Fraction Of Polychlorinated Biphenyls Research Articles

Polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in soil samples from airport areas of Croatia

Levels and patterns of polychlorinated biphenyls (PCBs) were studied in surface soil samples collected in the coastal part of Croatia within and surrounding four different airports and in the vicinity of two partially devastated electrical transformer stations. The compounds accumulated from air-dried soil samples by multiple ultrasonic extraction with an n-hexane : acetone 1 : 1 mixture were analysed by capillary gas chromatography with electron capture and ion-trap detection. PCBs were quantified against a standard Aroclor 1242/Aroclor 1260 mixture and a standard mixture of 17 individual PCB congeners (IUPAC No.: 28, 52, 60, 74, 101, 105, 114, 118, 123, 138, 153, 156, 157, 167, 170, 180, and 189). The mass fractions of total PCBs in 18 soil samples collected within the airport premises ranged from 3 to 41 327 µg/kg dry weight (dw) (median: 533 µg/kg dw), and those in 21 samples collected at a distance ranging from several metres to 5 km away from the airport fence, from <1 to 39 µg/kg dw (median: 5 µg/kg dw). The highest PCB levels were determined in soils along the airport aprons where the aircrafts were serviced and refuelled. The PCB pattern was very similar to technical Aroclor 1260 in all airport soils. The PCB pattern in 22 soils collected in the vicinity of electrical transformer stations was dominated by congeners contained in Aroclor 1242. These soils contained 7 to >400 µg/kg dw of total PCBs. One highly PCB-contaminated airport soil sample was analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). With an international toxic equivalent (I-TEQ) of 9.7 ng/kg dw, the airport soil contamination was within values typical for urban and rural areas, and the congener patterns gave no clear indication for PCBs as the only source of PCDDs/PCDFs.

Analysis of polychlorinated biphenyls in food products

Polychlorinated biphenyls (PCBs) are highly persistent, lipophilic and bioaccumulative toxic industrial contaminants formed as a result of human activities. Most of its uses have been banned since the late 1970s. This article describes the importance of matrix pretreatment, sample extraction, clean-up and fractionation of PCBs from food matrices. It reviews detection techniques, such as cGC, for these congeners and their enantiomers, using different columns and detectors, with emphasis on MS methods, together with the limitations of these techniques. It also discusses other methods, such as MEKC, immunoassays and bioassays, as applied to the detection of PCBs in foods.

Global distribution and budget of PCBs and HCB in background surface soils: implications for sources and environmental processes.

This paper presents data from a survey of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) concentrations in 191 global background surface (0-5 cm) soils. Differences of up to 4 orders of magnitude were found between sites for PCBs. The lowest and highest PCB concentrations (26 and 97,000 pg/g dw) were found in samples from Greenland and mainland Europe (France, Germany, Poland), respectively. Background soil PCB concentrations were strongly influenced by proximity to source region and soil organic matter (SOM) content Most (>80%) of the estimated soil PCB burden remains in the "global source region" of the Northern Hemisphere (NH) temperate latitudes (30-60 degrees N) or in the OM-rich soils just north of that %SOM correlated with PCB and HCB in the global data set, with the correlation coefficients being greater for HCB and the lighter PCBs than for heavier homologues. OM-rich soils in the NH consistently contained the highest burdens; such soils are a key global compartment for these compounds. Evidence for global fractionation of PCBs was found in the subset of soils from latitudes north of the global source region but was not discerned with the global data set The full data set was used to estimate the burden for individual congeners/homologues in surface background soils and a global soil total PCB burden of 21,000 t. The significance of the inventory is briefly discussed in relation to the latest estimates of global production and atmospheric emission.

