And snowpack

Brown LE, Hannah DM, Milner AM (2007) Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks. Global Change Biol 13 958... 

Next to the temperature gradient inside the snowpack, an important driving force for snow metamorphism is wind, that lifts, transports and redeposits snow crystals, changing snowpack mass and density " and deposits aerosols inside the snowpack.Wind and temperature are climatic variables that determine metamorphism and snowpack physical properties such as albedo and heat conductivity. These properties affect the energy balance of the snow-atmosphere and of the soil-snow interfaces, which in turn affect climate. 

Narukawa M., Kawamura K., Li S.-M. and Bottenheim J. W. (2002) Dicarboxylic acids in the arctic aerosols and snowpacks collected during ALERT2(XX). Atmos. Environ. 36, 2491-2499. 

Because of concern about its environmental toxicity, the use of Cd has decreased in recent years. A few studies of lake sediments and snowpacks have documented the rise in Cd pollution as a result of the industrial revolution and its sharp decrease since the 1970s (Fig. 2) [3-5]. According to the data of Fig. 2, the present inputs of Cd to remote northern regions through aeolian transport of aerosols are near their pre-industrial value. As the industrial use of Cd declines, much of the remaining Cd pollution results from its presence as a contaminant in Zn-containing materials. 

Results to date indicate that levels of mercury in atmospheric fallout at Cranberry Lake are low rainfall and snowpack levels are usually less than 25 ng Hg/1 of liquid sample. The Cranberry Lake watershed contributes more mercury to the lake than it receives from the atmosphere, as stream inputs to the lake exceed... 

Figure 2. Cranberry Lake stream and precipitation, sediment and snowpack sampling locations.

One of the major effects of acidic deposition is felt by aquatic ecosystems in mountainous terrain, where considerable precipitation occurs due to orographic lifting. The maximum effect is felt where there is little buffering of the acid by soil or rock structures and where steep lakeshore slopes allow little time for precipitation to remain on the ground surface before entering the lake. Maximum fish kills occur in the early spring due to the "acid shock" of the first meltwater, which releases the pollution accumulated in the winter snowpack. This first melt may be 5-10 times more acidic than rainfall. 

Rainfall samples collected in the Great Lakes area of Canada in 1976 and 1977 contained mean concentrations of 1-2 ng/L (parts per trillion) a-endosulfan and 4—5 ng/L P-endosulfan. Endosulfan was detected in spring and summer rainfall samples but not in samples collected during the fall and winter (Strachan et al. 1980). a-Endosulfan has also been detected in snowpack samples obtained from widely distributed sites in the Canadian Arctic. Endosulfan concentrations in samples collected in the spring of 1986 ranged from 0.1 to 1.34 ng/L (Gregor and Gummer 1989). 

Estimates of THg loading (pg/m ) can be determined for a dated snowpack interval by the product of the interval Hg concentration and the snow water equivalent, which is determined from the interval density and thickness. Seasonal and, at many sites, near annual (-90%) loadings can then be estimated by summing the interval loadings (USEPA 2003). 

FIGURE 2.9 Total Hg concentrations (ng/L) in the 2002 snowpacks at snow-sampling sites in the Rocky Mountains of the United States (GP Ingersoll and others, U.S. Geological Survey, written commun., 2003). 

Sea ice is represented in the model as a two-dimensional surface covered with a snowpack. Ice advection, rheology and snow cover are calculated from the sea-ice model embedded in MPIOM [Hibler (1979)]. The only source of pollutants for the ice compartment is deposition from the atmosphere. Once pollutants enter the ice compartment they can diffuse into the snow pore space air, dissolve in the interstitial liquid water or adsorb to the ice surface. Together with the sea ice the pollutants undergo advection. Sinks considered for the ice compartment are volatilisation to the atmosphere and release into the ocean with melt water. 

Fig. 22 Monthly variations in total water storage volumes in Switzerland from 1940 to 1981. Water storage volumes include medium-term changes in soil moisture, groundwater, snowpack, lakes, and reservoirs. Long-term changes in groundwater and glaciers are not taken into account [71]. Minimum and maximum years are indicated...

An obvious correlation between polar and alpine environments is the decrease in temperature with increasing latitude or elevation. This temperature change leads to a shift in environmental phase distribution equilibria - i.e. a chemical moves from the atmosphere to terrestrial surfaces, including direct deposition to surface waters, but also to snowpack and soils from which movement into surface and groundwater is possible. This process has been termed cold condensation but should more correctly be called cold-trapping because the contaminants are not actually condensing. 

---