A dual dye approach to measuring sunlight in lotic systems.
2012-08
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
A dual dye approach to measuring sunlight in lotic systems.
Authors
Published Date
2012-08
Publisher
Type
Thesis or Dissertation
Abstract
Light is an energy source that affects the metabolism of an aquatic system by
providing energy for photosynthesis, the thermal structure by the transfer of light to heat
energy, and the chemical make-up by providing energy for both indirect and direct
photochemical reactions. This thesis considers the use of two dyes (rhodamine WT and
fluorescein) as a way to measure the amount of light affecting lotic systems. These dyes
are common tracers usually used in aquatic systems to measure water flow and mixing.
Rhodamine WT exhibits photo-stability; while fluorescein exhibits photo-lability.
Combining these two could potentially provide a Lagrangian measure of sunlight
exposure in a lotic system; a previously unattainable view of the light field in such
systems.
In this thesis, several lab experiments were performed to test the effects of temperature
and pH on the fluorescence of the dyes and to test the effects of pH and wavelength of
light on the photoresponse of the dyes upon irradiation. A correction factor for
temperature was found in lab experiments that matched previously published results.
When pH remained within the normal range of North Shore streams (6.99-7.54),
rhodamine WT exhibited photo-stability while fluorescein exhibited photo-lability;
however, changes in response were seen as a function of pH and there are indications that
rhodamine WT may be photo-labile at high pH. Irradiation of the dyes showed that
wavelengths at and/or above 420 nm degrade the fluorescein.
The dual-dye approach was tested in Amity Creek, a designated trout stream
located on the north shore of Lake Superior. During deployment along a given reach, the
dyes showed robust applicability on base flow, high irradiance days but no appreciable
photoresponse on high flow days. During base flow deployments, the fluorescein to rhodamine WT ratio decreased linearly over time (with an R2 ranging from 0.971-0.998).
Overall, in-stream Lagrangian deployments showed similar degradation rates to those
seen in batch samples of stream water placed on the stream bed in a fixed position in
sunlight for the same period of time. This concurs with visual observations that there is
no significant canopy cover down this stream reach. Although the dual-dye methodology
was successful in acting as an in situ light monitor and is applicable to streams if
temperature is recorded and pH is within a certain operating range, more work needs to
be done to demonstrate if the use of fluorescein and rhodamine WT is a practical
alternative to current methods of light measurement.
Keywords
Description
University of Minnesota M.S. thesis. August 2012. Major: Water Resources Science. Advisor: Dr. Elizabeth C. Minor. 1 computer file (PDF); v, 38 pages, appendix p. 37-38.
Related to
Replaces
License
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Other identifiers
Suggested citation
Welsh, Elizabeth J.. (2012). A dual dye approach to measuring sunlight in lotic systems.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/140171.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.