The influence of the physico-chemical composition of bottom sediments on their sorption capacity in relation to phosphates

This paper presents the results of a research on the impact of the composition of bottom sediments on their phosphate sorption capacity under aerobic and anoxic conditions. The research was carried out in 2013-2016 with the use of bottom sediments from two small-scale retention reservoirs (the Ozanna reservoir and the Rzeszow reservoir). A physical and chemical analysis of the bottom sediments was carried out, which led to the conclusion that the sediments deposited at the bottom of the examined water bodies differ both in terms of their physical properties and chemical composition. The isotherm best describing the course of phosphate sorption in the deposits of the examined reservoirs, as well as the theoretical maximum phosphate sorption capacity of the sediments (q(max)) under close-to-real conditions (i.e., on undisturbed sediment cores), were determined. The analysis of the results allowed to conclude that the phosphate sorption capacity of the sediments is influenced both by the aerobic conditions and the physical and chemical properties of the sediments, such as the granulometric composition, pH, organic matter content and the content of metals with which phosphorus forms sparingly soluble compounds.