PCB loading from sediment in the Hudson River: congener signature analysis of pathways

The upper Hudson River (NY) was subjected to massive PCB contamination over a period of three decades. A large inventory of PCBs remains in contaminated sediments of the river, most notably in the Thompson Island Pool. During the summer, flow crossing the Thompson Island Pool exhibits a large and consistent PCB load gain. This load gain is not associated with scouring flows and is not accompanied by an increase in suspended solids. A variety of hypotheses have been proposed to explain this load gain, including flux of contaminated porewater and dissolution of unverified reservoirs of pure PCBs. A wealth of congener-specific PCB data is available for the site throughout the 1990s. Interpretation of the Thompson Island Pool load gain is facilitated by examination of the PCB congener signature of the gain and comparison to the signature of potential sources. This examination suggests that neither the flux of porewater nor the dissolution of unaltered Aroclors are the predominant source of the load gain. Instead, the congener signature is consistent with a mixed source consisting of porewater flux and non-scour flux of contaminated sediments. The non-scour sediment flux, which reaches a maximum in the beginning of the summer growing season, is likely driven by a variety of biological and anthropogenic processes, including bioturbation by benthic organisms, bioturbation by demersal fish, scour by propwash, mechanical scour by boats and floating debris in nearshore areas, and uprooting of macrophytes.     

Polychlorinated biphenyl compounds in milk and dairy products

Summary The PCB content of 469 milk and dairy product samples was determined. The fat was extracted and cleaned up through aluminium oxide. The organochlorine pesticides and the PCBs were separated by chromatography through a silica gel column. The PCBs in the purified extracts were perchlorinated to decachlorobiphenyl and determined by gas chromatography. The mean PCB content of the samples investigated was 0.18 mg per kg fat. The results are comparable with those obtained in neighbouring countries and significantly lower than the interim FDA tolerance of 1.5 mg per kg fat.

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Polychlorierte Biphenylverbindungen in Milch und Milcherzeugnissen

Zusammenfassung Der Gehalt an polychlorierten Biphenylverbindungen wurde in 469 Milch- und Milcherzeugnis-Proben bestimmt. Das Fett wurde extrahiert und über Aluminiumoxid gereinigt. Die Organochlorpesticide und die PCB's wurden durch Chromatographie über eine Silicagelkolonne getrennt. Die PCB's der gereinigten Extrakte wurden zu Dekachlorbiphenyl perchloriert und durch Gaschromatographie bestimmt. Der durchschnittliche PCB-Gehalt der gesamten Muster betrug 0,18 mg pro kg Fett. Die Ergebnisse können mit denen der Nachbarländer verglichen werden und sind bedeutsam niedriger als die vorläufige FDA-Toleranz von 1,5 mg pro kg Fett.

     

Polychlorinated biphenyl residues in foods from a contaminated region of Yugoslavia.

PCB levels in food and the dietary intake of PCBs from food grown in a contaminated region in Bela Krajina (Slovenia, Yugoslavia) are reported. A large variation in the contribution of PCB congeners to total PCB levels in food of animal and leafy vegetable origin was found. Although guidelines for PCB tolerances exist only for food of animal origin, it was estimated that leafy vegetables and unpeeled fruits from the contaminated region present a significant source of human exposure to PCBs. PCB residues in fish and eggs exceeded the tolerances set by the FDA. Utilizing the official statistical data on food consumption, the dietary intake of PCBs from food of animal origin decreased from 1985 to 1988 from 14.5 to 1.6 mg/year per person, respectively, after the use of PCBs ceased in the nearby plant. The dietary intake in 1988 of PCBs from foodstuffs of vegetable origin and fruits was 4.6 mg/year per person. The quantitation of PCBs was made from the sum of 36 individual PCB congeners, obtained by high resolution gas chromatography with an electron capture detector.     

Enantiomeric composition of chiral polychlorinated biphenyl atropisomers in aquatic bed sediment

Enantiomeric ratios (ERs) for eight polychlorinated biphenyl (PCB) atropisomers were measured in aquatic sediment from selected sites throughout the United States by using chiral gas chromatography/mass spectrometry. Nonracemic ERs for PCBs 91, 95, 132, 136, 149, 174, and 176 were found in sediment cores from Lake Hartwell, SC, which confirmed previous inconclusive reports of reductive dechlorination of PCBs at these sites on the basis of achiral measurements. Nonracemic ERs for many of the atropisomers were also found in bed-sediment samples from the Hudson and Housatonic Rivers, thus indicating that some of the PCB biotransformation processes identified at these sites are enantioselective. Patterns in ERs among congeners were consistent with known reductive dechlorination patterns at both river sediment basins. The enantioselectivity of PCB 91 is reversed between the Hudson and Housatonic River sites, which implies that the two sites have different PCB biotransformation processes with different enantiomer preferences.     

Fluxes of polychlorinated biphenyls volatilizing from the Hudson River, New York measured using micrometeorological approaches

This study represents the first time that a micrometeorological technique, using turbulent transport measurements, has been used to determine the direction and magnitude of air-water exchange of polychlorinated biphenyls (PCBs). The study was conducted during July 2008 on the Hudson River estuary near the Tappan Zee Bridge, which is the site of some of the most serious PCB contamination in the world. Gas-phase ΣPCB concentrations measured at two heights above the water column averaged 1.1 ng m(-3), and concentrations were usually lower in the upper air sample, indicating net transport of PCBs from the water column to the air. Volatilization PCB fluxes were calculated using the modified Thornthwaite-Holzman equation. Values of friction velocity and atmospheric stability were calculated using the Aerodynamic Gradient and Eddy Correlation techniques. The PCB fluxes were corrected for changes in atmospheric stability using the atmospheric stability factor of water vapor (?(w)) calculated from empirical formulations which ranged from 1.0 to 3.2 (neutral to stable atmospheric boundary layer conditions). Vertical ΣPCB fluxes ranged from +0.5 μg m(-2) d (-1) to +13 μg m(-2) d (-1). Mono- through tri-homologues accounted for about half of ΣPCB fluxes, with tetra- through hexa-homologue accounting for the other half. This work demonstrates the utility of a micrometeorological approach to measuring the air-water exchange of organic contaminants.     

