Denitrification and ocean stratification during the last millennium in the oxygen minimum zone from Mexican Pacific
Periodo de realización: 0001/01/01 al 2019/01/01
Tipo: Artículo científico
Lugar(es) de estudio: Bahía Magdalena, Punta Banda I, 22890 Ensenada, B.C., México
Resumen: "The oceanographic reconstructions show different results on the mean state ocean conditions that predominate in the Medieval Climatic Anomaly and the Little Ice Age in the eastern margin of the Equatorial and North Pacific. Some records suggest for the Little Ice Age oceanographic conditions to El Niño-like but other records indicate oceanographic conditions to La Niña-like. In this work new data of d15N of the organic matter and d18O of Orbulina universal are presented with the purpose of determining changes in the denitrification conditions and thermal structure of the water column during the middle and late Holocene. A sediment core of 42 cm was collected within the oxygen minimum zone at 700 m depth in the Magdalena margin, front to the southwestern coast of peninsula Baja California. Stable nitrogen isotopes of organic matter and stable oxygen isotopes in O. universal were analysed every centimeter in an elemental analyser and Gasbench II, respectively, coupled to isotope ratio mass spectrometry. In the Little Ice Age, d15N of the organic matter indicated that it was characterized by a lower denitrification and stratified water column suggesting the advection of water mass of tropical origin, oceanographic conditions to the El Niño-like"