Analysis of the Distribution of Suspended Particulate Matter, Bacteria, Chlorophyll a and PO4 in the Upper St. Lawrence Estuary, Using a Two-Dimensional Box Model

A box model was used to study the importance of biogeochemical vs physical processes on suspended particulate matter (SPM), attached and free bacteria, chlorophyll a and dissolved PO4 in the Upper St. Lawrence Estuary (USLE), Flux calculation revealed that SPM distribution was in a steady state and that the dynamics of attached bacteria were closely related to that of SPM. The estuary was a sink for free bacteria and chl a, whereas PO4 was essentially controlled by estuarine hydrodynamics. Turn-over time values showed that the upstream portion of the estuary was the most biogeochemically active.