PCBs In Soil Research Articles

Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile

In this study the levels and distribution of some persistent toxic substances (PTS) were investigated in soils, superficial water, and snow along an altitudinal gradient in the Laja River Basin (South Central Chile). The principal objective was to establish the basin’s contamination status. The working hypothesis was that PTS levels and distribution in the basin are dependent on the degree of anthropogenic intervention. Fifteen PAHs, seven PCBs congeners, and three organochlorine pesticides were studied in superficial soil and water samples obtained along the altitudinal gradient and from a coastal reference station (Lleu–Lleu River). Soil samples were extracted using accelerated solvent extraction with acetone/cyclohexane (1:1) for PAHs and organochlorine compounds. Contaminants were extracted from water and snow samples by liquid–liquid extraction (LLE). PAH and organochlorine compound quantification was carried out by HPLC with fluorescence detection and GC–MS, respectively. PCBs in soils presented four different profiles in the altitudinal gradient, mainly determined by their chlorination degree; these profiles were not observed for the chlorinated pesticides. In general, the detected levels for the analyzed compounds were low for soils when compared with soil data from other remote areas of the world. Higher ∑PAHs levels in soils were found in the station located at 227 masl (4243 ng g −1 TOC), in a forestry area and near a timber industry, where detected levels were up to eight times higher than the other sampling sites. In general, PAH levels and distribution seems to be dependent on local conditions. No pesticides were detected in surface waters. However, congeners of PCBs were detected in almost all sampling stations with the highest levels being found in Laja Lake waters, where 1.1 ng/l were observed. This concentration is two times higher than values reported for polluted lakes in the Northern Hemisphere. The presence of organochlorine compound in snow sampled at the highest elevation point of the basin is indicative of the transport and atmospheric deposition phenomena of α-HCH, γ-HCH and PCB 52, with values being similar to the levels reported in Canadian snow samples. We conclude that environmental PTS substance levels are in general relatively low, although PAHs may be of concern in some areas of the basin.

Distribution and spatial trends of PAHs and PCBs in soils in the Seine River basin, France

Persistent organic pollutants (PAHs and PCBs) in soil samples from seven sites across the Seine basin were analysed. Samples were taken from industrialized, urban, suburban and remote sites. Results showed spatial differences, in terms of concentrations and congener profiles. PAH (∑14 PAHs) and PCB (∑7 PCBs) concentrations ranged from 450 to 5650 μg kg −1 and 0.09 to 150 μg kg −1, respectively. A clear gradient from industrial to remote sites was highlighted, with a ratio of up to one order of magnitude for PAHs and two orders of magnitude for PCBs. Fluoranthene and pyrene were predominant, while the carcinogenic PAHs represented 15–46% of the total PAH content. Using hierarchical cluster analysis, soil samples profiles were compared and the influence of site location and potential sources were identified: automobile traffic, domestic heating, and industrial emissions were the prevalent PAHs sources in the Seine basin. PCB profiles suggested different transport patterns among congeners. For remote sites, the congener fingerprint showed a relatively higher proportion of the most volatile congeners, which were attributed to increased atmospheric residence times. Thus, PAH and PCB distributions in soils provided information on sources and evidence for short-range transport, and profiles of compounds reflected differences between regional and local emissions. This study demonstrates that soil sampling can be used to investigate spatial differences in atmospheric inputs of persistent organic pollutants based on differences in the mixtures of compounds, reflecting differences in regional and local atmospheric emissions.

Determination of polychlorinated biphenyl compounds in electrical insulating oils by enzyme immunoassay

The development and performance of a competitive indirect immunoassay for the quantitation of polychlorinated biphenyl compounds (PCBs) in insulating oils is described. Reagent preparation and the assay characterisation, optimisation and validation steps are described. The dynamic range of the assay for Aroclors 1254 and 1260 in methanol was 30–1000 ng ml −1 with 50% signal inhibition values of 217 and 212 ng ml −1, respectively. Impending legislation in the UK is likely to decree that oils containing >50 μg ml −1 PCBs be considered contaminated. Assay sensitivity increased with the degree of PCB chlorination. The assay of structurally related compounds of environmental concern yielded cross-reactivity values of <0.6%. The immunoassay proved reliable for the analysis of diluted transformer oils containing >35 μg ml −1 PCB (neat) but over-estimated PCB levels in diluted oils containing <10 μg ml −1 of neat analyte. The oils required pre-treatment using either solid-phase extraction or washing with KOH–ethanol/sulphuric acid to remove matrix interferents. The analytical performance of the assay was compared against a commercially available semi-quantitative immunoassay kit for PCBs in soil and water.

