My research is centered on harmful algal blooms (HABs), nutrient speciation and dynamics, origin, sources, and management of freshwater ecosystems. Particularly, I am interested in addressing questions about the environmental factors controlling cyanobacterial blooms, sources and roles of nitrogen and phosphorus in eutrophication, cyanobacterial seasonal dynamics, nutrient limitation and stoichiometric ratios, and dynamics of toxin-producing HABs and eutrophication in aquatic ecosystems. I employ various approaches to address these issues, including empirical field observations, stable nitrate isotope analysis, nutrient enrichment bioassay experiments, and statistical modeling. I am interested in working with various freshwater ecosystems ranging from lakes, reservoirs, and urban streams to urban rivers. My work aims to inform recommendations and mitigation plans for nutrient enrichment and the development of HABs in freshwater ecosystems.

Role of intermittent artificial destratification on water column nutrient concentration and summer cyanobacterial blooms in lakes and reservoirs

Nutrient enrichment and excessive organic matter production have led to a suite of undesirable biogeochemical and ecological consequences, including the most prominent and troublesome being the HABs. We investigated the effects of intermittent artificial circulation, widely adopted as a restoration method to control summer cyanoHABs in eutrophic lakes/reservoirs. This collaborative effort was co-funded by NDSU, NDWRRI, and USGS.

Large-scale drinking water orthophosphate addition on urban stream chemistry, algal growth, and nutrient limitation in hydrologically connected urban streams.

Despite the importance of using phosphate addition as a corrosion control approach to protecting human health, knowledge gaps exist regarding the role of aging and leaking drinking water infrastructure on urban stream nutrient dynamics, nutrient limitation, nutrient shift, and eutrophication potential in urban streams. This project uses various methods, including field sampling and onsite water quality monitoring, stable nitrate isotope analyses, algal bioassays, and e- DNA techniques. The findings of this work are applicable to other cities that are adding (or are planning to add) phosphate to drinking water. This is a collaborative project between researchers from the Department of Civil and Environmental Engineering and the Department of Geology and Environmental Science at the University of Pittsburgh (PITT) with our collaborator Pittsburgh Water and Sewer Authority (PWSA), funded by a RAPID grant from the National Science Foundation (NSF) with contributions from Pittsburgh Water Collaboratory.\

What are the factors driving bloom proliferation, including changes in nutrient concentrations, fluxes, and limitations to the Ohio River system and hydrological context for Ohio River discharge?

This collaborative effort started during the COVID pandemic to understand potential factors driving cyanobacterial bloom proliferation in the Ohio River. In 2015 and 2019, there were two unprecedented Microcystis blooms on the Ohio River, and microcystin toxin concentration exceeded both EPA and WHO standards. Although HAB outbreaks in lakes occur often and have been the focus of many research efforts, HABs incidents in rivers are less common and understudied relative to lakes and coastal systems in lakes and reservoirs. Here, we use a regression-based approach to understand long-term nutrient concentrations and fluxes to the Ohio River.