov, V A; Rudchenko, A E; Dgebuadze, Y Y

2017-05-01

We compared the composition and content of fatty acids (FAs) in fish with different feeding habits (sardine (least) cisco Coregonus sardinella, goggle-eyed charr (pucheglazka) form of Salvelinus alpinus complex, humpback whitefish Coregonus pidschian, broad whitefish Coregonus nasus, boganid charr Salvelinus boganidae, and northern pike Esox lucius from an Arctic Lake. Feeding habits of the studied fish (planktivore, benthivore, or piscivore) significantly affected the composition of biomarker fatty acids and the ratio of stable isotopes of carbon and nitrogen in their biomass. The hypothesis on a higher content of eicosapentaenoic and docosahexaenoic acids in the fish of higher trophic level (piscivores) when compared within the same taxonomic group (order Salmoniformes) was confirmed.

Feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) using fatty acid trophic markers in seston food in two salt lakes in South Siberia (Khakasia, Russia)

OpenAIRE

Tolomeev, A.; Sushchik, N.N.; Gulati, R.D.; Makhutova, O.N.; Kalacheva, G.S.; Zotina, T.A.

2010-01-01

During two vegetation seasons (2004–2005), we compared feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) populations inhabiting two neighboring salt lakes, Shira and Shunet, Khakasia, Russia, using fatty acid (FA) trophic markers. Sestonic FA composition in two lakes moderately differed, whereas levels of diatom FA markers were higher in Lake Shunet and of Cyanobacteria and green algae markers in Lake Shira. In general, markers in storage lipids—triacylglycerols (TAG) of A. sali...

TRPM5 mediates acidic extracellular pH signaling and TRPM5 inhibition reduces spontaneous metastasis in mouse B16-BL6 melanoma cells.

Science.gov (United States)

Maeda, Toyonobu; Suzuki, Atsuko; Koga, Kaori; Miyamoto, Chihiro; Maehata, Yojiro; Ozawa, Shigeyuki; Hata, Ryu-Ichiro; Nagashima, Yoji; Nabeshima, Kazuki; Miyazaki, Kaoru; Kato, Yasumasa

2017-10-03

Extracellular acidity is a hallmark of solid tumors and is associated with metastasis in the tumor microenvironment. Acidic extracellular pH (pH e ) has been found to increase intracellular Ca 2+ and matrix metalloproteinase-9 (MMP-9) expression by activating NF-κB in the mouse B16 melanoma model. The present study assessed whether TRPM5, an intracellular Ca 2+ -dependent monovalent cation channel, is associated with acidic pH e signaling and induction of MMP-9 expression in this mouse melanoma model. Treatment of B16 cells with Trpm5 siRNA reduced acidic pH e -induced MMP-9 expression. Enforced expression of Trpm5 increased the rate of acidic pH e -induced MMP-9 expression, as well as increasing experimental lung metastasis. This genetic manipulation did not alter the pH e critical for MMP-9 induction but simply amplified the percentage of inducible MMP-9 at each pH e . Treatment of tumor bearing mice with triphenylphosphine oxide (TPPO), an inhibitor of TRPM5, significantly reduced spontaneous lung metastasis. In silico analysis of clinical samples showed that high TRPM5 mRNA expression correlated with poor overall survival rate in patients with melanoma and gastric cancer but not in patients with cancers of the ovary, lung, breast, and rectum. These results showed that TRPM5 amplifies acidic pH e signaling and may be a promising target for preventing metastasis of some types of tumor.

A mathematical model for the generation and control of a pH gradient in an immobilized enzyme system involving acid generation.

Science.gov (United States)

Chen, G; Fournier, R L; Varanasi, S

1998-02-20

An optimal pH control technique has been developed for multistep enzymatic synthesis reactions where the optimal pH differs by several units for each step. This technique separates an acidic environment from a basic environment by the hydrolysis of urea within a thin layer of immobilized urease. With this technique, a two-step enzymatic reaction can take place simultaneously, in proximity to each other, and at their respective optimal pH. Because a reaction system involving an acid generation represents a more challenging test of this pH control technique, a number of factors that affect the generation of such a pH gradient are considered in this study. The mathematical model proposed is based on several simplifying assumptions and represents a first attempt to provide an analysis of this complex problem. The results show that, by choosing appropriate parameters, the pH control technique still can generate the desired pH gradient even if there is an acid-generating reaction in the system. Copyright 1998 John Wiley & Sons, Inc.

Measurement of pH, alkalinity and acidity in ultra-soft waters | Lahav ...

African Journals Online (AJOL)

In the "blend" method, equilibrium chemistry data were used to calculate total acidity for each point based on the known total alkalinity, pH reading, temperature and ionic strength. The two methods gave excellent results (in terms of both repetition and accuracy) as compared to characterisation based on total alkalinity and ...

Managing ecosystems without prior knowledge: pathological outcomes of lake liming

Directory of Open Access Journals (Sweden)

David G. Angeler

2017-12-01

Full Text Available Management actions often need to be taken in the absence of ecological information to mitigate the impact of pressing environmental problems. Managers counteracted the detrimental effects of cultural acidification on aquatic ecosystems during the industrial era using liming to salvage biodiversity and ecosystem services. However, historical contingencies, i.e., whether lakes were naturally acidic or degraded because of acidification, were largely unknown and therefore not accounted for in management. It is uncertain whether liming outcomes had a potentially detrimental effect on naturally acidic lakes. Evidence from paleolimnological reconstructions allowed us to analyze community structure in limed acidified and naturally acidic lakes, and acidified and circumneutral references. We analyzed community structure of phytoplankton, zooplankton, macroinvertebrates (littoral, sublittoral, profundal, and fish between 2000 and 2004. Naturally acidic limed lakes formed communities that were not representative of the other lake types. The occurrence of fish species relevant for ecosystem service provisioning (fisheries potential in naturally acidic limed lakes were confounded by biogeographical factors. In addition, sustained changes in water quality were conducive to harmful algal blooms. This highlights a pathological outcome of liming lakes when their naturally acidic conditions are not accounted for. Because liming is an important social-ecological system, sustained ecological change of lakes might incur undesired costs for societies in the long term.

Effect of pH, ionic strength and humic acid on the sorption of uranium(VI) to attapulgite

Energy Technology Data Exchange (ETDEWEB)

Niu Zhiwei [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China); Fan Qiaohui [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China)], E-mail: fanqiaohui@gmail.com; Wang Wenhua; Xu Junzheng [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China); Chen Lei [School of Chemical Engineering, Shandong University of Technology, 255049 Zibo, Shandong (China); Wu Wangsuo [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China)], E-mail: wuws@lzu.edu.cn

2009-09-15

Attapulgite was investigated to remove UO{sub 2}{sup 2+} from aqueous solutions because of its strong sorption capacity. Herein, the attapulgite sample was characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and acid-base titration in detail. Sorption of UO{sub 2}{sup 2+} on attapulgite was strongly dependent on pH values and ionic strength. The presence of humic acid enhanced the sorption of UO{sub 2}{sup 2+} on attapulgite obviously because of the strong complexation of humic acid (HA) with UO{sub 2}{sup 2+} on attapulgite surface. Sorption of UO{sub 2}{sup 2+} on attapulgite was mainly dominated by ion-exchange or outer-sphere complexation at low pH values, and by inner-sphere complexation at high pH values. The results indicated that attapulgite was a suitable material for the preconcentration and solidification of UO{sub 2}{sup 2+} from large volume of solutions because of its negative surface charge and large surface areas.

Organic geochemistry and pore water chemistry of sediments from Mangrove Lake, Bermuda

Science.gov (United States)

Hatcher, P.G.; Simoneit, B.R.T.; MacKenzie, F.T.; Neumann, A.C.; Thorstenson, D.C.; Gerchakov, S.M.

1982-01-01

Mangrove Lake, Bermuda, is a small coastal, brackish-water lake that has accumulated 14 m of banded, gelatinous, sapropelic sediments in less than 104 yr. Stratigraphic evidence indicates that Mangrove Lake's sedimentary environment has undergone three major depositional changes (peat, freshwater gel, brackish-water gel) as a result of sea level changes. The deposits were examined geochemically in an effort to delineate sedimentological and diagenetic changes. Gas and pore water studies include measurements of sulfides, ammonia, methane, nitrogen gas, calcium, magnesium, chloride, alkalinity, and pH. Results indicate that sulfate reduction is complete, and some evidence is presented for bacterial denitrification and metal sulfide precipitation. The organic-rich sapropel is predominantly algal in origin, composed mostly of carbohydrates and insoluble macromolecular organic matter called humin with minor amounts of proteins, lipids, and humic acids. Carbohydrates and proteins undergo hydrolysis with depth in the marine sapropel but tend to be preserved in the freshwater sapropel. The humin, which has a predominantly aliphatic structure, increases linearly with depth and composes the greatest fraction of the organic matter. Humic acids are minor components and are more like polysaccharides than typical marine humic acids. Fatty acid distributions reveal that the lipids are of an algal and/or terrestrial plant source. Normal alkanes with a total concentration of 75 ppm exhibit two distribution maxima. One is centered about n-C22 with no odd/even predominance, suggestive of a degraded algal source. The other is centered at n-C31 with a distinct odd/even predominance indicative of a vascular plant origin. Stratigraphic changes in the sediment correlate to observed changes in the gas and pore water chemistry and the organic geochemistry. ?? 1982.

Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

Science.gov (United States)

Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

2014-05-01

The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

Influence of pH of acid irrigation water on the transfer of elements into rice plant from soils

International Nuclear Information System (INIS)

Maeno, Tomokazu; Tanizaki, Yoshiyuki

1996-01-01

Rice plant samples were grown in 14 cultivative pots under six different pH conditions of acid irrigation water (pH: 6.5, 6.0, 4.5, 3.5, 3.0. 2.5) and ion exchange water (pH: 7.5), in order to study an influence of pH of irrigation water on the transfer of elements into rice plant from soils. The acid irrigation water was prepared by adding mixed solution of 1N H 2 SO 4 and 1N HNO 3 (1:1) to ion exchange water. The rice grain yielded was separated into three parts, i.e., polished rice, bran and chaff and they were powdered one by one. The contents of twenty five elements in the three parts of grain (14 samples each) were determined by a neutron activation analysis. It was clarified that the contents of Cu, Zn, Fe, Cr, Mg, Rb, Mo, Ni, and Cs in the polished rice increased with decreasing pH of the acid irrigation water. The contents of Se and Br, on the contrary, decreased. Significant changes of the contents were not observed for Na, Al, Sc, Mn, Cl, Ca, V and Co. The relationships between the contents of elements in the bran or chaff and pH of the acid irrigation water were not so clear as the case of polished rice. The enrichment factor of trace elements from soils was calculated for the polished rice, bran and chaff The high enrichment of Cl, Mo, Zn, Se and Cu was observed in the polished rice. Manganese and Cr were concentrated more in the bran than in the polished rice. (author)

Controlling the pH of acid cheese whey in a two-stage anaerobic digester with sodium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Ghaly, A.E.; Ramkumar, D.R.

1999-07-01

Anaerobic digestion of cheese whey offers a two-fold benefit: pollution potential reduction and biogas production. The biogas, as an energy source, could be used to reduce the consumption of traditional fuels in the cheese plant. However, as a result of little or no buffering capacity of whey, the pH of the anaerobic digester drops drastically and the process is inhibited. In this study, the effect of controlling the pH of the second chamber of a two-stage, 150 L anaerobic digester operating on cheese whey on the quality and quantity of biogas and the pollution potential reduction, was investigated using sodium hydroxide. The digester was operated at a temperature of 35 C and a hydraulic retention time of 15 days for three runs (no pH control, pH control with no reseeding, and pH control with reseeding) each lasting 50 days. The results indicated that operating the digester without pH control resulted in a low pH (3.3) which inhibited the methanogenic bacteria. The inhibition was irreversible and the digester did not recover (no methane production) when the pH was restored to 7.0 without reseeding, as the observed increased gas production was a false indication of recovery because the gas was mainly carbon dioxide. The addition of base resulted in a total alkalinity of 12,000 mg L as CaCO{sub 3}. When the system was reseeded and the pH controlled, the total volatile acid concentration was 15,100 mg L (as acetic acid), with acetic (28 %), propionic (21%), butyric (25%), valeric (8%), and caproic (15%) acids as the major constituents. The biogas production was 62.6 L d (0.84m{sup 3}m{sup 3} d) and the methane content was 60.7%. Reductions of 27.3, 30.4 and 23.3 % in the total solids, chemical oxygen demand and total Kjeldahl nitrogen were obtained, respectively. The ammonium nitrogen content increased significantly (140%). (author)

Changes in composition and enamel demineralization inhibition activities of gallic acid at different pH values

NARCIS (Netherlands)

Zhang, J.; Huang, X.; Huang, S.; Deng, M.; Xie, X.; Liu, M.; Liu, H.; Zhou, X.; Li, J.; ten Cate, J.M.

2015-01-01

Background. Gallic acid (GA) has been shown to inhibit demineralization and enhance remineralization of enamel; however, GA solution is highly acidic. This study was to investigate the stability of GA solutions at various pH and to examine the resultant effects on enamel demineralization. Methods.

Removal of Radium-226 from Radium-Contaminated Soil using Distilled Water and Humic Acid: Effect of pH

International Nuclear Information System (INIS)

Phillips, E.; Muhammad Samudi Yasir; Muhamat Omar

2011-01-01

Effect of washing solutions' pH removal of radium-226 from radium-contaminated soil using distilled water and humic acid extracted from Malaysian peat soil was studied by batch washing method. The study encompassed the extraction of humic acid and the washing of radium-contaminated soil using distilled water and humic acid solutions of 100 ppm, both with varying pHs in the range of 3 to 11. The radioactivity concentration of radium-226 was determined by gamma spectrometer.The removal of radium-226 was greater when humic acid solutions were used compared to distilled water at the pH range studied and both washing solutions showed greater removal of radium-226 when basic solutions were used. Nevertheless, comparable removal efficiencies were observed when neutral and highly basic humic acid solutions were used. (author)

Photochemical Reactivity of Dissolved Organic Matter in Boreal Lakes

Science.gov (United States)

Gu, Y.; Vuorio, K.; Tiirola, M.; Perämäki, S.; Vahatalo, A.

2016-12-01

Boreal lakes are rich in dissolved organic matter (DOM) that terrestrially derived from forest soil and wetland, yet little is known about potential for photochemical transformation of aquatic DOM in boreal lakes. Transformation of chromophoric dissolved organic matter (CDOM) can decrease water color and enhance microbial mineralization, affecting primary production and respiration, which both affect the CO2 balance of the lakes. We used laboratory solar radiation exposure experiments with lake water samples collected from 54 lakes located in Finland and Sweden, representing different catchment composition and watershed location to assess photochemical reactivity of DOM. The pH of water samples ranged from 5.4 to 8.3, and the concentrations of dissolved iron (Fe) were between samples received simulated solar radiation corresponding to a daily dose of sunlight, and photomineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) was measured for determination of spectral apparent quantum yields (AQY). During irradiation, photobleaching decreased the absorption coefficients of CDOM at 330 nm between 4.9 and 79 m-1 by 0.5 to 11 m-1. Irradiation generated DIC from 2.8 to 79 μmol C L-1. The AQY at 330 nm ranged between 31 and 273 ×10-6 mol C mol photons-1 h-1, which was correlated positively with concentration of dissolved Fe, and negatively with pH. Further statistical analyze indicated that the interaction between pH and Fe may explain much of the photochemical reactivity of DOM in the examined lakes, and land cover concerns main catchment areas also can have impact on the photoreaction process. This study may suggest how environmental conditions regulate DOM photomineralization in boreal lakes.

Prolonged acid rain facilitates soil organic carbon accumulation in a mature forest in Southern China.

Science.gov (United States)

Wu, Jianping; Liang, Guohua; Hui, Dafeng; Deng, Qi; Xiong, Xin; Qiu, Qingyan; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

2016-02-15

With the continuing increase in anthropogenic activities, acid rain remains a serious environmental threat, especially in the fast developing areas such as southern China. To detect how prolonged deposition of acid rain would influence soil organic carbon accumulation in mature subtropical forests, we conducted a field experiment with simulated acid rain (SAR) treatments in a monsoon evergreen broadleaf forest at Dinghushan National Nature Reserve in southern China. Four levels of SAR treatments were set by irrigating plants with water of different pH values: CK (the control, local lake water, pH ≈ 4.5), T1 (water pH=4.0), T2 (water pH=3.5), and T3 (water pH=3.0). Results showed reduced pH measurements in the topsoil exposed to simulated acid rains due to soil acidification. Soil respiration, soil microbial biomass and litter decomposition rates were significantly decreased by the SAR treatments. As a result, T3 treatment significantly increased the total organic carbon by 24.5% in the topsoil compared to the control. Furthermore, surface soil became more stable as more recalcitrant organic matter was generated under the SAR treatments. Our results suggest that prolonged acid rain exposure may have the potential to facilitate soil organic carbon accumulation in the subtropical forest in southern China. Copyright © 2015 Elsevier B.V. All rights reserved.

Using a mass balance to understand the geology and geochemistry of a reservoir receiving and discharging acid mine drainage

International Nuclear Information System (INIS)

Turney, D.C.; Edwards, K.

