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Rolla, MO, United States

Stoner S.A.,Geological Survey Program | Pierce Jr. L.D.,Geological Survey Program | Boswell C.E.,Geological Survey Program
Carbonates and Evaporites | Year: 2013

In the fall of 2009 and spring of 2010, the Missouri Department of Natural Resources Division of Geology and Land Survey's Geological Survey Program (GSP) conducted an investigation to further delineate the groundwater recharge area of Hahatonka Spring at Lake of the Ozarks in central Missouri. The goal of the study was to determine the hydrologic connections of the karst system near the town of Montreal in Camden County, Missouri, to Hahatonka Spring utilizing fluorescent dye tracing techniques. Conventional charcoal receptor packets and spectro-fluorometric analysis were used in conjunction with a newly acquired multi-sensor submersible fluorometer. The primary purpose of the groundwater investigation was to assess the durability and capability of the fluorometer to continuously monitor for multiple fluorescent tracers and water quality parameters during an extended deployment. Camden County is located in central Missouri where considerable karst development has occurred from the dissolution of the underlying Ordovician Roubidoux Formation and Gasconade Dolomite. The terrain is characterized by sinkholes, losing streams, caves, and springs. The major source of discrete groundwater recharge in the area is from losing streams and, to a lesser extent, sinkholes. A hydrologic connection has been established using water tracing methods at Lancaster Road sinkhole in Laclede County to Hahatonka Spring (Vandike 1992). The travel time of the dye peak concentration, including the arrival of the leading edge and elapsed time of the trailing edge of the dye to Hahatonka Spring was delineated by the fluorometer using 4-h data collection intervals. Groundwater velocity was calculated from the resulting data and determined to be 3.1 km per day (1.98 miles per day). The fluorometer also shows relations in the data among long-term natural fluxes of spring discharge, temperature, and turbidity. © 2013 Springer-Verlag Berlin Heidelberg (outside the USA). Source

Pierce Jr. L.D.,Geological Survey Program | Stoner S.,Geological Survey Program | Boswell C.E.,Geological Survey Program
Carbonates and Evaporites | Year: 2013

In fall of 2008, the Missouri Geological Survey Program, Missouri Department of Natural Resources began testing a remotely deployed, multi-sensor submersible fluorometer. The submersible data logging fluorometer is capable of integrating up to six sensors, including fluorescence and turbidity, with the device's standard temperature and pressure sensors. Fluorescein, Rhodamine WT™ (Acid Red 388, manufactured by Chemcentral), optical brightener, and turbidity probes were installed on the unit. The instrument measures fluorescence in relative fluorescence units (RFU) that can be correlated to known concentrations. Data from laboratory testing indicated that the unit was capable of detecting tested water tracers in concentrations as low as one part per billion (ppb) in a zero turbidity environment and at concentrations of 10 ppb, even in turbid water. Background reflectance and fluorescence levels from organics in the environment and other tracers were determined to be insignificant for the fluorescein and optical brightener sensors. However, the Rhodamine WT probe gave false-positive readings when fluorescein dye was present due to spectral overlap from the fluorescein sensors excitations source. Spectral overlap was reduced to <1 % at all concentrations with the addition of a light-reducing shield to the Rhodamine WT sensor. The unit allowed simultaneous detection of multiple fluorescent water tracers and measured water quality parameters during extended remote deployments for continuous field monitoring. Field testing indicated the fluorometer was reliable detecting the three tracers tested and more precisely delineating the time of travel for tracers than conventional methods. Field testing revealed the unit provides more confidence in the detection of optical brightener than using carbon packet sampling methods and was less time consuming that collecting and analyzing numerous water samples. © 2013 Springer-Verlag Berlin Heidelberg (outside the USA). Source

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