ON DIFFERENCES IN CHEMICAL COMPOSITION OCCURRING BETWEEN SURFACE AND NEAR BOTTOM WATER IN THE SZCZECIN LAGOON

Abstract

The occurrence of differences in chemical composition between surface and near bottom water in the Great Szczecin Lagoon (Wielki Zalew) was studied between 1986-1994 under calm weather conditions, i.e. with the state of the Lagoon remaining <1ºB for at least three days. In the study 54 measurement series were obtained at 21 measurement stations and the measurements included: water temperature, dissolved oxygen concentration, pH and chlorinity taken at every 0.5-1.0 m on vertical profiles. At selected stations 7 series of day-round measurements were performed with sampling frequency of 2 hours. The selected water quality indicators (temperature, oxygen concentration, pH, Eh, chlorinity, alkalinity and nitrate concentration) were measured in the surface layer (0.5 m below the water surface) and 0.5 m above the bottom. It was found out that under calm conditions water of the Szczecin Lagoon undergoes chemical transformations similar to those in enclosed water bodies.

Key words: aquatic chemistry, estuary, Szczecin Lagoon