Characterizing and distinguishing losses of hydrocarbons from evaporation and dissolution are necessary for calculating mass balances, assessing exposures, and estimating damages following a spill. We investigated these processes following the 2007 M/V Cosco Busan heavy fuel oil spill (San Francisco Bay, CA). We examined oil-covered rocks from the coastline of San Francisco Bay by comprehensive two-dimensional gas chromatography (GCXGC). GCXGC retention times were used to estimate compound vapor pressures and solubilities. Data within the chromatograms are presented as mass loss tables (MLTs), which allow for visualization of weathering trends as a function of vapor pressure and aqueous solubility. To gain a more quantitative understanding, a physiochemical model was developed to describe evaporation and dissolution. This model is distinct from previous efforts because it allows composition of the oil film to vary with depth as diffusion out of the oil occurs. The trends from the model results are consistent with evaporation and dissolution trends observed in the MLTs. The model enables quantitative estimation of evaporation and dissolution for petroleum hydrocarbon compounds following a spill. The model underestimates observed losses for compounds with vapor pressures <~10-3 Pa. Model sensitivity to input parameters and uncertainty were also examined.

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