1996-01-01

Howard-Williams Lake is a 14.5 acre reservoir located in an abandoned coal mine in Perry County, Ohio. With a pH of 3.0 and acidity values of 300--400 mg/L, the reservoir has no plants or fish currently surviving in the lake. Reclamation of spoil piles adjacent to the lake to the north in the late 1980s was not successful in reducing the acidity of the lake. Currently, papermill sludge is being used on the reclaimed area to the north to promote vegetation, but the reservoir has shown no signs of improving. The goal of this project is to transform the lake into a fishable and swimmable one. The reservoir is receiving about 175 gallons per minute of acid mine drainage, not including seepage into the lake, from eight different sources. Three of the sources account for about 165 gallons per minute of the surface water that enters the lake. These inflows have relatively low acidity readings, which range from 66 mg/L to 568 mg/L. The other five sources of acid mine drainage have much lower flowrates, but have acidity values as high as 3,000 mg/L. Samples of all of the surface inflows and the outflow of the lake were taken and sent to a laboratory and tested for the following parameters: total acidity as CaCO 3 , total alkalinity as CaCO 2 , specific conductivity, total suspended solids, sulfate, chloride calcium, magnesium, sodium, potassium, total iron, total manganese, aluminum, and hardness. During sampling of the surface inflows, volumetric flowrates were measured for each inflow. Once the flowrates and the concentrations of the various parameters were known, a mass balance could be constructed which would show how much of each parameter was entering the lake each day. These data were then used to gain an understanding of the geochemistry and geology of the site

Differences in functional traits between invasive and native Amaranthus species under simulated acid deposition with a gradient of pH levels

Science.gov (United States)

Wang, Congyan; Wu, Bingde; Jiang, Kun; Zhou, Jiawei

2018-05-01

Co-occurring invasive plant species (invaders hereafter) and natives receive similar or even the same environmental selection pressures. Thus, the differences in functional traits between natives and invaders have become widely recognized as a major driving force of the success of plant invasion. Meanwhile, increasing amounts of acid are deposited into ecosystems. Thus, it is important to elucidate the potential effects of acid deposition on the functional traits of invaders in order to better understand the potential mechanisms for the successful invasion. This study aims to address the differences in functional traits between native red amaranth (Amaranthus tricolor L.; amaranth hereafter) and invasive redroot pigweed (A. retroflexus L.; pigweed hereafter) under simulated acid deposition with a gradient of pH levels. Pigweed was significantly taller than amaranth under most treatments. The greater height of pigweed can lead to greater competitive ability for resource acquisition, particularly for sunlight. Leaf shape index of pigweed was also significantly greater than that of amaranth under all treatments. The greater leaf shape index of pigweed can enhance the efficiency of resource capture (especially sunlight capture) via adjustments to leaf shape and size. Thus, the greater height and leaf shape index of pigweed can significantly enhance its competitive ability, especially under acid deposition. Acid deposition of pH 5.6 significantly increased amaranth leaf width in the co-cultivation due to added nutrients. The pH 4.5 acid deposition treatment significantly increased the specific leaf area of amaranth in the monoculture compared with the pH 5.6 acid deposition treatment and the control. The main mechanism explaining this pattern may be due to acid deposition mediating a hormesis effect on plants, promoting plant growth. The values of the relative competition intensity between amaranth and pigweed for most functional traits were lower than zero under most

Notable decomposition products of senescing Lake Michigan Cladophora glomerata

Science.gov (United States)

Peller, Julie R.; Byappanahalli, Muruleedhara N.; Shively, Dawn A.; Sadowsky, Michael J.; Chun, Chan Lan; Whitman, Richard L.

2013-01-01

Massive accumulations of Cladophora, a ubiquitous, filamentous green alga, have been increasingly reported along Great Lakes shorelines, negatively affecting beach aesthetics, recreational activities, public health and beachfront property values. Previously, the decomposition byproducts of decaying algae have not been thoroughly examined. To better understand the negative consequences and potential merit of the stranded Cladophora, a three month mesocosm study of the dynamic chemical environment of the alga was conducted using fresh samples collected from southern Lake Michigan beaches. Typical fermentation products, such as organic acids, sulfide compounds, and alcohols were detected in the oxygen–deprived algae. Short chain carboxylic acids peaked on day seven, in correspondence with the lowest pH value. Most low molecular mass carbon compounds were eventually consumed, but 4-methylphenol, indole, and 3-methylindole were detected throughout the incubation period. Natural oils were detected in fresh and decomposing algae, indicating the stable nature of these compounds. The mesocosm experiment was validated by directly sampling the fluid within decomposing Cladophora mats in the field; many of the same compounds were found. This study suggests that the problematic Cladophora accumulations may be harvested for useful byproducts, thereby reducing the odiferous and potentially harmful mats stranded along the shorelines.

Four years of continuous monitoring of the Meirama end-pit lake and its impact in the definition of future uses.

Science.gov (United States)

Delgado-Martin, J; Juncosa-Rivera, R; Falcón-Suárez, I; Canal-Vila, J

2013-11-01

Following the technical closure of the brown lignite Meirama mine (NW Spain) in April 2008, the reclamation of the mined area is being accomplished with the controlled flooding of its large pit. During the first 7 months of flooding, the sequential arrest of the ground water dewatering system led to the growth of an acidic water body of about 2 hm3. Since October 2008, the surface waters from some local streams have been diverted towards the pit so that these have become the major water input in the flooding process. Surface water has promoted a major change in the chemical composition of the lake water so that, at present, its surface has a circum neutral pH, net alkalinity, and low conductivity. At present, the lake has slightly more than one half of its final volume, and it is expected the overflow in 3 to 3.5 years. The lake is meromictic, with a sharp chemocline separating the acidic monimolimnion (pH≈3.2, acidity≈150 mg CaCO3/L, κ 25≈2.4 mS/cm) from the main water body (pH≈6.5, alkalinity≈15 mg CaCO3/L, κ 25≈0.3 mS/cm). Oxygen is being depleted at the bottom of the lake so that the monimolimnion became anoxic in January 2011. Above the chemocline, the composition of the lake is similar, but not identical, to that of the flooding stream waters. Close to the surface, some constituents (pH, metals) show strong seasonal variations in coincidence with the phytoplankton growing periods. Those parameters whose limits are legally prescribed comply with the corresponding water quality standards, and they are also consistent with the forecasting results obtained in early modeling. At present, a project considering the construction of an uptake tunnel to exploit the lake is being developed for the emergency water supply of the metropolitan area of A Coruña.

Dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs with poor water solubility.

Science.gov (United States)

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Lee, Kyoung-Ho; Kim, Dong-Jin; Lee, Beom-Jin

2010-05-01

Although the solid dispersion method has been known to increase the dissolution rate of poorly water-soluble drugs by dispersing them in hydrophilic carriers, one obstacle of the solid dispersion method is its limited solubilization capacity, especially for pH-dependent soluble drugs. pH-modified solid dispersion, in which pH modifiers are incorporated, may be a useful method for increasing the dissolution rate of weakly acidic or basic drugs. Sufficient research, including the most recent reports, was undertaken in this review. How could the inclusion of the pH the pH modifiers in the solid dispersion system change drug structural behaviors, molecular interactions, microenvironmental pH, and/or release rate of pH modifiers, relating with the enhanced dissolution of weakly acidic or weakly basic drugs with poor water solubility? These questions have been investigated to determine the dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs. It is believed that step-by-step mechanistic approaches could provide the ultimate solution for solubilizing several poorly water-soluble drugs with pH-dependent solubility from a solid dispersion system, as well as provide ideas for developing future dosage systems.

Influence of in ovo mercury exposure, lake acidity, and other factors on common loon egg and chick quality in Wisconsin

Science.gov (United States)

We conducted a field study in Wisconsin to characterize in ovo mercury (Hg) exposure in common loons (Gavia immer). Total Hg mass fractions ranged from 0.17 to 1.23 ìg/g wet weight (ww) in eggs collected from nests on lakes representing a wide range of pH (5.0 - 8.1) and ...

Streptomyces lonarensis sp. nov., isolated from Lonar Lake, a meteorite salt water lake in India.

Science.gov (United States)

Sharma, Trupti K; Mawlankar, Rahul; Sonalkar, Vidya V; Shinde, Vidhya K; Zhan, Jing; Li, Wen-Jun; Rele, Meenakshi V; Dastager, Syed G; Kumar, Lalitha Sunil

2016-02-01

A novel alkaliphilic actinomycete, strain NCL716(T), was isolated from a soil sample collected from the vicinity of Lonar Lake, an alkaline salt water meteorite lake in Buldhana district of Maharashtra State in India. The strain was characterised using a polyphasic taxonomic approach which confirmed that it belongs to the genus Streptomyces. Growth was observed over a pH range of 7-11 at 28 °C. The cell wall was found to contain LL-diaminopimelic acid and traces of meso-diaminopimelic acid. The major fatty acid components were identified as iso-C16:0 (46.8 %), C17:1 (12.4 %), anteiso-C15:0 (5.1 %) and anteiso-C17:1 (4.8 %). The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The major menaquinones were determined to be MK-9 (H6) (70.3 %), MK-9 (H4) (15.5 %) and MK-9 (H8) (7.2 %). The G+C content of the DNA of the type strain was determined to be 71.4 mol %. The 16S rRNA gene sequence has been deposited in GenBank with accession number FJ919811. Although the 16S rRNA gene sequence analysis revealed that strain NCL716(T) shares >99 % similarity with that of Streptomyces bohaiensis strain 11A07(T), DNA-DNA hybridization revealed only 33.2 ± 3.0 % relatedness between them. Moreover, these two strains can be readily distinguished by some distinct phenotypic characteristics. Hence, on the basis of phenotypic and genetic analyses, it is proposed that strain NCL716(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces lonarensis sp. nov., is proposed. The type strain is NCL 716(T) (=DSM 42084(T) = MTCC 11708(T) = KCTC 39684(T)).

Evaluation of Salivary Uric Acid and pH in Human Immunodeficiency Virus Infected Patients: A Historical Cohort Study.

