Aluminum control of phosphorus sorption by lake sediments.
Release of reactive (phosphate-like) phosphorus (P) from freshwater sediments represents a significant internal P source for many lakes. Hypolimnetic P release occurs under reducing conditions that cause reductive dissolution of ferric hydroxide [Fe(OH)3]. This hypolimnetic P release may be naturally low or artificially reduced by sediment with naturally high or artificially elevated concentrations of aluminum hydroxide [Al(OH)3]. We presentfield and laboratory data for a common extraction analysis of sediments from 43 lakes differing in trophic status, pH regime, climate, and P loading. The results indicate that a simple sequential extraction of sediment may be a useful predictor of sediment's ability to release P. Sequential extractions of sediment P, Al, and Fe by water (H2O), bicarbonate-dithionite (BD), and NaOH (at 25 degrees C) showed that negligible amounts of P would be released from lake sediments during hypolimnetic anoxia if either (1) the molar Al(NaOH-25):Fe(BD) ratio is > 3 or (2) the molar Al(NaOH-25):P(H2O+BD) ratio is > 25. These ratios can be used as operational targets for estimation of sediment P release potential and Al dosing of P-rich sediment to prevent hypolimnetic P release under anoxic conditions.
Kopácek
Jirí
J
Hydrobiological Institute, Academy of Sciences of the Czech Republic, Faculty of Biological Sciences USB, Na Sádkách 7, 37005 Ceské Budĕjovice, Czech Republic. jkopacek@hbu.cas.cz
Borovec
Jakub
J
Hejzlar
Josef
J
Ulrich
Kai-Uwe
KU
Norton
Stephen A
SA
Amirbahman
Aria
A
D000536:Aluminum Hydroxide / Q000032:analysis / Q000378:metabolism; D001639:Bicarbonates; D004227:Dithionite; D005060:Europe; D005290:Ferric Compounds / Q000032:analysis / Q000378:metabolism; D005618:Fresh Water; D019015:Geologic Sediments / Q000032:analysis*; D009656:North America; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism*; D012972:Sodium Hydroxide; D014867:Water
D001639:Bicarbonates; D005290:Ferric Compounds; D014867:Water; D004227:Dithionite; D010758:Phosphorus; C021024:ferric hydroxide; D012972:Sodium Hydroxide; D000536:Aluminum Hydroxide