My PhD research

I received my PhD in geology and environmental science from the University of Pittsburgh advised by Dr. Daniel Bain. My thesis focused on legacy metal pollution in roadside water bodies and the microbial communities in those sediments. I compared two systems, a large pond flanked by a highway and shopping center in the greater Pittsburgh area, and a small lake adjacent to a road in Rocky Mountain National Park. Roadside lentic ecosystems accumulate metals and nitrogen, a unique combination of contaminants that are rarely quantified in tandem. My overarching questions were 1) How much and what mixtures of metals and nitrogen have accumulated in roadside sediments over time? 2) How have metal source contributions changed over time, and 3) How do these contaminant mixtures impact microbial community composition and potential function across different environments over time?

I used radiometric dating of core sediments to reconstruct the history of metal contamination. I used ICP-MS to quantify metal concentrations and then constructed metal ratios to decipher the relative contributions of industrial and roads/vehicles sources. I also used molecular biology and genomics techniques to explore the microbial communities in these sediment cores with the goal of identifying biomarkers of road contaminated ecosystems.

As expected, the more urban system retained ~3x more lead (Pb) and cadmium (Cd), 2x more copper (Cu), and 5x more Zinc (Zn). I focused on these four metals because they are commonly constituents with industrial and vehicle related pollution. All four metals steadily increased in concentration after the construction of nearby roads. In both cores, sediment Pb concentrations peaked during the used of leaded gasoline. Interestingly, all four metals peaked in concentration decades earlier in Harmar than in Poudre. This is likely due to earlier population growth and industry development in the Pennsylvanian than in Colorado. Zinc concentrations were the highest of the four metals in both cores. Poudre core Zn concentrations peaked around 2000 CE at ~100ug/g and Harmar core Zn peaked around 1980 CE at ~500ug/g.

As is often the case, my lake core 16S sequencing data created more questions than answers. In my new position at the University of Alaska Anchorage, I am continuing to develop my bioinformatics skills and plan to dive deeper into my sequencing data. More studies of metals and microbial communities in lake sediment cores are needed to identify biomarkers of polluted systems, i.e. key microbes or unique community compositions associated with roadside pollution mixtures. Ultimately, by identifying such biomarkers, freshwater systems most heavily impacted and/or most needed for freshwater resources can be targeted for infrastructure upgrades to reduce metal loadings from roads.

Poudre Lake and our catamaran

Territorial moose at Poudre Lake

Coring Harmar Pond

Ducks in Harmar Pond