Bioavailability Of Polycyclic Aromatic Hydrocarbons Research Articles

The role of salicylate and biosurfactant in inducing phenanthrene degradation in batch soil slurries

The majority of polycyclic aromatic hydrocarbons (PAHs) sorb strongly to soil organic matter posing a complex barrier to biodegradation. Biosurfactants can increase soil-sorbed PAHs desorption, solubilisation, and dissolution into the aqueous phase, which increases the bioavailability of PAHs for microbial metabolism. In this study, biosurfactants, carbon sources, and metabolic pathway inducers were tested as stimulators of microorganism degradation. Phenanthrene served as a model PAH and Pseudomonas putida ATCC 17484 was used as the phenanthrene degrading microorganism for the liquid solutions and soil used in this investigation. Bench-scale trials demonstrated that the addition of rhamnolipid biosurfactant increases the apparent aqueous solubility of phenanthrene, and overall degradation by at least 20% when combined with salicylate or glucose in liquid solution, when compared to solutions that contained salicylate or glucose with no biosurfactant. However, salicylate addition, with no biosurfactant addition, increased the total degradation of phenanthrene 30% more than liquid systems with only biosurfactant addition. In soil slurries, small amounts of biosurfactant (0.25 g/L) showed a significant increase in total removal when only biosurfactant was added. In soil slurries containing salicylate, the effects of biosurfactant additions were negligible as there was greater than 90% removal, regardless of the biosurfactant concentration. The results of experiments performed in this study provide further evidence that an in situ enhancement strategy for phenanthrene degradation could focus on providing additional carbon substrates to induce metabolic pathway catabolic enzyme production, if degradation pathway intermediates are known.

Influence of temperature and origin of dissolved organic matter on the partitioning behavior of polycyclic aromatic hydrocarbons

The behavior of polycyclic aromatic hydrocarbons (PAHs) is affected by dissolved organic matter (DOM) present in pore water of soils and sediments. Since partitioning to DOM reduces the bioavailable or freely dissolved PAH concentration in pore water, it is important to assess the effect of environmental variables on the magnitude of dissolved organic matter to water partition coefficients (K (DOC)). The objective of this study was to apply passive samplers to measure freely dissolved PAHs allowing depletion from the aqueous phase. The method was applied to determine K (DOC) at different temperatures for a selection of PAHs with natural DOM of very different origin. Freely dissolved concentrations of (spiked) phenanthrene, anthracene, fluoranthene, pyrene, and benzo[e]pyrene were determined by exposing polydimethylsiloxane (PDMS) fibers to aqueous solutions containing DOM extracted from freshwater sediments from Finland and the Netherlands. The K (DOC) values were subsequently calculated at different temperatures (3.2, 20, and 36 degrees C) by including temperature-dependent PDMS to water partition coefficients (K (PDMS)) in a mass balance. Furthermore, the effect of temperature on partitioning of PAHs to PDMS fibers or DOM was assessed by comparing the enthalpy of sorption to the excess enthalpy of dissolution of liquid PAHs. Partitioning to DOM resulted in a decrease of freely dissolved concentrations with increasing DOM concentrations and a large range in log K (DOC) values at 20 degrees C for benzo[e]pyrene was observed (log K (DOC) = 4.93-6.60 L kg(-1) organic carbon). An increase of 10 degrees C in temperature resulted in a decrease of K (PDMS) by 0.09 to 0.13 log units for phenanthrene to pyrene and a decrease of K (DOC) by 0.13 log units for pyrene. The calculated enthalpies of sorption were less exothermic than the (negative) excess enthalpies of dissolution as expected for non-specific interactions between PAHs and PDMS or DOM. The bioavailability of PAHs in sedimentary pore waters can be accurately determined by application of PDMS fibers (without requiring negligible depletion) in the presence of natural DOM with different sorption affinity for PAHs. The observed natural variability in log K (DOC) values for different sediments shows that large differences can occur in freely dissolved PAH concentrations in pore water and properties of DOM should be taken into account in predicting the bioavailability of PAHs. Furthermore, the effect of temperature on the partitioning behavior of PAHs shows that interactions between PAHs and environmental sorbents are comparable to interactions between PAHs in their pure condensed liquid phase and calculated excess enthalpies can be safely used to directly correct partition coefficients for temperature. The application of PDMS fibers in measuring freely dissolved PAH concentrations can be used to study structural and thermodynamic aspects of PAH sorption to natural DOM as well as other environmental processes such as enhanced diffusion phenomena in pore water that are dependent on the amount (or concentration) of DOM, sorption affinity of DOM, and hydrophobicity of PAHs. These environmental factors will therefore give further insight into the site-specific exposure to freely dissolved PAH concentrations in soil and sedimentary pore water.

Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates

Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance ( P = 0.0004) and richness ( P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments.

Suspended C 60 nanoparticles protect against short-term UV and fluoranthene photo-induced toxicity, but cause long-term cellular damage in Daphnia magna

The increased production of nanotechnology materials is a potential source of nano-sized particles (NSPs) in aquatic ecosystems. Meanwhile, polycyclic aromatic hydrocarbons (PAHs), in the presence of ecologically relevant levels of ultraviolet radiation (UV), can be acutely toxic to aquatic species including fish and invertebrates. Considering that suspended carbon-based NSPs (e.g., C 60 fullerenes) may act in similar ways as dissolved organic matter (DOM) by altering the bioavailability of PAHs, the objective of this research was to determine the effect of suspended C 60 on the photo-induced toxicity of fluoranthene. Transmission electron microscopy indicated that the presence of C 60 protected cellular components (e.g., mitochondria, microvilli, and basal infoldings) in organisms exposed to UV and fluoranthene phototoxicity in short-term exposures. However, we found that long-term exposure (21 d) of low-level C 60 caused significant cellular damage in the Daphnia magna alimentary canal. This paper highlights the importance of examining the interactions between existing stressors and nanoparticles in the aquatic environment.

Effect of different non-ionic surfactants on the biodegradation of PAHs by diverse aerobic bacteria

The aim of this work was to evaluate the effect of several non-ionic surfactants (Tween-80, Triton X-100 and Tergitol NP-10) on the ability of different bacteria ( Enterobacter sp., Pseudomonas sp. and Stenotrophomonas sp.) to degrade polycyclic aromatic hydrocarbons (PAHs). Bacterial cultures were performed at 25 °C in an orbital shaker under dark conditions in BHB medium containing 1% of surfactant and 500 mg l −1 of each PAH. Experiments performed with Tween-80 showed the highest cell density values and maximum specific growth rate because this surfactant was used as a carbon source by all bacteria. High degree of PAHs degradation (>90%) was reached in 15 days in all experiments. Toxicity increased at early times using Tween-80 but decreased to low levels in a short time after the firsts 24 h. On the other hand, Triton X-100 and Tergitol NP-10 were not biodegraded and toxicity kept constant along time. However, PAHs-degradation rate was higher, especially by the action of Enterobacter sp. with Tween-80 or Triton X-100. Control experiments performed without surfactant showed a significant decrease in biomass growth rate with a subsequent loss of biodegradation activity likely due to a reduced solubility and bioavailability of PAHs in absence of surfactant.

Bioavailability of Polycyclic Aromatic Hydrocarbons (PAHs) from Soil and Hay Matrices in Lactating Goats

This experiment was aimed at determining the bioavailability of three polycyclic aromatic hydrocarbons (PAHs) in goats: phenanthrene, pyrene, and benzo[a]pyrene. A Latin square design procedure was carried out involving three alpine lactating goats and three PAH-contaminated matrices (soil, hay, and oil as a control). Milk and urine samples were collected to assess PAH and hydroxy-PAH excretion kinetics and to compare the carry-over rates for the different matrices. PAHs were found to be excreted mainly in urine; metabolite concentrations were about 20 times higher in urine than in milk. 1-Hydroxypyrene was the major metabolite in both body fluids (8000 ng/mL urine and 450 ng/mL milk); it may be considered as a valuable indicator of the ruminant exposure to PAHs. Apparent absorption of PAHs estimated by the metabolite excretion in urine and milk reached 34% for pyrene from soil, and the bioavailability of soil-bound PAHs was found to be similar to the bioavailability of PAHs from the other matrices.

