Distribution and composition of polycyclic aromatic hydrocarbons within experimental microcosms treated with liquid creosote

Temporal changes in the distribution and relative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in water, sediment, and absorbed to polyvinylchloride (PVC) strips were assessed following direct application of liquid creosote to aquatic microcosms. Fourteen microcosms were treated with nominal creosote concentrations ranging from 0.06 to 109 mg/L and two microcosms served as controls. Quantitative analysis of PAHs was performed using high-performance liquid chromatography equipped with a fluorescence detector. Post-treatment concentration of PAHs in water decreased exponentially with time. At 2 d posttreatment, total PAHs (∑ PAH) ranged from 7.3 μg/L (lowest treatment) to 5,803.2 μg/L (highest treatment); by 84 d, ∑ PAH in the same microcosms was reduced to between 0.8 μg/L and 13.9 μg/L, respectively. The relative composition of PAHs in the water also changed with time; at 2 d posttreatment, ∑ PAH in the lowest treatment (7.3 μg/L) reflected contribution from nine PAHs, whereas only two PAHs contributed to this concentration (0.8 μg/L) at 84 d. Low and high molecular weight (mol. wt.) PAHs were lost first from the water column, followed by PAHs of intermediate mol wt. In sediments, a dose-dependent increase in ∑ PAH was observed above 0.59 mg/L creosote up to 28 d, followed by a decline thereafter in all but the highest treatment. Total PAHs in sediment ranged from 0.91 μg/g (lowest treatment) to 63.9 μg/g (highest treatment) at 28 d. A dose-dependent relationship was also observed in PVC strips, with ∑ PAH on PVC ranging from 0.05 to 88 μg/cm2 at 31 d and 0.04 to 18.4 μg/cm2 at 58 d posttreatment. A mass balance evaluation showed that 88.3% of PAHs was lost from the system after 1 month, indicating that liquid creosote is attenuated relatively quickly in aquatic environments.