Radiation emitted from deep-sea ferromanganese crusts from the Rio Grande Rise (South Atlantic): Safety protocols and isotopic dating

• Grant number: 24/08619-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2024
• End date: October 31, 2027
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Carina Ulsen
• Grantee: Muhammad Bin Hassan
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Ferromanganese (FeMn) crusts are polymetallic oxides that typically accrete on deep-sea elevations by deposition of colloids enriched in various chemical elements scavenged or coprecipitated from seawater. FeMn crusts are envisaged as a potential source of rare earth elements and critical metals of increasing economic interest. Despite its high economic potential, deep-sea mining may result in severe environmental impacts. Among these, the emission of radiation from marine FeMn oxides is one of the least studied. Deep-sea FeMn crusts scavenge naturally occurring uranium-series radioisotopes, emitting different types of radiation. This project aims to study the radioactivity of FeMn crusts from the Rio Grande Rise (S. Atlantic), a large oceanic elevation of critical economic importance for Brazil. The concentration of radionuclides and the emission of alpha, beta, and gamma radiation will be measured in layers of FeMn crusts of different ages, collected at different sites of the RGR during scientific cruises of the IO-USP. The emission of radioactive Radon gas (222Rn) will also be assessed, with the aim of informing safety protocols for handling FeMn crust samples in scientific laboratories and other workplaces. The results expected from this project are potentially relevant in terms of health safety, considering that the scientific interest in FeMn crusts is rising, both in Brazil and worldwide, increasing the number of researchers and students manipulating these materials. Furthermore, we will test the use of a novel dating method based on Osmium (Os) isotopes, to determine the formation age of FeMn crusts at the RGR. Accurate age determination plays a pivotal role in understanding the (paleo) environmental factors influencing the growth rate and the abundance of FeMn crusts in the South Atlantic Ocean.