Multivariate analysis of a biologically activated carbon (BAC) system and its efficiency for removing PAHs and aliphatic hydrocarbons from wastewater polluted with petroleum products

The efficiency of a biologically activated carbon system for treating wastewater polluted with petroleum products was examined and the effects of process parameters on its efficacy were evaluated. In each experiment 17 alkylated and 19 non-alkylated polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs, C 10–C 40) were extracted using semipermeable membrane devices from wastewater before and after treatment. The acquired data during experiments were analyzed using principal component analysis (PCA). The treatment system robustly removed dissolved PAHs across the studied ranges of the process parameters, providing overall removal efficiencies of 96.9–99.7% for the sum of 36 PAHs. However, the major contributor to their removal was sorption rather than biodegradation, and despite the general efficiency of the process there was up to a 9-fold range in the sums of quantified PAHs in the effluents between experiments. Combinations of long process contact time (24 h) with high temperature (24 °C) and moderate oxygen concentration (6–7 mg O 2 L −1) resulted in good removal of bioavailable PAHs. The removal of TPHs was more dependent on biological activities during the wastewater treatment, and consequently more dependent on the process parameters. In addition, small but significant proportions of PAHs were volatilized and released during the wastewater treatment.

Predicting Sediment Toxicity at Former Manufactured Gas Plants Using Equilibrium Partitioning Benchmarks for PAH Mixtures

This study was conducted to examine the application of Equilibrium Partitioning Sediment Benchmarks (ESBs) for assessing the toxicity of polycyclic aromatic hydrocarbons (PAHs) in sediments at former manufactured gas plant (MGP) and coke sites. Samples of freshwater sediment from four MGP and coke sites in the U.S. Northeast and Midwest were analyzed for 34 individual PAHs, total organic carbon, “black” carbon (potentially composed of pitch, soot, and other forms of pyrogenic carbon), and sediment toxicity (28-day Hyalella azteca toxicity test). The sum of the Toxic Units in each sample was calculated from a one-phase model that accounts for sorption of PAHs to total sediment organic carbon, and a two-phase model that accounts for sorption to black carbon as well as to natural organic carbon. Although both the one-phase and two-phase models accurately predicted concentrations of PAHs that were not toxic to aquatic invertebrates, the two-phase model was more often in agreement with results of sediment toxicity tests. While the bioavailability and toxicity of PAHs may vary at other sites, the two-phase model correctly predicted that sediments from these sites with concentrations of total PAHs as high as 52 mg/kg were not toxic to invertebrates.

Microbial populations related to PAH biodegradation in an aged biostimulated creosote-contaminated soil

A previous bioremediation survey on a creosote-contaminated soil showed that aeration and optimal humidity promoted depletion of three-ringed polycyclic aromatic hydrocarbons (PAHs), but residual concentrations of four-ringed benzo(a)anthracene (B(a)A) and chrysene (Chry) remained. In order to explain the lack of further degradation of heavier PAHs such as four-ringed PAHs and to analyze the microbial population responsible for PAH biodegradation, a chemical and microbial molecular approach was used. Using a slurry incubation strategy, soil in liquid mineral medium with and without additional B(a)A and Chry was found to contain a powerful PAH-degrading microbial community that eliminated 89% and 53% of the added B(a)A and Chry, respectively. It is hypothesized that the lack of PAH bioavailability hampered their further biodegradation in the unspiked soil. According to the results of the culture-dependent and independent techniques Mycobacterium parmense, Pseudomonas mexicana, and Sphingobacterials group could control B(a)A and Chry degradation in combination with several microorganisms with secondary metabolic activity.

Changes of solid phase toxicity during sewage sludge composting in relation to bioavailability of polycyclic aromatic hydrocarbons

The aim of the present study was to determine the content of the bioaccessible fraction of polycyclic aromatic hydrocarbons (PAHs) in sewage sludges and composts by means of three techniques (solid phase extraction with Tenax-TA and non-exhaustive extraction with hydroxypropyl[β]cyclodextrin and n-butanol) and at the same time to establish their influence on toxicity for Heterocypris incongruens (OstracodtoxkitTM test) and Lepidium sativum (PhytotoxkitTM test). In the majority of cases sewage sludges negatively influenced on organisms. Generally, sewage sludge composting exerted a positive influence on phytotoxicity, whereas in the case of ecotoxicity a negative effect was noted. The content of the potentially bioaccessible PAHs fraction varied depending on the method applied. Composting usually lowered the content of the potentially bioaccessible fraction. Significant positive relationships were observed mainly between Tenax-TA extracted fraction of individual PAHs and growth inhibition of H. incongruens. Only negative correlations were noted in the case of phytotoxicity.

