Galla Professor, Biology
Research in the Tank lab focuses on the influence of human activities on ecosystem function in streams and rivers. The Tank Lab is committed to interdisciplinary, translational research that includes outreach to a broad community of policy makers, NGOs, and agencies.
Key research themes in the Tank Lab include:
1. Biogeochemistry of streams and rivers:
We study nutrient and carbon cycling in streams and rivers and the effect of human activities on water quality and ecosystem function. To prevent nutrient runoff from polluting downstream ecosystems, we need to understand the role that streams and rivers play in removing nitrogen and phosphorus from water. The movement of nutrients from agricultural areas in the Midwest to the downstream water bodies such as the Great Lakes and Gulf of Mexico have been linked to the recurring “Dead Zones”. For example, we have projects quantifying greenhouse gas emissions in watersheds of contrasting land use, examining regional and seasonal nutrient limitation status in river biofilms, and quantifying the effects of agricultural and urban land use on the uptake and retention of nutrients through biotic pathways.
2. Influence of agricultural land use and conservation on streams:
Researchers in the Tank lab are also working to assess the efficacy of agricultural conservation practices designed to keep nutrients on fields, where farmers need them. For example, we are measuring how the planting of winter cover crops can influence nutrient export in agricultural streams, by preventing nutrient runoff from fields to adjacent waterways. We are also exploring how improved soil health equates to changes in water quality via the planting of cover crops.
3. Stream restoration:
Floodplains connect streams to riparian areas and often function as hotspots for nitrogen removal as well as sediment deposition. Conventionally-managed agricultural streams are generally channelized, and are characterized by high nutrient and sediment export due to runoff and unstable banks. We are studying the "two-stage ditch” practice which restores floodplains to formerly incised streams, reducing erosion, sediment, and associated phosphorus export to sensitive downstream ecosystems. We also study how floodplains, with their saturated organic-rich soils, may increase biological nitrogen removal through the promotion of microbial denitrification.
4. Using experiments to quantify stream transport at ND-LEEF:
The Tank Lab also uses experiments conducted at the Notre Dame Linked Experimental Ecosystem Facility (ND-LEEF), which is a globally-unique research facility associated with the Notre Dame Environmental Change Initiative (ND-ECI). The facility includes two replicated watersheds that each contain linked streams, ponds, and wetlands, and the Tank Lab is investigating the influence of stream substrate on nutrient uptake and particle retention including the transport of novel materials in flowing waters such as environmental DNA (eDNA).