Anomalous Concentrations and Chlorination of Polychlorinated Biphenyls in Sediment Downwind of Lake Ontario

Relatively high concentrations (up to 98.5 ng/g dry wt) of polychlorinated biphenyls (PCBs) have been found in two cores penetrating fluvial sands east of Lake Ontario. One core was taken from the upper Salmon River reservoir on the Tug Hill Plateau and the other from Rice Creek near the lake at Oswego. In both instances, portions of the cores containing PCBs and other organochlorines (OCs) lack excess radiogenic 210Pb and 137Cs, implying depositional ages predating widespread OC commercial production, use, and release. Within each core there is little vertical variation in PCB composition and highly chlorinated congeners dominate the pattern. In addition, the PCB signature is analytically indistinguishable between cores despite collection over 50 km apart. This argues against local sources, and implies deposition and accumulation by processes operating over a substantial area and time period. Transport and introduction of a residual fraction of colloidal-bound PCBs to the sands via tannin-rich riverine waters is proposed. The PCB congener-specific pattern of air samples collected during the spring and summer of 1999 downwind of the lake at two locations (Rice Creek and Sterling) are similar to the sediments and display anomalous concentrations and chlorination with respect to other air sampling localities in the Great Lakes. A link between the residual fraction of PCBs observed in the sediment and air patterns via volatilization from the terrestrial surface is proposed. Elevated PCB concentrations and chlorination in non radiogenic fluvial sands and air may reflect regional accumulation and weathering processes operating over many decades and/or enhancement of contaminant deposition and partitioning downwind of the lake related to lake-effect precipitation.

Availability of polychlorinated biphenyls (PCBs) and lindane for uptake by intestinal Caco-2 cells.

Children may ingest contaminated soil from hand to mouth. To assess this exposure route, we need to know the oral bioavailability of the contaminants. Two determining steps in bioavailability of soil-borne contaminants are mobilization from soil during digestion, which is followed by intestinal absorption. The first step has been investigated in previous studies that showed that a substantial fraction of PCBs and lindane is mobilized from soil during artificial digestion. Furthermore, almost all contaminants are sorbed to constituents of artificial human small intestinal fluid (i.e., chyme), whereas only a small fraction is freely dissolved. In this study, we examine the second step using intestinal epithelial Caco-2 cells. The composition of the apical exposure medium was varied by addition of artificial chyme, bile, or oleic acid at similar or increasing total contaminant concentrations. The uptake curves were described by rate constants. The uptake flux seemed to be dose-dependent. Furthermore, different exposure media with similar total contaminant concentrations resulted in various uptake rates. This can be attributed to different freely dissolved concentrations and carrier effects. In addition, the large fractions of contaminants in the cells indicate that PCBs and lindane sorbed to bile, oleic acid, and digestive proteins contributed to the uptake flux toward the cells. These results can be extrapolated qualitatively to in vivo conditions. Because the sorbed contaminants should be considered available for absorption, the first step of mobilization from soil is the most important step for oral bioavailability of the presently investigated soil-borne contaminants.

Availability of Polychlorinated Biphenyls (PCBs) and Lindane for Uptake by Intestinal Caco-2 Cells

Children may ingest contaminated soil from hand to mouth. To assess this exposure route, we need to know the oral bioavailability of the contaminants. Two determining steps in bioavailability of soil-borne contaminants are mobilization from soil during digestion, which is followed by intestinal absorption. The first step has been investigated in previous studies that showed that a substantial fraction of PCBs and lindane is mobilized from soil during artificial digestion. Furthermore, almost all contaminants are sorbed to constituents of artificial human small intestinal fluid (i.e., chyme), whereas only a small fraction is freely dissolved. In this study, we examine the second step using intestinal epithelial Caco-2 cells. The composition of the apical exposure medium was varied by addition of artificial chyme, bile, or oleic acid at similar or increasing total contaminant concentrations. The uptake curves were described by rate constants. The uptake flux seemed to be dose-dependent. Furthermore, different exposure media with similar total contaminant concentrations resulted in various uptake rates. This can be attributed to different freely dissolved concentrations and carrier effects. In addition, the large fractions of contaminants in the cells indicate that PCBs and lindane sorbed to bile, oleic acid, and digestive proteins contributed to the uptake flux toward the cells. These results can be extrapolated qualitatively to in vivo conditions. Because the sorbed contaminants should be considered available for absorption, the first step of mobilization from soil is the most important step for oral bioavailability of the presently investigated soil-borne contaminants.

