Clark Fork near Galen

MONTANA PROJECTS

• Major Projects
  • Tongue River Monitoring
  • Clark Fork Monitoring
  • Diel Metal Cycling

USGS IN YOUR STATE

USGS Water Science Centers are located in each state.

DIEL CYCLING OF TRACE METALS IN STREAMS

Home Project Description Fact Sheet Publications   Photo Gallery Contacts

Historically, scientists have assumed that a properly collected water sample will provide an accurate assessment of constituent concentrations in a water body on a given day assuming constant hydrologic conditions.  However, an increasing body of evidence indicates that the concentration of many potentially toxic trace elements (such as arsenic, cadmium, copper, manganese, zinc) in streams can vary over a large range (up to 500 percent) during a 24-hour period irrespective of changes in streamflow.  These diel concentration cycles have been shown to be robust and reproducible, having been documented in many streams separated by large distances, in different geologic environments, and over a large range of metal concentrations.

Graph of diurnal variation of metals in Prickly Pear Creek and High Ore Creek, Montana

This research project is supported by the U.S. Geological Survey Toxic Substances Hydrology Program as part of this program's investigations of Watershed Contamination from Hard-Rock Mining.