Phosphate adsorption by different sediment fractions in Lake Balaton and its protecting reservoirs

• Published in: Water research (Oxford) 1989-11, Vol.23 (11), p.1357-1366
• Main Authors: Istvánovics, Vera, Herodek, Sándor, Szilágyi, Ferenc
• Format: Article
• Language: English
• Subjects: Freshwater; internal loading; isotopic exchange; Langmuir isotherm; phosphate saturation
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/0043-1354(89)90074-2

Adsorption of phosphate by sediments could be described by the Langmuir isotherm. The adsorption capacity of the sediments increased with their NaOH-extractable iron content, and the energy of adsorption was proportional to their calcite content. Increasing phosphate saturation of the sediments could be demonstrated near the inlet of the Zala River into the Kis-Balaton reservoir, as a result of high external loading. Phosphate saturation of the sediments remained similar in the hypertrophic and mesotrophic basins of Lake Balaton. This was explained by the continuous renewal of calcite, the main phosphate sorbent in this calcareous lake. A comparison of the interstitial SRP concentration and the adsorption/desorption concentration limit, derived from the Langmuir isotherm, indicated that sorption is of major importance in regulation of the interstitial phosphate concentration. In Lake Balaton desorption occurs whenever the sediments are resuspended; adsorption takes place only in the sediments. In the two reservoirs, adsorption and biotic uptake are equally important in the removal of phosphorus from the water, depending on the actual loading and primary production.