Predicting PAH Bioaccumulation and Toxicity in Earthworms Exposed to Manufactured Gas Plant Soils with Solid-Phase Microextraction

Abstract

Soils from former manufactured gas plant (MGP) sites are often heavily contaminated with polycyclic aromatic hydrocarbons (PAHs). Current risk assessment methods that rely on total PAH concentrations likely overstate adverse effects of such soils since bioavailability is ignored. In this study, solid-phase microextraction (SPME) was applied to estimate bioavailable PAH concentrations and toxicity in earthworms exposed to 15 MGP soils. In addition, PAH sorption to all soils (K0o values) was determined. The results showed a several orders of magnitude variation in Koc values, demonstrating that generic organic carbon-normalized sorption coefficients will typically be overconservative at MGP sites. SPME-predicted bioaccumulation generally was within a factor of 10 of measured bioaccumulation (in earthworm bioassays), in contrast to current risk assessment model estimates that overpredicted bioaccumulation 10-10 000 times. Furthermore, on the basis of estimated total body residues of narcotic PAHs, SPME correctly predicted worm mortality observed during bioassays in the majority of cases. For MGP sites where current risk assessment procedures indicate concerns, SPME thus provides a useful tool for performing a refined, site-specific assessment.

Influence of single-walled carbon nanotubes on microbial availability of phenanthrene in sediment

“…Influence on C free of phenanthrene Concurrent with the measurement of microbial mineralization of PHE, C free of PHE in sediment slurry was measured using a previously developed SPME method (Mayer et al 2000;Jonker et al 2007;Hunter et al 2008;Yang et al 2009). The partition coefficients (K d ) of PHE were then calculated from the derived C free (Table 1).…”

“…The fiber pieces were cleaned using Soxhlet extraction with ethyl acetate for 72 h before use. The detailed procedure for C free measurement by PDMS fiber was performed similarly to that in previous studies (Mayer et al 2000;Jonker et al 2007;Hunter et al 2008;Yang et al 2009). Other chemical reagents used in this study were of gas chromatography (GC) or analytical grade.…”

Application of Biochar for Soil Remediation

“…The concentration of contaminant present in the extraction solution can then be determined analytically. There is consensus in more recent work that measuring freely dissolved concentrations of organic and inorganic contaminants with passive samplers (e.g., solid-phase micro extraction [Jonker et al, 2007], polyethylene [Adams et al, 2007] [Tao et al, 2009], or diffusive gradients in thin films [Zhang et al, 2001]) can provide the best indication of the actual bioavailability of contaminants in soils (Gomez-Eyles et al, 2012;Nolan et al, 2005). These methods enable an assessment of the efficacy of a particular biochar by its ability to reduce the mobility or availability of contaminants in contaminated soils.…”

Bioavailability of Hydrophobic Organic Contaminants in Sediment with Different Particle-Size Distributions

“…However, using total extractable concentrations may overestimate the risk due to the limited bioavailability of HOCs (Jonker et al 2007;You et al 2008). A variety of factors, such as biological features of the organisms, chemical properties, chemical-sediment contact time, and sediment characteristics (Harkey et al 1994;Hendriks et al 2001;Cornelissen et al 2005;Kukkonen et al 2005;You et al 2007a;Sormunen et al 2008;Trimble et al 2008), may affect bioavailability of HOCs in sediment.…”

“…Non-exhaustive chemical extraction has been shown to be a more accurate method for predicting bioavailability and toxicity of sediment-associated HOCs compared with exhaustive extraction methods because it estimates only the bioavailable fractions within the system (Conder et al 2004;You et al 2006;Jonker et al 2007;You et al 2007b;Styrishave et al 2008;van der Heijden and Jonker 2009;Oleszczuk 2009), and it has been effective in evaluating bioavailability of various classes of HOCs in sediment with different OC Jonker et al 2007) and black carbon contents (Cornelissen et al 2005;Yang et al 2008). However, relatively few studies have examined whether non-exhaustive extraction techniques can accurately predict the bioavailable fractions of HOCs when differing physical factors, such as particle-size distribution, occur.…”