Over a century of PAH contamination history to New York City

Abstract:

Spatially and temporally integrated urban lake sediments have the potential to be used for reconstructing air contamination history, with data being available even before the start of urban air quality monitoring. In a previous study, fine-grained sediment sample cores were collected from the Lower Hudson River basin and dated via radionuclides. An objective source appointment method has been established based on several source-sensitive molecular indicators we found. An over 100 year historical record of energy usage in New York City has been reconstructed in cores from Central Park Lake. The reconstructed history is consistent with historical energy consumption data of NYS complied by the US Department of Energy. Wood combustion was dominant one century ago in Manhattan, followed by coal combustion dominance from the 1900s to the 1940s. Petroleum combustion, mainly from motor vehicles in Manhattan, increased gradually from the 1920s, and became the dominant PAH input after 1940s. In most samples collected from elsewhere in the lower Hudson River Basin, petroleum combustion was the dominant PAH input in the last half century. From 2001 to 2012, indoor and outdoor air filter samples were collected from NYC apartments; though non-volatile PAH levels were quite stable, pyrene, which is a semi-volatile PAHs compound, increased over these 12 years, especially in the heating season. The burning of No.6 oil in NYC boilers is thought to lead to this increase and the recent effort in switching No. 6 heating oil to No.2 oil has the potential to overturn the increasing trend.