Seminar: Simon Schröter

Heavy precipitation, drought, and other hydroclimatic extremes are becoming increasingly common in Europe. Given their strong effect on groundwater recharge dynamics, these phenomena increase the vulnerability of groundwater quantity and quality. Over the course of the past decade, we have documented changes in the composition of dissolved organic matter in groundwater. We show that fractions of ingressing surface-derived organic molecules increased significantly as groundwater levels declined. Rates of molecular composition changeover as much as doubled following 2018’s extreme summer drought. These findings suggest that hydroclimatic extremes promote rapid transport between surface ecosystems and groundwaters, thereby enabling naturally occurring xenobiotic substances to evade microbial processing, accrue in greater abundance in groundwater, and compromise the safe nature of these potable water sources. Groundwater quality is far more vulnerable to the impact of recent climate anomalies than is currently recognized.