Extensive chemical and bioassay analysis of polycyclic aromatic compounds in a creosote-contaminated superfund soil following steam enhanced extraction

Polycyclic aromatic compounds (PACs) are organic compounds commonly found in contaminated soil. Previous studies have shown the removal of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soils during steam enhanced extraction (SEE). However, less is known about the removal of alkyl-PAHs and heterocyclic compounds, such as azaarenes, and oxygen- and sulfur-heterocyclic PACs (OPACs and PASHs, respectively). Further, the impact of SEE on the freely dissolved concentration of PACs in soil as well as the soil bioactivity pre- and post-SEE have yet to be addressed. To fulfil these research gaps, chemical and bioanalytical analysis of a creosote-contaminated soil, collected from a U.S. Superfund site, pre- and post-SEE were performed. The decrease of 64 PACs (5-100%) and increase in the concentrations of nine oxygenated-PAHs (OPAHs) (150%) during SEE, some of which are known to be toxic and can potentially contaminate ground water, were observed. The freely dissolved concentrations of PACs in soil were assessed using polyoxymethylene (POM) strips and the concentrations of 66 PACs decreased post-SEE (1-100%). Three in vitro reporter gene bioassays (DR-CALUX®, ERα-CALUX® and anti-AR CALUX®) were used to measure soil bioactivities pre- and post-SEE and all reporter gene bioassays measured soil bioactivity decreases post-SEE. Mass defect suspect screening tentatively identified 27 unique isomers of azaarenes and OPAC in the soil. As a remediation technique, SEE was found to remove alkyl-PAHs and heterocyclic PACs, reduce the concentrations of freely dissolved PACs, and decrease soil bioactivities.

Investigating the mycobiome of the Holcomb Creosote Superfund Site

Even though many fungi are known to degrade a range of organic chemicals and may be advantageous for targeting hydrophobic chemicals with low bioavailability due to their ability to secrete extracellular enzymes, fungi are not commonly leveraged in the context of bioremediation. Here we sought to examine the fungal microbiome (mycobiome) at a model creosote polluted site to determine if fungi were prevalent under high PAH contamination conditions as well as to identify potential mycostimulation targets. Several significant positive associations were detected between OTUs and mid-to high-molecular weight PAHs. Several OTUs were closely related to taxa that have previously been identified in culture-based studies as PAH degraders. In particular, members belonging to the Ascomycota phylum were the most diverse at higher PAH concentrations suggesting this phylum may be promising biostimulation targets. There were nearly three times more positive correlations as compared to negative correlations, suggesting that creosote-tolerance is more common than creosote-sensitivity in the fungal community. Future work including shotgun metagenomic analysis would help confirm the presence of specific degradation genes. Overall this study suggests that mycobiome and bacterial microbiome analyses should be performed in parallel to devise the most optimal in situ biostimulation treatment strategies.

Bacteria involved in biodegradation of creosote PAH - A case study of long-term contaminated industrial area

Polycyclic aromatic hydrocarbons (PAH) contained in creosote oil are particularly difficult to remove from the soil environment. Their hydrophobic character and low bioavailability to soil microorganisms affects their rate of biodegradation. This study was performed on samples of soil that were (for over forty years) subjected to contamination with creosote oil, and their metagenome and physicochemical properties were characterized. Moreover, the study was undertaken to evaluate the biodegradation of PAHs by autochthonous consortia as well as by selected bacteria strains isolated from long-term contaminated industrial soil. From among the isolated microorganisms, the most effective in biodegrading the contaminants were the strains Pseudomonas mendocina and Brevundimonas olei. They were able to degrade more than 60% of the total content of PAHs during a 28-day test. The biodegradation of these compounds using AT7 dispersant was enhanced only by Serratia marcescens strain. Moreover, the addition of AT7 improved the effectiveness of fluorene and acenaphthene biodegradation by Serratia marcescens 6-fold. Our results indicated that long-term contact with aromatic compounds induced the bacterial strains to use the PAHs as a source of carbon and energy. We observed that supplementation with surfactants does not increase the efficiency of hydrocarbon biodegradation.

Characterization of polycyclic aromatic hydrocarbons in urban-rural integration area soil, North China: Spatial distribution, sources and potential human health risk assessment

The promotion of urbanization has accelerated the development of small manufacturing workshops and brought serious environmental problems. In this study, spatial distribution, sources and potential health risk for polycyclic aromatic hydrocarbons (PAHs) in urban-rural integration area soil in North China (800 km²) were discussed. The average total concentration of 16 PAHs was 225 μg kg^-1, and range from 25 to 15155 μg kg^-1 (n = 250). According to the European soil quality standards, more than 70% of the samples don't reach the pollution level, while around the small workshop concentration area and non-ferrous metal smelter were more contaminated than other area. The spatial distribution of soil PAHs concentration shows that low molecular weight, medium molecular weight and high molecular weight is very similar to the distribution of total PAHs, indicating that is likely to be caused by point source pollution. The sources of PAHs were identified by positive matrix factorization. The main six sources in the region are coal and biomass combustion, creosote, coke tar, vehicle and oil, which is consistent with the local energy consumption structure. Finally, a deterministic assessment of the cancer risk showed that the range for children was 5.94 × 10^-8 to 2.53 × 10^-5, and adults it ranged from 2.11 × 10^-8 to 9.01 × 10^-6. There is not a carcinogenic risk value greater than 10^-4 in the entire region, but potential carcinogenic risks persisted in some areas. We conclude that PAHs pollution of soil in the area is an issue that deserves urgent attention for the relevant departments.

Assessment of preservative migration from wood using a soil sachet method

The ability of standard soils to capture heavy metals or polycyclic aromatic hydrocarbons (PAHs) from ammoniacal copper zinc arsenate (ACZA)- or creosote-treated wood, respectively, was assessed using pressure-treated posts immersed in a freshwater pond. The soil, in heat-sealed, permeable plastic mesh sachets, was able to intercept copper, zinc, arsenic, and PAHs migrating from the posts. Chemical levels were much higher immediately adjacent to the posts and declined with distance from the posts. Metals were consistently detected around ACZA-treated posts, while 10 of the 16 EPA priority pollutants were detected in at least one sachet embedded around creosote-treated posts at each sampling point. These results were consistent with traditional sediment sampling methods. The primary advantages of the sachets were their consistency in terms of soil characteristics and the ease with which they could be retrieved from the pond. Further studies are planned to better understand the role of soil characteristics in the sachets on the ability to capture migrating preservatives.

