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Holocene palaeoenvironment in a former coastal lagoon of the arid south eastern Iberian Peninsula: salinization effects on delta N-15

By Marc Estiarte, Josep Peñuelas, Constancia López-Martínez and Ramón Pérez-Obiol

Abstract

8 páginas, 1 tabla, 2 figuras.The palaeoenvironment of a former coastal lagoon in the south eastern Iberian Peninsula (San Rafael, Almeria, Spain) were inferred from one core analyzed for particulate organic matter content (POM) together with its C/N, d 13 C, d 15 N to depict the biogeochemical record from the Late Glacial to the Holocene. The results, complemented by previously reported pollen assemblages, indicate the appearance of a freshwater lagoon at 7300 B.P. (uncalibrated 14 C age), its salinization at 6200 B.P. and its disappearance at 4400 B.P. The period of existence of the lagoon coincided with a period of wetter conditions as inferred from terrestrial vegetation. The lagoon’s salinization was not related to a decrease in precipitation but to a stronger maritime influence since there were no parallel changes in terrestrial vegetation. Salinization caused an increase in d 13 C, associated with a higher relative presence of C4 plants, and an increase in d 15 N, due to a decrease in plant N demand. The late period of the lagoon, from about 5100 to 4400 B.P., shows a progressive drying and salinization not detected in isotopes but reflected in a decrease in POM, and in the pollen records. Increases in d 15 N were related to increases in salinity within the lagoon, and are indicative of a more open N cycle, because the absence of changes in terrestrial vegetation rules out changes in the catchment area as the cause for changes in d 15 N.This research was supported by the Spanish Government projects REN2003-04871/GLO and CGL2004-01402/ BOS, the Catalan Government project SGR 2005-00312, the European projects ALARM (Contract 506675) and NUE (Contract 017841), and a Fundacio´n BBVA 2004 grant. Marc Estiarte acknowledges support from Spanish Ministerio de Educacio´n y Ciencia (Ramon y Cajal contract).Peer reviewe

Topics: Holocene, Mediterranean, Climate, Salinization, C/N, d 13 C, d 15 N
Publisher: 'Springer Science and Business Media LLC'
Year: 2008
DOI identifier: 10.1007/s00334-008-0153-y
OAI identifier: oai:digital.csic.es:10261/58751
Provided by: Digital.CSIC
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