Research Blog
My research interests include high-resolution monitoring and modeling techniques to better understand groundwater flow in spatially and temporally complex geologic systems. Methods include geochemical sampling of groundwater after recharge events, fracture flow modeling, and the use of thermal imagery from drones. My study sites have included areas in Minnesota, Missouri, Pennsylvania, Florida, and now western Montana. |
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A chapter that I helped with in the Handbook of Environmental Chemistry 68 on "Karst Water Environment: Advances in Research, Management and Policy" was recently published! Largely the work of several years of spring monitoring that had been going on even before I arrived at Temple, I joined the project more recently so some of the data going into my dissertation is in the chapter. This was also the first opportunity for us to publish some of our preliminary rare earth element (REE) results from our karst springs during baseflow conditions.
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We were finally able to perform the dye trace at one of my field sites! After some extensive preparation to make sure that the dye would be in detectable limits at the spring while also not being too high of concentration to overload the loggers and anger some neighbors (which was an awkward mixture of high precision calculations mixed with a dash of fudge factor), the dye trace commenced with the flipping of the dye pump switch on a sunny Friday morning last week.Dye pump activated! Pump dripping dye into the stream. At high concentration the fluorescein dye is red (the tubing is clear), but turns bright green when diluted with the stream water.Dr. Laura Toran checking the drip rate of the small peristaltic pump, which didn't skip a beat for nearly 9 hours! That little pump exceeded all my expectations. Dye turning the sinking stream bright green as it flows from upland (right) to the sinkhole (left). Dr. Ellen Herman and Dr. Laura Toran discussing karst in the background. The dye thoroughly mixed with the stream before plunging into the sinkhole. We constructed a small rock weir to promote mixing and to help estimate discharge (3-4 gallons per second). The stream has a dye concentration of around 500 ppb before finally plunging into the cave and conduit networks below. Half a kilometer and 30 hours later we saw half of the dye re-emerging at this spring, reduced to below 10% its original concentration due to dilution, diffusion, and flow piracy. Do you get the sense that this water is greener than it should be? Or might your eyes be tricking you? We did get one report from a local resident that the stream turned green around the time our loggers showed it arriving. The timing of the dye arrival, the shape of the concentration curve, and mass recovery gives us some very useful information on the flow behavior of the conduit network connecting these features. This information will then be used to construct improved conduit flow models, which is a ongoing challenge in karst studies. Interestingly enough, just 30 meters away at this spring's counterpart, no dye was detected at all! But that's karst for you.
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