Towards a complete mass balance and model for PCBs and PAHs in a small rural lake, Cumbria U.K.

This paper summarizes the processes of exchange/fluxes for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in a small well‐studied rural lake, Esthwaite Water in northwest England. Measurements of PCB and PAH concentrations have been made in rain, air, water, dated sediment cores, and sediment trap samples over a 2‐yr study period and used to determine fluxes to and from the lake. A steady state mass balance model was used to construct an input‐output budget for the chemicals and to investigate the relative importance of transport into and out of the lake. The hydraulic transport from the lake was the most important loss mechanism for both PCBs and PAHs. Volatilization, not sedimentation, is currently the dominant loss process for PCBs in the water column, whereas, sedimentation exceeds volatilization for PAHs. The data further suggest that the current sediment‐water flux is upward for PCBs and downwards for PAHs, indicating that the sediments might be acting as a secondary source for PCBs but continue to act as a sink for PAHs. Riverine, catchment runoff, or both are believed to be the most important input for PCBs and PAHs to the lake although direct aerial deposition to the lake is also important for PCBs. Differences in the mixtures of compounds in the various compartments suggests significant fractionation of PCBs and PAHs in the air‐water‐sediment system in the lake.

Separation of non-ortho polychlorinated biphenyl congeners on pre-packed carbon tubes. Application to analysis in sewage sludge and soil samples

The analysis of planar (non-ortho) polychlorinated biphenyls (PCB) by HRGC-ECD or HRGC-HRMS requires a fractionation step to avoid the interferences of the bulk of PCB, usually in much higher concentration than the planar ones. In this paper, a new method, based on the fractionation of PCB on SPE commercial tubes pre-packed with Carbopack B, has been developed. After the extract has been applied on the stationary phase, the bulk of PCD are eluted with 15 ml of hexane (fraction I), mono-ortho PCB with 20 ml of hexane/toluene 99:1 (fraction II) and planar PCB with 20 ml of toluene (fraction III) in a station under vacuum. The method has been validated: accuracy (expressed as recovery in %) is >70% and precision (expressed as % RSD) is <20% considering changes of day, analyst and batch of tubes. The method is linear in the range studied. Other advantages are that the method is simple, rapid and it can be easily automated. The application of this separation to the determination of planar PCB in fly-ash extracts from an intercalibration exercise and to sewage sludge, sediment and soil samples has been successful. In addition, this method removes hydrocarbons from the planar PCB fraction and allows its concentration to very small volumes.

Chemical and biological availability of sediment‐sorbed hydrophobic organic contaminants

AbstractThe ability to predict accumulation levels of sediment‐sorbed hydrophobic organic contaminants (HOCs) by depositfeeding organisms based on sediment concentrations is limited in part by an incomplete understanding of the chemistry that controls assimilation efficiency. This study was designed to test the hypothesis that desorption is an important process that controls the bioavailability of HOCs to deposit‐feeding organisms; we planned to do so by conducting desorption and bioavailability experiments with field‐contaminated sediments collected from New York Harbor, New York, USA. Three classes of organic contaminants, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and linear alkylbenzenes (LABs) were studied. In order to address the effects of contaminant aging, we compared the contaminant desorption rates from sediments collected from surface and at depth in an area of known high‐sediment accumulation to retarded intraparticle model predictions. Measured desorption rates of the LABs and the most hydrophobic PCBs compare well with model predictions. However, the PAH and less hydrophobic PCB desorption rates range from one to four orders of magnitude slower than model predictions. We postulate that these compounds are present in a resistant sedimentary phase and may represent only a small fraction of what was originally sorbed. The fraction of PCBs, PAHs, and LABs desorbed after 48 h correlate well with measured biota‐sediment factors (BSFs) in Yoldia limatula that were exposed to the same sediments, indicating that desorption rate‐limited assimilation. Several studies have related field BSFs with log Kow and have observed a maximum at intermediate Kows (∼6.0‐6.5). This maximum may be due to predictably slow desorption of high‐Kow compounds and may be lower than predicted rates and extent of desorption of the low‐Kow compounds because of association with resistant phases.

