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. Machta's 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.

Carbon Dioxide Transport by Ocean Currents at 25{degrees}N Latitude in the Atlantic Ocean.

Measured concentrations of CO(2), O(2), and related chemical species in a section across the Florida Straits and in the open Atlantic Ocean at approximately 25 degrees N, have been combined with estimates of oceanic mass transport to estimate both the gross transport of CO(2) by the ocean at this latitude and the net CO(2) flux from exchange with the atmosphere. The northward flux was 63.9 x 10(6) moles per second(mol/s); the southward flux was 64.6 x 10(6) mol/s. These values yield a net CO(2) flux of 0.7 x 10(6) mol/s (0.26 +/- 0.03 gigaton of C per year) southward. The North Atlantic Ocean has been considered to be a strong sink for atmospheric CO(2), yet these results show that the net flux in 1988 across 25 degrees N was small. For O(2) the equivalent signal is 4.89 x 10(6) mol/s northward and 6.97 x 10(6) mol/s southward, and the net transport is 2.08 x 10(6) mol/s or three times the net CO(2) flux. These data suggest that the North Atlantic Ocean is today a relatively small sink for atmospheric CO(2), in spite of its large heat loss, but a larger sink for O(2) because of the additive effects of chemical and thermal pumping on the CO(2) cycle but their near equal and opposite effects on the CO(2) cycle.

Complexation of aluminum with DNA.

The extent of complexation of aluminum(III) with DNA (Calf thymus, Sigma type I) was estimated by means of two experimental techniques: potentiometric titration with a fluoride selective indicator electrode and dialysis followed by aluminum determination by graphite furnace AAS. Both types of experiments indicate that aluminum(III) is bound to DNA. The data are treated by assuming an ion exchange reaction with the phosphate diester groups. Using Rt to denote the concentration of these groups the values of log [AlMn-3R]/(Rt-3[AlMn-3R])[Al3+] decrease from approx. 7.6 to 5.6 when the concentration of sodium chloride is increased from 1 to 100 mM. In the pH range 4.5-5.5 the ion exchange constant increases approximately 0.5 log units. Dialysis gives lower values for the complex formation constant than potentiometry.