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1.
Ideally, the correction of the measured CO2 fugacity (fCO2) at temperature Tm to fCO2 at the in-situ temperature Tin should be made by using at least 2 known parameters (pH-AT, CT-AT,…) and the reliable constants for carbonic acid. In practice however, a measured CO2 property pair is not always available. When fCO2 is measured alone, one must make an estimate of the effect of temperature on seawater fCO2 from the accurate knowledge of seawater salinity and temperature and the approximate knowledge of the carbonate parameters. In this paper we present an empirical relationship that can be used to estimate the effect of temperature on fCO2. The equation is of the form: where fCO2[t] and fCO2[20] represent fCO2 at temperatures t°C and 20°C, respectively; the parameters A, B, etc. are functions of the ratio X = CT/AT: where the parameters ai, bi, etc. are functions of salinity.The 25-parameter equation is fitted by the values of fCO2 calculated using the constants of Goyet and Poisson (1989), when X varies from 0.8 to 1.0, t varies from −1dgC to 40°C, and S varies from 30 to 40. For Tm - Tin within ± 10°C, direct measurements of fCO2 as a function of the temperature (from −I to 30°C verify this equation within less than ±5 μatm. 相似文献
ƒCO2[t] − ƒCO2[20]=A + Bt + Ct2 + Dt3 + Et4
E = e0 + e1X + e2X2ln(X) + e3exp(X) + e4/ln(X)
2.
Rabindra N Roy Lakshimi N Roy Kathleen M Vogel C Porter-Moore Tara Pearson Catherine E Good Frank J Millero Douglas M Campbell 《Marine Chemistry》1993,44(2-4)
The pK1* and pK2* for the dissociation of carbonic acid in seawater have been determined from 0 to 45°C and S = 5 to 45. The values of pK1* have been determined from emf measurements for the cell: where X is the mole fraction of CO2 in the gas. The values of pK2* have been determined from emf measurements on the cell: The results have been fitted to the equations: where T is the temperature in K, S is the salinity, and the standard deviations of the fits are σ = 0.0048 in lnK1* and σ = 0.0070 in lnK2*.Our new results are in good agreement at S = 35 (±0.002 in pK1*and ±0.005 in pK2*) from 0 to 45°C with the earlier results of Goyet and Poisson (1989). Since our measurements are more precise than the earlier measurements due to the use of the Pt, H2|AgCl, Ag electrode system, we feel that our equations should be used to calculate the components of the carbonate system in seawater. 相似文献
Pt](1 − X)H2 + XCO2|NaHCO3, CO2 in synthetic seawater|AgC1; Ag
Pt, H2(g, 1 atm)|Na2CO3, NaHCO3 in synthethic seawater|AgC1; Ag
lnK*1 = 2.83655 − 2307.1266/T − 1.5529413 lnT + (−0.20760841 − 4.0484/T)S0.5 + 0.08468345S − 0.00654208S1
InK*2 = −9.226508 − 3351.6106/T− 0.2005743 lnT + (−0.106901773 − 23.9722/T)S0.5 + 0.1130822S − 0.00846934S1.5
3.
The rates of the reduction of Cr(VI) with S(IV) were measured in deaerated NaCl solution as a function of pH, temperature and ionic strength. The rates of the reaction were found to be first order with respect to Cr(VI) and second order with respect to S(IV), in agreement with previous results obtained at concentrations two order higher than the present study. The reaction also showed a first-order dependence of the rates on the concentration of the proton and a small influence of temperature with an apparent energy of activation ΔHapp of 22.8 ± 3.4 kJ/mol. The rates were independent of ionic strength from 0.01 to 1 M. The rate of Cr(VI) reduction is described by the general expression
−d[Cr(VI)]/dt=k[Cr(VI)][S(IV)]2