Equipment for measuring volatilization from sealcoated pavement

In 2009, USGS had a test plot professionally sealed with coal-tar-based sealcoat in preparation for measurements of volatilization from the pavement after application. This photo shows the "hat" sampler, which measures PAH concentrations in air just above the pavement surface, and the accompanying piece of equipment that measures PAH concentrations in air about 4 feet from the surface. The difference between the two establishes a gradient that can be used to compute PAH flux. Read about the results here and here.