The usefulness of total concentrations and pore water concentrations of pesticides in soil as metrics for the assessment of ecotoxicological effects ‐ Scientific Opinion of the Panel on Plant Protection Products and their Residues (PPR)

The usefulness of total concentrations and pore water concentrations of pesticides in soil as metrics for the assessment of ecotoxicological effects ‐ Scientific Opinion of the Panel on Plant Protection Products and their Residues (PPR)

Forms of polycyclic aromatic hydrocarbon in the formation of sewage sludge toxicity to Heterocypris incongruens

The aim of the present study was to evaluate to what degree polycyclic aromatic hydrocarbon (PAH) determines sewage sludge toxicity in relation to Heterocypris incongruens. Six differing sewage sludges with increasing contents of polycyclic aromatic hydrocarbons were selected for the present study. As well as total PAH content, the content of the potentially bioavailable fraction was also determined in the sewage sludges using a method of mild-solvent extraction (with n-butanol). The PAH content was also calculated in the sewage sludge pore water by the equilibrium partitioning method. The total PAH content in the sewage sludges studied were in the range 3.60 to 27.95 mg kg − 1 . The contribution of the n-butanol extracted fraction was in the range 38.7 to 75.4%. In the group of individual PAHs, 4- and 5-ring compounds had the highest content in the potentially bioavailable group. H. incongruens mortality in the range 6.7 to 100%, depending both on the sewage sludge and the dose applied. An increase of the sewage sludge dose usually resulted in an increase in toxicity. At the highest dose, a 100% mortality of H. incongruens was found in half of the sludges. The lowest dose, irrespective of the sludge type, caused over 40% growth inhibition. However, the results obtained did not allow for the establishing of an unambiguous relationship between various sludge toxicity levels and the content of potentially bio-available PAHs. In some cases only, the extraction using n-butanol explained the high difference in toxicity despite a slight differentiation in the PAH content.

Contaminant accumulation and biomarker responses in caged mussels, Mytilus galloprovincialis, to evaluate bioavailability and toxicological effects of remobilized chemicals during dredging and disposal operations in harbour areas

Remobilization of chemicals from contaminated sediments is a major risk associated with dredging and disposal operations in harbour areas. In this work caged mussels, Mytilus galloprovincialis, were chosen as bioindicator organisms to reveal the impact and recovery of organisms from these activities in the harbour of Piombino (Tuscany, Italy) where approximately 100,000 m 3 of sediments were removed and disposed in a local confined disposal facility (CDF). Organisms were deployed before, during and after the end of operations, selecting sites differently impacted by these activities. Temporal changes in environmental bioavailability and biological effects of pollutants were assessed by integrating analyses of trace metals and polycyclic aromatic hydrocarbons (PAHs) accumulated in tissues of caged mussels with a wide array of biomarkers reflecting exposure to specific classes of pollutants and different levels of cellular unbalance or toxicity. Such biological responses included levels of metallothioneins, activity of acyl CoA oxidase (AOX) as a marker of peroxisome proliferation, oxidative stress biomarkers (content of glutathione, enzymatic activities of catalase, glutathione S-transferases, glutathione reductase, glutathione peroxidases), total oxyradical scavenging capacity (TOSC) toward peroxyl and hydroxyl radicals, lysosomal membrane stability and genotoxic effects measured as DNA strand breaks and frequency of micronuclei. Obtained results indicated that a general disturbance was already present in the whole harbour area and especially in the inner site before the beginning of operations, when caged mussels exhibited a significant accumulation of PAHs and Pb, lower TOSC values and higher levels of both lysosomal and genotoxic damages. Bioavailability of trace metals and PAHs markedly increased during dredging activities with values up to 40 μg/g for Pb and up to 2200 ng/g for PAHs in tissues of caged mussels, a significant inhibition of antioxidant efficiency and increase of oxidative damages. While bioavailability of trace metals returned to the pre-dredging values after the end of operations, the accumulation of PAHs, oxidative effects and genotoxic damages remained elevated in mussels caged in the inner area and in front of CDF. Overall this study confirmed the utility of caged mussels to assess the remobilization of chemicals from dredged sediments and the onset of potentially harmful biological effects.