Extraction of PAHS from an aged creosote-polluted soil by cyclodextrins and rhamnolipids. Side effects on removal and availability of potentially toxic elements

This study evaluated the effect of several cyclodextrins (CDs) and a rhamnolipid (RL) on the removal of polycyclic aromatic hydrocarbons (PAHs) from a co-contaminated soil which had received historically creosote and inorganic wood preservatives for almost 100 years, and the effect of such extractions on the potentially toxic elements (PTEs). The influence on such processes of an electrolyte (0.01 M Ca(NO₃)₂) was also studied. Up to 15.4% of the ∑16 PAHs were extracted using RL in the absence of the electrolyte as washing solution, but decreases until reaching 0.60% in the presence of Ca²⁺ due to RL precipitation and partial inactivation. Only up to 2% of the ∑16 PAHs was extracted with CDs (4-ring PAHs in higher concentrations), but the electrolyte had no effect on extraction. In relation to PTEs, CDs proved to be inefficient for their extraction, and even RL in the presence of the background electrolyte. But in the absence of electrolyte PTEs extraction by RL increased. Apart from that, the availability of Ni, Cr, and As, those more associated to Fe and Al soil surfaces, increased after extraction with RLs in the presence of Ca²⁺ (about 100% for Cr and Ni and 200% for As). Under these conditions Fe and Al availability increased two- and ten-fold, respectively, indicating that Fe-Al soil surfaces were altered. Therefore, the ionic strength and the cations present in the soil solution of soils have to be considered when RLs are used as extractants for remediation purposes.

Comprehensive composition of Creosote using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS)

Creosote is a distillation product of coal tar and is widely used as wood preservative for railway sleepers, utility poles and for other applications. Creosote can have potentially negative effects on the environment and many of the components are toxic. This study presents the analysis of a Creosote sample from a former wood impregnation plant located in the UK. The sample was analysed using two dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) and a database of compounds that could be detected was produced. The GCxGG-TOFMS was capable of detecting 1505 individual compounds, which is far more than previous estimates for the number of compounds present within Creosote. Post extraction derivatization using BTSFA with 1% TMCS was employed to increase the potential number of compounds detected with 255 derivatized compounds detected, 231 of which would not have been detected without prior derivatization. Selected derivatized compounds were quantified with limits of detection ranging from 0.6 mg/kg to 1.6 mg/kg from a concentrated dense non-aqueous phase liquid (DNAPL). This work presents the first published full analysis of a Creosote using GCxGC-TOFMS combined with derivatization.

Biosurfactant-enhanced bioremediation of aged polycyclic aromatic hydrocarbons (PAHs) in creosote contaminated soil

The potential for biological treatment of an environment contaminated by complex petrochemical contaminants was evaluated using creosote contaminated soil in ex situ bio-slurry reactors. The efficacy of biosurfactant application and stimulation of in situ biosurfactant production was investigated. The biosurfactant produced was purified and characterised using Fourier transform infrared (FTIR) spectroscopy. Biosurfactant enhanced degradation of PAHs was 86.5% (with addition of biosurfactant) and 57% in controls with no biosurfactant and nutrient amendments after incubation for 45 days. A slight decrease in degradation rate observed in the simultaneous biosurfactant and nutrient, NH4NO3 and KH2PO4, supplemented microcosm can be attributed to preferential microbial consumption of the biosurfactant supplemented. The overall removal of PAHs was determined to be mass transport limited since the dissolution rate caused by the biosurfactant enhanced the bioavailability of the PAHs to the microorganisms. The consortium culture was predominated by the aromatic ring-cleaving species Bacillus stratosphericus, Bacillus subtilis, Bacillus megaterium, and Pseudomonas aeruginosa.

Pyrosequencing reveals the effect of mobilizing agents and lignocellulosic substrate amendment on microbial community composition in a real industrial PAH-polluted soil

Bacterial and fungal biodiversity throughout different biostimulation and bioaugmentation treatments applied to an industrial creosote-polluted soil were analyzed by means of polyphasic approach in order to gain insight into the microbial community structure and dynamics. Pyrosequencing data obtained from initial creosote polluted soil (after a biopiling step) revealed that Alpha and Gammaproteobacteria were the most abundant bacterial groups, whereas Fusarium and Scedosporium were the main fungal genera in the contaminated soil. At the end of 60-days laboratory scale bioremediation assays, pyrosequencing and DGGE data showed that (i) major bacterial community shifts were caused by the type of mobilizing agent added to the soil and, to a lesser extent, by the addition of lignocellulosic substrate; and (ii) the presence of the non-ionic surfactant (Brij 30) hampered the proliferation of Actinobacteria (Mycobacteriaceae) and Bacteroidetes (Chitinophagaceae) and, in the absence of lignocellulosic substrate, also impeded polycyclic aromatic hydrocarbons (PAHs) degradation. The results show the importance of implementing bioremediation experiments combined with microbiome assessment to gain insight on the effect of crucial parameters (e.g. use of additives) over the potential functions of complex microbial communities harbored in polluted soils, essential for bioremediation success.

In vivo measurement, in vitro estimation and fugacity prediction of PAH bioavailability in post-remediated creosote-contaminated soil

In this study, PAH bioavailability was assessed in creosote-contaminated soil following bioremediation in order to determine potential human health exposure to residual PAHs from incidental soil ingestion. Following 1,000 days of enhanced natural attenuation (ENA), a residual PAH concentration of 871 ± 8 mg kg(-1) (∑16 USEPA priority PAHs in the <250 μm soil particle size fraction) was present in the soil. However, when bioavailability was assessed to elucidate potential human exposure using an in vivo mouse model, the upper-bound estimates of PAH absolute bioavailability were in excess of 65% irrespective of the molecular weight of the PAH. These results indicate that a significant proportion of the residual PAH fraction following ENA may be available for absorption following soil ingestion. In contrast, when PAH bioavailability was estimated/predicted using an in vitro surrogate assay (FOREhST assay) and fugacity modelling, PAH bioavailability was up to 2000 times lower compared to measured in vivo values depending on the methodology used.

An integrated assessment of sediment remediation in a midwestern U.S. stream using sediment chemistry, water quality, bioassessment, and fish biomarkers

A comprehensive biological, sediment, and water quality study of the lower Little Scioto River near Marion, Ohio, USA, was undertaken to evaluate the changes or improvements in biotic measurements following the removal of creosote-contaminated sediment. The study area covered 7.5 river miles (RMs), including a remediated section between RMs 6.0 and 6.8. Fish and macroinvertebrate assemblages, fish biomarkers (i.e., polycyclic aromatic hydrocarbon [PAH] metabolite levels in white sucker [Castostomus commersoni] and common carp [Cyprinus carpio] bile and DNA damage), sediment chemistry, and water quality were assessed at five locations relative to the primary source of historical PAH contamination-upstream (RM 9.2), adjacent (RM 6.5), and downstream (RMs 5.7, 4.4, and 2.7). Overall, the biomarker results were consistent with the sediment PAH results, showing a pattern of low levels of PAH bile metabolites and DNA damage at the upstream (reference or background location), as well as the remediated section, high levels at the two immediate downstream sites, and somewhat lower levels at the furthest downstream site. Results show that remediation was effective in reducing sediment contaminant concentrations and exposure of fish to PAHs and in improving fish assemblages (60% increase in index of biotic integrity scores) in remediated river sections. Additional remedial investigation and potentially further remediation is needed to improve the downstream benthic fish community, which is still heavily exposed to PAH contaminants.

