Isotopes of dissolved oxygen as dynamic tracers for aerobic turnover in surface and shallow groundwaters (IsoDO)

• Applicants: Professor Johannes Barth, Ph.D.; Dr. Christian Schmidt
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Mineralogy, Petrology and Geochemistry
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 290026025

Steep gradients of dissolved oxygen (DO) indicate that critical zones of aerobic activity exist in riparian and hyporheic subsurface environments. These important zones need new tools to quantify sources and sinks of dissolved oxygen as a key parameter for aquatic biogeochemical activity. Together with concentration measurements, we plan to investigate stable isotope ratios of DO together with those of dissolved and particulate carbon in order to trace their biological components. The approach enables quantification of atmospheric and photosynthetic sources of DO. In addition, systematic 18O-enrichment in the DO pool will quantify aerobic respiration rates. The survey will focus on the Selke River field laboratory in the Harz Mountains with riparian, ripple and in- as well as below stream sampling. The work aims to investigate the hypothesis of biological controls on oxygen and related carbon dynamics in continental waters. The approach will enable to differentiate and quantify rates of oxygen consumption and input that will also be verified with reactive transport models. Applied and tested methods will also be available to investigations of other aquatic systems including lakes, rivers and groundwaters.

• DFG Programme: Research Grants
• Co-Investigator: Privatdozent Dr. Robert van Geldern