Some Physico-Chemical Investigations of Stratification in Abbot's Pool, Somerset: The Distribution of Some Dissolved Substances

Abstract

Chemical investigations of surface water from Abbot's Pool have been carried out since autumn 1962 (Karim 1965; Eaton 1967) and will be discussed by Eaton, Karim & Moss (in prep.). Briefly, this work indicated that the nutrient content of the water was high, reflecting the fertile nature of the catchment area (Moss 1967), and analysis of the phytoplankton (Karim 1965) and epipelic flora (Eaton 1967) demonstrated that many species present were characteristic of eutrophic waters. After the establishment of thermal stratification as a regular occurrence in summer together with extreme oxygen gradients both in winter and spring (Moss 1969; Happey 1970a, 1970b), investigations into the chemical content of the deeper water in the pool were made. Muller (1938), Einsele & Vetter (1938), Pearsall & Mortimer (1939) and Mortimer (1941, 1942) all demonstrated that the exhaustion of dissolved oxygen in the hypolimnion of a lake during thermal stratification is accompanied by reduction processes producing an increase in the concentration of dissolved substances, such as silica, phosphate and ammonia; but in a shallow water mass, such as Abbot's Pool, it was thought that chemical changes might not be as extreme as in larger deeper lakes.