39. The N, O, S Isotopes of Oxy-Anions in Ice Cores and Polar Environments

For more than 60 years, ice from the polar caps has been used to unravel the evolution of our past climate and environment. Throughout technological improvements, climate researchers have gradually adapted their scientific tools to study the isotope content of the impurities present in it, with the hope to gather more and better information of the Earth’s shattered history. In this chapter, we present an overview of the techniques and studies which use stable isotope analysis to gain new insight. This domain has become so vast that we have limited our presentation to the recent analysis of the two major oxy-anions present in snow: sulfate and nitrate. These species are characteristic of the sulfur and nitrogen cycles. Describing the results obtained on ice without discussing the present atmosphere make little sense as ice is precisely used as a proxy for our past atmosphere. Consequently, beyond the analytical methods to measure the sulfur, nitrogen and oxygen isotopes of sulfate and nitrate, this chapter presents the results obtained at the interface between atmosphere, snow and ice with a focus on polar regions. The current state-of-the-art is presented for these two oxy-anions, including their non-mass-dependent isotope effects.