National Oceanic and
Atmospheric Administration
United States Department of Commerce


 

FY 1981

Hydrocarbons associated with suspended matter in the Green River, Washington

Hamilton, S.E., and J.D. Cline

NOAA Tech. Memo. ERL PMEL-30, NTIS: PB82-148677, 116 pp (1981)


In 1978 a systematic study of suspended hydrocarbons in the Green-Duwamish River was undertaken. The goal of the study was to define the suspended hydrocarbon composition both seasonally and spatially. Emphasis was placed on hydrocarbon budgets of the river and the significance of the Renton Secondary Treatment Plant. Concentrations of total aliphatics, total "aromatics" (which were contaminated with fatty-acid esters), and the unresolved complex mixture increase downriver. The upper river above Auburn, Washington, is dominated by odd-carbon paraffins contributed by aquatic and terrestrial plants. Concentrations of the even-carbon n-alkanes, pristane, and phytane increase downriver as plant wax hydrocarbons decrease in abundance. Compositional changes in suspended hydrocarbons within the upper river are attributed to highway runoff. Stations encompassing the sewage outfall show influence of wastewater discharge. CPI indices approach unity, demonstrating relative increases in the even-carbon paraffins. The most distinctive seasonal feature is the paucity of the algal alkanes (C and C) in December. A budget of suspended hydrocarbons was calculated for the lower river based on analysis of riverine suspended matter obtained by centrifugation and effluent-suspended solids recovered by filtration. Results indicate a preferential loss of the heavy hydrocarbons below the sewage outfall. The deficits may be the result of (1) flocculation or desorption of suspended hydrocarbons in the effluent as waste water mixes with river water and/or (2) an overestimation of suspended hydrocarbons in the effluent caused by retention of a lipid fraction on the glass fiber filters that is not recovered by the centrifuge. Results of a budget in the upper river suggest that sediments gained by resuspension, erosion, or runoff are diluting the suspended hydrocarbons characteristic of plant waxes. GC-MS analyses of the "aromatic" fractions confirm the presence of retene, benz(e)pyrene, perylene, benz(g,h,i)perylene, chrysene, and fluoranthene in concentrations ranging from 0.08 to 2.2 µg/g dry weight of riverine suspended matter. Concentrations of perylene and benz(g,h,i)perylene in the effluent are approximately 40 µg/g. Esters of the even-carbon fatty acids typical of waste water and higher plants are also found in these samples.




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