Research Watch: PCBs in soil

Research Watch: PCBs in soil

Measuring and modelling the vertical distribution of semi-volatile organic compounds in soils. II: model development

A dynamic air-soil exchange model which divides the soil into multiple soil layers has been developed and used to simulate the vertical distribution of PCBs in an undisturbed grassland soil. An historical emission profile for PCBs to the UK atmosphere was used to deduce concentrations in the air compartment. Model simulations were tuned by varying the most uncertain model input parameters, namely soil turnover rates by bioturbation and emission estimates. Comparison of model output and reported PCB concentration profiles agreed within a factor of six. Insights were gained into the relative importance of the soil transport processes and specifically bioturbation was shown to be the dominant transport mechanism for PCBs in this soil. It was concluded that the model is sufficiently accurate for incorporation into regional mass balance models, although vertical layering of the soil may be unnecessary in models describing the long-term air-soil interaction of organic compounds.

Formula omitted] decomposition of PCBs in soil using microwave energy

The decomposition of individual PCBs and of Aroclors in soil using microwave energy and graphite fibers occurs quantitatively in a machinable ceramic alumina bomb. As a model for in situ remediation, the reactions were then carried out in open vessels equipped with rudimentary condensers, and using either pencil lead (as a cheap graphite rod equivalent) or iron wire. Most of the chlorinated aromatics decomposed (none left in the soil), and a small portion was desorbed, collected, and dechlorinated quantitatively by catalytic hydrogenation. This procedure should allow soil remediation to any preset depth by using the appropriate length of graphite or iron rods. When 14C-2,2′,5,5′-tetrachlorobiphenyl was used (with thinner pencil lead) 27% was desorbed and 1–2.5% of 14CO 2 was evolved. The remaining material could not be extracted from the soil under any conditions, and this suggests that the dechlorinated fragments are very tightly bound, and possibly encapsulated, by the vitrified soil.

High sensitivity of ortho-substituted polychlorobiphenyls in negative ion mass spectrometry (NCI - MS): A comparison with El - MS and ECD for the determination of regulatory PCBs in soils

Selected ortho-substituted PCBs (IUPAC no. 28, 52, 101, 118, 153, 138, 180) were quantified at trace levels in twenty different agricultural soils using high resolution gas chromatography (HRGC) and negative-ion chemical ionization mass spectrometry (NCI-MS), electron impact mass spectrometry (EIMS) and electron capture detection (ECD). In NCI PCBs generated simple mass spectra with the molecular ion as base peak. The dissociative electron capture mechanism increased for higher chlorinated PCBs. After ion source optimization (pressure, temperature) detection of the tri-and tetrachloro-PCBs became possible. NCI-MS showed comparable sensitivity with the ECD for most of the PCBs analyzed, excellent linearity and good repeatability. A comparison of the PCB soil concentrations obtained with the three detection techniques revealed that NCI-MS gave values closest to the overall mean with the smallest deviations.

GC/MS procedures for the determination of PCBs in environmental matrices

This paper describes GC/MS methods for the determination of PCBs in air, fish, sediment, soil, vegetation and water, all validated by analysis of appropriate standard reference materials. An important feature is the fact that up to 92 PCB congeners containing between three and seven chlorines are determined. The use of such a large number of individual congeners results in ΣPCB values that exceed those obtained using the smaller number of individual congeners routinely reported in some laboratories. Such underestimation of ΣPCB has important implications for the studies of the environmental fate of these compounds and may have led to an underestimation of their environmental persistence as an overall class.

Independent Comparison of Soxhlet and Supercritical Fluid Extraction for the Determination of PCBs in an Industrial Soil

An independent comparison between supercritical fluid extraction (SFE) and Soxhlet extraction methods was conducted as part of a certification of PCB congeners in industrial soil. The study was performed in the framework of the PCB group for the Measurements and Testing Program (former BCR) under the Commission of the European Union. It involved 21 selected and independent laboratories experienced in congener-specific PCB analysis. The comparison was performed using both interlaboratory and intralaboratory data. SFE was performed independently by three laboratories, and the obtained data showed that SFE is a very competitive alternative in terms of both accuracy and precision. The soil was certified for eight PCB congeners ranging from 7.0 to 137 μg/g with interlaboratory RSDs of 9-13% using all but two (out of 34) individual results from the SFE group.

