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Forms and Mobility of Sediment Phosphorus in Shallow Eutrophic Lake Võrtsjärv (Estonia)
Author(s) -
Nõges Peeter,
Kisand Anu
Publication year - 1999
Publication title -
international review of hydrobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 1434-2944
DOI - 10.1002/iroh.199900027
Subject(s) - eutrophication , sediment , phosphorus , anoxic waters , environmental chemistry , phosphate , aeration , nutrient , hydrology (agriculture) , chemistry , environmental science , geology , geomorphology , geotechnical engineering , organic chemistry
Abstract The surficial sediment (0–10 cm) of shallow eutrophic Lake Võrtsjärv (Estonia) was characterized by an acid insoluble residue of 50% dry weight and low nutrient, Fe and Mn content. Among phosphorus (P) fractions (H ieltjes and L ijklema , 1980), NaOH‐NRP amounted on an average to 50%, HCl‐RP to 30%, NaOH‐RP to 16%, and NH 4 Cl‐RP to 4% of their sum. Seasonal changes in sediment P content were inconsistent with mass balance calculations and could be attributed to sediment redistribution caused by decreasing water level. High Fe/P ratio (26–30) and the aeration of surficial sediment by frequent resuspension kept phosphate adsorbed. Low pore‐water SRP (commonly <10 μg l −1 ) usually prevented phosphate release from surficial sediment. However, a storm in September 1996 (max. wind speed 16 m s −1 ) which coincided with the extremely low water level in the lake (mean depth 1.44 m), denuded deeper anoxic sediment layers and caused a SRP release of 193 mg P m −2 d −1 .