Bioavailability of PCBs from field-collected sediments: Application of Tenax extraction and matrix-SPME techniques
ABSTRACT Two chemical approaches, Tenax extraction and matrix solid phase microextraction (matrix-SPME), were evaluated for their potential to improve the prediction of bioavailability by equilibrium partitioning theory (EPT) across sediments with various characteristics. Biota-sediment accumulation factors (BSAFs) and body residues were quantified by exposing Lumbriculus variegatus to three PCB-contaminated field sediments. The concentration of PCBs in biota was positively correlated to the total PCB sediment concentration, the PCB concentration in the rapidly desorbing fraction estimated using Tenax extraction, and the PCB concentration on the SPME fibers. Results showed EPT was acceptable for estimating bioavailability from the tested sediments with sum PCB BSAFs of 1.18-2.47; however, it overestimated PCB bioavailability from sandy sediment. Both Tenax extraction and matrix-SPME, which take sequestration into account, reduced variability in prediction of PCB bioavailability across sediments, including the sandy sediment, and could be used as cost- and time-efficient alternatives for bioassay. Matrix-SPME was considered the better technique due to its ability to directly predict PCB body residues in the exposed biota and its potential use with in situ applications in the field.
- SourceAvailable from: Philipp Mayer
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- "For example, bioavailability in processes such as biodegradation is more closely dependent on bioaccessibility (Cornelissen et al., 1997; Cuypers et al., 2002; Reid et al., 2000), while in other processes (e.g., baseline and acute aquatic toxicity), it is regulated by chemical activity such as C free (Leslie et al., 2002a; Xu et al., 2007). However, both parameters have been used to describe bioaccumulation of HOCs into invertebrates, often with similar successes (Jonker et al., 2007; Kraaij et al., 2003; Leppänen et al., 2003; Trimble et al., 2008; Yang et al., 2008; You et al., 2007b, 2011). The validity in using C free to predict bioaccumulation may be attributed to the fact that small organisms such as aquatic invertebrates accumulate HOCs passively via diffusion e a process driven by chemical activity gradient (Reichenberg and Mayer, 2006). "
ABSTRACT: Many important environmental contaminants are hydrophobic organic contaminants (HOCs), which include PCBs, PAHs, PBDEs, DDT and other chlorinated insecticides, among others. Owing to their strong hydrophobicity, HOCs have their final destination in soil or sediment, where their ecotoxicological effects are closely regulated by sorption and thus bioavailability. The last two decades have seen a dramatic increase in research efforts in developing and applying partitioning based methods and biomimetic extractions for measuring HOC bioavailability. However, the many variations of both analytical methods and associated measurement endpoints are often a source of confusion for users. In this review, we distinguish the most commonly used analytical approaches based on their measurement objectives, and illustrate their practical operational steps, strengths and limitations using simple flowcharts. This review may serve as guidance for new users on the selection and use of established methods, and a reference for experienced investigators to identify potential topics for further research.Environmental Pollution 10/2012; 172C:223-234. DOI:10.1016/j.envpol.2012.09.013 · 4.14 Impact Factor
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- "The rapidly desorbing fraction has been used successfully to predict the extent of PAH degradation in field-contaminated soils (Baczynski et al. 2012). Among a variety of biomimetic extraction techniques, consecutive desorption for 400 h with Tenax TA (a polymer based on 2,6-diphenyl-p- phenylene oxide) extraction has been demonstrated to be a very useful method to predict the desorption kinetics and bioaccessibility of PAHs (Schwab and Brack 2007; Trimble et al. 2007). "
ABSTRACT: The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F sl and F vl ) became larger and the rate constants of slow and very slow desorption (k sl and k vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.Biodegradation 09/2012; 24(3). DOI:10.1007/s10532-012-9593-2 · 2.34 Impact Factor
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- "), most of which has been demonstrated in the laboratory (e.g. You et al., 2006; Trimble et al., 2008; Lu et al., 2011). To validate the ability of the SPME pore water sampling method to predict in situ bioaccumulation of PAHs in marine systems, fibers with a 210 mm core and a 10-mm PDMS coating (outer diameter of 230 mm) were deployed in a stainless steel rod-shaped SPME sampling device in close (w2e5 cm) proximity, in triplicate, to the SEA Rings. "
ABSTRACT: A comprehensive, weight-of-evidence based ecological risk assessment approach integrating laboratory and in situ bioaccumulation and toxicity testing, passive sampler devices, hydrological characterization tools, continuous water quality sensing, and multi-phase chemical analyses was evaluated. The test site used to demonstrate the approach was a shallow estuarine wetland where groundwater seepage and elevated organic and inorganic contaminants were of potential concern. Although groundwater was discharging into the surficial sediments, little to no chemical contamination was associated with the infiltrating groundwater. Results from bulk chemistry analysis, toxicity testing, and bioaccumulation, however, suggested possible PAH toxicity at one station, which might have been enhanced by UV photoactivation, explaining the differences between in situ and laboratory amphipod survival. Concurrently deployed PAH bioaccumulation on solid-phase micro-extraction fibers positively correlated (r(2) ≥ 0.977) with in situ PAH bioaccumulation in amphipods, attesting to their utility as biomimetics, and contributing to the overall improved linkage between exposure and effects demonstrated by this approach.Environmental Pollution 12/2011; 162:457-65. DOI:10.1016/j.envpol.2011.11.013 · 4.14 Impact Factor