Researchers from Dickinson College broadened our geographical understanding of the problem of coal tar sealants with research published in the journal. The study was in the 524 square mile Conodoguinet Creek basin in south central Pennsylvania along its 100 mile or so length. The watershed is just upstream of the state capitol, Harrisburg and tributary to the Susquehanna River and ultimately to Chesapeake Bay.

Key findings in the of the study were:
coal tar sealants are a major source of PAH is urban streams
high PAH values from sealants are “strongly related” to residential and commercial/industrial land use
coal tar sealants are an important PAH source in the Conodoguinet Creek watershed

Previous studies have included harbors (New York Academy of Sciences), urban ponds across the US (USGS’ 40 Lakes Study) and urban creeks (Missouri State University), but not a lot along a rural-suburban transect. The study included composite samples of sediment in 35 locations in the creek. This creek was chosen by the researchers because it “provides significant economic and societal services within the region that typify many other small watersheds throughout the U.S. and may serve as a model for areas undergoing [urbanization].”

Some additional observations were made regarding the concentrations found and the researchers’ interpretations of the concentrations. We hope to go into those further in a future article.