Creosote released from railway-ties recycled and the sanitary risks

Through the history of railways, wooden crossties impregnated with potentially hazardous creosote tar, have been used for years. There are six major classes of compounds in the creosote: aromatic hydrocarbons; tar acids/phenolics; tar bases/nitrogen-containing heterocycles; aromatic amines; sulfur-containing heterocycles; and oxygen-containing heterocycles. The creosote molecules applied in railway crossties can be released in the environment and they can bioaccumulate in animals and vegetables. Some constituents (benzo(a)pyrene and phenolics like benzene) are considered as being carcinogenic which renders the entire complex of creosote to be classified as potentially carcinogenic. After several decades of use the railway-ties are been recycled for varies uses like fences, stakes for agriculture and fruit production or bank protection. In this paper are examined some environmental and sanitary risks from wood impregnated with creosote reported in the literature.

A comparative toxicity assessment of materials used in aquatic construction

Comparative toxicity testing was performed on selected materials that may be used in aquatic construction projects. The tests were conducted on the following materials: (1) untreated wood species (hemlock [Tsuga ssp], Western red cedar (Thuja plicata), red oak [Quercus rubra], Douglas fir [Pseudotsuga menziesii], red pine [Pinus resinosa], and tamarack [Larix ssp]); (2) plastic wood; (3) Ecothermo wood hemlock stakes treated with preservatives (e.g., chromated copper arsenate [CCA], creosote, alkaline copper quaternary [ACQ], zinc naphthenate, copper naphthenate, and Lifetime Wood Treatment); (4) epoxy-coated steel; (5) hot-rolled steel; (6) zinc-coated steel; and (7) concrete. Those materials were used in acute lethality tests with rainbow trout, Daphnia magna, Vibrio fischeri and threespine stickleback. The results indicated the following general ranking of the materials (from the lowest to highest LC(50) values); ACQ > creosote > zinc naphthenate > copper naphthenate > CCA (treated at 22.4 kg/m(3)) > concrete > red pine > western red cedar > red oak > zinc-coated steel > epoxy-coated steel > CCA (6.4 kg/m(3)). Furthermore, the toxicity results indicated that plastic wood, certain untreated wood species (hemlock, tamarack, Douglas fir, and red oak), hot-rolled steel, Ecothermo wood, and wood treated with Lifetime Wood Treatment were generally nontoxic to the test species.

Self-sustaining smoldering combustion for NAPL remediation: laboratory evaluation of process sensitivity to key parameters

Smoldering combustion has been introduced recently as a potential remediation strategy for soil contaminated by nonaqueous phase liquids (NAPLs). Published proof-of-concept experiments demonstrated that the process can be self-sustaining (i.e., requires energy input only to start the process) and achieve essentially complete remediation of the contaminated soil. Those initial experiments indicated that the process may be applicable across a broad range of NAPLs and soils. This work presents the results of a series of bench-scale experiments that examine in detail the sensitivity of the process to a range of key parameters, including contaminant concentration, water saturation, soil type, and air flow rates for two contaminants, coal tar and crude oil. Smoldering combustion was observed to be self-sustaining in the range 28,400 to 142,000 mg/kg for coal tar and in the range 31,200 to 104,000 mg/kg for crude oil, for the base case air flux. The process remained self-sustaining and achieved effective remediation across a range of initial water concentrations (0 to 177,000 mg/kg water) despite extended ignition times and decreased temperatures and velocities of the reaction front. The process also exhibited self-sustaining and effective remediation behavior across a range of fine to coarse sand grain sizes up to a threshold maximum value between 6 mm and 10 mm. Propagation velocity is observed to be highly dependent on air flux, and smoldering was observed to be self-sustaining down to an air Darcy flux of at least 0.5 cm/s for both contaminants. The extent of remediation in these cases was determined to be at least 99.5% and 99.9% for crude oil and coal tar, respectively. Moreover, no physical evidence of contamination was detected in the treatment zone for any case where a self-sustaining reaction was achieved. Lateral heat losses to the external environment were observed to significantly affect the smoldering process at the bench scale, suggesting that the field-scale lower bounds on concentration and air flux and upper bound on grain size were not achieved; larger scale experiments and field trials where lateral heat losses are much less significant are necessary to define these process limits for the purposes of field application. This work provides valuable design data for pilot field trials of both in situ and ex situ smoldering remediation applications.

Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added 13C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass.

Bioavailability of residual polycyclic aromatic hydrocarbons following enhanced natural attenuation of creosote-contaminated soil

The impact of residual PAHs (2250 +/- 71 microg total PAHs g(-1)) following enhanced natural attenuation (ENA) of creosote-contaminated soil (7767 +/- 1286 microg total PAHs g(-1)) was assessed using a variety of ecological assays. Microtox results for aqueous soil extracts indicated that there was no significant difference in EC(50) values for uncontaminated, pre- and post-remediated soil. However, in studies conducted with Eisenia fetida, PAH bioaccumulation was reduced by up to 6.5-fold as a result of ENA. Similarly, Beta vulgaris L. biomass yields were increased 2.1-fold following ENA of creosote-contaminated soil. While earthworm and plant assays indicated that PAH bioavailability was reduced following ENA, the residual PAH fraction still exerted toxicological impacts on both receptors. Results from this study highlight that residual PAHs following ENA (presumably non-bioavailable to bioremediation) may still be bioavailable to important receptor organisms such as earthworms and plants.

Rebound of a coal tar creosote plume following partial source zone treatment with permanganate

The long-term management of dissolved plumes originating from a coal tar creosote source is a technical challenge. For some sites stabilization of the source may be the best practical solution to decrease the contaminant mass loading to the plume and associated off-site migration. At the bench-scale, the deposition of manganese oxides, a permanganate reaction byproduct, has been shown to cause pore plugging and the formation of a manganese oxide layer adjacent to the non-aqueous phase liquid creosote which reduces post-treatment mass transfer and hence mass loading from the source. The objective of this study was to investigate the potential of partial permanganate treatment to reduce the ability of a coal tar creosote source zone to generate a multi-component plume at the pilot-scale over both the short-term (weeks to months) and the long-term (years) at a site where there is >10 years of comprehensive synoptic plume baseline data available. A series of preliminary bench-scale experiments were conducted to support this pilot-scale investigation. The results from the bench-scale experiments indicated that if sufficient mass removal of the reactive compounds is achieved then the effective solubility, aqueous concentration and rate of mass removal of the more abundant non-reactive coal tar creosote compounds such as biphenyl and dibenzofuran can be increased. Manganese oxide formation and deposition caused an order-of-magnitude decrease in hydraulic conductivity. Approximately 125 kg of permanganate were delivered into the pilot-scale source zone over 35 days, and based on mass balance estimates <10% of the initial reactive coal tar creosote mass in the source zone was oxidized. Mass discharge estimated at a down-gradient fence line indicated >35% reduction for all monitored compounds except for biphenyl, dibenzofuran and fluoranthene 150 days after treatment, which is consistent with the bench-scale experimental results. Pre- and post-treatment soil core data indicated a highly variable and random spatial distribution of mass within the source zone and provided no insight into the mass removed of any of the monitored species. The down-gradient plume was monitored approximately 1, 2 and 4 years following treatment. The data collected at 1 and 2 years post-treatment showed a decrease in mass discharge (10 to 60%) and/or total plume mass (0 to 55%); however, by 4 years post-treatment there was a rebound in both mass discharge and total plume mass for all monitored compounds to pre-treatment values or higher. The variability of the data collected was too large to resolve subtle changes in plume morphology, particularly near the source zone, that would provide insight into the impact of the formation and deposition of manganese oxides that occurred during treatment on mass transfer and/or flow by-passing. Overall, the results from this pilot-scale investigation indicate that there was a significant but short-term (months) reduction of mass emanating from the source zone as a result of permanganate treatment but there was no long-term (years) impact on the ability of this coal tar creosote source zone to generate a multi-component plume.

