Occurrence of salt and lead in snow dump sites

Sodium, Cl and Pb contents of snow, meltwater and soil from ten Metropolitan Toronto snow dumps were determined. Contaminant concentrations were related to the source of the snow. Although initially very high, Na and Cl concentrations in the snow decreased with time while piled at the dump site. Conversely, Pb content increased with time as the snow gradually melted and the Pb-containing particulates accumulated on the snow surface. The Na and Cl content of the meltwater was related to the concentrations in the snow, but the mean levels decreased with time, indicating that parts of the piles with higher salt concentrations were melting and draining away before the remaining areas. Although some Na and Cl is leached from the soil during the summer months, much of the salt and most of the Pb remains to accumulate from year to year. Adjacent to the snowpiles, the soil contained contaminant concentrations that were higher than control samples, possibly as a result of the movement of meltwater runoff.