CHEMICAL AND BIOLOGICAL AVAILABILITY OF SEDIMENT-SORBED HYDROPHOBIC ORGANIC CONTAMINANTS

The ability to predict accumulation levels of sediment-sorbed hydrophobic organic contaminants (HOCs) by depositfeeding organisms based on sediment concentrations is limited in part by an incomplete understanding of the chemistry that controls assimilation efficiency. This study was designed to test the hypothesis that desorption is an important process that controls the bioavailability of HOCs to deposit-feeding organisms; we planned to do so by conducting desorption and bioavailability experiments with field-contaminated sediments collected from New York Harbor, New York, USA. Three classes of organic contaminants, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and linear alkylbenzenes (LABs) were studied. In order to address the effects of contaminant aging, we compared the contaminant desorption rates from sediments collected from surface and at depth in an area of known high-sediment accumulation to retarded intraparticle model predictions. Measured desorption rates of the LABs and the most hydrophobic PCBs compare well with model predictions. However, the PAH and less hydrophobic PCB desorption rates range from one to four orders of magnitude slower than model predictions. We postulate that these compounds are present in a resistant sedimentary phase and may represent only a small fraction of what was originally sorbed. The fraction of PCBs, PAHs, and LABs desorbed after 48 h correlate well with measured biota-sediment factors (BSFs) in Yoldia limatula that were exposed to the same sediments, indicating that desorption rate-limited assimilation. Several studies have related field BSFs with log Kow and have observed a maximum at intermediate Kows (∼6.0-6.5). This maximum may be due to predictably slow desorption of high-Kow compounds and may be lower than predicted rates and extent of desorption of the low-Kow compounds because of association with resistant phases.

Loading capacity and chromatographic behavior of a porous graphitic carbon column for polychlorinated biphenyls

A porous graphitic carbon column (Hypercarb) was used for the fractionation of polychlorinated biphenyls (PCBs) into classes of 2-4 ortho chlorines, 1 ortho chlorine and 0 ortho chlorine congeners. A method was developed that combined the fractionation of PCBs, polychlorinated dibenzo- p-dioxins and dibenzofurans in a variety of biotic environmental samples. Many of these samples have high concentrations of PCBs which cause fractionation problems as adsorption sites on the graphitic surface are occupied. The loading capacity of the column for PCBs was determined by injecting up to 1 mg of total PCBs and monitoring changes in chromatographic behavior of tetra-/di- ortho, mono- ortho and non- ortho substituted PCBs. Effective loading capacities were 1 mg for tetra-/di- ortho PCBs, but only 3–5 μg for non- ortho PCBs and about 2 μg for mono- ortho PCBs. Loading capacity of the PGC column for environmental fish and avian egg samples was determined to depend on the mono- ortho and non- ortho PCB levels found in these samples.

Snow Scavenging of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in Minnesota

Snow and rain events were collected with concurrent air samples during the winter of 1991−1992 at a suburban site in Minnesota to investigate atmospheric scavenging of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Particle scavenging was the dominant contributor to the total concentrations in snow and was less important in rain. Gas scavenging was only important for low molecular weight PCB congeners and PAHs. Enrichment of dissolved-phase concentrations over levels predicted from temperature-corrected Henry's Law constants was observed for low molecular weight compounds in both rain and snow. The particulate fraction (φ) of atmospheric PCBs and PAHs was the best indicator of total scavenging (WT) by snow according to the equations log WT = 0.71 (±0.08) log φ + 5.34 (±0.08) for PCB congeners (r = 0.62) and log WT = 0.89 (±0.12) log φ + 6.07 (±0.13) for PAHs (r = 0.73).

