HISTORY OF POLYCYCLIC AROMATIC HYDROCARBON (PAH) DEPOSITION IN THE NEW YORK HARBOR

Isotopic and molecular analysis of individual polycyclic aromatic hydrocarbons (PAH) was conducted on extracts taken from dated sediment samples from New York Harbor. The sampling area included Newark Bay, Raritan Bay, and Jamaica Bay, with the sediment cores collected representing deposition from 1930's to 1990. Compound-specific carbon isotope analysis was performed using a HP 6890 gas chromatograph coupled to a Micromass Optima Isotope Ratio Mass Spectrometer. Individual PAH peaks were identified by comparing retention times with known PAH standards.

Newark Bay sediments show dramatic d¹³C shifts of 2 – 3 ^o/_oo from 1937 to 1985. Between 1970 and 1985, d¹³C values for Fluoranthene and Pyrene shifted from -24.5 and -24.8 ^o/_oo respectively to -26.1 and -26.6 ^o/_oo, suggesting a decreased importance of combustion-related sources. The isomeric ratio of Phenanthrene/Anthracene, shows almost perfect anti-correlation with d¹³C values of Fluoranthene and Pyrene. Raritan Bay shows d¹³C values ranging from -27.5 to -25.9 ^o/_oo from 1940 - 1970. The trend since the early 1970’s is opposite of Newark Bay, and has seen an almost 4 ^o/_oo shift towards lighter values in 1990. Molecular data from Raritan Bay shows very little correlation to the isotope data collected. Jamaica bay shows the largest variations by far. Fluoranthene and Pyrene values in 1954 were -29.0 and -29.7 ^o/_oo suggesting a dominance of petroleum inputs. From the late 1950’s to mid 1970’s values fluctuate between -24.0 and -27.0 ^o/_oo. From the mid 1970’s to 1988 the d¹³C show an almost 6 ^o/_oo shift towards lighter values suggesting a move towards combustion dominated inputs. With the exception of the 1954 sample, the molecular data correlates nicely with the isotope data. The unique behavioral patterns and variations in isotope values collected from each bay suggest that the PAH sources in these systems are very localized.