Stable Isotope composition of the Río de La Plata estuary. An attempt to relate to meteorological variables

PANARELLO, HECTOR; DAPEÑA, CRISTINA

COMUNICACIONES - DEPARTAMENTO DE GEOLOGIA. FACULTAD DE CIENCIAS FISICAS Y MATEMATICAS. UNIVERSIDAD DE CHILE

Universidad de Chile

Lugar: Santiago, Chile; Año: 2001 vol. 52 p. 112 - 112

0069-357X

The Río de la Plata estuary is the collector of a vast drainage basin of about 3.1 x 10-6km2.  Their major tributaries are the Paraná, Paraguay and Uruguay rivers. The main course of the Paraná river starts at the "Planalto do Brasil", located at the central east Brazil. Pilcomayo and Bermejo rivers contribute to Paraná water from the high Andes range.  Paraguay river release water coming from the Mato Grosso.  The Uruguay river, directly and the Iguazú river through the Paraná, also contribute water from braziliam east coastal hills to the estuary.  Less significant are other rivers like the Salado, Negro, etc. The objective of this work is to study the variations isotopic composition of the Río de la Plata river and its correlation with the ITCZ , ENSO and other meteorological phenomena.  The methodoly consists in the monthly collection of a 2 liter sample in the estuary and the measurement of 18-O and 2-H concentration. An aliquot is reserved for further  tritium analysis .In this first report 40 isotope analysis for the Río de la Plata estuary have been presented. Cyclical variations of oxygen isotopes, with minima in winter and maxima in summer has been observed. 2-H excess also change cyclicaly, probably with  longer period of time. We are gathering data for a more detailed and longer record in order to estasblish a fine correlation of the isotopic composition with the ITCZ seasonality and the ENSO phenomena.