SPATIAL AND TEMPORAL DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) WITHIN SEDIMENT AND FISH TISSUE OF THE LOWER CHESAPEAKE BAY BASIN, USA

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic persistent organic pollutants that pose serious environmental risks in aquatic ecosystems. The presence of PAHs is related to various anthropogenic activities, predominantly fossil fuel combustion. We report an ongoing analysis of the spatial and temporal distribution of PAHs in the fluvial and lacustrine systems of the Virginia portion of the Chesapeake Bay watershed. The study area has a population of over 6.7 million and maintains a cover of 16% urban development, although anthropogenic alterations, mainly along the I-95 transportation corridor, are increasing. PAH analysis is being done on surficial sediment samples and dated sediment cores (²¹⁰Pb and ¹³⁷Cs) as well as on muscle and liver tissues of largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), and blue catfish (Ictalurus furcatus).

The analysis employs accelerated solvent extraction and gas chromatography mass spectrometry (GCMS) with selected ion monitoring. Preliminary results show that PAH hot spots are also areas with multiple identified PAH sources, both point and atmospheric. Overall, surficial sediment PAH levels had a mean value of 3.9x10³ ±2.5x10⁴ ng/g, while fish tissue PAH levels had a mean value of 8.1 ±8.2 ng/g. This disparity may be due to the low efficiency of PAH bioconcentration. Fish tissue PAH levels were randomly distributed, while surficial sediments reveal high clusters. This may be due to fish mobility and migration. Additionally, apex predator species were shown to have PAH values greater than could be accounted for by direct exposure alone, as seen in bottom feeding fish. This reveals that bio-magnification is occurring.