论文信息 - The ammonia-ammonium equilibrium in seawater at temperatures between 5 and 25°C

The ammonia-ammonium equilibrium in seawater at temperatures between 5 and 25°C

The stability constantK1of the equilibrium NH3+H+⇌NH4+ was determined by potentiometric titration in synthetic seawaters of 5 to 40‰ (per mille) salinity and sodium chloride solutions between 0.2 and 0.7M ionic strength at temperatures of 5, 15 and 25°C. Moreover,K1was determined in sulfate-free seawater of 35‰ salinity and 25°C. The dependence of logK1on salinity (or ionic strength) and temperature can be reasonably well described by linear relations. TheK1obtained for sulfate-free seawater agrees very well with earlier experimental results and theoretical predictions. From the measuredK1and literature data on the equilibrium NH3(atm)⇌NH3(aq., NaCl), the atmospheric concentration of ammonia at equilibrium with seawater was estimated.

Olof Johansson | M. Wedborg | O. Johansson | Margareta Wedborg

[1] M. Whitfield,et al. The Hydrolysis of Ammonium Ions in Sea Water-a Theoretical Study , 1974, Journal of the Marine Biological Association of the United Kingdom.

[2] K. Leander,et al. The Determination of Dissociation Constants of Carbonic Acid in Synthetic Sea Water in the Salinity Range of 20--40 ‰ and Temperature Range of 5--30 degrees C. , 1973 .

[3] R. Bates,et al. Acidic dissociation constant of ammonium ion at 0 to 50 C, and the base strength of ammonia , 1949 .

[4] K. H. Khoo,et al. Determination of hydrogen ion concentrations in seawater from 5 to 40.degree.C: standard potentials at salinities from 20 to 45% , 1977 .

[5] K. H. Khoo,et al. Thermodynamics of the dissociation of ammonium ion in seawater from 5 to 40°C , 1977 .

[6] T. Anfält,et al. PDP 11 computer system for the multiterminal processing of several analytical instruments in an interpretative language , 1975 .

[7] M. Wedborg,et al. Stability constants of phosphoric acid in seawater of 5–40‰ salinity and temperatures of 5–25°C , 1979 .

[8] D. Dyrssen,et al. Ionic medium effects in sea water — A comparison of acidity constants of carbonic acid and boric acid in sodium chloride and synthetic sea water , 1973 .