My talk will be two-fold: I will first summarize the benefits of (high-resolution) environmental tracer measurements to elucidate surface water-groundwater interactions and associated pollutant turnover based on a few examples from Switzerland (Popp et al., 2020, 2021a,b; Moeck, Popp, 2021). Secondly, I will highlight some of my ongoing work that aims at better understanding the rapid hydrological and biogeochemical changes occurring in high-latitude environments. To this end, my colleagues and I use field- and satellite-derived data from (sub-)arctic catchments in Norway (including Svalbard). We analyzed various water sources including streams, lakes, groundwater, snow and ice for environmental tracers (i.e., major ions, stable water isotopes, radon-222) and greenhouse gases (GHG; i.e., CO2, CH4 and N2O). Combining the environmental tracer data with an end-member mixing model (Popp et al., 2019) allows us to estimate mixing between those water sources and link it to the observed GHG concentrations. Finally, we assess the connection between hydrological and biogeochemical processes, and snow cover changes estimated using satellite imagery (Aalstad et al., 2020).

References:
Aalstad, K., Westermann, S., & Bertino, L. (2020). Evaluating satellite retrieved fractional snowcovered area at a high-Arctic site using terrestrial photography. Remote Sensing of Environment, 239, 111618, http://dx.doi.org/10.1016/j.rse.2019.111618
Moeck, C., Popp, A.L., Brennwald, M.S., Kipfer R., Schirmer, M. (2021) Combined method of 3H/3He apparent age and on-site helium analysis to identify groundwater flow processes and transport of perchloroethylene (PCE) in an urban area, Journal of Contaminant Hydrology, 238,103773, https://doi.org/10.1016/j.jconhyd.2021.103773
Popp, A. L., Scheidegger, A., Moeck, C., Brennwald, M. S., & Kipfer, R. (2019). Integrating Bayesian groundwater mixing modeling with on-site helium analysis to identify unknown water sources. Water Resources Research, 55(12), 10602– 10615. https://doi.org/10.1029/2019WR025677
Popp, A. L.; Manning, C. C.; Brennwald, M. S.; Kipfer, R. (2020) A new in situ method for tracing denitrification in riparian groundwater, Environmental Science and Technology, 54, 3, 1562-1572, https://doi.org/10.1021/acs.est.9b05393
Popp, A. L., Pardo-Alvarez, A., Schilling, O., Musy, S., Peel, M., Purtschert, R., et al. (2021a). A framework for untangling transient groundwater mixing and travel times. Water Resources Research, 57. https://doi.org/10.1029/2020WR028362
Popp, A.L., Manning, C., Knapp, J.L.A. (2021b). Rapid advances in mobile mass spectrometry enhance tracer hydrology and water management, Water Resources Research, 57, 6, https://doi.org/10.1029/2021WR029890