Rapid Analysis of PCBs in Soil by Enzyme Immunoassay

Abstract A commercially available kit has been applied successfully to screening for polychlorinated biphenyls (PCB's) in soil samples. The kit uses a competitive inhibition Enzyme ImmunoAssay (EIA) for recognition of the PCB structure. Test specificity is restricted to PCB's, primarily Aroclors 1016, 1242, 1248, 1254, and 1260. Soil sample preparation and analysis can be performed in the field or lab using disposable kit components. Screening of unidentified Aroclors at 4 levels from 1 to 50 μg/g in soil is possible using the calibrators in the kit. This screening use has been reviewed by the USEPA Office of Solid Waste and will be proposed for inclusion in the 4000 series of screening methods in the next SW846 update. Conventional analysis (Soxhlet/GC-ECD) and the EIA kit were compared by Manitoba Hydro using 112 field samples over one year. EIA technology was found to be an effective screening tool for determining PCB concentration at contaminated sites. Routine use of these kits in conjunction with conventional Soxhlet extraction procedures has increased the lab's testing capability and reduced the amount of samples requiring conventional testing, providing substantial savings to the corporation.

Evidence for short-range transport of polychlorinated biphenyls in the Canadian Arctic using congener signatures of PCBs in soils

The Distant Early Warning (DEW) Line, a series of radar stations spanning the Canadian Arctic, is closing. In order to determine the environmental status of these installations, the Canadian Department of National Defence has sponsored an assessment of soil contamination, the partial results of which are presented here. A comparison of PCB concentrations in background samples taken from pristine areas near the radar sites and samples taken in remote locations (> 20 km distant) provides evidence for short-range redistribution of PCBs. Principal component analysis, which was used to highlight differences in congener composition, provided confirmation of this observation. The PCB congener signatures for background samples taken at the radar sites correlated well with PCB signatures from contaminated locations at the radar sites. In contrast, the congener signature attributed to long-range transport, contained a relatively higher proportion of more volatile congeners, which can be attributed to the increased atmospheric residence time.

Effects of cosolvency in the fate and transport of PCBs in soil

AbstractUnder the purview of EPA's Remedial Engineering Management (REM III) Superfund contract, a CERCLA RI/FS was performed at the Pinettes Salvage Yard site located in Washburn, Maine (EPA Region I). The purpose of the RI/FS was to fully characterize the nature, extent, and fate and transport of PCB contamination resulting from an alleged surface spill of transformer dielectric fluid containing Arochlor 1260 (a polychlorinated biphenyl) and various volatile and semivolatile organic constituents. The RI/FS was performed subsequent to both an immediate removal action (IRA) and a deletion remedial investigation (DRI) performed by EPA contractors. Results of both efforts indicated that the site was unsuitable for deletion from the National Priorities List (NPL) because the site soils contained elevated levels of PCBs.This article presents a case history of the extensive field investigations performed to characterize the contaminant source and evaluate the fate and transport of PCBs in site soils. These investigations included on‐site mobile laboratory gas chromatograph (GC) analytical techniques for PCBs and targeted volatile and semivolatile organic compounds; confirmatory Contact Laboratory Program (CLP) laboratory analyses of soils, sediments, surface water, and groundwater samples; statistical analyses and correlation of field mobile laboratory GC data with CLP laboratory analytical results; and an evaluation of the potential effects of cosolvency in the fate and transport of PCBs in subsurface soils.

Risk Variability from Uniform Soil Remediation Goals for PCBs

A methodology for evaluating the variability of risk resulting from the use of uniform, concentration‐based soil‐quality criteria is developed and applied to polychlorinated‐biphenyl‐(PCB‐) contaminated soil as an example. A modified version of a soil risk model developed by the U.S. Environmental Protection Agency is used to assess risk variability for different levels of PCBs in soil, representing different cleanup goals. Continuous distributions representing the variability in site conditions across the United States are assigned to parameters in the fate and transport model to examine the effect that such variability has on individual risk when uniform cleanup levels for PCBs in soil are used. It is found that for a fixed cleanup goal applied uniformly to all sites, the risk varies little for the case where the hypothetical exposure occurs on‐site, but by as much as two orders of magnitude for the case where the hypothetical maximally exposed individual resides off‐site. Depending on the risk goal of the remediation program, some risk variability may be acceptable and a uniform cleanup goal may be warranted to expedite the remediation process.

Degradation of PCBs by white rot fungi, methylotrophic and hydrocarbon utilizing yeasts and bacteria

Of the white rot fungi tested, two strains alone and other three in combination with specific yeasts or bacteria degraded PCBs in polluted soil within interval 20–30%. When all organisms were applied together PCB degradation achieved was about 50%.