2,3,7,8‐tetrachlorodibenzo‐p‐dioxin equivalents in extracts of Baltic white‐tailed sea eagles

AbstractConcentrations of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin‐(TCDD) equivalents were measured in extracts of Baltic white‐tailed sea eagle tissues. Extracts of salmon, ringed seal, and grey seal were analyzed as other predatory species of the same area. Concentrations in eagle and seal tissues were greater than those in salmon. Concentrations of TCDD equivalents (TCDD‐EQs) determined by the H4IIE bioassay were compared with toxic equivalents (TEQs) derived from instrumental chemical analyses in fractions containing polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans (PCDD/PCDF) or coplanar polychlorinated biphenyls (PCBs). Toxic equivalents were calculated by use of an additive model in which the product of the concentrations of instrumentally measured individual congeners were multiplied by their TCDD equivalency factors and were summed to give a total concentration of TEQs. The TCDD‐EQs were compared with TEQs to develop a mass balance to determine whether all the TCDD‐like activity was accounted for. For example, the concentration of TCDD‐EQs in the coplanar PCB fraction of the most contaminated eagle was 980 pg/g fresh weight (fw), and that of the PCDD/PCDF fraction was 240 pg/g fw. The TEQs determined by chemical analyses for coplanar PCBs was 770 pg/g fw, and that of PCDD/PCDFs was 270 pg/g fw in this eagle. Thus, concentrations of TCDD‐EQs were approx. 20% greater than those of TEQs. The true difference in activities is probably greater because of lower recoveries and infra‐additivities among congeners in the bioassay. This indicates that there are compounds present in the extracts that can contribute to the total concentrations of TCDD‐EQs that were not accounted for by TEQs. The hazard quotient, calculated as the ratio of current concentrations of TCDD‐EQs in white‐tailed sea eagle eggs to the no‐observable‐adverse‐effect concentration, ranged from 7.3 to 141 (mean = 52.7, SD = 43). This indicates that current concentrations of TCDD‐EQs in these eggs are likely causing adverse effects in the Baltic populations of white‐tailed sea eagles. This study indicated that the H4IIE bioassay is useful for monitoring the presence and biological activity of TCDD‐like compounds in environmental samples like white‐tailed sea eagles.

Potential importance of protozoan grazing on the accumulation of polychlorinated biphenyls (PCBs) in the pelagic food web

Experiments were conducted to study the distribution of three selectedpolychlorinated biphenyl (PCB) congeners within the microbial food web attwo different nutrient levels; control and nutrient enriched. The objectivewas to quantify the uptake of PCBs through grazing by protozoa. The14C-PCBs tested were 4-chlorobiphenyl (IUPAC # 3),2,2′,5,5′-tetrachlorobiphenyl (IUPAC # 52), and2,2′,4,4′,5,5′-hexachlorobiphenyl (IUPAC # 153). EachPCB was incubated in triplicate seawater samples at 20 idref;Cover one week. Daily, samples were separated into four fractions; 10 µm (microplankton; phytoplankton andprotozoa) by selective filtration. Of the PCB fraction that initiallyadsorbed to particles, 60–100% was associated to the bacterialfraction and 0–5% to the microplankton fraction. The totaluptake was highest in the nutrient enriched samples, but when normalized tothe carbon biomass the concentration was lower or equal to the control inall particle fractions. The recovery of the PCBs in the particulatefractions depended on the degree of chlorination, as the highest values wereobserved for the 2,2′,4,4′,5,5′-hexachlorobiphenyl and thelowest for the 4-chlorobiphenyl. The concentrations in the bacterial andflagellate fractions decreased over the first 48–96 hours whilst theconcentration increased in the highest trophic level (>10 µmfraction). Approximately 75% of the increase in concentration of the2,2′,4,4′,5,5′-hexachlorobiphenyl in the > 10 µmfraction was estimated to be the result of bacterivory. Our results indicatethe microbial food web can contribute to a rapid uptake of higherchlorinated PCBs, particularly in oligotrophic ecosystems where thebacterial biomass dominates.

