Abstract:
The behaviour of dissolved Al in the Great Ouse estuary, in particular with respect to salinity, is complex. There is, however, evidence from field data as well as laboratory mixing experiments to suggest that flocculation and sorption mechanisms play important roles affecting the concentrations of dissolved Al during the early stages of estuarine mixing. In contrast, a near-buffering of dissolved Al occurs in the entire stretch of the estuary (salinity greater than 0.2) with concentrations varying around 1.4 mu g l(-1). This distribution and lack of variation with salinity is attributable to sorption processes which might dominate over other processes in these turbid estuarine waters (suspended particulate load 48-888 mg l(-1)) impacting dissolved Al levels. Sorption models have been developed for both dissolved and leachable particulate Al concentrations in these waters. These observations provide compelling evidence of sorption processes that might be important in the geochemistry of Al in estuarine waters.