Science.gov (United States)

Ahmadi-Motamayel, Fatemeh; Amjad, Samaneh Vaziri; Goodarzi, Mohammad Taghi; Poorolajal, Jalal

2018-01-01

Antioxidants protect the body against cellular damage. Saliva has immunological, enzymatic and antioxidant defense systems. Uric acid is the main and predominant salivary antioxidant. The aim of this study was to evaluate salivary uric acid levels and pH in HIV-infected patients in the west of Iran. HIV-infected patients were selected from behavioral advisory centers of Hamadan and Kermanshah Provinces, west of Iran. Saliva was collected between 8 and10 in the morning. Five mL of whole unstimulated saliva was collected in 5 minutes by spitting into sterilized Falcon tubes based on Navazesh method; pH was measured with a pH meter and uric acid was assessed with spectrophotometric method. Data were analyzed with STATA 12. Salivary pH in the HIV-positive group was lower (6.99±0.46) than the healthy controls (7.14±1.03) but the difference was not statistically significant (P=380). Uric acid concentrations in HIV-infected patients (2.94±2.14) were significantly lower in comparison to the healthy controls (5.21±2.30). The results showed a statistically significant decrease in the case group (P=0.001). Mean age and DMFT index of the case group were higher than the control group. Uric acid, the main antioxidant of saliva, was significantly lower in HIVinfected individuals; pH also was lower in these patients. HIV can alter salivary antioxidant status, which can influence patients' oral health status. Diet with antioxidant properties might be helpful in these patients. More research is necessary to discover true antioxidant and salivary changes and their relation with HIV consequences in future. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Pd(II)/PhI(OAc)2 promoted direct cross coupling of glucals with aromatic acids.

Science.gov (United States)

Begum, Zubeda; Shankar, G; Sirisha, K; Reddy, B V Subba

2018-05-22

A highly efficient oxidative C2-aroyloxylation of D-glucal with aromatic carboxylic acids has been achieved for the first time using 5 mol% Pd(OAc) 2 and 1 equiv of PhI(OAc) 2 to produce C2-aroyloxyglycals in good yields. The use of excess of PhI(OAc) 2 (2 equiv) provides C2-acyloxyglycal exclusively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Novel Halomonas sp. B15 isolated from Larnaca Salt Lake in Cyprus that generates vanillin and vanillic acid from ferulic acid.

Science.gov (United States)

Vyrides, Ioannis; Agathangelou, Maria; Dimitriou, Rodothea; Souroullas, Konstantinos; Salamex, Anastasia; Ioannou, Aristostodimos; Koutinas, Michalis

2015-08-01

Vanillin is a high value added product with many applications in the food, fragrance and pharmaceutical industries. A natural and low-cost method to produce vanillin is by microbial bioconversions through ferulic acid. Until now, limited microorganisms have been found capable of bioconverting ferulic acid to vanillin at high yield. This study aimed to screen halotolerant strains of bacteria from Larnaca Salt Lake which generate vanillin and vanillic acid from ferulic acid. From a total of 50 halotolenant/halophilic strains 8 grew in 1 g/L ferulic acid and only 1 Halomonas sp. B15 and 3 Halomonas elognata strains were capable of bioconverting ferulic acid to vanillic acid at 100 g NaCl/L. The highest vanillic acid (365 mg/L) at these conditions generated by Halomonas sp. B15 which corresponds to ferulic acid bioconversion yield of 36.5%. Using the resting cell technique with an initial ferulic acid concentration of 0.5 g/L at low salinity, the highest production of vanillin (245 mg/L) took place after 48 h, corresponding to a bioconversion yield of 49%. This is the first reported Halomonas sp. with high yield of vanillin production from ferulic acid at low salinity.

Feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) using fatty acid trophic markers in seston food in two salt lakes in South Siberia (Khakasia, Russia)

NARCIS (Netherlands)

Tolomeev, A.; Sushchik, N.N.; Gulati, R.D.; Makhutova, O.N.; Kalacheva, G.S.; Zotina, T.A.

2010-01-01

During two vegetation seasons (2004–2005), we compared feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) populations inhabiting two neighboring salt lakes, Shira and Shunet, Khakasia, Russia, using fatty acid (FA) trophic markers. Sestonic FA composition in two lakes moderately

The effects of pH on N-methacryloyl glycine primer on bond strength to acid-etched dentin.

Science.gov (United States)

Nishiyama, N; Suzuki, K; Asakura, T; Nakai, H; Yasuda, S; Nemoto, K

1996-07-01

To develop a more effective adhesive primer, it is imperative to understand the adhesion mechanisms of the resin to the demineralized dentin through a dentin primer. When the bonding agent was directly applied to the dentin etched by 40 wt % phosphoric acid without a primer pretreatment, the bond strength of the resin to the dentin was 5 MPa. Conversely, when the demineralized dentin was pretreated with the N-methacryloyl glycine (NM alpha A) primer solution with a pH value of 1.5, the bond strength increased considerably to 15 MPa. However, the bond strength dropped dramatically from 15 to 3 MPa when the sodium salt of NM alpha A was added, thereby increasing the pH value of the NM alpha A primer solution from 3.2 to 5.0. When the pH value was increased above 3.5 (pKa value), the number of ionized NM alpha A species increased in the solution. As a result, the bond strength of the resin fell to approximately 3 MPa. This result was obtained despite the 5-micron-thick hybrid layer that was created in the subsurface of the intertubular dentin. The number of unionized NM alpha A species increased by lowering the pH value below 3.5. As a result, the NM alpha A primer provided a higher bond strength of the resin to the demineralized dentin. In contrast, when 10 wt % citric acid containing 3 wt % ferric chloride was applied to the dentin, maximum bond strength was obtained when the pH value of the NM alpha A primer solution was 3.5. The pH dependency of the bond strength obtained following 10 wt % citric acid containing 3 wt % ferric chloride etching is different from the results obtained from 40 wt % phosphoric acid etching. This can be attributed to the difference in the characteristics of the demineralized collageous layer.

Trends in the chemistry of atmospheric deposition and surface waters in the Lake Maggiore catchment

Directory of Open Access Journals (Sweden)

M. Rogora

2001-01-01

Full Text Available The Lake Maggiore catchment is the area of Italy most affected by acid deposition. Trend analysis was performed on long-term (15-30 years series of chemical analyses of atmospheric deposition, four small rivers draining forested catchments and four high mountain lakes. An improvement in the quality of atmospheric deposition was detected, due to decreasing sulphate concentration and increasing pH. Similar trends were also found in high mountain lakes and in small rivers. Atmospheric deposition, however, is still providing a large and steady flux of nitrogen compounds (nitrate and ammonium which is causing increasing nitrogen saturation in forest ecosystems and increasing nitrate levels in rivers. Besides atmospheric deposition, an important factor controlling water acidification and recovery is the weathering of rocks and soils which may be influenced by climate warming. A further factor is the episodic deposition of Saharan calcareous dust which contributes significantly to base cation deposition. Keywords: trend, atmospheric deposition, nitrogen, stream water chemistry.

Evaluation of citric acid and GDL in the recovery at different pH levels of Clostridium sporogenes PA 3679 spores subjected to HTST treatment conditions.

Science.gov (United States)

Silla Santos, M H; Torres Zarzo, J

1996-04-01

Spores of Clostridium sporogenes PA 3679 were treated at different temperatures (121, 126, 130 and 135 degrees C) in white asparagus purée (pH 5.8) and acidified with glucono-delta-lactone (GDL) and citric acid to pH levels of 5.5, 5.0 and 4.5. Afterwards, the spores were recovered in MPA3679 medium in various conditions: unacidified (pH 7.5), acidified with GDL (500 ppm) and acidified with citric acid (500 and 250 ppm) to pH levels of 6.5, 6.0 and 5.0. The results indicated that the pH levels, concentration and type of acid used act synergistically rather than independently. Citric acid has a stronger inhibiting effect than GDL on the recovery of C. sporogenes PA 3679 spores. At the higher heat treatments (130 and 135 degrees C) the major injury on the spores sensitize more than against the acids and low pH values.

A radioanalytical study of radionuclides in a dysoligotrophic lake in Southern Sweden

Energy Technology Data Exchange (ETDEWEB)

Eriksson, M; Roos, P; Holm, E [Lund University Hospital, Lund, (Sweden). The Jubileum Institute, Department of Radiation Physics; Peck, G [University of Melbourne, Parkville, VIC (Australia). School of Physics, Marine Chemistry Laboratory

1998-07-01

Unusually high activity concentration of various artificial radionuclides (from nuclear test fallout and the Chernobyl accident) and some natural radionuclides, have been discovered in lakes with high amounts of humic substances. These lakes tend to have low pH, at times down to pH 5. The lake, Svartsjoen, in the southern part of Sweden is one of these lakes. The food chain and resulting concentration factors in Svartsjoen were investigated and compared to results for other 'normal' lakes. Fish and water samples were collected and analysed for {sup 137}Cs {sup 239+240}Pu, {sup 241}Am and {sup 210}Po during a 4-month visit to Lund. The level of {sup 239/240}Pu in the water of Svartsjoen was found to be elevated. The work on fish from the lake indicates that these elevated levels are not transferred into the food chain. It appears that the humic substances could be blocking plutonium from entering the food chain.

