TURNOVER OF PARTICULATE MATTER IN A BALTIC ESTUARY

The turnover of particulate material in Gardsfjarden, a semi-enclosed, non-tidal estuary of the Baltic Sea, was studied during 1 year. Large temporal variation characterized the particle dynamics. The estuary h ad a stable stratification during most of the year, being mainly contr olled by temperature. Under stratified conditions, inflowing particula te material of fluvial origin was largely transported straight through the estuary to the sea. At the spring and autumn turnover of the wate r column, there was a net erosion of the surface sediment due to re-su spension. Barotrophically forced seawater intrusions destabilized the stratification on a few occasions in the summer, and probably more oft en in the winter, causing increased retention of suspended particulate matter in the summer, and increased re-suspension and erosion of the surface sediment in the winter. The morphology of the basin, the bi-an nual turnover of the water column and irregular seawater intrusions we re the three most important factors governing the turnover of particul ate material in Gardsfjarden. (C) 1997 Academic Press Limited.