Fungal bioremediation of the creosote-contaminated soil: influence of Pleurotus ostreatus and Irpex lacteus on polycyclic aromatic hydrocarbons removal and soil microbial community composition in the laboratory-scale study

The aim of this study was to determine the efficacy of selected basidiomycetes in the removing of polycyclic aromatic hydrocarbons (PAH) from the creosote-contaminated soil. Fungi Pleurotus ostreatus and Irpex lacteus were supplemented with creosote-contaminated (50-200 mg kg(-1) PAH) soil originating from a wood-preserving plant and incubated at 15 °C for 120 d. Either fungus degraded PAH with 4-6 aromatic rings more efficiently than the microbial community present initially in the soil. PAH removal was higher in P. ostreatus treatments (55-67%) than in I. lacteus treatments (27-36%) in general. P. ostreatus (respectively, I. lacteus) removed 86-96% (47-59%) of 2-rings PAH, 63-72% (33-45%) of 3-rings PAH, 32-49% (9-14%) of 4-rings PAH and 31-38% (11-13%) of 5-6-rings PAH. MIS (Microbial Identification System) Sherlock analysis of the bacterial community determined the presence of dominant Gram-negative bacteria (G-) Pseudomonas in the inoculated soil before the application of fungi. Complex soil microbial community was characterized by phospholipid fatty acids analysis followed by GC-MS/MS. Either fungus induced the decrease of bacterial biomass (G- bacteria in particular), but the soil microbial community was influenced by P. ostreatus in a different way than by I. lacteus. The bacterial community was stressed more by the presence of I. lacteus than P. ostreatus (as proved by the ratio of the fungal/bacterial markers and by the ratio of trans/cis mono-unsaturated fatty acids). Moreover, P. ostreatus stimulated the growth of Gram-positive bacteria (G+), especially actinobacteria and these results indicate the potential of the positive synergistic interaction of this fungus and actinobacteria in creosote biodegradation.

The creosote content of used railway crossties as compared with European stipulations for hazardous waste

Through the history of railways, wooden crossties impregnated with potentially hazardous creosote tar have supported the rails. With impregnated crossties having a lifespan of approximately 50 years, their creosote content is considered as quite safely stored while in dug-down usage. This situation of relative safety does, however, change into acute risk upon replacement and destruction. Carrying a highly flammable content, creosote crossties discharge a pulse of carcinogenic PAH compounds if burnt as ordinary waste. Safe destruction is therefore required if concentrations exceed a critical limit stipulated by the European Union. Since safe destruction is a process of considerable expense, there is a tendency among financial stakeholders to underestimate the creosote content of used railway crossties. In order to actually test whether concentrations generally exceed the critical limit, a set of used creosote ties was therefore sampled while still situated in the railway embankment. With a standard sum of sixteen PAH compounds used as an expression of their total creosote content, the generic concentration was formally inferred and found to significantly exceed the critical limit. The same applies to the fraction of seven carcinogenic PAH compounds, that alone exceed the stipulated limit for hazardous waste. It was also found that the material of railway embankments, whether or not the crossties were used in switches and/or railway yards, and sample depth within the crossties, has a significant effect on creosote concentrations. Regardless of the status of these factors, the concentrations significantly exceed the critical limit that defines hazardous waste within the European Union.

VOCs and PAHs emissions from creosote-treated wood in a field storage area

In this study, the emissions of volatile organic compounds (VOCs, in this case aromatic hydrocarbons containing one benzene ring and furans) and polycyclic aromatic hydrocarbons (PAHs) from wood recently treated with creosote are examined. The VOCs and PAHs were identified and quantified in the gas phase. Additionally, the PAHs were quantified in the particulate phase. Glass multi-sorbent tubes (Carbotrap, Carbopack X, Carboxen-569) were used to hold the VOCs. The analysis was performed using automatic thermal desorption (ATD) coupled with capillary gas chromatography/mass spectrometry (GC/MS). PAHs vapours were collected on XAD-2 resin, and particulate matter was collected on glass fibre filters. The PAHs were analysed using GC/MS. The main components of the vapours released from the creosote-treated wood were naphthalene, toluene, m+p-xylene, ethylbenzene, o-xylene, isopropylbenzene, benzene and 2-methylnaphthalene. VOCs emission concentrations ranged from 35 mg m(-3) of air on the day of treatment to 5 mg m(-3) eight days later. PAHs emission concentrations ranged from 28 microg m(-3) of air on the day of treatment to 4 microg m(-3) eight days later. The air concentrations of PAHs in particulate matter were composed predominantly of benzo[b+j]fluoranthene, benzo[a]anthracene, chrysene, fluoranthene, benzo[e]pyrene and 1-methylnaphthalene. The emission concentrations of particulate polycyclic aromatic hydrocarbons varied between 0.2 and 43.5 ng m(-3). Finally, the emission factors of VOCs and PAHs were determined.

Spatial covariation of microbial community composition and polycyclic aromatic hydrocarbon concentration in a creosote-polluted soil

Little is known about the spatial connection between soil microbial community composition and polycyclic aromatic hydrocarbon (PAH) concentration. A spatially explicit survey at a creosote-contaminated site demonstrated that microbial biomass (total concentration of phospholipid fatty acids [PLFAs]) and microbial community composition (PLFA fingerprints) were spatially autocorrelated, mostly within a distance of 25 m, and covaried with PAH concentrations. The concentration of PLFAs indicative of gram-negative bacteria (16:1omega7c, 16:1omega7t, 18:1omega7, cy17:0, and cy19:0) increased in the PAH hot spots, whereas PLFAs representing fungi and gram-positive bacteria (including actinomycetes) were negatively correlated to PAH concentrations. Most PLFAs were spatially autocorrelated, with distances varying between 4 and 25 m. Those PLFAs that increased in PAH-contaminated soil had autocorrelation ranges between 4 and 16 m, whereas the fungal indicator PLFA 18:2omega6,9 had the largest autocorrelation range (25 m). Bacterial strains isolated using a spray-plate technique and with the same PLFA composition as that in contaminated soil samples were capable of degrading phenanthrene, fluoranthene, and pyrene, indicating that the main PAH degraders could be isolated.