Distribution patterns of polycyclic aromatic hydrocarbons among different organic carbon fractions of polluted agricultural soils

Differences in the distribution patterns of polycyclic aromatic hydrocarbons (PAHs) among soil organic matter pools may influence PAH mobility and bioavailability in the soil. Here, we studied the distribution of 15 USEPA priority PAHs in soil light fractions (LF), heavy fractions (HF) and three additional organic matter fractions (loosely combined humus (H 1), stably combined humus (H 2) and tightly combined humus (H 3)) further separated from HF by fractionating the soil organo-mineral complexes. The contents of total PAHs in LF ranged from 51 676 to 618 651 μg kg − 1 , far greater than in HF in which the range of values was 657 to 3869 μg kg − 1 . Although the LF accounted for only 0.1 to 1.4% of the soil, they were associated with 17.9 to 64.1% of the PAHs present. The PAHs in HF were mainly associated with H 3, ranging from 80.8 to 92.7% of the total amount of PAHs. The degree of enrichment of the different organic matter fractions decreased in the order of LF > H 3 > H 2 > H 1. The environmental risks of PAHs associated with different organic matter fractions are also discussed.

Chemical and Ecotoxicological Assessment of Selected Biologically Activated Sorbents for Treating Wastewater Polluted with Petroleum Products with Special Emphasis on Polycyclic Aromatic Hydrocarbons

A chemical and ecotoxicological assessment of treatment of wastewater that had been polluted with petroleum products using only Activated Sludge (AS) and four biologically activated sorbents (BASs), consisting of activated sludge plus: coal-based activated carbon (-C1), coconut shell-based activated carbon (-C2), zeolite (-Z), and anthracite (-A) were conducted. The efficiency and robustness of the four wastewater treatment systems were evaluated by calculating the reduced total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) contents and the acute ecotoxicity of the effluents. The chemical analysis showed that the combined treatment systems were very effective for reducing the total petroleum hydrocarbon and readily bioavailable PAH contents. The most efficient systems were the BAS-C1 and -C2, which removed 60–88% and 99.5–99.6% of TPH and PAH, respectively. The activated sludge-only treatment was the least effective for purifying the wastewater. Chemical oxygen demand was reduced by >90% by all carbon-based BASs (BAS-C1, BAS-C2 and BAS-A). Shifts in the relative composition of the individual PAHs were identified in samples taken before and after treatment. Algal and bacterial bioassays showed that the toxicities of effluents following treatment by all four systems (except AS for algae) were reduced by more than 80% and 90%, respectively. However, crustacean tests indicated that the carbon-based BASs reduced the toxicity [Vtox(50)] only by 19–67%. Our results indicated that the combination of sorption and biodegradation processes have great potential in the treatment of petroleum products polluted wastewater and is less sensitive for inhibitors of the biological process than treatments in which activated sludge alone is used. The assessment of chemical and ecotoxicological endpoints provided valuable information, but contrasting results for one of the assays indicates that further analysis on the capacity of the different treatment systems is warranted.

In situ biomonitoring of PAH-contaminated sediments using juvenile coho salmon ( Oncorhynchus kisutch)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous marine and freshwater sediment contaminants. Extensive data exist to confirm that PAHs are toxic to aquatic receptors. However, limited information is available regarding the bioavailability and genotoxicity of sediment PAHs to aquatic organisms. This study investigated an integrated biomonitoring approach using chemical analyses and biomarkers to characterize the bioavailability and genotoxicity of a complex PAH mixture in freshwater lake sediments associated with a former manufactured gas plant (MGP). Sediment PAH genotoxicity was assessed by flow cytometry (FCM), DNA adduct 32P-postlabeling, and erythrocyte micronuclei in juvenile coho salmon ( Oncorhynchus kisutch) caged in the water column. Significant PAH-induced genotoxicity was observed with FCM and 32P-postlabeling, but not with erythrocyte micronuclei. Chromosome damage in peripheral blood and hepatic DNA adducts correlated with sediment, but not water column PAH concentrations. Total hepatic DNA adducts in salmon caged nearest the former MGP facility was 39±6.5 (RAL×10 9), while salmon caged in a reference lake had 28±2.3 total hepatic DNA adducts per 10 9 nucleotides. These results indicate that in situ biomonitoring using biomarkers and caged fish can be a sensitive indicator of genotoxic PAHs in sediments.

