Initial snow chemistry survey of the Mogollon rim in Arizona

Fresh snowpack samples collected from high-elevation forests of north-central Arizona during late winter/early spring 1992–1994 were analyzed by ion chromatography and by instrumental neutron activation. Eleven major ions, including the organic species acetate and formate, and twenty-eight elements were determined. The results indicate a relatively pristine snowpack—most samples exhibited low ionic strengths (20 ± 15 μeq ℓ−1) and moderate pH (range 4.9–5.7, mean 5.4). Typical snow-producing storms moved northeast under the influence of southwesterly flow of marine air. Northwesterly winds associated with a cutoff low pressure system centered over southern Utah on 31 January and 1 February 1993 brought snowfall with increased chemical loading. The snowpack was apparently enriched with Zn, As, Sb, and Cu when compared to regional soils. Regional source emissions (smelters, metropolitan Phoenix) may have influenced the snow chemistry but their impact appears to be minimal. These apparent trace metal enrichments are similar to those found in precipitation in remote and rural locations worldwide.