PhD Students

Megan Behnke

I am intrigued by how climate change affects the biogeochemistry of vulnerable carbon stocks in high-latitudes. I am especially interested in the photochemistry of dissolved organic matter (DOM), and how DOM composition changes as it moves through high-latitude watersheds and into the coastal ocean. My current work is focusing on how photochemistry interacts with microbial processing of DOM in the Kolyma River in north-eastern Siberia. I am also collaborating with the Arctic Great Rivers Observatory to investigate changes in pan-Arctic riverine DOM composition, and examining DOM biogeochemistry in the temperate coastal rainforest of Southeast Alaska. In my work, I use a suite of analytical techniques including FT-ICR mass spectrometry, bioincubations, and carbon isotopes to better understand climate change’s influence on carbon chemistry and thus its ultimate impact on high-latitude communities and ecosystems.

Amy Holt

I am interested in understanding the sources and cycling of DOM in glacial environments. Glacially exported DOM has a unique characteristic of being old yet highly bioavailable. As such, it may help sustain microbial activity in downstream ecosystems. Currently, a source and mechanistic explanation for glacial DOM’s unique character remains the source of debate. Through my research, I hope to elucidate which end-member sources contribute to glacial DOM’s unique signature and how these sources are processed on the glacier surface. I am also collaborating with the Stream Biofilm and Ecosystem Research Laboratory at EPFL on their global ‘Vanishing Glaciers Project’, in order to better understand the characteristics of glacially exported DOM worldwide. This will help to ascertain whether there is spatial variation in glacier DOM composition and source. I will use a suite of analytical tools to understand these questions including: fluorescence, FT-ICR mass spectrometry, bioincubations, and radiocarbon dating. Together, I hope this will provide a mechanistic understanding of the source, cycling, and composition of exported DOM, helping to explain how glacial DOM can exhibit its unusual characteristic.

Martin Kurek

My research interests lie at the edge of transition zones: both at the molecular and ecological scale. I am interested in how dissolved organic carbon in dynamic redox interfaces reacts with reduced metals, reactive sulfur species, nutrients, and microbial communities. Many of these processes have the potential to change the overall composition of organic carbon making it more stable, or in some cases, more reactive. These hotspots for carbon cycling are often found in terrestrial wetland-lake transitional environments across a gradient of latitudes from the arctic to the tropics. I use a wide range of analytical tools to study the chemical composition of these sites, from ultra-high resolution mass spectrometry (FT-ICR MS) to electrochemistry with micro-electrodes. By studying the organic geochemistry of wetlands, rivers, and lakes in a changing world, I hope to understand why some carbon stays in these systems and why other forms of carbon escape into the atmosphere.