David Dyrssen

SPECIES FORMED IN THE POTENTIOMETRIC TITRATION OF FLUORIDE WITH THORIUM OR LANTHANUM NITRATE AND FUNCTIONS SUITABLE FOR THE EVALUATION OF THE EQUIVALENCE POINTS.

Abstract Calculations by means of SILLENs HALTAFALL program have been performed on experimental curves by LINGANE for the potentiometric titration of fluoride with thorium and lanthanum in different media. After adjusting the stability constants for some of the main species formed during the titration a good fit was obtained between the experimental data and the calculated titration curves. In the cases where the solution was buffered with acetate it was necessary to consider the formation of mixed fluoride-acetate complexes. Suitable functions for the evaluation of the equivalence point could be derived from the calculations. If the functions: F 1 =( v 0 + v )[F - ] and F 3 =( v 0 + v )[F - ] -3 are used before and after the equivalence point, respectively, it ought to be possible to determine fluoride very accurately by titration with lanthanum nitrate in an unbuffered solution. A value proportional to [F - ] is obtained from 10 exp (—EF/RT In 10), the Nernst e.m.f. equation.

Framvaren and the Black Sea – Similarities and Differences

The following determinations in the Norwegian fjord Framvaren and the Black Sea have been compared: carbon-14, carbon-13, alkalinity, total dissolved inorganic carbon, sulfide, tritium (HTO), trace metals, silica, ammonium and phosphate. The historical development of the two anoxic basins is quite different. The carbon-14 age of the total inorganic dissolved carbonate in the deep water is 2000 years in the Black Sea, but only 1600 in Framvaren. The fresh water supply and composition are different. The rivers entering the Black Sea have a high alkalinity, but the river input and runoff to Framvaren has a very low alkalinity. The alkalinity, carbonate and sulfide concentrations in the anoxic waters below the chemoclines are much higher in Framvaren. This is mainly an effect of the different surface to volume ratios. The difference in carbon-13 (-8‰ for the Black Sea deep water, -19‰ in the Framvaren bottom water) is mainly due to the smaller imprint of the decomposition of organic matter on the Black Sea deep water.The concentration of trace metals in the particulate form are about the same in the deep water. About 76% of the molybdate in seawater is lost in the sulfidic water of Framvaren, and about 82–96% of the molybdate carried into the Black Sea by the Bosporus undercurrent is lost in the deep water. The relation between silica, ammonium and phosphate can be understood if part of the ammonium is being removed by denitrification, a process that most likely has been going on for thousands of years.

Time dependence of organic matter decay and mixing processes in Framvaren, a permanently anoxic fjord in South Norway

Three different layers have been identified in Framvaren, which has a maximum water depth of 184 m. One oxic layer above the redoxcline at 18–20 m. One anoxic layer from 20 to 100 m which is occasionally ventilated by a flow over the sill (which has a depth of 2.5 m), and finally a stagnant layer below 100 m. Using the release rate of silica from the bottom and measurements of the concentration of HTO it is possible to make some calculations on the annual volume of interleaving in the layers 25–50 m, 50–75 m, and 75–100 m together with the advective flows. Reliable values of the sulfide concentration were obtained by precipitating and weighing HgS together with careful protection of all anoxic water samples with argon. The light yellow color of the precipitate in the depth range 25 to 80 m indicates that the occasional ventilation will cause such reactions as 0.502 + H2S S(colloidal) + H2O. The elemental sulfur, being stabilized with HS−, is set free upon the precipitation of HgS. The new data for the concentration of sulfide give an acceptable stoichiometry for the decay reaction of organic matter. This is not the case with the data of Yao and Millero. The mean values for the concentrations of ammonium and phosphate agree with the new data of Yao and Millero. The mol/mol C/N ratio of 10.1 found in trapped material by Naess and coworkers (1988) agrees with the stoichiometry of the dissolved constituents, i.e. C/N = 9.92 ± 0.45. A denitrification reaction is suggested to explain the high values of C/N. The vertical diffusion coefficient at 100 m calculated from the depth profile of silica was 0.92 × 10−6 m2 s−1 which lies in the range of values given by Fröyland. Finally, the 14C age of the total dissolved inorganic carbon (Ct) in the water below 90 m was about 1600 years indicating a bioproduction in the period 8000 years B.P. to A.D. 1853 when a channel was opened between the fjord outside (Helvikfjord) and Framvaren.

