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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Microbial ecology 11 (1985), S. 289-298 
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A negative correlation between adsorption of low molecular weight organic acids and sugars onto a hydroxyapatite surface and biodegradation rates of the compounds in the presence of the mineral was observed. Qualitatively, the effect was the same whether the organics were equilibrated with the surface prior to the addition of organisms or the organisms were preattached to the surface. Glucose, acetic acid, succinic acid, glutamic acid, and citric acid showed equilibrium adsorption values ranging from 0–94% from a 2μM solution. Changes in both respiration and assimilation of the substrates in the presence of hydroxyapatite were inversely correlated with adsorption.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic geochemistry 1 (1995), S. 53-88 
    ISSN: 1573-1421
    Keywords: Anoxic waters ; the Framvaren fjord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In the summer of 1993, a number of chemical parameters (H2S, O2, pH, TA, TCO2, NH 4 + , PO 4 3− , SiO2, Mn2+ and Fe2+) were measured in the Framvaren Fjord, a permanently super-anoxic fjord in southern Norway. The extremely steep gradient of sulfide near the interface suggests that other than downward flux of oxygen, three other possible oxidants, particulate manganese and iron oxides, phototrophic sulfur oxidation bacteria and horizontally transported oxygen account for the oxidation of the upward flux of H2S. Water intrusion through the sill accounts for the temperature inflection above the interface, which, together with internal waves (Stigerbrandt and Molvaer, 1988), may cause fluctuations of the depth of interface. Significant gradients of hydrographic properties and chemical species between 80–100 m suggest that there is a “second interface” at about 90 m that separates the deep and older bottom waters. A stoichiometric model is applied to examine the biogeochemical cycles of S, C, N and P in the Framvaren. High C:S, C:N and C:P ratios are found while the nutrients (N, P) have Redfield ratio. Based on the C:N:P ratio of 155:16:1 in organic matter, about 30% of sulfide produced by sulfate reduction is estimated to be removed by processes such as oxidation, formation of FeS2, degassing and incorporation into organic matter. The rates of oxidation of H2S by Mn and Fe oxides in the water near the interface were slightly faster than the observed values in the laboratory, probably due to the presence of bacteria.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic geochemistry 4 (1998), S. 1-2 
    ISSN: 1573-1421
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic geochemistry 4 (1998), S. 153-199 
    ISSN: 1573-1421
    Keywords: Activity coefficients ; activity ; ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract This paper reviews the present status of the Pitzer chemical equilibrium model, which can be used to characterize the one-atmosphere activity coefficients of ionic and non-ionic solutes in natural waters as a function of temperature and ionic strength. The model considers the ionic interactions of the major seasalt ions (H, Na, K, Mg, Ca, Sr, Cl, Br, OH, HCO3, B(OH)4, HSO4, SO4, CO3, CO2, B(OH)3, H2O) and is based on the 25 °C model of Weare and co-workers. The model has been extended by a number of workers so that reasonable estimates can be made of the activity coefficients of most of the major seasalt ions from 0 to 250 °C. Recently coefficients for a number of solutes that are needed to determine the dissociation constants of the acids from 0 to 50 °C (H3CO3, B(OH)3, H2O, HF, HSO 4 - , H3PO4, H2S, NH 4 + etc.) have been added to the model. These results have been used to examine the carbonate system in natural waters and determine the activity of inorganic anions that can complex trace metals. The activity and osmotic coefficients determined from the model are shown to be in good agreement with measured values in seawater. This model can serve as the foundation for future expansions that can examine the activity coefficient and speciation of trace metals in natural waters. At present this is only possible from 0 to 50 °C over a limited range of ionic strengths (〈1.0) due to the limited stability constants for the formation of the metal complexes. The future work needed to extend the Pitzer model to trace metals is discussed.