A radioanalytical study of radionuclides in a dysoligotrophic lake in Southern Sweden

International Nuclear Information System (INIS)

Eriksson, M.; Roos, P.; Holm, E.; Peck, G.

1998-01-01

Unusually high activity concentration of various artificial radionuclides (from nuclear test fallout and the Chernobyl accident) and some natural radionuclides, have been discovered in lakes with high amounts of humic substances. These lakes tend to have low pH, at times down to pH 5. The lake, Svartsjoen, in the southern part of Sweden is one of these lakes. The food chain and resulting concentration factors in Svartsjoen were investigated and compared to results for other 'normal' lakes. Fish and water samples were collected and analysed for 137 Cs 239+240 Pu, 241 Am and 210 Po during a 4-month visit to Lund. The level of 239/240 Pu in the water of Svartsjoen was found to be elevated. The work on fish from the lake indicates that these elevated levels are not transferred into the food chain. It appears that the humic substances could be blocking plutonium from entering the food chain

Removal of heavy metals from sludge of Sanaru-Lake by electrokinetics

Energy Technology Data Exchange (ETDEWEB)

Seno, T.; Shiba, S.; Hirata, Y. [Dept. of Systems Engineering, Shizuoka Univ., Hamamatsu (Japan)

2001-07-01

Two kinds of experiments were carried out for the removal of heavy metals from soils by electrokinetic technique. One was the removal of lead from kaolinite by using a small-sized test cell. The effect of the kind of purging solutions (such as distilled water, tap water, acetic acid and nitric acid) on removal efficiency was examined. High removal efficiency was obtained for the acetic acid solution. It was found that the controlling pH of solution surrounding cathode had a significant influence on the removal efficiency. The other experiment was the removal of heavy metals from the bottom sludge of Sanaru Lake. Zinc, nickel and copper in the sludge were successfully removed, but lead and chromium were hardly able to remove from the sludge. The simplified one-dimensional mathematical model was proposed. The prediction by the model was qualitatively agreed with the experimental result. (orig.)

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

OpenAIRE

Musa Ahmad; T.W. Tan

2017-01-01

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to ...

Monomeric banana lectin at acidic pH overrules conformational stability of its native dimeric form.

Directory of Open Access Journals (Sweden)

Javed M Khan

Full Text Available Banana lectin (BL is a homodimeric protein categorized among jacalin-related family of lectins. The effect of acidic pH was examined on conformational stability of BL by using circular dichroism, intrinsic fluorescence, 1-anilino-8-napthalene sulfonate (ANS binding, size exclusion chromatography (SEC and dynamic light scattering (DLS. During acid denaturation of BL, the monomerization of native dimeric protein was found at pH 2.0. The elution profile from SEC showed two different peaks (59.65 ml & 87.98 ml at pH 2.0 while single peak (61.45 ml at pH 7.4. The hydrodynamic radii (R h of native BL was 2.9 nm while at pH 2.0 two species were found with R h of 1.7 and 3.7 nm. Furthermore at, pH 2.0 the secondary structures of BL remained unaltered while tertiary structure was significantly disrupted with the exposure of hydrophobic clusters confirming the existence of molten globule like state. The unfolding of BL with different subunit status was further evaluated by urea and temperature mediated denaturation to check their stability. As inferred from high Cm and ΔG values, the monomeric form of BL offers more resistance towards chemical denaturation than the native dimeric form. Besides, dimeric BL exhibited a Tm of 77°C while no loss in secondary structures was observed in monomers even up to 95°C. To the best of our knowledge, this is the first report on monomeric subunit of lectins showing more stability against denaturants than its native dimeric state.

The effect of antacid on salivary pH in patients with and without dental erosion after multiple acid challenges.

Science.gov (United States)

Dhuhair, Sarah; Dennison, Joseph B; Yaman, Peter; Neiva, Gisele F

2015-04-01

To evaluate the effect of antacid swish in the salivary pH values and to monitor the pH changes in subjects with and without dental erosion after multiple acid challenge tests. 20 subjects with tooth erosion were matched in age and gender with 20 healthy controls according to specific inclusion/exclusion criteria. Baseline measures were taken of salivary pH, buffering capacity and salivary flow rate using the Saliva Check System. Subjects swished with Diet Pepsi three times at 10-minute intervals. Changes in pH were monitored using a digital pH meter at 0-, 5-, and 10- minute intervals and at every 5 minutes after the third swish until pH resumed baseline value or 45 minutes relapse. Swishing regimen was repeated on a second visit, followed by swishing with sugar-free liquid antacid (Mylanta Supreme). Recovery times were also recorded. Data was analyzed using independent t-tests, repeated measures ANOVA, and Fisher's exact test (α= 0.05). Baseline buffering capacity and flow rate were not significantly different between groups (P= 0.542; P= 0.2831, respectively). Baseline salivary pH values were similar between groups (P= 0.721). No significant differences in salivary pH values were found between erosion and non-erosion groups in response to multiple acid challenges (P= 0.695) or antacid neutralization (P= 0.861). Analysis of salivary pH recovery time revealed no significant differences between groups after acid challenges (P= 0.091) or after the use of antacid (P= 0.118). There was a highly significant difference in the survival curves of the two groups on Day 2, with the non-erosion group resolving significantly faster than the erosion group (P= 0.0086).

Lake acidification in the Adirondack Mountains of New York causes and consequences

Science.gov (United States)

Carl L. Schofield

1976-01-01

Current and historic geographic distributions of acidity in Adirondack lakes were examined in relation to regional edaphic, climatic, and physiographic features. Acid conditions are currently predominant in high elevation drainage lakes having small watershed/surface area ratios. Comparable levels of acidity were found only in small seepage lakes and bog ponds during...

Chemical and biological quality of water in Grand Lake St. Marys, Ohio, 2011-12, with emphasis on cyanobacteria

Science.gov (United States)

Dumouchelle, Denise H.; Stelzer, Erin A.

2014-01-01

Grand Lake St. Marys (GLSM) is a shallow lake in northwest Ohio, which is about 9 miles long and 3 miles wide with depths averaging less than 8 feet. Cyanobacteria blooms are common in GLSM, and high concentrations of microcystins—toxins produced by cyanobacteria—have been documented therein. During 2011–12, the U.S. Geological Survey collected 11 sets of water samples at 6 locations in the lake. The water samples were analyzed for concentrations of nutrients, chlorophyll, and microcystin and to determine plankton community structure and abundance. Analysis by quantitative polymerase chain reaction (qPCR) and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was used to identify the relations between microcystin concentrations and Planktothrix and Microcystisgenotypes (toxic versus non-toxic). The qPCR analysis targets deoxyribonucleic acid (DNA) genes and quantifies the potential for toxin production, whereas the qRT-PCR analysis targets ribonucleic acid (RNA) transcripts and quantifies the expression of the toxin gene. Water samples were collected six times at one site for analyses of major ions and trace elements. In addition, field measurements were made to determine transparency, temperature, dissolved oxygen, pH, and specific conductance of the water.

Geochemical monitoring of volcanic lakes. A generalized box model for active crater lakes

Directory of Open Access Journals (Sweden)

Franco Tassi

2011-06-01

Full Text Available

In the past, variations in the chemical contents (SO42−, Cl−, cations of crater lake water have not systematically demonstrated any relationships with eruptive activity. Intensive parameters (i.e., concentrations, temperature, pH, salinity should be converted into extensive parameters (i.e., fluxes, changes with time of mass and solutes, taking into account all the internal and external chemical–physical factors that affect the crater lake system. This study presents a generalized box model approach that can be useful for geochemical monitoring of active crater lakes, as highly dynamic natural systems. The mass budget of a lake is based on observations of physical variations over a certain period of time: lake volume (level, surface area, lake water temperature, meteorological precipitation, air humidity, wind velocity, input of spring water, and overflow of the lake. This first approach leads to quantification of the input and output fluxes that contribute to the actual crater lake volume. Estimating the input flux of the "volcanic" fluid (Qf- kg/s –– an unmeasurable subsurface parameter –– and tracing its variations with time is the major focus during crater lake monitoring. Through expanding the mass budget into an isotope and chemical budget of the lake, the box model helps to qualitatively characterize the fluids involved. The (calculated Cl− content and dD ratio of the rising "volcanic" fluid defines its origin. With reference to continuous monitoring of crater lakes, the present study provides tips that allow better calculation of Qf in the future. At present, this study offers the most comprehensive and up-to-date literature review on active crater lakes.

Infectious pancreatic necrosis virus in fish by-products is inactivated with inorganic acid (pH 1) and base (pH 12).

