Polycyclic aromatic hydrocarbon (PAH) distributions and associations with organic matter in surface waters of the York River, VA Estuary

Abstract

Surface water samples were collected along the salinity gradient of the York River, VA Estuary, between June 1998 and April 1999, to examine spatial and temporal variability in particulate polycyclic aromatic hydrocarbon (PAH) concentrations and their interactions with suspended particulate organic matter (POM). Specifically, relationships with source-specific lipid biomarker compounds (sterols and fatty acids) were examined to assess PAH associations with POM and to help elucidate PAH sources and modes of entry into the estuary. Principal component analysis (PCA) revealed that PAHs in the estuary can be classified into three groups: volatile, soot-associated and perylene. The three PAH groups differed in their relationships with particulate organic carbon (POC) as well as with source-specific lipid biomarkers reflecting processes controlling their delivery to the estuary. The more volatile PAHs showed a strong positive correlation with biomarkers for autochthonous (i.e. plankton-derived) POM, but only weak correlations with total POC in spring/early summer. In contrast, all PAHs except perylene were correlated with sterols of vascular plant/freshwater microalgal origin (i.e. allochthonous) during fall/winter. Perylene concentrations decreased from the head to the mouth of the estuary and were correlated with terrestrial biomarkers, suggesting that the freshwater end-member is the dominant source of perylene to this system. The varying relationships between distinct groups of PAHs and lipid biomarkers indicate that very specific pools of POM play an important role in the fate and transport of hydrophobic organic contaminants.