THE BEHAVIOR OF ALUMINUM IN WATERS OF THE MANDOVI ESTUARY, WEST-COASTOF INDIA

The concentration of dissolved Al in both the freshwater (similar to 0 .08-0.23 mu M) and seawater (less than or equal to 0.07 mu M) endmembe rs of the Mandovi estuary is low, the former being always greater in m agnitude than the latter. In high-salinity (> 10) waters an increase i n dissolved Al levels is conspicuous while it is uniform at salinities similar to 1-10. Although a removal of Al from solution in the low-sa linity region is apparent, the magnitude of this removal is, however, relatively small. On the contrary, a steady increase in concentration of dissolved Al downstream reveals a significant input of Al into the high-salinity waters of the mid-and lower estuary. The data indicate t hat the removal of dissolved Al onto riverine sediments tends to occur during the initial stages of estuarine mixing but with little or no n et permanent loss, as the sediments on resuspension release sorbed Al into solution. These observations suggest that sorption exchange proce sses dominate the geochemical interactions of Al in estuarine waters.