There are 18 major river basins in the lower 48 contiguous United States, comprising more than 250,000 rivers, primarily dominated by the Pacific Northwest, Great, Colorado, and Mississippi Rivers.
These veins of the land, the American river systems, do much more than just carry water across the land. They provide essential services to humanity, yet many challenges from agricultural runoff, climate change, and other human activities create significant negative impacts.
In the past year, Assistant Professor Kevin Roche in the Department of Civil Engineering secured more than $600,000 in funding to advance the mechanistic understanding of how rivers generate and degrade several of these socially relevant chemicals.
Expanded research on microzones
Building on its previous funding for Idaho riverbed pollution from the Environmental Molecular Sciences Laboratory, a Department of Energy facility, Roche’s research grant from the National Science Foundation aims to increase understanding of nitrous oxide emissions from river systems and their impact on greenhouse gases.
In his previous DOE-funded work, using advanced laboratory techniques, his team developed new experimental reactors to monitor the complex interactions of bacterial growth, fluid flow, and oxygen availability in river sediments. Roche’s latest contribution allows his team to use these reactors, along with additional experimental and modeling tools, to quantify how these interactions affect discharges from river sediments.
“We are excited to build on some of the great work that other Boise State researchers have done and help unravel this paradox,” Roche said. “Many scientists believe that bacterial communities are so good at using oxygen that they create small areas of anoxia that are ripe for nitrous oxide generation.”
Taking a more comprehensive look at the dynamics between river and groundwater systems, Roche believes the team’s experiments and simulations will help provide an interdisciplinary understanding of how these regions change over time and link observations to larger-scale experiments.
Local river impact
Roche’s second NSF grant will use Boise River sediments to better understand how pharmaceuticals and personal care products (PPCPs) move and degrade in river systems. These chemicals can adversely affect aquatic organisms at very low concentrations, but most are still not regulated.
“Cities in water-stressed climates will need to rely increasingly on treated water to meet demand,” Roche said. “So, it’s critical for the public to understand how to properly dispose of PPCPs, as well as for scientists and engineers to understand how we can better design these compounds so that they break down more easily into benign products.”
Roche said that often when bacteria break down these compounds, they generate byproducts that can be just as toxic as the original compound. “It is critical that we have predictive tools that account for the fact that these compounds are generated diffusely in the river network.”
Roche and his team in the Hydrologic Interfaces and Processes Laboratory will utilize advanced measurement capabilities at the Biomolecular Research Institute to monitor PPCPs and their degradation byproducts in controlled laboratory experiments. By combining these lab results with mathematical models, the team expects to better predict how, when and where PPCP concentrations exceed levels of concern to aquatic organisms or human health.
The team expects the insights will help other researchers better understand how degradation byproducts can persist and the toxic effects in river systems, improve strategies to mitigate these effects and protect aquatic ecosystems.
“It’s expensive and difficult to measure these compounds in environmental waters, which means we can’t monitor everything everywhere all the time,” Roche said. “That’s where modeling comes in. I think the models we’re developing will be useful for cities and regulatory agencies to identify where and when they should invest in these monitoring efforts.”
Engage future environmentalists
In addition to advancing scientific knowledge, Roche’s NSF grants include a commitment to reach education. The research team plans to leverage existing outreach programs at Boise State to mentor K-12 students and engage the community through STEM programs.
The team has partnered with the Intermountain Bird Observatory to expand its educational program at the Diane Moore Nature Center, which includes a recently restored side channel of the Boise River. This initiative aims to increase public awareness of the connections between groundwater quality and river health.
