Phthalate esters discharged from a plasticizer-manufacturing plant were distinguished from those of other sources in the Chester River, Maryland by comparing the distinctive patterns of alkyl phthalate species of the plant to those of sediment samples from sites along the mid-river axis. The magnitude of the changes in individual phthalate species were placed in perspective by charting their concentrations with distance along the river. Short sediment cores were also analyzed to determine the profile of phthalate ester pollution in the Chester River during the previous decade in which the river experienced a significant oyster mortality. A significant level of phthalate ester pollution was found in the Chester River sediment but its source was not found to be the plasticizer plant.