Science.gov (United States)

Myrmel, M; Modahl, I; Nygaard, H; Lie, K M

2014-04-01

The aquaculture industry needs a simple, inexpensive and safe method for the treatment of fish waste without heat. Microbial inactivation by inorganic acid (HCl) or base (KOH) was determined using infectious pancreatic necrosis virus (IPNV) as a model organism for fish pathogens. Salmonella and spores of Clostridium perfringens were general hygiene indicators in supplementary examinations. IPNV, which is considered to be among the most chemical- and heat-resistant fish pathogens, was reduced by more than 3 log in 4 h at pH 1.0 and pH 12.0. Salmonella was rapidly inactivated by the same treatment, whereas spores of C. perfringens were hardly affected. The results indicate that low and high pH treatment could be particularly suitable for fish waste destined for biogas production. pH treatment at aquaculture production sites could reduce the spread of fish pathogens during storage and transportation without disturbing the anaerobic digestion process. The treatment could also be an alternative to the current energy-intensive steam pressure sterilization of fish waste to be used by the bioenergy, fertilizer and soil improver industries. © 2013 John Wiley & Sons Ltd.

pH effects of the addition of three biochars to acidic Indonesian mineral soils

DEFF Research Database (Denmark)

Martinsen, V; Alling, V; Nurida, N L

2015-01-01

of increasing amounts (0–30%; weight:weight) of three types of field-produced BCs (from cacao (Theobroma cacao. L.) shell, oil palm (Elaeis guineensis. Jacq.) shell and rice (Oryza sativa. L.) husk) on soil pH and CEC. Soils were sampled from croplands at Java, Sumatra and Kalimantan, Indonesia. All BCs caused...... a significant increase in mean soil pH with a stronger response and a greater maximum increase for the cacao shell BC addition, due to a greater acid neutralizing capacity (ANC) and larger amounts of extractable base cations. At 1% BC addition, corresponding to about 30 tons ha−1, the estimated increase in soil...... pH from the initial mean pH of 4.7 was about 0.5 units for the cacao shell BC, whereas this was only 0.05 and 0.04 units for the oil palm shell and rice husk BC, respectively. Besides depending on BC type, the increase in soil pH upon the addition of each of the three BCs was mainly dependent...

Embryonic common snapping turtles (Chelydra serpentina) preferentially regulate intracellular tissue pH during acid-base challenges.

Science.gov (United States)

Shartau, Ryan B; Crossley, Dane A; Kohl, Zachary F; Brauner, Colin J

2016-07-01

The nests of embryonic turtles naturally experience elevated CO2 (hypercarbia), which leads to increased blood PCO2  and a respiratory acidosis, resulting in reduced blood pH [extracellular pH (pHe)]. Some fishes preferentially regulate tissue pH [intracellular pH (pHi)] against changes in pHe; this has been proposed to be associated with exceptional CO2 tolerance and has never been identified in amniotes. As embryonic turtles may be CO2 tolerant based on nesting strategy, we hypothesized that they preferentially regulate pHi, conferring tolerance to severe acute acid-base challenges. This hypothesis was tested by investigating pH regulation in common snapping turtles (Chelydra serpentina) reared in normoxia then exposed to hypercarbia (13 kPa PCO2 ) for 1 h at three developmental ages: 70% and 90% of incubation, and yearlings. Hypercarbia reduced pHe but not pHi, at all developmental ages. At 70% of incubation, pHe was depressed by 0.324 pH units while pHi of brain, white muscle and lung increased; heart, liver and kidney pHi remained unchanged. At 90% of incubation, pHe was depressed by 0.352 pH units but heart pHi increased with no change in pHi of other tissues. Yearlings exhibited a pHe reduction of 0.235 pH units but had no changes in pHi of any tissues. The results indicate common snapping turtles preferentially regulate pHi during development, but the degree of response is reduced throughout development. This is the first time preferential pHi regulation has been identified in an amniote. These findings may provide insight into the evolution of acid-base homeostasis during development of amniotes, and vertebrates in general. © 2016. Published by The Company of Biologists Ltd.

Low pH, aluminum, and phosphorus coordinately regulate malate exudation through GmALMT1 to improve soybean adaptation to acid soils.

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Liang, Cuiyue; Piñeros, Miguel A; Tian, Jiang; Yao, Zhufang; Sun, Lili; Liu, Jiping; Shaff, Jon; Coluccio, Alison; Kochian, Leon V; Liao, Hong

2013-03-01

Low pH, aluminum (Al) toxicity, and low phosphorus (P) often coexist and are heterogeneously distributed in acid soils. To date, the underlying mechanisms of crop adaptation to these multiple factors on acid soils remain poorly understood. In this study, we found that P addition to acid soils could stimulate Al tolerance, especially for the P-efficient genotype HN89. Subsequent hydroponic studies demonstrated that solution pH, Al, and P levels coordinately altered soybean (Glycine max) root growth and malate exudation. Interestingly, HN89 released more malate under conditions mimicking acid soils (low pH, +P, and +Al), suggesting that root malate exudation might be critical for soybean adaptation to both Al toxicity and P deficiency on acid soils. GmALMT1, a soybean malate transporter gene, was cloned from the Al-treated root tips of HN89. Like root malate exudation, GmALMT1 expression was also pH dependent, being suppressed by low pH but enhanced by Al plus P addition in roots of HN89. Quantitative real-time PCR, transient expression of a GmALMT1-yellow fluorescent protein chimera in Arabidopsis protoplasts, and electrophysiological analysis of Xenopus laevis oocytes expressing GmALMT1 demonstrated that GmALMT1 encodes a root cell plasma membrane transporter that mediates malate efflux in an extracellular pH-dependent and Al-independent manner. Overexpression of GmALMT1 in transgenic Arabidopsis, as well as overexpression and knockdown of GmALMT1 in transgenic soybean hairy roots, indicated that GmALMT1-mediated root malate efflux does underlie soybean Al tolerance. Taken together, our results suggest that malate exudation is an important component of soybean adaptation to acid soils and is coordinately regulated by three factors, pH, Al, and P, through the regulation of GmALMT1 expression and GmALMT1 function.

Crystallogenesis of bacteriophage P22 tail accessory factor gp26 at acidic and neutral pH

Energy Technology Data Exchange (ETDEWEB)

Cingolani, Gino, E-mail: cingolag@upstate.edu; Andrews, Dewan [Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210 (United States); Casjens, Sherwood [Department of Pathology, Division of Cell Biology and Immunology, University of Utah Medical School, Salt Lake City, UT 84112 (United States); Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210 (United States)

2006-05-01

The crystallogenesis of bacteriophage P22 tail-fiber gp26 is described. To study possible pH-induced conformational changes in gp26 structure, native trimeric gp26 has been crystallized at acidic pH (4.6) and a chimera of gp26 fused to maltose-binding protein (MBP-gp26) has been crystallized at neutral and alkaline pH (7-10). Gp26 is one of three phage P22-encoded tail accessory factors essential for stabilization of viral DNA within the mature capsid. In solution, gp26 exists as an extended triple-stranded coiled-coil protein which shares profound structural similarities with class I viral membrane-fusion protein. In the cryo-EM reconstruction of P22 tail extracted from mature virions, gp26 forms an ∼220 Å extended needle structure emanating from the neck of the tail, which is likely to be brought into contact with the cell’s outer membrane when the viral DNA-injection process is initiated. To shed light on the potential role of gp26 in cell-wall penetration and DNA injection, gp26 has been crystallized at acidic, neutral and alkaline pH. Crystals of native gp26 grown at pH 4.6 diffract X-rays to 2.0 Å resolution and belong to space group P2{sub 1}, with a dimer of trimeric gp26 molecules in the asymmetric unit. To study potential pH-induced conformational changes in the gp26 structure, a chimera of gp26 fused to maltose-binding protein (MBP-gp26) was generated. Hexagonal crystals of MBP-gp26 were obtained at neutral and alkaline pH using the high-throughput crystallization robot at the Hauptman–Woodward Medical Research Institute, Buffalo, NY, USA. These crystals diffract X-rays to beyond 2.0 Å resolution. Structural analysis of gp26 crystallized at acidic, neutral and alkaline pH is in progress.

pH sensitivity of Swedish forest streams related to catchment characteristics and geographical location - Implications for forest bioenergy harvest and ash return

Science.gov (United States)

Ågren, Anneli; Löfgren, Stefan

2013-04-01

Whole-tree harvesting acidifies forest soils more than conventional harvest of stems. There is concern that this excess acidification will also affect surface waters and counteract the well-documented recovery from acid deposition in streams and lakes. Here we present a first attempt to identify the landscape types within Sweden where the streams are most sensitive to acidification and potentially in need of protection from excessive biomass harvest or countermeasures such as ash application. Conservative estimates indicate that forest slash must be harvested from >30 ha to produce the amount of ash needed to restore 1 ha acidified surface water. This highlights the need for careful planning of where ash should be distributed. Streams with a high pH are well buffered by the bicarbonate system and not sensitive to a potential pH decline. Streams with a low pH are also well buffered by dissolved organic carbon and aluminum and are not likely affected by bioenergy harvest. However, streams in the intermediate pH range (5-6.2) are potentially sensitive to acidification from excess base cation removal due to whole-tree harvesting. In such streams a small change in acid neutralizing capacity (ANC) can change pH dramatically. The pH sensitivity of 218 streams in different regions (northern, central, southern, and southwest Sweden) was defined from stream water pH and related to catchment characteristics and stream water acid-base chemistry. At the national level, catchments with till soils and a large proportion of forested wetlands formed the most pH sensitive areas. Because of regional variability in acidification history, amount and distribution of quaternary deposits, vegetation cover, etc. pH sensitivity was determined by different landscape elements in different regions. For example, in northern Sweden streams draining forest mires were the most pH sensitive streams. The patchy spatial distribution of this landscape type, makes it difficult from an administrative

