FY 1987

Hydrocarbon distributions and transport in an urban estuary

Bates, T.S., P.P. Murphy, H.C. Curl, Jr., and R.A. Feely

Environ. Sci. Technol., 21(2), doi: 10.1021/es00156a010, 193–198 (1987)

Aliphatic and polycyclic aromatic (PAH) hydrocarbons were quantified on suspended particulates and surficial bottom sediments from the main basin of Puget Sound, WA. Total four-, five-, and six-ring PAH concentrations ranged from 0.6 to 3.2 µg/g dry weight of sediment. Concentrations of total n-alkanes and the unresolved complex mixture ranged from 3 to 35 and from 35 to 1100 µg/g, respectively. The highest hydrocarbon concentrations on particulates were found in the surface waters near Seattle. Concentrations decreased with depth in the water column and with distance from Seattle. Hydrocarbon distributions and concentration gradients show vertical flux as the major transport process. Although the hydrocarbon residence time in the water column is too short to horizontally mix the compounds, resuspension and lateral transport in the bottom nepheloid layer disperse the hydrocarbons through the fine-grained sediments in the center of the basin.