Date of Original Version
Passive samplers can be useful tools to determine truly dissolved concentrations of organic contaminants in the water. Polyethylene (PE) samplers were validated for measuring polycyclic aromatic hydrocarbons (PAHs), with a focus on alkylated PAHs that can dominate in an oil spill. Equilibrium partition coefficients (KPEw) between water and PE passive samplers were measured for 41 PAHs both at ambient conditions (20 °C, no salt), down to -15 °C and 245 psu present in ice brine. For each additional alkylated carbon, log KPEw increased by an average of 0.40 (± 0.20) log units, close to predictions. The increase per aromatic carbon was only 0.33 (± 0.02) log units. Apparent PE-water distributions of pyrene and deuterated pyrene (performance reference compound) were within 0.1 log unit for all experiments at 20 and 2 °C, but started to diverge by 0.8 log units (-4 °C, 100 psu) and 3.1 log units (-15 °C, 245 psu). The delay in equilibrating PAHs in these experiments was dominated by increases in the water’s viscosity, which in turn affected both the PAHs’ aqueous diffusivity and the thickness of the water boundary layer. In a simulated marine oil spill in the laboratory, PE-based results were within a factor of 2 for the most abundant PAHs compared to conventional sampling results.
Reitsma, P., Adelman, D., & Lohmann, R. (2013). The challenges of using polyethylene passive samplers to determine dissolved concentrations of parent and alkylated PAHs under cold and saline conditions. Environmental Science and Technology 47 (18), pp 10429–10437.
Available at: http://dx.doi.org/10.1021/es402528q