Chemical composition of WAF made with traditional CROSERF method and two passive dosing methods and comparison with predicted concentrations from PETROTOX model

This study compared the Chemical Response to Oil Spills: Ecological Research Forum (CROSERF) Water Accommodated Fraction (WAF) procedure with two alternative techniques in which crude oil is passively dosed via partitioning from silicone tubing or O-rings. Using fresh Macondo surrogate oil (MC252), WAFs were prepared at a 10, 30, 100, 360 mg/L loading using each dosing approach. Following equilibration, the aqueous test media was analytically characterized by measurement of total polycyclic aromatic and aliphatic hydrocarbons using GC-MS and dissolved hydrocarbons using GC-FID biomimetic solid phase microextraction (BE). Total measured concentrations of speciated hydrocarbons were fit to an oil solubility model to estimate dissolved and droplet oil concentrations for each treatment. Detailed GCxGC compositional input obtained on this oil was used as input to the PETROTOX model to calculate dissolved toxic units (TUs) at each oil loading as an improved exposure metric for toxicity prediction.