Snow covers much of the earth permanently or seasonally, acting as both a filter and chemical reactor. In filter mode, snow collects contaminants and chemical tracers from the atmosphere. In regions where snow is ephemeral, contaminants enter surface and soil waters during snowmelt. Continual exchange of air and chemical species between the snow and atmosphere makes the near-surface snow the site of active chemical reactions that affect reactive species such as ozone and hydrogen peroxide, which affect the oxidation capacity of the atmosphere. Also affected are volatile species such as explosive compounds, which may be differentially absorbed and released into the atmosphere according to changes in temperature and weather. Trace metals, aerosols, and dust also are entrained in the snow record.
|
Description of Research