Watershed Contamination from Metal and Uranium Mining
Big Hole River in southwestern Montana. USGS
scientists and their university colleagues have shown that photosynthesis by aquatic plants causes large diel (daily) cycles
in pH, dissolved oxygen concentrations, and the isotopes of oxygen and carbon. In addition, the aquatic plants are thought to cause large changes in streamflow as oxygen production during photosynthesis stiffens the plants and thereby retards downstream flow during the day.
Deposit of iron-cemented stream gravel (ferricrete) with embedded wood fragments that can be age dated using radiocarbon to determine the age of the ferricrete deposit. Knowing the age of the ferricretes helps scientists determine if the associated enrichment of metals in streams occurred before or after mining in the watershed started.
Mineral Creek watershed in southwestern Colorado has natural and mining-related sources of contamination. In the background of this photo is a large naturally occurring seep that discharges acidic, metal-rich water to a tributary of Mineral Creek. Natural sources of contamination like this one make it difficult to determine appropriate water-quality standards for cleanup actions.
Field experiment designed to compare survival of trout fry (newly hatched fish) exposed to constant versus varying metal concentrations, High Ore Creek, Montana Water stored in the streamside tanks was used to refresh plastic containers in the stream. Water in the tanks had high, medium, or low metal concentrations. The fourth tank contained metal-free water used as an experimental control.
Scientists checking fish held in plastic containers that were exposed to a constant metal concentration as part of a field experiment to compare survival of trout fry (newly hatched fish) exposed to constant versus varying metal concentrations, High Ore Creek, Montana.
Fish held in flow-through containers are exposed to metal concentrations with daily high and low cycles (diel cycles). Scientists conducted a field experiment to compare survival of newly hatched trout (fry) exposed to constant versus varying metal concentrations, High Ore Creek, Montana The experiment will help scientists understand the effect of diel variations in the concentration of metals on fish in mining affected areas.
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