CHEMODYNAMICS OF TRACE POLLUTANTS DURING SNOWMELT ON ROOF AND STREET SURFACES

In order to investigate the concentration levels and chemodynamic behaviour of organic micropollutants and heavy metals in snowmelt runoff from urban sealed surfaces, meltwater was sampled from one street and four different roof catchments. Apart from peak concentrations of suspended solids during short intense street runoff from rain, concentrations of suspended solids in snowmelt runoff are two to fivefold higher than in rain runoff. However, the specific metal concentrations in suspended solids of snowmelt (except Zn) are lower than in suspended solids of rainwater runoff. This partly compensates the higher concentration of suspended solids. There are no distinct differences in concentrations of heavy metals between rain and meltwater runoff with the exception of dissolved Cd; its concentrations are increased when high concentrations of macro ions are present. We explain high concentrations of PAH with a molecular weight of 202 or less in snowmelt with longer equilibration times available during melting than during rain runoff. An enhancement of solubility by DOC seems to be likely. The physical and chemical properties of various roof surfaces greatly influence the temporal variation of PAH concentrations during snowmelt runoff.