Survey and evaluation of contaminants in earthworms and in soils derived from dredged material at confined disposal facilities in the Great Lakes Region

Soils derived from dredged material were collected, together with earthworms from nine confined disposal facilities located in the Great Lakes Region. These samples were analyzed for 18 elements, 11 organochlorine pesticides, PCBs, and 24 polycyclic aromatic hydrocarbons. The concentrations detected in earthworms were evaluated in terms of their potential hazard to wildlife, which for the sake of the evaluation were assumed to prey entirely either on earthworms or on other soil invertebrates having similar concentrations. The soil concentrations (dry wt.) of the contaminants of greatest concern were <1.9 to 32 ppm Cd, <0.053 to 0.94 ppm Hg, 4.6 to 550 ppm Pb, and <0.1 to 1.0 ppm PCBs. The concentrations in earthworms (dry wt., ingested soil included) were as high as 91 ppm Cd, 1.6 ppm Hg, 200 ppm Pb, and 1.8 ppm PCBs. Based on laboratory toxicity studies of relatively sensitive species, and on concentration factors calculated from the earthworm and soil data, we estimated that lethal or serious sublethal effects on wildlife might be expected at concentrations of 10 ppm Cd, 3 ppm Hg, 670 ppm Pb, and 1.7 ppm PCBs in alkaline surface soils derived from dredged material. Concentrations of polycyclic aromatic hydrocarbons in earthworms were well below those in soil.

Concentrations of two organic contaminants in precipitation, soils and plants in the Essex region of Southern Ontario

Recent research has indicated that the atmosphere is an important pathway by which pollutants enter terrestrial and aquatic ecosystems. We report here concentrations of PCBs and octachlorostyrene (OCS) in precipitation, soils and plants in Essex County, Ontario. The average PCB concentration in urban precipitation (23 ng litre −1) was lower than that previously reported for urban areas in the Great Lakes basin. Differences between sites and with varying wind directions were not significant. OCS concentrations in precipitation averaged 1·6 ng litre −1. Concentrations of PCBs in soils were 2–3 orders of magnitude greater than in precipitation. Concentrations of these pollutants in city soils and plant roots were consistently higher than those from suburban and rural sites. Ratios of urban to suburban concentrations in soils and precipitation were approximately 5:1 for PCBs. However, concentrations of OCS were similar in urban and suburban samples of precipitation, soils and plant tissues. These comparisons suggest an urban source for PCBs, but not OCS. Concentrations of all contaminants in plant leaves, unlike those in precipitation, roots and soils, were relatively similar in urban and suburban areas. That similarity suggests that direct foliar uptake is not an important pathway for pollutant uptake in plants.

PCB concentrations in soil from central and southern Wales

Soil samples were collected from 84 locations in central and southern Wales. PCB concentrations ranged from 1.9 μg/kg to 1208 μg/kg with a mean of 86 μg/kg. with a mean and median of 11 μg/kg. Concentrations were highest in the southern, industrialised region, and decreased towards the northern boundary of the sampling area. The study was combined with a re-evaluation of an earlier survey of PCBs in British soils, to assess the significance of potential PCB emission sources impacting onto the sampling sites.

PCB destruction: A novel dehalogenation reagent

Alkali metal polyethylene glycolate complexes (APEGs) are being investigated as reagents for the in-situ decontamination of soils containing PCBs and other haloorganics in the U.S. Environmental Protection Agency's Industrial Environmental Research Laboratory, Cincinnati, Ohio. APEG reagents can be formulated with either an alkali metal or hydroxide and the corresponding polyglycol or polyglycol monoalkyl ethers. These alkali PEGs were found to be very reactive toward halogenated organics, particularly at elevated temperatures (ca. 60–100°C) and have been applied for decontamination of PCBs in transformer oils. The primary products were an alkali metal halide, i.e., sodium chloride in the case of PCBs and polyglycol ether aromatics. The reaction mechanism is nucleophilic substitution at the halogen-carbon bond. The reactive APEG species is theorized to be a crown ether metal coordinated structure. Previous formulation of these APEGs required reaction of the alkali metals with a desired polyethylene glycol under anhydrous conditions. These formulations were very susceptible to decomposition by water, and dehalogenation rates were likewise vastly reduced. Recent studies have shown that this is not an insurmountable problem when APEGs are formulated with the alkali metal hydroxide. This work examines the effect of APEG concentration and dilution in water and organic solvent on the dehalogenation of Aroclors 1242 and 1260 with potential application for the in-situ destruction of PCBs in soils.

A New Technique for the Rapid Analysis of Soil for the Presence of Polychlorinated Biphenyls

Abstract A new technique for rapidly screening for the presence of PCBs in soil has been developed and tested in a field monitoring situation. The technique employs an atmospheric pressure chemical ionization mass spectrometer system mounted in a van to provide on-site mass spectrometric identification and quantitation of the compounds. A small soil sample is heated in a flowing stream of pure nitrogen, and the vaporized material is trapped on an adsorber which is thermally desorbed into the ion source of the mass spectrometer. A detection limit of approximately 1 /ig/g of Aroclor 1254 has been achieved, with a total analysis time per sample of approximately 5 minutes. The process makes possible the direct analysis of soil samples without any chemical workup or preseparation.