Research

My research explores biogeochemical connections between land and water at landscape to macrosystem scales.  I use a combination of field/lab methods, satellite remote sensing, and GIS analyses to learn about streams, lakes, rivers, and estuaries. My CV is available here.

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DISSOLVED ORGANIC MATTER IN ARCTIC RIVERS

In the Arctic, my research uses satellite remote sensing and laboratory analyses to address two questions: Where does riverine organic matter come from? And how are OM dynamics changing in response to climate?

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REMOTE SENSING OF WATER QUALITY IN TEMPERATE LAKES

Using remote sensing products , I am looking for trends in lakes DOM across Minnesota, associated with climate, atmospheric chemistry, and land use. I also am examining watershed controls on lake CDOM in three ecoregions of northern MN, WI, and MI.

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STORM-DRIVEN NITROGEN EXPORT TO TEXAN ESTUARIES

Nitrogen from agricultural run-off and wastewater is a major driver of estuarine ecosystems. In coastal Texas, alternating wet-dry years results in large variations in nitrogen delivery from rivers.

 
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Aquatic Organic Matter in the Arctic

Remote SEnsing of DOM

Colored dissolved organic matter (CDOM) can be measured from satellite imagery in many aquatic ecosystems, and used to quantify changes in aquatic carbon cycling. My dissertation research built remote sensing models for six large Arctic rivers to estimate CDOM (Griffin et al., 2018), then applied those models to historical imagery from 1985 - 2017 (Griffin, 2016).  Time series analyses showed changes to discharge-normalized CDOM in the Ob' and Yenisey rivers, likely associated with increases in permafrost thaw.

River export of OM

I have been lucky to be involved with the Arctic Great Rivers Observatory, which provided the data used for my remote sensing methods. Through Arctic-GRO, I have contributed to work on fluxes of particulate organic matter (POM), addressing the variability in export driven by both seasonal and annual hydrology (McClelland et al., 2016). Organic matter in Arctic rivers generally increases in age by the end of the ice-free season. Radiocarbon dating of lignins demonstrated that such ancient pools of carbon are far more prevalent in the Kolyma River than the Mackenzie River (Feng et al., 2017).

 

 
 
 
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CDOM in Midwestern Lakes

Watershed controls on CDOM

More soon!

Time Series analysis of CDOM

More soon!

 
 
 
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Nitrogen in Texas Rivers

More soon!