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  • 5
    ISSN: 1573-1421
    Keywords: dependence on medium of hydrolysis constants ; ΔH° for the hydrolysis of (CH3)2Sn2+ ; hydrolysis of (CH3)2Sn2+ ; Pitzer interaction parameters ; speciation of (CH3)2Sn2+ in natural waters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Hydrolysis constants of dimethyltin(IV) cation, in different salt solutions (CaCl2: 0.15 ≤ I ≤ 0.90; MgCl2: 0.30 ≤ I ≤ 0.60; NaCl-–NaClO4, NaCl-–NaNO3 mixtures: I = 3; NaCl-–Na2SO4 mixtures: I = 1 mol dm-3) were determined by potentiometric ([H+]-glass electrode) measurements. These data, together with previous data (De Stefano et al., 1996b) were interpreted in terms of DHT (Debye–Hückel type) and Pitzer equations. The mixed electrolyte solution results also allowed us to obtain Θ and Ψ parameters for the Pitzer equation. Calorimetric measurements were made at different ionic strengths in order to find the temperature dependence of hydrolysis constants and of the relative interaction parameters. The body of results allows us to determine the speciation of natural waters in a wide range of ionic strengths and temperatures.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic geochemistry 6 (2000), S. 1-17 
    ISSN: 1573-1421
    Keywords: lakes ; density ; compressibility ; expansibility ; conductivity ; stability ; pvt properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In recent years, a number of workers have studied the stability of deep lakes such as Lake Tanganyika, Lake Baikal and Lake Malawi. In this paper, the methods that can be used to determine the effect that the components of lakes have on the equation of state are examined. The PVT properties of Lakes have been determined by using apparent molal volume data for the major ionic components of the lake. The estimated PVT properties (densities, expansibility and compressibilities) of the lakes are found to be in good agreement with the PVT properties (P) of seawater diluted to the same salinity. This is similar to earlier work that showed that the PVT properties of rivers and estuarine waters could also be estimated from the properties of seawater. The measured densities of Lake Tanganyika were found to be in good agreement (± 2 × 10-6 g cm-3) with the values estimated from partial molal properties and the values of seawater at the same total salinity (ST = 0.568‰). The increase in the densities of Lake Tanganyika waters increased due to changes in the composition of the waters. The measured increase in the measured density (45 × 10-6 g cm-3) is in good agreement (46 × 10-6 g cm-3) with the values calculated for the increase in Na+, HCO3 -, Mg2+, Ca2+ and Si(OH)4. Methods are described that can be used to determine the conductivity salinity of lakes using the equations developed for seawater. By combining these relationships with apparent molal volume data, one can relate the PVT properties of the lake to those of seawater.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 1 (1972), S. 309-327 
    ISSN: 1572-8927
    Keywords: Effect of pressure ; ionization of water ; molal volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molal volumes of dilute (0.002 to 1.0m) aqueous HCl and NaOH solutions have been determined at 0, 25, and 50°C and NaCl solutions at 50°C. The partial molal volumes ( $$\bar V$$ ) of HCl, NaOH, and NaCl solutions have been determined from these apparent molal volumes and other reliable data from the literature. The partial-molal-volume changes ( $$\Delta \bar V_1 $$ ) for the ionization of water, H2O→H++OH−, have been determined from 0 to 50°C and 0 to 1m ionic strength from the partial molal volumes of HCl, NaOH, NaCl, and H2O. The partial molal compressibilities ( $$\bar K$$ for HCl, NaOH, NaCl, and H2O have been estimated from data in the literature and used to determine the partial molal compressibility changes ( $$\Delta \bar K_1 $$ ) for the ionization of water from 0 to 50°C and 0 to 1m ionic strength. The effect of pressure on the ionization constant of water has been estimated from partial-molal-volume and compressibility changes using the relation $$RTln(K^P /K) = - \Delta \bar V(P - 1) + \tfrac{1}{2}\Delta \bar K(P - 1)^2 $$ from 0 to 50°C and 0 to 2000 bars. The results agree very well with the directly measured values.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 20 (1991), S. 361-373 
    ISSN: 1572-8927
