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TitleSedimentary phosphate fractions related to calcite precipitation in an eutrophic hardwater lake (Lake Alserio, northern Italy)
AbstractP-fractional composition has been studied in a 64-cm long sediment core collected in an eutrophic hardwater lake (Lake Alserio, northern Italy) in an attempt to identify the main mechanisms (chemical or biologic) controlling CaCO3 precipitation in the water column. The results of the sedimentary phosphate fractionation showed that the most important P fraction was an organic fraction extracted with hot NaOH: org-Palkali (26% of Psed). A digestion of the supernatant of the P-fraction bound to CaCO3 allowed the detection of a large pool of org-P (19% of Psed). Although the nature of this fraction is unclear, we suggest that it may be involved in the biologically mediated precipitation of CaCO3. The high CaCO3 concentration in the entire vertical sediment profile, as well as the presence of inorg- and org-P bound to Ca in both laminated and non-laminated zones, suggest that the CaCO3 precipitation is not a recent process but is a process that has been occurring in the lake for some time. Accordingly, the change from a homogeneous sediment to a laminated sequence might be caused by the eutrophication process of Lake Alserio occurring since the 1960s, which has allowed the preservation of the varved sediment as a consequence of the drastic reduction in bioturbation.
SourceJournal of paleolimnology 35, pp. 55–64
KeywordsCalciteCoprecipitationFractionationPhosphateSediment
JournalJournal of paleolimnology
EditorKluwer Academic, Boston, Paesi Bassi
Year2006
TypeArticolo in rivista
DOI10.1007/s10933-005-6786-2
Authorsde Vincente I.(1); Cattaneo K.; Cruz-Pizarro l.(1); Brauer A.(2); Guilizzoni P.
Text52926 2006 10.1007/s10933 005 6786 2 ISI Web of Science WOS 000233939300004 Calcite Coprecipitation Fractionation Phosphate Sediment Sedimentary phosphate fractions related to calcite precipitation in an eutrophic hardwater lake Lake Alserio, northern Italy de Vincente I. 1 ; Cattaneo K.; Cruz Pizarro l. 1 ; Brauer A. 2 ; Guilizzoni P. 1 Instituto del Agua, Universidad de Granada, Granada, Spain; 2 GeoForschungsZentrum Postdam, Projektbereich 3.3, Postdam, Germany P fractional composition has been studied in a 64 cm long sediment core collected in an eutrophic hardwater lake Lake Alserio, northern Italy in an attempt to identify the main mechanisms chemical or biologic controlling CaCO3 precipitation in the water column. The results of the sedimentary phosphate fractionation showed that the most important P fraction was an organic fraction extracted with hot NaOH org Palkali 26% of Psed . A digestion of the supernatant of the P fraction bound to CaCO3 allowed the detection of a large pool of org P 19% of Psed . Although the nature of this fraction is unclear, we suggest that it may be involved in the biologically mediated precipitation of CaCO3. The high CaCO3 concentration in the entire vertical sediment profile, as well as the presence of inorg and org P bound to Ca in both laminated and non laminated zones, suggest that the CaCO3 precipitation is not a recent process but is a process that has been occurring in the lake for some time. Accordingly, the change from a homogeneous sediment to a laminated sequence might be caused by the eutrophication process of Lake Alserio occurring since the 1960s, which has allowed the preservation of the varved sediment as a consequence of the drastic reduction in bioturbation. 35 Sedimentary phosphate fractions related to calcite precipitation in an eutrophic hardwater lake Lake Alserio, northern Italy JOPL_Ada_Alserio.pdf Articolo in rivista Kluwer Academic 0921 2728 Journal of paleolimnology Journal of paleolimnology J. paleolimnol. piero.guilizzoni GUILIZZONI PIERO TA.P02.005.002 Uso della paleolimnologia come strumento per lo studio del paleoclima e dell evoluzione climatica