Temporal variations in dissolved and particulate aluminum during a spring bloom

Abstract

Dissolved and acetic acid leachable particulate Al ([Al] HAc) concentrations have been measured as a time series during a spring phytoplankton bloom in Bedford Basin off Nova Scotia, Canada. Two factors were observed to influence Al levels: the spring bloom and river runoff. Changes in dissolved Al and [Al] HAc associated with intense biological activity resulted in a 55–65 n m (40%) decrease in dissolved Al and a coincident similar increase in [Al] HAc over 15–20 days. The intensity of Al removal is apparently a function of biogenic particle loads. A pulse in river runoff caused dissolved Al to increase roughly 10 fold (up to 1130 n m) and [Al] HAc by nearly 4 fold (up to 175 n m) in the surface 5 m. These data indicate that biological activity can significantly alter concentrations of Al in coastal waters and distributions among dissolved and particulate forms. In the presence of strong sources, such as river runoff, these effects can be obscured.