Trace Metal Concentrations in the Anoxic Bottom Water of Framvaren

The landlocked Norwegian fjord Framvaren is NE of Farsund. The depest part, our sampling station at 180 m, is situated at 58°09.27′N and 6°45.0′E. Dr. Jens Skei at the Norwegian Institute of Water Research in Oslo started in 1979 an international cooperation on a major investigation of Framvaren of our times. Our poster at the Texel meeting showed the depth profiles of in situ temperature, density, oxygentotal sulphide, alkalinity, pH, loss of sulphate, phosphate, ammonia, and the trace metals (except mercury) in unfiltered water. In addition the values of δ34S for sulphate and sulphide were shown.

The biogeochemical cycling of carbon dioxide in the oceans--perturbations by man.

The purpose of the paper is to follow up the contribution by Dyrssen and Turner to the Hemavan meeting in 1993 on CO2 chemistry. Machtas treatment from 1971 of the role of oceans and biosphere in the carbon dioxide cycle is reviewed. Using data on the emission of CO2 and the atmospheric content in addition to the value recently presented by Takahashi et al. for the net sink for global oceans the following numbers have been calculated for the period 1990 to 2000, annual emission of CO2, 6.185 PgC (Petagram = 10(15) g). Annual atmospheric accumulation, 2.930 PgC. Annual sinks, 3.255 PgC. Net uptake for 1990 by the oceans, 1.151 PgC/year. Solubility pump into the mixed layer, 0.828 PgC/year. Residual input (e.g. riverborne), 0.323 PgC/year. Annual uptake by land phytomass, 2.104 PgC. In addition, perturbations involving irrigation and fertilization, limestone dissolution, iron and clathrate addition are mentioned.

The Source of Silica and Trace Metals in Particulate Matter in Framvaren Fjord

The lake and streams in the Framvarenwatershed were sampled and analyzed in September 1983.The results can be explained by the precipitation ofacid rain containing some sea salts and thedissolution of Farsundite, the dominating rock in thecatchment area. The runoff supplies the surface waterof Framvaren with silica, aluminium, manganese, iron,copper, zinc, cadmium and lead. Reasonablecalculations show that the runoff most likely is themain source for the particulate matter found insediment traps and by filtering off suspendedparticles. Thus the calculations supplement recentstudies of Skei et al. (1996).

Benthic chamber chemistry@@@Chemie der Benthalkammer

ZusammenfassungZur Beurteilung des Umsatzes von Substanzen und Spurenmetallen im Meer ist es von Bedeutung, die Freisetzung von Verunreinigungen und natürlichen Bestandteilen aus den Sedimenten in das Bodenwasser zu messen. Die Technik der Benthalkammer wird zusammenfassend dargestellt und die analytischen Methoden erwähnt, die zur Aufklärung der chemischen Reaktionen im Bodenwasser und der oberen Sedimentschicht benutzt werden. An zwei Beispielen wird die Wirkung von Benthalorganismen auf die Geschwindigkeit der Freisetzung gezeigt.SummaryThe release of pollutants and natural constituents from the sediments to the bottom water is an important flux measurement which is required in order to establish the turnover of substances and trace metals in the marine environment. The article summarizes the benthic chamber technique and the analytical methods used to establish the chemical reactions that occur in the bottom water and the top layer of the sediments. Two results illustrate the effect of benthic organisms on the release rates.

Stepwise Formation of Metal Complexes in Non-Aqueous Solvents

Stepwise complex formation in non-aqueous solvents is a much less frequent phenomena than in aqueous solutions, where the stepwise substitution of water molecules by mono-dentate ligands is a common process with hydrated metal ions. Experience from work with aqueous solutions demonstrates two essential factors for a study of stepwise complex formation: a) effective solvation, which dissociates the metalsalt MXm into M(H2O)n + and mX , b) the possibility to vary the central ion and the ligand concentration over a wide range. These two conditions are not so easy to realize in non-aqueous solvents, and this may be one reason why most stability constants have been determined in aqueous solutions. However, the knowledge of a metalligand system will be more complete if it is studied in several different media (states). the stability of a complex in water, may, for example, be due to a mixed ligand stabilization of a complex ML4 (H2O)2 , which is built into the water lattice. Two examples are taken here to illustrate this point and to demonstrate some techniques of studying stepwise complex formation in non aqueous solvents. Further material will be delivered at the conference.