FACTORS INFLUENCING METAL DEPOSITION AND MOBILITY NEAR ROADWAYS IN THE BINGHAMTON, NY URBAN CORRIDOR

In order to examine how the near roadway environment affects spatial, as well as seasonal, variation in atmospheric deposition in the northeastern United States, arrays of bulk deposition collectors were deployed at distances ranging from 0 – 150 m at four sites in Binghamton, NY. These collectors were sampled on a weekly to biweekly basis from June 2009 – May 2010. In addition to precipitation volume, pH, and conductivity, samples were analyzed using sector field – mass spectrometry to determine concentrations for over 50 major and minor elements.

Many of the elements exhibit exponential decreases in concentration perpendicular to the roadway corridors. Considerable seasonal variation is also evident with an increase of several orders of magnitude in the concentrations of many elements deposited during the winter months. Using multi-element analysis coupled with spatial variation, it is possible to differentiate pollutant signals from deicing salts, road surface degradation, brake and tire wear, and natural sources of materials including canopy interception. Roadway abrasion and vehicular emissions were found to be important sources of atmospheric deposition near roadways.

Additional experiments were conducted which examined the relationship between metal phases, pH, NaCl concentration, and distance from the roadway source. These were done in order to gauge the potential for metal mobility once deposited on roadside soil. Preliminary analysis shows that each metal displays its own dissolved vs particulate phase behavior with pH being the controlling variable. Because the pH in deposition collection is highest adjacent to roadways, a smaller proportion of metals is deposited in the dissolved phase as one nears the roadway. It is possible that the higher pH of near-roadway deposition may partially offset the ecological impacts of greater metal loading that tends to occur adjacent to roadways.