Forms and Mobility of Sediment Phosphorus in Shallow Eutrophic Lake Võrtsjärv (Estonia)

摘要: The surficial sediment (0-10 cm) of shallow eutrophic Lake Vortsjarv (Estonia) was characterized by an acid insoluble residue 50% dry weight and low nutrient, Fe Mn content. Among phosphorus (P) fractions (HIELTJES LIJKLEMA, 1980), NaOH-NRP amounted on average to 50%, HCl-RP 30%, NaOH-RP 16%, NH 4 Cl-RP 4% their sum. Seasonal changes in P content were inconsistent with mass balance calculations could be attributed redistribution caused decreasing water level. High Fe/P ratio (26-30) the aeration frequent resuspension kept phosphate adsorbed. Low pore-water SRP (commonly <10 μg l -1 ) usually prevented release from sediment. However, a storm September 1996 (max. wind speed 16 m s which coincided extremely level lake (mean depth 1.44 m), denuded deeper anoxic layers 193 mg -2 d .