D. R. Norton | USGS Science

USGS2002

Spectrophotometric determination of uric acid and some redeterminations of its solubility

The present study was initiated in order to develop a rapid and accurate method for the determination of uric acid in fresh, brackish, and sea water. It was found that the spectrophotometric determination of uric acid based upon its reaction with arsenophosphotungstic acid reagent in the presence of cyanide ion meets this objective. The absorbancy of the blue complex was measured at 890 m μ . Slight variations from Beer's law were generally found. The results show the effects of pH, reaction time, concentration of reagents, and temperature upon color development and precipitate formation. Disodium dihydrogen ethylenediamine tetraacetate (Versene) was used as a buffering and complexirig agent. The results are significant in that they give the absorption spectrum of the blue complex and the effects of variables upon its absorbancy. Studies were made with the method to determine the stability of reagents and standard solutions and to determine the rate of bacterial decomposition of uric acid. Measurements of the solubility of uric acid are reported.

Analytical Chemistry↗

USGS1990

Anomalous chloride flux discharges from Yellowstone National Park

The chloride concentration of some thermal springs in and adjacent to Yellowstone National Park is constant through time although their discharge varies seasonally. As a result the chloride flux from these springs increases during periods of increased discharge. We believe that this is caused by changes in the height of the local groundwater table, which affects the discharge of the springs but not their chloride concentration. The discharge from Mammoth Hot Springs varies seasonally, but its chloride concentration remains constant. We take this as evidence that this major thermal feature is derived from orifices that are tapping the local water table close to its surface. Three of the four major rivers (Yellowstone, Snake and Falls) exiting the Park also show an increased chloride flux during the spring runoff that cannot be explained solely by the contribution of snowmelt, nor by release of hot-spring-derived chloride stored in the soil during the winter and released in the spring. The increased chloride flux in these rivers is attributed to their draining shallow hot springs similar to those mentioned above. In contrast to the Yellowstone, Snake and Falls Rivers, the Firehole and Gibbon Rivers, which unite to form the Madison River and which collectively drain several major geyser basins, display a poor correlation between chloride flux and discharge. The cause, we believe, is that a large part of the thermal water input to these two rivers originated at great depths where the seasonal variation in the height of the water table had a negligible effect on hot spring discharge. Monitoring of seasonal discharge and chloride concentration of thermal features yields information on the depths at which these thermal features tap the local water table. ?? 1990.

Journal of Volcanology and Geothermal Research↗