Carol M. Parmenter | USGS Science

USGS2024

Talc in the suspended matter of the northwestern Atlantic

Knowledge of the distribution, concentration, and composition of suspended particulate matter in seawater is important to the understanding of sedimentation processes on the Continental Shelf. Because the surfaces of both organic and inorganic particles have high affinities for pollutants, such as certain trace metals, chlorinated hydrocarbons, and petroleum (Bothner et al., 1981a), suspended matter plays a major role in the transport and fate of pollutants introduced into shelf and coastal waters. Although the composition of bottom sediments on the shelf off the northeastern United States is reasonably well known, the mineralogical composition and distribution of inorganic suspended matter is less well studied.

Northwestern Atlantic↗

USGS1981

Temporal and spatial variations in suspended matter in continental shelf and slope waters off the north-eastern United States

Seston in waters of Georges Bank originates primarily from biological production and from resuspension of bottom sediments. The concentrations of suspended matter observed on the central shoals are more influenced by storms than by seasonal changes. Winter storms produce highest concentrations of non-combustible material throughout the water column, and summer storms appear to increase biological production by mixing additional nutrients into the photic zone. On the south-east flank of the bank, in water depths between 80 and 200 in, the concentrations of total suspended matter and non-combustible material show little variation compared with the central shoals, and storm effects are far less noticeable. Highest concentrations (>15 mg 1 −1 ) of suspended matter occur in bottom waters south of Nantucket Island after winter storms and appear to be primarily resuspended bottom sediment. Resuspended sediment is also common in near-bottom waters of the south-western Gulf of Maine, and occasionally near the intersection of the shelf/slope water mass front and the bottom. Seasonal variations were observed in the distribution and species composition of phytoplankton. Coccoliths are predominant on the central bank during the winter, but during the spring and summer they are concentrated on the eastern flank at deeper depths.

Georges Bank↗