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

International Nuclear Information System (INIS)

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

2014-01-01

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

Energy Technology Data Exchange (ETDEWEB)

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat [Faculty of Science and Technology, University Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Amin, Mohd. Cairul Iqbal Mohd [Faculty of Pharmacy, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia)

2014-09-03

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

Effect of urine pH changed by dietary intervention on uric acid clearance mechanism of pH-dependent excretion of urinary uric acid

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Kanbara Aya

2012-06-01

Full Text Available Abstract Background The finding reported in a previous paper - alkalization of urine facilitates uric acid excretion - is contradictory to what one might expect to occur: because food materials for the alkalization of urine contain fewer purine bodies than those for acidification, less uric acid in alkaline urine should have been excreted than in acid urine. To make clear what component of uric acid excretion mechanisms is responsible for this unexpected finding, we simultaneously collected data for the concentration of both creatinine and uric acid in serum as well as in urine, in order to calculate both uric acid and creatinine clearances. Methods Within the framework of the Japanese government’s health promotion program, we made recipes which consisted of protein-rich and less vegetable-fruit food materials for H + -load (acidic diet and others composed of less protein and more vegetable-fruit rich food materials (alkaline diet. This is a crossover study within some limitations. Healthy female students, who had no medical problems at the regular physical examination provided by the university, were enrolled in this consecutive 5-day study for each test. From whole-day collected urine, total volume, pH, organic acid, creatinine, uric acid, titratable acid and all cations (Na+,K+,Ca2+,Mg2+,NH4+ and anions (Cl−,SO42−,PO4− necessary for the estimation of acid–base balance were measured. In the early morning before breakfast of the 1st, 3rd and 5th experimental day, we sampled 5 mL of blood to estimate the creatinine and uric acid concentration in serum. Results and discussion Urine pH reached a steady state 3 days after switching from ordinary daily diets to specified regimens. The amount of acid generated ([SO42−] + organic acid − gut alkaliwas linearly related with the excretion of acid (titratable acid + [NH4+] − [HCO3−], indicating that H + in urine is generated by the metabolic degradation of

Intracellular pH regulation by acid-base transporters in mammalian neurons

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Ruffin, Vernon A.; Salameh, Ahlam I.; Boron, Walter F.; Parker, Mark D.

2014-01-01

Intracellular pH (pHi) regulation in the brain is important in both physiological and physiopathological conditions because changes in pHi generally result in altered neuronal excitability. In this review, we will cover 4 major areas: (1) The effect of pHi on cellular processes in the brain, including channel activity and neuronal excitability. (2) pHi homeostasis and how it is determined by the balance between rates of acid loading (JL) and extrusion (JE). The balance between JE and JL determine steady-state pHi, as well as the ability of the cell to defend pHi in the face of extracellular acid-base disturbances (e.g., metabolic acidosis). (3) The properties and importance of members of the SLC4 and SLC9 families of acid-base transporters expressed in the brain that contribute to JL (namely the Cl-HCO3 exchanger AE3) and JE (the Na-H exchangers NHE1, NHE3, and NHE5 as well as the Na+- coupled HCO3− transporters NBCe1, NBCn1, NDCBE, and NBCn2). (4) The effect of acid-base disturbances on neuronal function and the roles of acid-base transporters in defending neuronal pHi under physiopathologic conditions. PMID:24592239

Spontaneous aggregation of humic acid observed with AFM at different pH.

Science.gov (United States)

Colombo, Claudio; Palumbo, Giuseppe; Angelico, Ruggero; Cho, Hyen Goo; Francioso, Ornella; Ertani, Andrea; Nardi, Serenella

2015-11-01

Atomic force microscopy in contact (AFM-C) mode was used to investigate the molecular dynamics of leonardite humic acid (HA) aggregate formed at different pH values. HA nanoparticles dispersed at pH values ranging from 2 to 12 were observed on a mica surface under dry conditions. The most clearly resolved and well-resulted AFM images of single particle were obtained at pH 5, where HA appeared as supramolecular particles with a conic shape and a hole in the centre. Those observations suggested that HA formed under these conditions exhibited a pseudo-amphiphilic nature, with secluded hydrophobic domains and polar subunits in direct contact with hydrophilic mica surface. Based on molecular simulation methods, a lignin-carbohydrate complex (LCC) model was proposed to explain the HA ring-like morphology. The LCC model optimized the parameters of β-O-4 linkages between 14 units of 1-4 phenyl propanoid, and resulted in an optimized structure comprising 45-50 linear helical molecules looped spirally around a central cavity. Those results added new insights on the adsorption mechanism of HA on polar surfaces as a function of pH, which was relevant from the point of view of natural aggregation in soil environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cation-anion imbalance: Effect on PWR steam generator crevice pH - an acidic case study

International Nuclear Information System (INIS)

Paine, J.P.N.; Shoemaker, C.E.

1990-01-01

Ion exchange resins remove cations more efficiently than anions from feedwater to nuclear steam generators. The resulting imbalance is made up in the feedwater train by ammonia additions. In the steam generator, the ammonia is quickly flashed off leaving acid ions for an ionic balance. The almost pure water concentrates by boiling in heated crevices, in theory, to levels permitted by the available superheat (difference between primary and secondary temperatures). The concentrations may reach an ionic strength of greater than 20 molal on the hot leg, depending on bulk water concentration, time of steady state operation, fouling of crevice locations, and solubilities of the various salts, i.e., kinetic as well as thermodynamic considerations. While some of the acid species distill out of the crevices, more may be trapped by corrosive reactions. In the paper, theoretical crevice pH is calculated by MULTEQ. An attempt is made to relate pH to steady state operation time and crevice fouling. The data are normalized to be independent of bulk water concentration. Neutralization of the acid is explored

Crater lake and post-eruption hydrothermal activity, El Chichón Volcano, Mexico

Science.gov (United States)

Casadevall, Thomas J.; De la Cruz-Reyna, Servando; Rose, William I.; Bagley, Susan; Finnegan, David L.; Zoller, William H.

1984-01-01

Explosive eruptions of Volcán El Chichón in Chiapas, Mexico on March 28 and April 3–4, 1982 removed 0.2 km3 of rock to form a 1-km-wide 300-m-deep summit crater. By late April 1982 a lake had begun to form on the crater floor, and by November 1982 it attained a maximum surface area of 1.4 × 105 m2 and a volume of 5 × 106 m3. Accumulation of 4–5 m of rainfall between July and October 1982 largely formed the lake. In January 1983, temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115°C; by October 1983 the maximum temperature of fumarole emissions was 99°C. In January 1983 fumarole gas emissions were greater than 99 vol. % H2O with traces of CO2, SO2, and H2S. The water of the lake was a hot (T = 52–58°C), acidic (pH = 0.5), dilute solution (34,046 mg L−1 dissolved solids; Cl/S = 20.5). Sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits, together with less than 1% of elemental sulfur. The composition and temperature of the lake water is attributed to: (1) solution of fumarole emissions; (2) reaction of lake water with hot rocks beneath the lake level; (3) sediments washed into the lake from the crater walls; (4) hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement; (5) evaporation; and (6) precipitation.

Acidic pH shock induces the expressions of a wide range of stress-response genes

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Hong Soon-Kwang

2008-12-01

Full Text Available Abstract Background Environmental signals usually enhance secondary metabolite production in Streptomycetes by initiating complex signal transduction system. It is known that different sigma factors respond to different types of stresses, respectively in Streptomyces strains, which have a number of unique signal transduction mechanisms depending on the types of environmental shock. In this study, we wanted to know how a pH shock would affect the expression of various sigma factors and shock-related proteins in S. coelicolor A3(2. Results According to the results of transcriptional and proteomic analyses, the major number of sigma factor genes were upregulated by an acidic pH shock. Well-studied sigma factor genes of sigH (heat shock, sigR (oxidative stress, sigB (osmotic shock, and hrdD that play a major role in the secondary metabolism, were all strongly upregulated by the pH shock. A number of heat shock proteins including the DnaK family and chaperones such as GroEL2 were also observed to be upregulated by the pH shock, while their repressor of hspR was strongly downregulated. Oxidative stress-related proteins such as thioredoxin, catalase, superoxide dismutase, peroxidase, and osmotic shock-related protein such as vesicle synthases were also upregulated in overall. Conclusion From these observations, an acidic pH shock was considered to be one of the strongest stresses to influence a wide range of sigma factors and shock-related proteins including general stress response proteins. The upregulation of the sigma factors and shock proteins already found to be related to actinorhodin biosynthesis was considered to have contributed to enhanced actinorhodin productivity by mediating the pH shock signal to regulators or biosynthesis genes for actinorhodin production.