GC-MS-MS analysis of bacterial fatty acids in heavily creosote-contaminated soil samples

Phospholipid fatty acid profiles of soil samples enable rapid and reproducible measurement and characterization of the dominant soil microbial communities. When extensive polycyclic aromatic hydrocarbon (PAH) pollution is present in the soil it is very difficult, or even impossible, to distinguish specific fatty acids in GC-MS chromatograms in full-scan mode, because of the PAHs which, because of their lipophilic character, are co-extracted with the lipids. Selected ions in the samples were scanned in MS-MS mode to eliminate the aromatic hydrocarbon signals and obtain clear chromatograms of the fatty acids. By using this technique it was possible to clearly distinguish at least eleven fatty acids in heavily creosote-contaminated soil samples (PAH concentration approximately 15 g kg(-1) dry weight of soil).

A review of taste and odour events in Barcelona's drinking water area (1990-2004)

The main, relevant, solved problems associated with taste and odour incidents in Barcelona's drinking water area in the last 14 years are reviewed. Events produced by creosote, dioxanes and dioxolanes, dicylopentadiene, and diacetyl, among the anthropogenic compounds; geosmin, MIB and iodinated trihalomethanes and chlorobromoanisoles as examples of compounds of natural origin are exemplified. The determination of the odour threshold concentrations of selected odorous compounds is also shown as a tool to gain a better knowledge of future taste and odour events.

Anaerobic degradation of naphthalene in a fluvial aquifer: a radiotracer study

A radiotracer study was conducted in a creosote-contaminated aquifer beneath the Fraser River, British Columbia Canada to investigate the in situ degradation of naphthalene. The groundwater is anaerobic, with abundant methane, ferrous iron and carbon dioxide. This study followed earlier work at the site where the contaminant distribution could only be explained by invoking a mass loss through degradation, even though extensive field and laboratory microcosm studies closer to the source zone onshore could not confirm degradation. Accordingly, 14C-naphthalene was injected into the aquifer offshore, further from the source zone where modeling suggested degradation was occurring. During the 230-day monitoring period, 14CO2 was detected, confirming the degradation of the radio-labeled naphthalene tracer. A zero-order degradation rate of naphthalene of 5 microg/L-day was estimated based on the decrease in 14C-naphthalene concentration with time. While the degradation pathway could not be determined from the radiotracer study alone, the geochemistry of the site suggests that either iron reduction or methanogenesis is the terminal electron accepting processes responsible for naphthalene oxidation.

Monitoring of polycyclic aromatic hydrocarbons and water-extractable phenols in creosotes and creosote-treated woods made and procurable in Japan

The recycling of disused railway sleepers treated with wood preservatives such as creosote as exterior wood for use in gardens has recently become popular in Japan. Creosote contains high quantities of polycyclic aromatic hydrocarbons (PAHs), and can lead to skin irritation and disease. In this work we have determined the amount of PAHs and water-extractable phenols in creosote and creosote-treated wood products such as railway sleepers and stakes for agricultural use that are either made or are procurable in Japan. PAHs were extracted with dichloromethane and analyzed by gas chromatography-mass spectrometry. Among carcinogenic PAHs, benz(a)anthracene was detected in the highest concentration, varying between 228 and 6328 microg/g in creosotes. Benzo(b)fluoranthene, benzo(k)fluoranthene and benzo(a)pyrene (BaP) were found in the range of 67-3541 microg/g. Almost all creosotes contained more than 50 microg/g of BaP, which is the upper limit level that is permitted in the European Union (EU). Creosote-impregnated wood products, such as brand-new or secondhand railway sleepers and foundations, contained large amounts of BaP (58-749 microg/g) and benz(a)anthracene (250-1282 microg/g). Concentrations of between 692 and 2489 microg/g of phenols were determined in the water extracts from creosotes, but the level was considerably less than the EU control value (3% by mass), and there was no correlation between the amount of water-extractable phenols and the amount of PAHs detected in each sample. The situation that consumers are free to use the creosotes containing a high concentration of carcinogens such as BaP may cause unacceptable damage to the health of persons handling these creosote products.

[Spatial variation of microbial properties in a creosote-contaminated soil]

By the methods of geostatistics, this paper studied the spatial variation of microbial biomass, microbial community structure and microbial activity in a creosote-contaminated soil. The microbial biomass was indicated by the total amount of 26 examined phospholipid fatty acids (totPLFA), the microbial community structure was characterized by the first two principal components (PC1 and PC2) of the PLFA patterns through subjecting the PLFAs to principal component analysis, and the total amount of CO2-C respired (C(re)) during incubation was used to describe the soil microbial activity. The results showed that most of the variables exhibited various degrees of spatial autocorrelation, and spherical models with nugget could fit their semivariograms. The estimated spatial dependence distances of the variables varied from 2.50 to 16.60 m. The PLFA PC1, totPLFA and C(re) displayed relatively high spatial dependences, their relative structural variance, i.e., the proportion of total variance that can be attributed to the spatial autocorrelation, being 82.3%, 79.6% and 64.7%, respectively, while PLFA PC2 was not spatially autocorrelated. The kriged maps showed that there were several hot spots with relatively high microbial biomass and high microbial activity located in the study site. Gram- negative bacteria characterized by PLFAs 16:1omega7t, cyl7:0, 18:1omega7 and cyl9:0 were the dominant community in these hot spots. The concentration and spatial distribution of polycyclic aromatic hydrocarbons as the main contaminants in the soil could be one of the important factors affecting the spatial variation of soil microbial properties.

Exposure assessment of residents living near a wood treatment plant

We report the results of environmental sampling and modeling in a neighborhood adjacent to a wood processing plant. This plant used creosote and pentachlorophenol (PCP) to treat wood for over 70 years. Between 1999 and 2001, environmental samples were obtained to quantify the level of environmental contamination from the wood processing plant. Blood from 10 residents was measured for chlorinated dioxins and dibenzofurans. Soil sediment samples from drainage ditches and attic/dust samples from nearby residents' homes were tested for polychlorinated dioxins, furans, and polycyclic aromatic hydrocarbons (PAH). The dioxin congeners analysis of the 10 residents revealed elevated valued for octachlorodibenzo-p-dioxin and heptachlorodibenzo-p-dioxin compatible with PCP as the source. The levels of carcinogenic PAHs were higher than background levels and were similar to soil contamination on wood preserving sites. Wipe sampling in the kitchens of 11 homes revealed that 20 of the 33 samples were positive for octachlorinated dioxins with a mean value of 10.27 ng/m2. The soil, ditch samples, and positive wipe samples from the homes indicate a possible ongoing route of exposure to the contaminants in the homes of these residents. Modeled air exposure estimated for the wood processing waste chemicals indicate some air exposure to combustion products. The estimated air levels for benzo(a)pyrene and tetrachlorodibenzodiozin in this neighborhood exceeded the recommended levels for these compounds in some states. The quantitative data presented suggest a significant contamination of a neighborhood by wood processing waste chemicals. These findings suggest the need for more stringent regulations on waste discharges from wood treatment plants.