Application of hydroxypropyl[β]cyclodextrin to evaluation of polycyclic aromatic hydrocarbon losses during sewage sludges composting

The aims of the present study were to test the application of the non-exhaustive extraction technique (NEET) with hydroxypropyl[β]cyclodextrin (HPCD) for the evaluation of the content of potentially bioavailable polycyclic aromatic hydrocarbon (PAH) fraction as well as the evaluation of changes in the content of this fraction during composting of municipal sewage sludges. A possibility to apply this method for the forecasting of PAH losses during composting was also studied. Four sludges (from different sewage treatment plants) with varied properties have been selected for the present experiment. The sludges were composted for 76 days. PAH content was determined as extracted with dichloromethane (exhaustive extraction technique) and potentially bioavailable PAH content by means of HPCD (non-exhaustive extraction technique) in both sewage sludges and composts obtained from them. The content of fraction extracted with HPCD ranged from 63.5 to 83.1% depending on the sludge. After composting, a significant lowering of this fraction contribution was noted for 3 sludges. However, in the composts obtained, the fraction extracted with HPCD still constituted 54.7–62.1% of the total PAH content. The composting process clearly influenced a decrease in the bioavailable fraction in the case of 3- and 5-ring PAHs. However, the 4-ring PAHs content of bioavailable fraction did not undergo any significant changes. No satisfactory results were obtained when HPCD was used as a tool to forecast PAH losses. In a number of cases only, PAH remaining after HPCD extraction achieved a value similar to that of PAH after the composting process. In the case of a number of PAH, the method with HPCD application changed the values of the bioavailable fraction.

Humic substances modify accumulation but not biotransformation of pyrene in salmon yolk-sac fry

Humic substances may influence the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in aquatic environment. Relatively little is known how humic substances affect the biotransformation of PAHs in aquatic animals. Here we report how two different types of humic substances affected the accumulation of pyrene, a four-ringed PAH, to yolk-sac fry of landlocked salmon ( Salmo salar m. sebago). The accumulation of pyrene to yolk-sac fry tissues was inversely related to humic substance concentration in a short term (72 h) exposure. However, the biotransformation of pyrene was not affected by humic substances. Pyrene or humic subtances did not induce CYP1A activity in yolk-sac fry tissues contrasting to β-naphthoflavone, which was used as a positive control. Yolk-sac fry were capable to biotransform pyrene to phase I (1-hydroxypyrene) and phase II (pyrene-1-sulphate) products. Interestingly, glucuronide conjugate (i.e. pyrene-1-glucuronide) was not present in yolk-sac fry tissues. The concentration of parent pyrene and 1-hydroxypyrene remained the same throughout the experiment but the concentration of pyrene-1-sulphate more than doubled from 24 to 72 h. This finding suggests that salmon yolk-sac fry are not capable to excrete phase II biotransformation products or the excretion is very slow. Further, this could indicate that early life stage toxicity of many CYP1A inducing compounds is related to accumulation of phase II conjugates in fry tissues.

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

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.

A non-lethal chemically based approach to investigate the quality of harbour sediments

A non-lethal chemically based approach was used to investigate the quality of harbour sediments receiving combined road runoff and sewage effluents. A previous investigation of the behaviour of the amphipod Corophium volutator linked polycyclic aromatic hydrocarbons (PAH) in sediments corresponding to the probable effects levels listed in the sediment quality guidelines of the Canadian Council of the Marine Environment to a sediment avoidance response. Since the amphipods did not biotransform contaminants, bioaccumulation was the only fate pursued to examine the bioavailability of PAH. For five Halifax Harbour sediments, a relationship was established between the threshold effects level representing the amphipods' avoidance response and the bioaccumulation of PAH. A body burden of 0.3–1.1 μmol/kg (wet weight) was determined for the sum of abundant parental PAH in amphipods exposed to sediments that initiated the behavioural effect. PAH were much more available from spiked sediments than from field sediments, with biota-sediment accumulation factors of 2.2–7.8 compared to < 0.01–0.3, respectively. Animals exposed to PAH-spiked sediments avoided contaminated sediments when their body burden was up to seven times higher than observed with field sediments. This latter result and two exposures to sediments collected further away from sewage discharges point to a role for unidentified chemicals in the body burden and behaviour relationship. Further research is warranted to develop this promising assessment tool.