Rocky Mountain Snowpack Chemistry at Selected
By George P. Ingersoll, M. Alisa Mast, Leora Nanus, David J. Manthorne,
David W. Clow, Heather M. Handran, Jesse A. Winterringer, and Donald H.
Open-File Report 2004-1027-Online only
This document is available in pdf format:
The citation for this report, in USGS format, is as follows:
Ingersoll, G.P., Mast, M.A., Nanus, L., Manthorne, D.J., Clow, D.W., Handran,
H.M., Winterringer, J.A., and Campbell, D.H., 2004, Rocky Mountain Snowpack
Chemistry at Selected Sites, 2002: U.S. Geological Survey Open-File Report
2004-1027, 15 p.
During spring 2002, the chemical composition of annual snowpacks in the
Rocky Mountain region of the Western United States was analyzed. Snow
samples were collected at 75 geographically distributed sites extending
from New Mexico to Montana. Near the end of the 2002 snowfall season,
the snow-water equivalent (SWE) in annual snowpacks sampled generally
was below average in most of the region. Regional patterns in the concentrations
of major ions (including ammonium, nitrate, and sulfate), mercury, and
stable sulfur isotope ratios are presented.
The 2002 snowpack chemistry in the region differed from the previous year.
Snowpack ammonium concentrations were higher at 66 percent of sites in
Montana compared to concentrations in the 2001 snowpack but were lower
at 74 percent of sites in Wyoming, Colorado, and New Mexico. Nitrate was
lower at all Montana sites and lower at all but one Wyoming site; nitrate
was higher at all but two Colorado sites and higher at all New Mexico
sites. Sulfate was lower across the region at 77 percent of sites. The
range of mercury concentrations for the region was similar to those of
2001 but showed more variability than ammonium, nitrate, and sulfate concentrations.
Concentrations of stable sulfur isotope ratios exhibited a strong regional
pattern with values increasing northward from southern Colorado to northern
Colorado and Wyoming.
Purpose and Scope
Summary and Conclusions