Determination of chlorinated pesticides and PCB in pine needles - improved method for the monitoring of airborne organochlorine pollutants.

A method to determine organochlorine pollutants in pine needles is described. Fresh, whole needles have been extracted for 48 h in dichloromethane to obtain the epicuticular wax fraction. The remainder has been cut into small pieces and again extracted with dichloromethane to obtain the internal lipids. Prior to gas chromatography, both the wax and the internal lipid extracts have been fractionated on two columns: first a silica gel/silica gel : sulphuric acid 2 : 1 column with dichloromethane as eluent and then a nitrophenyl silica column with hexane as eluent. Three fractions have been collected, fraction 1 containing hexachlorobenzene (HCB), fraction 2 containing polychlorinated biphenyls (PCB) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (DDE), and fraction 3 containing the remaining, more polar, organochlorine pesticides. For some pine species, the nitrophenyl silica column has been combined with a short aminopropyl silica column to obtain chromatograms of the PCB fraction free from negative peaks. The precision is in the range of 4-12% relative standard deviation, and the overall recovery is around 65-90%.

Method for the group separation of non- ortho-, mono- ortho- and multi- ortho-substituted polychlorinated biphenyls and polychlorinated dibenzo- p-dioxins/polychlorinated dibenzofurans using activated carbon chromatography

A cheap, efficient and reliable method for the separation of mono- ortho-/non- ortho-substituted polychlorinated biphenyls (PCBs), multi- ortho-PCBs and polychlorinated dibenzo- p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) from one another and from other interferents was developed. A mixture of activated carbon AX-21 (50 mg and Celite 545 as a carbon support (1:19) packed in a diposable tube was used. The compounds were gradually eluted with cyclohexane-dichloromethane-methanol (2:2:1) and toluene (a coplanar PCB fraction). PCDDs and PCDFs were regained by extraction of the inverted AX-21-Celite column with a small volume of toluene in a special miniaturized extraction apparatus. Recoveries from the column for PCBs and PCDDs/PCDFs varied from 63% to 100%. The method was used successfully for the fractionation of PCB technical formulations (Delor 103 and 105), municipal waste incinerator fly ash and biological samples (human adipose tissue, butter, egg and fish samples). The method is suitable for both mass spectrometric and electron-capture detection.

Application of a permeant/polymer diffusional model to the desorption of polychlorinated biphenyls from Hudson River sediments

The desorption of polychlorinated biphenyls (PCBs) from Hudson River sediments was examined using XAD-4 resin as a PCB adsorbent. Both a rapidly desorbing labile component and a more slowly desorbing resistant component were observed. The fraction of PCBs in the resistant component was found to be a function of PCB concentration and total organic carbon in the sediment, independent of inorganic particle size. Milling the sediment had no effect on PCB desorption, while pretreatment of the sediment using heat (with and without caustic addition) enhanced the rate ofdesorption and significantly decreased the resistant fraction. We propose that the labile and resistant fractions arise from disparate diffusional rates of PCBs from the swollen and condensed phases of the sediment organic matter

Release of polychlorinated biphenyls (PCB) in a salt-wedge estuary as induced by dredging of contaminated sediments

An evaluation of the input of polychlorinated biphenyls (PCB) in the Duwamish River, Seattle, Wash., resulting from the dredging of contaminated sediments is presented. The mean concentrations of PCB during the monitoring period were 12.8 to 24.5 ng/liter in water and 1.03 to 1.77 μg/g dry weight in suspended particulate matter. These values were within the ranges normally observed in the river, suggesting that the dredging operations did not induce a significant PCB pulse of potential hazard to the estuary. The fractionation of PCB in suspended particulate matter was determined by computing component concentration ratios, KdN. These quantities indicate an enrichment factor of 105 from ambient water. Based on the ambient PCB load and normal discharge, the input of PCB into Puget Sound via the Duwamish River was estimated to be 36 kg/year.