Creosote toxicity to photosynthesis and plant growth in aquatic microcosms

To assess photosynthesis as a bioindicator of toxicity from polycyclic aromatic hydrocarbons (PAHs), the response of chlorophyll-a fluorescence to creosote exposure was compared with effects on population-level plant growth. Large, outdoor, freshwater microcosms containing Eurasian watermilfoil (Myriophyllum spicatum) received either a single application or multiple applications of liquid creosote at nominal concentrations from 0.109 to 32.7 mg L(-1). For several weeks following treatment, photosynthetic electron transport was measured using pulse amplitude-modulated chlorophyll-a fluorescence. The maximum efficiency of photosystem II electron transport (Fv/Fm) and the quantum yield of photochemistry (deltaF/F'm) were diminished in plants shortly after the addition of creosote. In microcosms that received a single treatment of creosote only, the 50% effective concentrations (EC50s), expressed as the aqueous concentration of 15 of the most abundant PAHs, were 0.28 mg L(-1) for Fv/Fm and 0.30 mg L(-1) for deltaF/F'm. Chlorophyll-a fluorescence was diminished to a greater extent in microcosms that received multiple treatments of creosote, with EC50s of 0.13 mg L(-1) for Fv/Fm and 0.10 mg L(-1) for deltaF/F'm. Plant biomass accumulation was inhibited in a concentration-dependent manner in all microcosms treated with creosote, but this inhibition occurred to a greater degree in microcosms treated with multiple creosote applications. The response of chlorophyll-a fluorescence, measured only 8 d after creosote treatment, was similar to plant growth over the entire growing season, indicating that this technique can be used to estimate potential effects of contaminants before detrimental impacts on populations.

Microbial toxicity tests and chemical analysis as monitoring parameters at composting of creosote-contaminated soil

Traditionally, chemical analyses are used in the assessment of contaminated soil and in monitoring the efficiency of soil remediation processes. We investigated if chemical analysis could be supported and even partly replaced by biological toxicity tests. In two case studies creosote-contaminated soil was composted outdoors in 5- and 100-m3 windrows. Degradation of polyaromatic hydrocarbons (PAHs) was followed by chemical analysis and toxicity tests. Polyaromatic hydrocarbons were quantified and identified by HPLC. Because the soil was also contaminated by copper-, chromium-, and arsenic-containing fungicides, these elements were analyzed by atomic absorption spectrometry. The toxicity of soil samples was assessed by a soil-contact modification of the luminescent bacteria (Vibrio fischeri) test and in the other case also by enzyme synthesis inhibition (Toxi-ChromoPad test, Escherichia coli). The toxicity of soil water extracts was measured by the standard luminescent bacteria (V. fischeri) test and bacterial (Pseudomonas putida) growth inhibition test. After the first 4 months of the composting period the total amount of PAHs was reduced in all windrows, and in particular, the loss of two- and some three-ring compounds was high, almost 90%. Toxicity decreased concurrently with the decrease in PAH concentration during composting, but after 4 months, one of the piles inoculated with mycobacteria and containing more three- and four-ring compounds was found to be more toxic than at the beginning. After the next summer, total PAH content was further reduced but some four-ring or heavier compounds were demonstrated to be poorly degraded. The toxicity was also reduced to the same level as in the control pile. The total PAH content and the toxicity were both reduced significantly during 5 months of composting.

Scanning ultraviolet two-step laser mass spectroscopy of polycyclic aromatic hydrocarbon distributions on creosote-contaminated soil particles

The distribution of polycyclic aromatic hydrocarbons (PAHs) on creosote-contaminated soil has been examined with scanning ultraviolet two-step laser desorption/laser ionization mass spectroscopy (UV-L2MS). The instrument has been constructed in-house by modifying a reflectron time-of-flight mass spectrometer. Two-dimensional chemical maps were accurately generated from model patterned PAH distributions. From examination of three-dimensional substrates, the depth of field of the experiment allows surfaces with roughness of up to 120 microm to be treated as a two-dimensional system and still achieve an accurate representation of the surface deposits. Soil was obtained from a former wood treatment facility. Individual particles of 100-1000 microm were mounted on indexed sample plates and examined by reflectance infrared microscopy, optical microscopy, and imaging UV-L2MS. The most intense PAH signals were associated with regions on the particles where clay/organic carbon deposits were found.

Cytochrome P4501A (CYP1A) in killifish (Fundulus heteroclitus): heritability of altered expression and relationship to survival in contaminated sediments

Previous research has shown that killifish (Fundulus heteroclitus) inhabiting a creosote-contaminated site on the Elizabeth River in Virginia exhibit little induction of cytochrome P4501A (CYP1A) protein expression and activity upon exposure to typical CYP1A-inducing chemicals. We characterized the CYP1A response of first, second, and third generation laboratory-raised offspring of feral Elizabeth River killifish to exposure to sediments from the contaminated site as well as the prototypical polycyclic aromatic hydrocarbon (PAH)-type CYP1A inducers beta-naphthoflavone (BNF) and 3-methylcholanthrene (3-MC). The Elizabeth River offspring's responses were compared to those of offspring of killifish from two reference sites (King's Creek, Virginia, and Russell Creek, North Carolina). As with feral Elizabeth River killifish, the first generation embryos and larvae were refractory to CYP1A induction. However, the response observed in 3-year-old first generation adults, as well as with second and third generation fish, was much closer to that observed in reference-site fish. We suggest that the pattern of altered CYP1A response in Elizabeth River killifish, while persistent and heritable for one generation, is mostly nongenetically based. Additionally, we investigated the hypothesis that low CYP1A activity (measured as in ovo EROD activity) would correlate to increased survival in Elizabeth River sediment pore water; this hypothesis was not supported by our results.

Determination of hydrocarbons in old creosote contaminated soil using headspace solid phase microextraction and GC-MS

Headspace solid phase microextraction (HS-SPME) has been used together with GC-MS to analyze organic substances directly in a soil, heavily contaminated with PAHs/creosote (approximately 300 mg/kg soil), from an old gaswork site in Stockholm, Sweden. The HS-SPME results, both qualitative and quantitative, were compared with traditional liquid extraction using ethyl acetate/hexane (20:80). It was shown that the concentrations determined with HS-SPME at 60 degrees C correlated well, for compounds containing up to two and three aromatic rings (naphthalenes, acenaphthene, acenaphthylene and fluorenes, while a lower concentration was obtained for phenanthrene, anthracene, fluoranthene and pyrene. The total concentrations for each compound determined with HS-SPME ranged from 2 to 25 microg/g soil. Quantification was done using standard addition of compounds directly to the soil samples. The bioavailable fraction of the compounds in the contaminated soil at 20 degrees C was analyzed using external calibration by spiking sterile uncontaminated sand (same texture and particle size as the contaminated soil but without a heavily sorbed organic fraction) with hydrocarbon standards in different concentrations. Storage of exposed fibers at 20 degrees C showed that analysis should be done within two days to make qualitative measurements and earlier (as soon as possible) for quantitative determinations.

