Análise de isótopos de chumbo em componentes bióticos sedimentares da Ilha da Trindade (Brasil) como indicador de contaminação antrópica em ambientes pristinos

Abstract

This work reports Pb isotopic data carried out by Laser Ablation Inductively Coupled Plasma Mass Spectrometry, (LA-ICP-MS) obtained in sea-urchin spines from the Tartaruga and Príncipe beaches from Trindade Island (Brazil, South Atlantic Ocean). The selected or-ganisms are abundantly present in marine environments, including in this pristine area which is one of the very few sites with little influence from human activity. Their carbonate spines can be analyzed by LA-ICP-MS using carbonate reference material (e.g. NIST 610 and NIST 612). In order to assess the quality of marine environments using lead isotopes through bio-genic records, this work presents the first results of Pb isotopes for sea-urchins and results vary from 1.240 to 1.309 for 206Pb/207Pb and, from 2.120 to 2.232, for the 208Pb/206Pb. The rocks of the Trindade Island have an isotopic composition changing between 1.184 and 1.247, for the 206Pb/207Pb ratio, and between 2.035 to 2.080 for the 208Pb/206Pb ratio. The results sug-gest that the sea urchin spines isotopic values were mainly influenced by the local fuel burning generator (Tartaruga beach) and represent the South Atlantic Ocean signature (Principe beach). Results reveal the Brazil Current Pb isotope signature identifying background values in biogenic materials in pristine environment.