Geologic Publications for Mount Rainier

Measurement of glacial meltwater outflow through water analysis for geohazard recognition

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Author(s): Laura L. German

Category: PUBLICATION
Document Type: BA Chemistry - Senior Independent Study Thesis
Publisher: The College of Wooster
Published Year: 2013
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Number:
Pages: 60
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Abstract:
Determining the status and level of glacial stagnation is important for protecting communities in areas downstream that would be affected by consequential outburst release floods. There are detectable chemical differences between glacial meltwater and mountain snowpack inlet streams that can be used to monitor glacial outflow. It is hypothesized that iron concentration, turbidity, temperature and pH levels may be used to monitor hydrology of the Nisqually Glacier in Mount Rainier National Park, Washington. A series of field tests (Fe, NO₃, hardness, pH/conductivity/ORP/temperature, turbidity) provided preliminary data to compare with further analytical testing in the lab, including ICP-AES, a bathophenanthroline colorimetric test, and total organic carbon measurements. Analysis showed dissolved iron concentration to be statistically higher in glacial meltwater than in snowpack inlets (t=9.26, p<0.001). Fe levels decreased downstream, presumably due to dilution from snowpack inlet streams. Turbidity followed an equivalent trend, decreasing as the zero-turbidity snowpack melt diluted the river at increasing distances from the glacial terminus. Temperature measurements followed suit by increasing in value along the Nisqually River, presumably due to contributions from warmer snowmelt inlet streams. pH levels were detected at similar values for each of the sampling sites, but according to Anderson et al, a drastic change in pH would indicate a hydrogeological shift in the glacier. Thus, Fe, turbidity, temperature, and pH appear to be effective signals for monitoring glacial output that may be quickly and easily tested using field kits. Utilization of a real-time method to test for stagnation would afford researchers the opportunity to predict jökulhlaups. Based on this work, it is also postulated that glacial meltwater may be an unappreciated source of nutrient Fe in river and ocean ecosystems. Future work includes continued measurements of Fe concentration, temperature, pH, and turbidity along with river flow to understand how these signals fluctuate as river flow changes. Daily measurements should be taken as close to the terminus as practical (i.e. Nisqually Glacier Bridge) to avoid increased dilution of glacial outflow signals. Continued measurements are important for chemical characterization of the Nisqually's glacial outflow. Correlating these results with ice velocity and/or ice elevation measurements would allot a geochemical profile of the Nisqually Glacier and River.

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German (2013) or (German, 2013)

References Citation:
German, L.L., 2013, Measurement of glacial meltwater outflow through water analysis for geohazard recognition: BA Chemistry - Senior Independent Study Thesis, The College of Wooster, 60 p..