Accumulation of PAHs and petroleum biomarkers in SPMDs and fish to discriminate petroleum sources (Polycyclic aromatic hydrocarbons)

Source discrimination of petroleum hydrocarbons in the environment is critical to the prioritization of resource management options and to the identification of potentially responsible parties in environmental restoration and litigation. In surface waters, the primary matrices available for measuring petroleum components are water and aquatic biota. However, the concentrations of petroleum components in water usually are very low and highly variable and selective uptake and metabolism can modify petroleum residues in biota. I hypothesized that semi-permeable membrane devices (SPMDs) might accumulate a distribution of PAHs and sterane/hopane biomarkers that is much more conserved than that found in fish. We conducted laboratory studies on the uptake kinetics of over 100 petroleum compounds from the water-soluble fraction of Alaska North Slope Crude into three different SPMD designs. SPMDs filled with iso-octane had higher sampling rates for compounds with a molecular weight <200 Daltons. This design also requires little or no cleanup before analysis. The SPMDs filled with triolein are the standard design. This design had a higher sampling rate for the majority of PAH with a log Kow < 6. Two drawbacks of this design are higher cost and additional cleanup required before analysis. The polyethylene strips had the highest sampling rates for compounds with a log Kow > 6 which included all of the petroleum biomarker compounds. They were the easiest to manufacture, but required the same number of cleanup steps as the triolein filled SPMDs. Compound specific differences in water solubility and vapor pressure changed some of the PAH diagnostic ratios in the water and SPMDs, but the biomarker ratios were unaffected. We also measured these same compounds in fish and SPMDs at the Delta National Wildlife Refuge (NWR). Diagnostic ratios calculated from the relative distribution of the PAH and biomarker compounds in the samples were compared to ratios determined from the analysis of the crude oil from Delta NWR and to local petroleum products. The ratios do not indicate a single source of contamination on Delta NWR, but the PAH distribution indicates the primary source of hydrocarbon contamination is from the atmospheric input of pyrogenic PAH.