Biogeochemical processes and the diversity of Nhecolândia lakes, Brazil

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Teodoro I. R Almeida

2011-06-01

Full Text Available The Pantanal of Nhecolândia, the world's largest and most diversified field of tropical lakes, comprises approximately 10,000 lakes, which cover an area of 24,000 km² and vary greatly in salinity, pH, alkalinity, colour, physiography and biological activity. The hyposaline lakes have variable pHs, low alkalinity, macrophytes and low phytoplankton densities. The saline lakes have pHs above 9 or 10, high alkalinity, a high density of phytoplankton and sand beaches. The cause of the diversity of these lakes has been an open question, which we have addressed in our research. Here we propose a hybrid process, both geochemical and biological, as the main cause, including (1 a climate with an important water deficit and poverty in Ca2+ in both superficial and phreatic waters; and (2 an elevation of pH during cyanobacteria blooms. These two aspects destabilise the general tendency of Earth's surface waters towards a neutral pH. This imbalance results in an increase in the pH and dissolution of previously precipitated amorphous silica and quartzose sand. During extreme droughts, amorphous silica precipitates in the inter-granular spaces of the lake bottom sediment, increasing the isolation of the lake from the phreatic level. This paper discusses this biogeochemical problem in the light of physicochemical, chemical, altimetric and phytoplankton data.O Pantanal da Nhecolândia é o maior e mais diversificado campo de lagos da região tropical do planeta, com cerca de 10.000 lagos de variadas salinidade, pH, alcalinidade, cor, fisiografia e atividade biológica dispostos em uma área de 24.000 km². Os lagos hipossalinos têm pH variável, baixa alcalinidade, macrófitas e baixa densidade de fitoplâncton. Os lagos salinos tem pH acima de 9 ou 10, elevada alcalinidade, alta densidade de fitoplâncton e praias de areia. A causa da diversidade desses lagos é uma questão ainda em aberto que é abordada nesta pesquisa. Propõe-se como principal causa um

Effect of pH and chloroauric acid concentration on the geometry of gold nanoparticles obtained by photochemical synthesis

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Conde Rodríguez, G. R.; Gauthier, G. H.; Ladeira, L. O.; Sanabria Cala, J. A.; Laverde Cataño, D.

2017-12-01

Due to their excellent surface properties, gold nanoparticles have been used in a wide range of applications from optics and catalysis to biology and cancer treatment by thermal therapy. Gold nanoparticles can absorb a large amount of radiation according to their geometry, such as nanospheres and nanorods. The importance of gold nanoparticles geometry is based on the electromagnetic spectrum wavelength where exists a greater absorption of radiation, which belongs to the visible region for nanospheres and ranges between visible and near infrared regions for nanorods, conferring greater biomedical applicability to the latter. When using photochemical synthesis method, which consists of reducing gold atoms to their metallic state with UV radiation, the geometry of gold nanoparticles depends on different variables such as: 1) pH, 2) concentration of chloroauric acid, 3) the surfactant, 4) concentration of silver nitrate, 5) temperature and 6) irradiation time. Therefore, in this study the geometry of the gold nanoparticles obtained by photochemical synthesis was determined as a function of solution pH and chloroauric acid concentration, using Spectrophotometry in the Ultraviolet Visible region (UV-vis) as characterization technique. From the analysis of the UV-vis spectra, it was determined that at an acidic pH the particles have two absorption bands corresponding to nanorods geometry, while at a basic pH only nanospheres are found and at a neutral pH the lower relative intensity of the second band indicates the simultaneous existence of the two geometries. The increase in the concentration of chloroauric acid produces a decrease in the amount of synthesized nanorods, seen as a decrease of the relative intensity of the second absorption band. Therefore, obtaining gold nanoparticles with nanorods geometry favours fields such as biomedicine, because they are capable of absorbing infrared radiation and can be used as photosensitive agents in localized thermal therapy

Technologies for lake restoration

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Helmut KLAPPER

2003-09-01

Full Text Available Lakes are suffering from different stress factors and need to be restored using different approaches. The eutrophication remains as the main water quality management problem for inland waters: both lakes and reservoirs. The way to curb the degradation is to stop the nutrient sources and to accelerate the restoration with help of in-lake technologies. Especially lakes with a long retention time need (eco- technological help to decrease the nutrient content in the free water. The microbial and other organic matter from sewage and other autochthonous biomasses, causes oxygen depletion, which has many adverse effects. In less developed countries big reservoirs function as sewage treatment plants. Natural aeration solves problems only partly and many pollutants tend to accumulate in the sediments. The acidification by acid rain and by pyrite oxidation has to be controlled by acid neutralizing technologies. Addition of alkaline chemicals is useful only for soft waters, and technologies for (microbial alkalinization of very acidic hardwater mining lakes are in development. The corrective measures differ from those in use for eutrophication control. The salinization and water shortage mostly occurs if more water is used than available. L. Aral, L. Tschad, the Dead Sea or L. Nasser belong to waters with most severe environmental problems on a global scale. Their hydrologic regime needs to be evaluated. The inflow of salt water at the bottom of some mining lakes adds to stability of stratification, and thus accumulation of hydrogen sulphide in the monimolimnion of the meromictic lakes. Destratification, which is the most used technology, is only restricted applicable because of the dangerous concentrations of the byproducts of biological degradation. The contamination of lakes with hazardous substances from industry and agriculture require different restoration technologies, including subhydric isolation and storage, addition of nutrients for better self

Low urine pH and acid excretion do not predict bone fractures or the loss of bone mineral density: a prospective cohort study

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Lyon Andrew W

2010-05-01

Full Text Available Abstract Background The acid-ash hypothesis, the alkaline diet, and related products are marketed to the general public. Websites, lay literature, and direct mail marketing encourage people to measure their urine pH to assess their health status and their risk of osteoporosis. The objectives of this study were to determine whether 1 low urine pH, or 2 acid excretion in urine [sulfate + chloride + 1.8x phosphate + organic acids] minus [sodium + potassium + 2x calcium + 2x magnesium mEq] in fasting morning urine predict: a fragility fractures; and b five-year change of bone mineral density (BMD in adults. Methods Design: Cohort study: the prospective population-based Canadian Multicentre Osteoporosis Study. Multiple logistic regression was used to examine associations between acid excretion (urine pH and urine acid excretion in fasting morning with the incidence of fractures (6804 person years. Multiple linear regression was used to examine associations between acid excretion with changes in BMD over 5-years at three sites: lumbar spine, femoral neck, and total hip (n = 651. Potential confounders controlled included: age, gender, family history of osteoporosis, physical activity, smoking, calcium intake, vitamin D status, estrogen status, medications, renal function, urine creatinine, body mass index, and change of body mass index. Results There were no associations between either urine pH or acid excretion and either the incidence of fractures or change of BMD after adjustment for confounders. Conclusion Urine pH and urine acid excretion do not predict osteoporosis risk.

The chemical and biological response of two remote mountain lakes in the Southern Central Alps (Italy to twenty years of changing physical and chemical climate

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Andrea LAMI

2004-02-01

Full Text Available Two small high mountain lakes in the Alps were monitored in 1984-2003 to follow their response to changes in human impact, such as deposition of atmospheric pollutants, fish stocking and climate change. The results were compared to occasional samplings performed in the 1940s, and to the remains found in sediment cores. When monitoring started, the most acid-sensitive of them, Lake Paione Superiore, was acidified, with evident effects in its flora and fauna: benthic diatoms assemblage was shifted towards acidophilous species, and zooplankton lost the dominant species, Arctodiaptomus alpinus. Palaeolimnological studies outlined that lake acidification paralleled the increasing input of long-range transported industrial pollutants, traced by spherical carbonaceous particles. On the contrary, the biota of Lake Paione Inferiore appeared to be mainly affected by fish stocking. In the last twenty years, decrease in acid load from the atmosphere led to an improvement in lake water quality, with an increase in both pH and alkalinity. First signs of biological recovery were identified, such as change in diatom flora and appearance of sensitive species among benthic insects. However, climate change and episodic deposition of Saharan dust were important driving factors controlling lake water chemistry. Further monitoring to assess the effects of climate change and of the increasing load of nitrogen and other pollutants is recommended.

Modeling of acetate-type fermentation of sugar-containing wastewater under acidic pH conditions.

Science.gov (United States)

Huang, Liang; Pan, Xin-Rong; Wang, Ya-Zhou; Li, Chen-Xuan; Chen, Chang-Bin; Zhao, Quan-Bao; Mu, Yang; Yu, Han-Qing; Li, Wen-Wei

2018-01-01

In this study, a kinetic model was developed based on Anaerobic Digestion Model No. 1 to provide insights into the directed production of acetate and methane from sugar-containing wastewater under low pH conditions. The model sufficiently described the dynamics of liquid-phase and gaseous products in an anaerobic membrane bioreactor by comprehensively considering the syntrophic bioconversion steps of sucrose hydrolysis, acidogenesis, acetogenesis and methanogenesis under acidic pH conditions. The modeling results revealed a significant pH-dependency of hydrogenotrophic methanogenesis and ethanol-producing processes that govern the sucrose fermentative pathway through changing the hydrogen yield. The reaction thermodynamics of such acetate-type fermentation were evaluated, and the implications for process optimization by adjusting the hydraulic retention time were discussed. This work sheds light on the acid-stimulated acetate-type fermentation process and may lay a foundation for optimization of resource-oriented processes for treatment of food wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Treating cooling pond water for Wabamun Lake level mitigation project in Alberta