Control of chemical risks during the treatment of soil contaminated with chlorophenol, creosote and copper-chrome-arsenic-wood preservatives

BACKGROUND

Exposure to chemicals in polluted soil was studied during the remediation of four polluted sites. They are sawmill areas contaminated with chlorophenols and polychlorinated dibenzo-p-dioxins and furanes (PCDD/F), wood impregnating plants contaminated with polycyclic aromatic hydrocarbons (PAH) from creosote oil, old gas works area contaminated with PAH, and a wood impregnation plant contaminated with copper-chromium-arsenic (CCA) preservative.

METHODS

The exposure levels were determined by both air and biological monitoring.

RESULTS

Air monitoring showed that the exposure levels were generally well below the current occupational exposure limits. The calculations indicated, however, that the lowest acceptable daily intake value recommended for PCDD/F by the U.S. Environmental Protection Agency was exceeded. Chlorophenol exposure was generally low. Exposure to volatile PAH was 0.038-0.884 mg/m(3) and that to particulate PAH was 0.004-0.183 mg/m(3). The biomonitoring results (urinary 1-pyrenol) suggested that some exposure occurs, probably through the contamination of hands or skin absorption. At the sites contaminated with CCA salts, no exposure limits were exceeded.

CONCLUSIONS

The results generally suggest that the exposure of cleanup workers is generally below the current occupational exposure limits but that short-term high exposure cannot be excluded. There was also some indication of poor skin protection, which should be improved when soil contaminated with PAH and creosote oil is handled.

Biological degradation of selected hydrocarbons in an old PAH/creosote contaminated soil from a gas work site

An old PAH/creosote contaminated soil (total approximately 300 microg PAH/g soil) from a former gas work site in Stockholm, Sweden, has been treated at 20 degrees C with the addition of various nutrients and inoculated with bacteria (isolated from the soil) to enhance the degradation of selected hydrocarbons. Microcosm studies showed that the soil consisted of two contaminant fractions: one available, easily degraded fraction and a strongly sorbed, recalcitrant one. The bioavailable fraction, monitored by headspace solid phase microextraction, contained aromatics with up to three rings, and these were degraded within 20 days down to non-detectable levels (ng PAH/g soil) by both the indigenous bacteria and the externally inoculated samples. The nutrient additives were: a minimal medium (Bushnell-Haas), nitrate, nitrite, potting soil (Anglamark, Sweden), sterile water and aeration with Bushnell-Haas medium. After 30 days treatment most of the sorbed fractions were still present in the soil. Stirring or mechanical mixing of the soil slurries had the greatest effect on degradation, indicating that the substances were too strongly sorbed for the microorganisms. When stirring the choice of nutrient seemed less important. For the non-stirred samples the addition of nitrate with the bacterial inoculum showed the best degradation, compared to the other non-stirred samples. At the end of the experiments, accumulations of metabolites/degradation products, such as 9H-fluorenone, 4-hydroxy-9H-fluorenone, 9,10-phenanthrenedione and 4H-cyclopenta[def]phenanthrenone were detected. The metabolite 4-hydroxy-9H-fluorenone increased by several orders of magnitude during the biological treatments. Microbial activity in the soil was measured by oxygen consumption and carbon dioxide production.

Assessment of toxicity hazards of dredged lake sediment contaminated by creosote

In order to predict the potential toxicity hazards of sediment remediation by dredging, an experimental laboratory simulation was made by investigating seven ratios of creosote-contaminated sediment (Lake Jämsänvesi, central Finland) and artificial lake water mixtures. Sediment was suspended in water at the ratios of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128 v/v. The elutriates were analysed for the acute toxicity by photoluminescence bacterial and waterflea (Daphnia magna Straus) tests. The concentrations of polycyclic aromatic hydrocarbons (PAHs) are determined by gas chromatography (GC/FID). The elutriate of ratio 1:2 was most toxic to bacteria (EC50 = 4.5%), whereas the ratio 1:4 was most toxic to waterfleas (EC50 = 21%). The elutriate of 1:1 contained the highest total PAH-concentration (1.67 mg/l) and total organic carbon (TOC) content (39.4 mg/l). When compared to the 1:1 ratio, taken as unity, the relative toxic emission yield (RTE) for bacteria was 307 for the ratio 1:128, so the high mixing ratio may cause a considerable ecotoxicological hazard. The highest amounts of PAHs were desorbed from sediment to water layer when the sediment was mixed with water at the ratios 1:1, 1:2 and 1:4 (v/v). It is assumed that dredging of creosote-contaminated sediment can potentially cause an ecotoxicological risk for a lake system at wide range of suspension ratios. We recommended that basic knowledge for these risks can be produced by simple laboratory simulation.

Assessment of the bioactivity of creosote-contaminated sediment by liver biotransformation system of rainbow trout

A sediment site in the Lake Jämsänvesi (municipality of Petäjävesi, Finland) contaminated by creosote was investigated to assess the possible ecotoxicological risks it may cause to benthic animals, including ones which may arise due to physical measures in remediating the site. It is suggested that polycyclic aromatic hydrocarbons (PAHs) are bioavailable to fish and other aquatic animals during exposure to contaminated water, sediment, and food. In order to assess toxicological risks of sediment contents to fish, juvenile rainbow trout (Onchorhynchus mykiss) were intraperitoneally dosed with extracts of the creosote-contaminated sediments and their elutriates. This was compared to pristine lake sediment spiked with creosote. Activity of CYP1A1 in trout liver was measured as ethoxyresorufin O-deethylase (EROD). When compared to vehicle controls and the pristine reference sediment (0.9-1.3 pmol/min/mg PMS protein), the extract of creosote-contaminated sediment of Lake Jämsänvesi induced EROD activity up 20-30 times with a dose of 100 mg/kg [total PAHs (mg)/(kg) in fish]. The rise of EROD was associated with increasing levels of PAH metabolites in bile, analyzed as 1-OH pyrene equivalents.

Toxicity of creosote water-soluble fractions generated from contaminated sediments to the bay mysid

Creosote, a globally used wood preservative, is a complex mixture consisting primarily of aromatic organic compounds (ACs). Creosote-derived ACs can persist for decades in aquatic sediments. Natural and anthropogenic activities may result in dissolution and resuspension of sediment-associated ACs. These processes were mimicked by generating a water-soluble fraction (WSF) from creosote-contaminated sediment (ERS) collected from a polluted site. The epibenthic mysid Mysidopsis bahia was exposed to five sublethal concentrations of WSF for 7 days. The WSF significantly decreased dry weight gain and proportion of gravid females (EC50=15 microgram/liter total identified ACs). Chemical analysis indicated that high-molecular-weight ACs (more than three aromatic rings) dominated the ERS, but were undetected in the WSF. Low-molecular-weight ACs (fewer than three aromatic rings) dominated the WSF. Compositional differences can thus result from fractionation processes and affect environmental fate and toxicity of the mixture.

