Troubled Waters: Hidden Challenges for Water Quality

Abstract

Human activities have substantially altered the world's carbon and nutrient cycles. Consequently, our freshwater systems are increasingly exposed to high nutrient concentrations and altered carbon export dynamics. These 'troubled waters' affect both aquatic ecosystems and the supply of drinking water. It is apparent that higher nutrient inputs also cause higher transport rates and export. However, not all impacts or consequences are intuitive, and are thus at risk of being overlooked.  In this talk, we will explore examples of these potentially ‘hidden’ changes for surface water quality.  

In the first part of this talk, we will explore how the increasing frequency of hydrological extremes, such as droughts and floods, can alter the way nutrients are mobilized, transported or retained within catchments, thereby potentially alleviating, but most of the time exacerbating the situation. Indirect consequences of such extremes, such as large-scale forest dieback, can cause additional nutrient mobilization in areas that were previously considered a natural safeguard of water quality.

In the second part of this talk, we will discuss how groundwater connects stream ecosystems to their landscapes and why understanding that connection is critical for us to predict the response of streams to changing land uses and climate. We will present an example of how we map and measure groundwater inputs along a river network, including nutrient and salt pollution inputs related to land uses and greenhouse gas emissions.

Our talk highlights how careful consideration of indirect drivers of water quality across spatial and temporal scales is needed to better understand and protect our valuable freshwater resources.

Bios

Carolin Winter works as an 'Akademische Rätin' (the German equivalent of an assistant professor) at the Chair of Environmental Hydrological Systems at the University of Freiburg. As a trained hydrologist, she is specialized in water quality and nutrient dynamics at the catchment scale. Her current research focuses on the direct and indirect effects of hydro-climatic changes and extremes on nutrient transport, retention and stoichiometry, and the advantages of high-frequency water quality monitoring in detecting these effects. Prior to joining the University of Freiburg, Carolin completed her PhD at the Helmholtz Centre for Environmental Research (UFZ) in Leipzig, Germany, investigating nitrate export dynamics across different timescales, from long-term trends to individual discharge events.

Ashley Helton is a professor of Landscape Biogeochemistry at the University of Connecticut in the Department of Natural Resources and the Center for Environmental Sciences and Engineering.  Ashley earned her BS from the University of Cincinnati, and both her MS and PhD in Ecology from the University of Georgia's Odum School of Ecology.  Ashley is interested in hydrology, biogeochemistry, and how water and elemental cycles are linked across broad spatial scales.  Her research centers on how land development and climate change alter water quality, greenhouse gas emissions, and biogeochemical functions of aquatic ecosystems.