Snow chemistry and physics of the Mogollon Rim in Arizona

Snowpack samples from the central mountain region of Arizona were analyzed for eleven major ions and thirty trace elements. The results indicate a relatively pristine snowpack that is weakly influenced by anthropogenic activity in most samples. Trace metals associated with human activity (Ag, As, Co, Cr, Hg, Se, Zn) were below detection limits. A pH range between 4.9 and 5.7 was measured with a mean value of 5.4, and these findings exhibit some temporal and spatial tendencies. A majority of samples had extremely low ionic strengths. The results suggest a combination of ammonium and calcium salts, sea salt, and inorganic and organic acids in the snowpack. The free proton (H+) accounted for a significant portion (32%) of the total cation availability. Meteorological influences were investigated by separating the observations by winter storm event. Samples collected on 2/4/93 exhibited a significantly greater ionic strength due to a different weather pattern during this storm. Spatial variations due to local effects were also evident in the snowpack.