CHEMODYNAMICS OF TRACE POLLUTANTS DURING SNOWMELT ON ROOF AND STREET SURFACES

In order to investigate the concentration levels and chemodynamic beha viour of organic micropollutants and heavy metals in snowmelt runoff f rom urban sealed surfaces, meltwater was sampled from one street and f our different roof catchments. Apart from peak concentrations of suspe nded solids during short intense street runoff from rain, concentratio ns of suspended solids in snowmelt runoff are two to fivefold higher t han in rain runoff. However, the specific metal concentrations in susp ended solids of snowmelt (except Zn) are lower than in suspended solid s of rainwater runoff. This partly compensates the higher concentratio n of suspended solids. There are no distinct differences in concentrat ions of heavy metals between rain and meltwater runoff with the except ion of dissolved Cd; its concentrations are increased when high concen trations of macro ions are present. We explain high concentrations of PAH with a molecular weight of 202 or less in snowmelt with longer equ ilibration 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 tem poral variation of PAH concentrations during snowmelt runoff.