    Keywords: Ionization ; sulfurous acid ; Pitzer equations ; solubility ; NaMgCl ; SO2 ; activity coefficient ; ion pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stoichiometric pK 1 * and pK 2 * for the ionization of sulfurous acid has been determined from emf measurements in NaCl solutions with varying concentrations of added MgCl2 (m=0.1, 0.2 and 0.3) from I=0.5 to 6.0 molal at 25°C. These experimental results have been treated using both the ion pairing and Pitzer's specific ion-interaction models. The Pitzer parameters for the interaction of Mg2+ with SO2 and HSO 3 − yielded λ=0.085±0.004, β(0) = 0.35±0.02, β(1) = 1.2±0.04, and Cφ = −0.072±0.007. The Pitzer parameters β(0) = −2.8±0.4, β(1) = 12.9±2.9 and β(2) = −2071±57 have been determined for the interactions of Mg2+ with SO 3 2− . The calculated values of pK 1 * and pK 2 * using Pitzer's equations reproduce the measured values to within ±0.04 pK units. The ion pairing model with log KMgSO3=2.36±0.02 and logγMgSO3 = 0.1021, reproduces the experimental values of pK 2 * to ±0.01. These results demonstrate that treating the data by considering the formation of MgSO3 yields a better fit of the experimental measurements with fewer adjustable parameters. With these derived coefficients obtained from the Pitzer equations and the ion pairing model, it is possible to make reliable estimates of the activity coefficients of HSO 3 − and SO 3 2− in seawater, brines and marine aerosols containing Mg2+ ions.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 6 (1977), S. 589-607 
    ISSN: 1572-8927
    Keywords: Lanthanum sulfate ; magnetic float densimeter ; sound velocimeter ; density ; apparent molal volume ; adiabatic apparent molal compressibility ; ion pair ; electrostriction ; hydration number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molal volumes (φv) and adiabatic compressibilities [φK(S)] of La2(SO4)3 solutions have been determined from density and sound speed data at 25°C. The large positive deviations of φv and φK(S) of La2(SO4)3 from the limiting law have been attributed to the formation of the ion pair LaSO 4 + . The observed values of φv and φK(S) have been used to estimate the change in the apparent molal volume and adiabatic compressibility for the formation of LaSO 4 + from $$\Delta \phi (LaSO_4^ + ) = [\phi (obs.) - \phi (2La^{3 + } ,3SO_4^{2 - } )]/\alpha$$ where ϕ(2La3+, 3SO 4 2− ) is the apparent molal volume or adiabatic compressibility of the free ions, and α is the degree of association. The value of $$\Delta \phi _v^o (LaSO_4^ + ) = \Delta \bar V^o (LaSO_4^ + ) = 22.8 \pm 1cm^3 - mole^{ - 1}$$ and $$\Delta \phi _{K(S)}^o (LaSO_4^ + ) = \Delta \bar K_S^o (LaSO_4^ + ) = 85 \pm 20 \times 10^{ - 4} cm^3 - mole^{ - 1} - bar^{ - 1}$$ at infinite dilution are in reasonable agreement with the values determined from the high-pressure conductance data of Fisher and Davis. The number of hydrated water molecules (ca. 11) associated with the formation of LaSO 4 + determined from the volume and compressibility data are in good agreement.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 3 (1974), S. 417-430 
    ISSN: 1572-8927
    Keywords: Ionization of boric acid ; molal volume ; effect of pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent, φ v , and partial, $$\bar V_2 $$ molal volumes of dilute (0.02 to 0.7m) aqueous boric acid, B(OH)3, and sodium borate, NaB(OH)4, solutions have been determined from 0 to 50° C from precision density measurements. The φ v of boric acid is a linear function of the first power of concentration. For sodium borate, the Debye-Hückel theoretical limiting law slope for the φ v as a function of the square root of molar concentration is approached at all temperatures studied. The positive deviations at higher concentrations increase with decreasing temperature. The infinite-dilution volume properties of both B(OH)3 and NaB(OH)4 indicate that these solutes behave like “structure breakers” between 0 and 50°C (that is ∂2φ v ° /∂T2 is negative). The volume change for the ionization of boric acid in water $$\Delta \bar V^\circ $$ , is calculated from the volume data at various temperatures. This volume change has been used to estimate the effect of pressure on the ionization of boric acid solutions from 0 to 50°C and 0 to 1000 bars. The calculated effect of pressure on the ionization is in good agreement with direct measurements.
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