Luise setting up a stream tracer experiment at the Dry Creek Experimental Watershed
Under this theme, we combine experiments, numerical experiments and analytical modeling in an effort to better predict how societally-relevant materials are transported and transformed in streams. Experiments are primarily conducted at the laboratory scale (micrometers to meters), with some experiments conducted at field scale (meters to kilometers).
Carbon, nutrients, and contaminants are transformed in highly reactive regions of the stream. The overall reactivity therefore depends both on local reactivity of these regions and on the rate that reactive materials are delivered to these regions. For example, while it is relatively simple to determine whether streams are net sources or sinks of CO2, it remains extremely difficult to predict how carbon fluxes will change with changing physical (e.g,. flow, temperature) or chemical (oxygen levels) conditions.
Current projects
Water in rivers and streams regularly exchanges between the water column and a region of groundwater called the hyporheic zone (hypo “below” + rheos “flow”). The hyporheic zone has been called “the river’s liver” due to its high capacity for filtering and transforming harmful contaminants and fertilizer runoff. It also plays a major role in basic ecosystem function by harboring a large quantity of the river’s biomass, which assimilate and transform carbon and nutrients. Transport and reaction rates vary sharply between the sediment-water interface and deeper locations in the hyporheic zone. We study how these variations influence stream-scale reactions.
Pharmaceuticals and personal care products (PPCPs) are a class of contaminants that threaten ecosystem and human health. In surface water systems such as rivers, PPCPs degrade in the water columns and sediments. However, their degradation byproducts can persist for long periods in aquatic systems with toxicities that are comparable or worse than those of the original compounds. Even at trace concentrations, PPCPs and their degradation products in river water columns and sediments pose a clear and increasing risk with impacts ranging from the spread of antibiotic resistant pathogens to the decline of fish populations. This ERI project will carry out foundational research to advance the development, validation, and implementation of next-generation risk assessment models that account for the spatial variability of contaminant concentrations in rivers with the goal of accurately quantifying PPCP exposure and risk in locations with high ecological sensitivity and/or impact on human health. To advance this goal, the Principal Investigator proposes to combine laboratory experiments, field studies, and contaminant transport modeling to identify the physical and biogeochemical properties of river sediments that control the degradation of both PPCPs and their transformation byproducts using sediments from the Boise River. The successful completion of this project will benefit society by providing an improved fundamental understanding of how PPCP exposure is linked to measurable properties of rivers and their sediments. Additional benefits to society will be achieved through education and training including the mentoring of one graduate student at Boise State University.
Recent advances and improvements in environmental analysis tools and protocols have established that pharmaceuticals and personal care products (PPCPs) are ubiquitous in surface water systems (e.g., rivers) with concentrations exceeding toxicity thresholds for many aquatic species. The growing number of detected PPCPs in rivers highlights the need for risk assessments that accurately quantify exposure. This ERI project will focus on the development and validation of an integrated experimental and reactive transport modeling framework to identify the key processes controlling the fate, biogeochemical reactivity, degradation, and transformations of PCCPs and their by-products in river sediments using the Boise River (Lander Street Water Renewal Facility) as a field site. The specific objectives of the research are to 1) characterize the transport and transformations of 10 model PCCPs and their degradation byproducts in a laboratory chamber designed to simulate the behavior of river sediments, (2) probe and unravel the mechanisms of attenuation of PPCPs in river sediments, and (3) use reactive transport modeling to identify the physical and biogeochemical processes that control the formation and transformations of PCCP degradation byproducts in river sediments. To implement the education and outreach activities of the project, the Principal Investigator plans to leverage existing programs at Boise State University to partner with the Intermountain Bird Observatory to expand their educational program for public and K-12 participants at the Diane Moore Nature Center, which encompasses a recently restored side channel of the Boise River. The proposed new educational activities will include demonstrations of surface water-groundwater interactions and contaminant transport in groundwater, using both a tabletop groundwater simulator and dye visualization experiments in the restored channel.
This project is supported by NSF Award CBET-2347707
