Stable isotopes are used as tracers of geo(bio)logical processes and are an effective
tool for deciphering the evolution of the Earth System over time. Key concepts in this approach
include isotopic mass balance, isotope mixing, and thermodynamic and kinetic isotope
fractionation. Recently, stable isotopes have been applied in human physiology—the study of
functions and processes in the human body—to investigate a wide range of pathologies, such as
osteoporosis, cancer, and kidney diseases. I will present examples from both the earth and medical
sciences to demonstrate how these fundamental isotope concepts bridge the gap between these
seemingly disparate disciplines. In the earth sciences, I will address the processes that led to the
late-Miocene emplacement of the Mediterranean Salt Giant, one of Earth’s largest and most recent
giant salt deposits. Chloride isotopes (37Cl/35Cl) in halite support the hypothesis that an exceptional
sea-level drawdown event (~2 km) was associated with the accumulation of the Mediterranean salt
layer, while multiple sulfur isotopes (34S/32S and 33S/32S) suggest microbial processes may have
contributed to the formation of marginal gypsum deposits in the Vena del Gesso (central
Apennines, Italy). In the medical sciences, I will show how calcium isotopes (44Ca/42Ca) are used to
deduce whole-body bone mineral balance, an elusive quantity crucial for the early diagnosis of
osteoporosis, and how dissolved chloride isotopes are used in exploratory studies to investigate
the nature of certain kidney diseases. These examples illustrate that the modern separation
between earth and medical sciences stems not from differences in underlying physical and
chemical laws but from the complexity of the studied systems, which require a highly specialized
training to be fully apprehended.
18/06/2024
Tuesday, June 18, 2024
3:30-4:15 p.m.
Lucchesi Classroom (Mineralogy Entrance - CU005)
Seminar: Stable isotope tracers from Earth System Science to human physiology
Giovanni Aloisi
Institut de Physique du Globe de Paris - Université Paris Cité - CNRS
1, rue Jussieu, 75005 Paris, France