Advancing the use of noble gases as paleoclimate indicators

Noble gases are established tools for paleotemperature reconstruction from the groundwater archive. However, the reliability of the derived temperatures depends on our ability to understand and correctly account for excess air in groundwater. Furthermore, other potential archives for the noble gas method are increasingly being studied. This project aims to develop and advance these current approaches in noble gas thermometry.

"Official" project information:

title: Advancing the use of noble gases as paleoclimate indicators (ADNOGAPALIN)

funding: EU, Marie Curie Fellowship (EIF)

Abstract:

The analysis of dissolved noble gas concentrations in groundwater has proven to be a reliable method to determine quantitative paleotemperatures. Noble gas studies in semi-arid regions have shown that in addition to recharge temperatures, the "excess air" phenomenon may be useful as a proxy for the important climate parameter humidity. A better understanding of gas partitioning during groundwater infiltration is a prerequisite for the reliable use of noble gases as paleoclimate proxies. In addition, such an understanding is important for several gas-tracer based methods for age-dating shallow groundwaters (3H-3He, CFCs, SF6).

The present project aims at advancing and broadening the scope and applicability of noble gases in paleoclimatology and hydrology, in particular at establishing the paleoclimatic significance of excess air. The primary goal is to obtain a detailed understanding of the the physical mechanisms linking climate and soil parameters to the noble gas patterns imprinted during groundwater recharge. This objective shall be achieved by careful analysis of noble gas, climate, and soil data from several semi-arid regions, complemented by experiments on the scale of laboratory soil columns and test-fields.

In order to study the distribution of noble gases in pore water with high resolution, improvements of sampling and analytical methods are planned, aiming at reducing the sample size. Such developments will provide a strong methodical link to concurrent efforts to the advancement of applications of noble gases in environments other than groundwater. Hence, this project is also expected to contribute to the development of new applications of the noble gas thermometer to important climate archives such as sediment pore waters or fluid inclusions in carbonate sinters.

The accomplishment of the above goals requires experience in tracer hydrology and specialised analytical methods, which is rather rare in Europe. This project will thus contribute to the establishment of a strong European expertise in hydrologic and paleoclimatic research based on noble gases and other environmental tracers.