Determination of coal tar and creosote constituents in the aquatic environment

Creosote and its parent material, coal tar, are complex mixtures. Upon release their components fractionate into the air, water, soil/sediment and biota; as a function of their physical and chemical properties. Therefore, assessment of their fate and concentrations in the environment must consider a wide variety of both compounds and matrices. Analyses are typically complicated, consisting of sample extraction, purification and chromatography-based final characterization steps. Several new techniques have been introduced to reduce or simplify the number of steps, solvent and time required. Recently developed extraction methods include supercritical fluid, accelerated solvent, microwave and solid-phase microextraction. On-line purification and coupling of extraction and chromatography have also emerged. HPLC and GC remain the major tools for performing the final separations. Application of mass spectrometry has increased as more reliable, versatile and less expensive units have become available, such as the ion trap and mass selective detectors. Fluorescence and diode array UV, in concert with HPLC, and C-, S- and N-selective gas chromatographic detectors are also being applied.

Suppression of intestinal smooth muscle contraction by 4-ethylguaiacol, a constituent of wood creosote

Wood creosote, a mixture of phenolic compounds, suppresses in vitro contractions of rat intestine. To identify a compound in wood creosote able to inhibit intestinal motility, we screened its constituent phenolic compounds and found 4-ethylguaiacol (4-EG) as an active compound. It suppressed the spontaneous phasic (IC50 = 513 +/- 48 mumol/l) as well as spasmogenic-agent-induced tonic longitudinal contractions of isolated rat ileum in a reversible and concentration-dependent manner. KCl-depolarization-induced tonic contraction, which was susceptible to a calcium channel blocking agent, was also suppressed by 4-EG with an IC50 of 433 +/- 41 mumol/l. Furthermore, calcium-ionophore-induced contraction, which was affected by an influx of extracellular calcium ion that bypassed calcium channels, was suppressed by 4-EG with an IC50 of 97 +/- 18 mumol/l. These results support the concept that the effect of wood creosote to suppress intestinal motility is attributable, partially or entirely, to its component 4-EG and that this effect of 4-EG on the intestinal muscle is produced at some stage(s) of the muscle contraction process after influx of extracellular calcium into the cytosol of smooth muscle.

High-performance liquid chromatographic determination of azaarenes and their metabolites in groundwater affected by creosote wood preservatives

Polynuclear azaheterocyclic compounds (azaarenes) are nitrogen-containing analogs of polycyclic aromatic hydrocarbons (PAHs). The nitrogen atom in the ring system causes these compounds to be slightly polar and considerably more water soluble than related PAHs. A method using a solid-surface sorption technique to extract and concentrate azaarenes and their principle metabolites present in groundwater that contains creosote waste is described. Analyte isolation and concentration is accomplished by solid-phase extraction on n-octadecyl cartridges followed by instrumental determination involving high-performance liquid chromatography. Separations and detection are achieved using flexible-walled, wide-bore columns with ultraviolet and fluorescence photometric detectors connected in series. Fluorescence detection alone is insufficient because the fluorescence response produced by two-ring azaarenes is limited. Short wavelength (229 nm) absorbance detection provides improved sensitivity for these compounds and peak rationing for more definitive identification. In this study, oxygen-containing metabolites of quinoline, isoquinoline, and acridine are detected in groundwater from hazardous waste sites in Pensacola, Florida and St. Louis Park, Minnesota. Concentrations ranging from mg/L to ng/L are measured. The dependence of measured octanol-water partition coefficients on pH is discussed in the context of the isolation chemistry. As a direct bacterial degradation product of acridine with a relatively long environmental persistence, 9-acridinone may serve as a biogenic marker signaling creosote contamination of groundwater.

Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography

Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

Exposure to creosote in the impregnation and handling of impregnated wood

The major components of vapors and polycyclic aromatic hydrocarbons in particulate matter were identified and quantified in two creosote impregnation plants and in the handling of treated wood. The vapors were collected on XAD-2 resin (recovery in the range of 82-102%) and analyzed by gas chromatography. Particulate polycyclic aromatic hydrocarbons were collected on glass fiber filters and analyzed with high-pressure liquid chromatography with a fluorescence detector. The main components of the vapors were naphthalene, methyl naphthalenes, indene, phenol, and its methyl homologues, benzothiophene, diphenyl, acenaphthene and fluorene. The exposure of the workers to vapors varied between 0.1 and 11 mg/m3. The concentrations of particulate polycyclic aromatic hydrocarbons varied between 0.2 and 46 micrograms/m3. The benzo(a)pyrene concentration was under 0.03 micrograms/m3, except in manual metal-arc welding and in the boring of railroad ties, where it was 0.24-0.89 micrograms/m3. In the measurement of creosote vapors, naphthalene could be used as an indicator agent.

Fluoranthene, a volatile mutagenic compound, present in creosote and coal tar

Creosote, a coal-tar distillation product, contains mutagens which are volatile at 37 degrees C. After distillation of creosote we found that these volatile mutagens were present in the distillation fraction with the highest boiling range (greater than 360 degrees C). The "volatile mutagenic activity" was connected with the presence of fluoranthene, a polycyclic aromatic hydrocarbon. Commercially available fluoranthene was positive in the so-called "taped-plate assay" (the test system used for the detection of volatile mutagens) towards the strains TA98 and TA100 in the presence of S9 mix. The tested creosote and coal tar contained fluoranthene in concentrations of 5.2 and 2.2%, respectively.

Detection of volatile mutagens in creosote and coal tar

Creosote and coal tar were examined for the presence of volatile mutagens by use of the so-called "taped plate assay". Application of this method, recently published by Distlerath et al., reveals that vapour escaping from creosote and coal tar at 37 degrees C was able to revert the Salmonella typhimurium strains TA98 and TA100 in the presence of S9 mix. The simplicity of this method makes it useful for routine screening of industrial fluids or solid products for the presence of volatile mutagens.

The presence of the mutagenic polycyclic aromatic hydrocarbons benzo[a]pyrene and benz[a]anthracene in creosote P1

Several fractions of creosote P1 separated by TLC showed mutagenicity towards Salmonella typhimurium TA98. Thus mutagenicity is probably caused by the presence of mutagenic aromatic hydrocarbons. The mutagenic polycyclic aromatic hydrocarbons, benzo[a]pyrene and benz[a]anthracene, were detected in concentrations of 0.18 and 1.1% respectively. Because these compounds are probably not essential for the wood-preserving properties of creosote , a more selective composition of the product should be considered.

Movement and identification of a creosote-derived PAH complex below a river pollution point source

High pressure liquid chromatography was used to determine the identity of a black, oily leachate seeping into a spring-fed river. The leachate was identified as creosote by comparing a sample of the material to a sample of commercial creosote. As creosote contains a complex mixture of polynuclear aromatic hydrocarbons (PAH), the direct introduction of creosote into a stream system provided an opportunity to study the kinetics of these hydrocarbons as sediment contaminants below the creosote source. Concentrations of PAH, calculated on the basis of the amounts of organic matter contained in the sediments, declined rapidly below the point source in a form readily approximated by double exponential equations. An important aspect of the pattern of decline encountered was that concentrations tended to become asymptotic. As a result, the river's sediments became contaminated over a considerable distance.