A closer look at bioaccumulation of petroleum hydrocarbon mixtures in aquatic worms

Abstract

Petroleum hydrocarbons (oils) are ubiquitous in the aquatic environment, and adequate risk assessment is thus essential. Bioaccumulation plays a key role in risk assessment, but the current knowledge on bioaccumulation of oils is limited. Therefore, this process was studied in detail, using the aquatic worm, Lumbriculus variegatus, and 14 field-contaminated sediments. The main focus during the present study was on uptake kinetics, the relationship between oil boiling point fraction and uptake, and effects of sediment characteristics. Uptake kinetics became slower with increasing boiling point fraction, but 70 to 90% of the equilibrium situation was reached within the standard exposure duration of 28 d. Worms accumulated sedimentary petroleum hydrocarbons in the range of C(10) to C(34), a range much wider than expected. Biota-to-sediment accumulation factors (BSAFs) for separate boiling point fractions were constant and around the proposed value of 1 to 2 up to C(22), but gradually decreased beyond this point. The decrease was probably caused by a combination of nonequilibrium conditions and enhanced sorption of higher boiling point fractions to sediments; the latter possibly due to the presence of strongly sorbing separate oil phases or black carbon. A negative relationship was observed between BSAF and oil concentration in sediment, which was explained by the presence of separate oil phases at high oil concentrations. These strongly sorbing phases may limit their own availability, particularly when being highly weathered; worms may also avoid them. The observed phenomena have obvious implications for bioaccumulation assessment of oils and suggest that the current risk assessment procedure for oils in sediments may lead to erroneous results.

A re‐evaluation of PETROTOX for predicting acute and chronic toxicity of petroleum substances

“…Initially the limit identified in Equation 1 was parameterized at log K OW of 6 [9,[40][41][42][43], which effectively reduced the bioavailability of more hydrophobic components while allowing fractional contribution to overall toxicity of the substance to be included in P TU calculations [44][45][46]. This nonlinear partitioning behavior may reflect the impact of low solubility and slow toxicokinetics [47] or other competing processes that limit accumulation in the target lipid for these low-solubility constituents.…”

Toxicity of sediment-associated unresolved complex mixture and its impact on bioavailability of polycyclic aromatic hydrocarbons

“…Most studies on crude oil spills have focused on polycyclic aromatic hydrocarbons (PAHs), and have shown that these contaminants caused detrimental effects on various aquatic organisms [2][3][4][5][6]. Conversely, other constituents in the oil matrix, which were commonly referred to as an unresolved complex mixture (UCM) were less studied [7][8][9][10]. The UCM was composed of weathered oils, which originated from natural and/or anthropogenic sources, and was first recognized as the "hump" in the quantification of petroleum-contaminated sediment samples using gas chromatography (GC) [11].…”

“…Recent studies, however, have showed that the UCM constituents in sediment not only accumulated in benthic organisms, but also caused sub-lethal effects to these organisms [7][8][9][10][11]15]. For example, UCM contributed to the overall toxic effects of oils to the marine amphipod Corophium volutator and its contribution was separate from the PAHs [7].…”

INVESTIGATION OF THE TOXICOKINETICS OF PETROLEUM HYDROCARBON DISTILLATES WITH THE EARTHWORM EISENIA ANDREI

“…Accumulation rates were greatest for the lowest-boiling-point distillate (F2) and progressively decreased as the boiling point range of the distillate increased (Table 2), as noted by others [23]. This likely is due to a decrease in the bioavailability of oil constituents resulting from changes in sorption and water solubility as the boiling point range for hydrocarbons increases [2,25].…”