USGS

WRD Colorado District

Rocky Mountain Snowpack Chemistry at Selected Sites for 2001

By George P. Ingersoll, M. Alisa Mast, David W. Clow, Leora Nanus, Donald H. Campbell, and Heather Handran

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Open-File Report 03-48, 11 p., 4 figs.

This document also is available in pdf format: Adobe Acrobat Icon OFR 03-48.pdf (7.3 MB)
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The citation for this report, in USGS format, is as follows:
Ingersoll, G.P., Mast, M.A., Clow, D.W., Nanus, L., Campbell, D.H., and Handran, H., 2003, Rocky Mountain Snowpack Chemistry at Selected Sites for 2001: U.S. Geological Survey Open-File Report 03-48, 11 p.


Abstract

Because regional-scale atmospheric deposition data in the Rocky Mountains are sparse, a program was designed by the U.S. Geological Survey, in cooperation with the National Park Service, U.S. Department of Agriculture Forest Service, and other agencies, to more thoroughly determine the chemical composition of precipitation and to identify sources of atmospherically deposited contaminants in a network of high-elevation sites. Samples of seasonal snowpacks at 57 geographically distributed sites, in a regional network from New Mexico to Montana, were collected and analyzed for major ions (including ammonium, nitrate, and sulfate), alkalinity, and dissolved organic carbon during 2001. Sites selected in this report have been sampled annually since 1993, enabling identification of increases or decreases in chemical concentrations from year to year. Spatial patterns in snowpack-chemical data for concentrations of ammonium, nitrate, and sulfate indicate that concentrations of these acid precursors in less developed areas of the region are lower than concentrations in the heavily developed areas. Results for the 2001 snowpack-chemistry analyses, however, indicate increases in concentrations of ammonium and nitrate in particular at sites where past concentrations typically were lower. Since 1993, concentrations of nitrate and sulfate were highest from snowpack samples in northern Colorado that were collected from sites adjacent to the Denver metropolitan area to the east and the coal-fired powerplants to the west. In 2001, relatively high concentrations of nitrate (12.3 to 23.0 microequivalents per liter (µeq/L) and sulfate (7.7 to 12.5 µeq/L) were detected in Montana and Wyoming. Ammonium concentrations were highest in north-central Colorado (14.5 to 16.9 µeq/L) and southwestern Montana (12.8 to 14.2 µeq/L).


Contents

Abstract

Introduction

Acknowledgments

Sampling Methods

Network Design and Sampling Locations

Timing of Sample Collection

Methods of Sample Collection

Snowpack Chemistry of Selected Sites

Summary and Future Considerations

References

Water Resources of Colorado
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