Isotopes Illuminate Chemical Change: Boron Isotope pH Proxy

摘要

A driving force for the evolution of life on Earth is adaptation to environmental change. Basic chemical principles are used by geochemists to study the evolution of the Earth system, including ancient climate. Because there is no way to obtain climate information directly, geochemists rely on proxies, and isotopes have been particularly useful tools. Boron isotopes are promising as a proxy for ancient ocean pH and for understanding natural variations in atmospheric CO_2 concentrations, due to the tight coupling between the atmosphere and surface ocean. Proxies for CO_2, combined with temperature proxies, are important for understanding the natural relationships between global warming and atmospheric CO_2, and thus will aid models that seek to predict future warming. The development of any proxy requires an understanding of fundamental chemical principles including atomic structure, vibrational energies, aqueous speciation, and isotopic fractionation, all within a dynamic system that is perturbed by biological influences.