TEMPORAL HEAVY METAL DELIVERY AND PARTITIONING IN URBAN SNOW EXPOSED TO TRAFFIC

Urban roadway snow is exposed to heavy metals from traffic and winter maintenance practices. These anthropogenic activities generate loadings of heavy metals as well as other constituents. Heavy metals once released in the highway environment are not degraded and partition between the dissolved and particulate-bound fractions. Parameters such as residence time, solids loadings, alkalinity, hardness and pH influence this partitioning. The study investigates Pb, Cu, Cd, Zn, Al, Ca, Na, Mg and Fe accretion and partitioning from a series of urban highway sites in Cincinnati, Ohio. Results from partitioning analysis indicate that Pb, Cu, Cd, Zn, Al, Mg and Fe were highly particulatebound, while Na and Ca were mainly dissolved. Partition coefficient for most heavy metals in snowmelt ranged from 103 to 106 L/kg. Characterization of heavy metal partitioning is a necessary first step towards development of best management practices to address urban highway snow pollution.