Controls on the variance in chemistry of three lakes in the Flat Tops Wilderness Area, Colorado
The chemistry of three dilute lakes in the Flat Tops Wilderness Area, Colorado, can be divided into three principal components: (1) biologically controlled characteristics or constituents that vary as a function of growing conditions, (2) constituents with concentrations that are determined by the degree of chemical weathering, and (3) constituents with concentrations that result from solubility controls, or a steady-state concentration resulting from relatively constant sources. pH is an example of a biologically controlled characteristic; calcium is an example of a chemical-weathering controlled constituent; aluminum is an example of a constituent that may be controlled by the solubility of a mineral (gibbsite), whereas sulfate is an example of a constituent controlled by precipitation. Although quite variable during the ice-free season, pH can be predicted from processes that regulate photosynthesis. The use of simple models relating pH to controls on light intensity (cloud cover and time-of-day), and to stage during the growing season (julian date), explains as much as 63% of the variance in pH. Thus, the detection of trends in pH resulting from changes in precipitation chemistry can be greatly simplified by the use of these models. Most chemical constituents measured in this study seem to vary in concentration about a mean value, with little or no trend during the ice-free season. Mineral solubility may control the concentration of some constituents, and tend to keep that concentration constant, barring major changes in watershed chemistry. Other constituents have concentrations that probably result from the averaging-effect of snowpack accumulation on atmospheric sources. Thus, changes of average concentrations in these lakes could be detected by statistically different mean values in the future. If the same changes are measured in precipitation, then the importance of the atmospheric source to lake chemistry will be documented. 8 refs., 1 fig., 11 tabs.
- Research Organization:
- Geological Survey, Lakewood, CO (USA)
- OSTI ID:
- 5570125
- Report Number(s):
- USGS-OFR-84-723; ON: TI85901774
- Country of Publication:
- United States
- Language:
- English
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