Dissolved-particulate interactions of aluminium in ocean waters
Abstract
Two N. Atlantic profiles of dissolved Al are reported, they show an increase in Al concentration with depth as reported previously for the central Arctic Ocean ( MOORE, 1981) and for the N.W. Atlantic below 1000 m ( HYDES, 1979). Laboratory experiments were carried out to investigate the effect of pressure on the equilibrium between dissolved Al and pelagic, red clays. These studies showed an increase in dissolved Al with increasing pressure; e.g. at 1000 atm. the concentration of Al in solution increased by about 30% in two days. It was also observed that when the pressure was released the excess dissolved Al was rapidly removed from solution onto the clays. Calculations of the effect of pressure on the equilibrium concentration of Al in the presence of Gibbsite show that the dissolution should be favoured by a pressure increase. Laboratory leaching experiments using dilute acid were also undertaken to assess the mobility of Al in atmospheric particulates. The results suggest that a significant proportion, up to 20%, of the Al is not strongly bound in mineral lattices: this figure represents the upper limit for the leachable fraction which greatly exceeds earlier estimates. These results improve our understanding of Al marine geochemistry by emphasising the importance of inorganic rather than biological processes in determining its oceanic distribution.
- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- February 1984
- DOI:
- 10.1016/0016-7037(84)90247-3
- Bibcode:
- 1984GeCoA..48..235M