Polychlorinated biphenyl residues in food and human milk: determination of co-planar and mono-ortho substituted congeners

An analytical method is described for determining the residues of coplanar as well as mono-ortho substituted PCB congeners both exhibiting toxicological relevance, in foods of animal origin and in human milk. The unsophisticated procedure, convenient for routine analyses, includes the extraction of lipids, clean-up steps using liquid/liquid partition and column chromatography, fractionation of the congeners using HPLC on a special carbon column with an optimal gradient elution, and capillary column gas chromatography with electron capture or mass spectrometric detection. As preliminary results indicate, the low-chlorinated PCB technical products contribute more to the actual contamination of environment and foods than has been estimated so far. Obviously the co-planar congeners are accumulated during the food chain in a portion different from that found for the other congeners.     

Modeling polychlorinated biphenyl mass transfer after amendment of contaminated sediment with activated carbon

The sorption kinetics and concentration of polychlorinated biphenyls (PCBs) in historically polluted sediment is modeled to assess a remediation strategy based on in situ PCB sequestration by mixing with activated carbon (AC). We extend our evaluation of a model based on intraparticle diffusion by including a biomimetic semipermeable membrane device (SPMD) and a first-order degradation rate for the aqueous phase. The model predictions are compared with the previously reported experimental PCB concentrations in the bulk water phase and in SPMDs. The simulated scenarios comprise a marine and a freshwater sediment, four PCB congeners, two AC grain sizes, four doses of AC, and comparison with laboratory experiments for up to 540 days of AC amendment slowly mixed with sediment. The model qualitatively reproduces the observed shifts in the PCB distribution during repartitioning after AC amendment but systematically overestimates the overall effect of the treatment in reducing aqueous and SPMD concentrations of PCBs by a factor of 2-6. For our AC application in sediment, competitive sorption of the various solutes apparently requires a reduction by a factor of 16 of the literature values for the AC-water partitioning coefficient measured in pure aqueous systems. With this correction, model results and measurements agree within a factor of 3. We also discuss the impact of the nonlinearity of the AC sorption isotherm and first-order degradation in the aqueous phase. Regular mixing of the sediment accelerates the benefit of the proposed amendment substantially. But according to our scenario, after AC amendment is homogeneously mixed into the sediment and then left undisturbed, aqueous PCB concentrations tend toward the same reduction after approximately 5 or more years.     

Atmospheric concentrations and deposition of polychorinated biphenyls to the Hudson River Estuary

The first estimates of atmospheric deposition fluxes of polychlorinated biphenyls (PCBs) to the Hudson River Estuary are presented. Concentrations of PCBs were measured in air, aerosol, and precipitation at nine sites representing a variety of land-use regimes at regular intervals from October 1997 through May 2001. Highest concentrations in the gas phase were observed at urban sites such as Camden and Jersey City (sigmaPCB concentrations averaged 3250 and 1260 pg m(-3), respectively). In great portions of the state encompassing forested, coastal, and suburban environments, gas-phase sigmaPCB concentrations were essentially the same (averaging 150-220 pg m(-3)). This spatial trend suggests that atmospheric PCBs arise from highly localized, urban sources which influence atmospheric concentrations and deposition fluxes over a distance of a few tens of kilometers. Atmospheric sigmaPCB deposition fluxes (gas absorption + dry particle deposition + wet deposition) ranged from 7.3 to 340 microg m(-2) yr(-1) and increased with proximity to urban areas. While the magnitude of the fluxes increased with urbanization,the relative proportions of wet, dry, and gaseous deposition remained largely constant. Because the Hudson River Estuary is adjacent to urban areas such as Jersey City, it is subject to higher depositional fluxes of PCBs. These depositional fluxes are at least 2-10 times those estimated for the Chesapeake Bay and Lake Michigan. Inputs of PCBs to the Hudson River Estuary from the upper Hudson River and from wastewater treatment plants are 8-18 times atmospheric inputs, and volatilization of PCBs from the estuary exceeds atmospheric deposition of low molecular weight PCBs.     

Polychlorinated biphenyl residues in the golden grey mullet (Liza aurata) from Tunis Bay,Mediterranean sea (Tunisia)

Concentrations of polychlorinated biphenyls (PCBs) were determinated in the muscle tissues of mullets (Liza aurata) caught from two coastal marine areas in Tunis bay, “Raoued” and “Radès”. Twenty congeners were detected in all the fish samples analyzed, among which were 4 congeners recommended by the European Union for assessing pollution and 4 “dioxin-like” congeners. Residue levels of total PCBs ranged from 45 to 194 ng/g wet wt in the mullet from “Radès” and from 43 to 65 ng/g w wt in specimens from “Raoued”. Hexachlorobiphenyls were predominant in fishes caught from both “Raoued” and “Radès” areas, accounting for 43% and 40%, respectively. The individual PCB profiles were dominated by congeners 153 in mullet from “Raoued” and PCB 200 in fishes from “Radès”. The levels of TEQs of “dioxin-like” congeners were 3.4 pg/g w wt for fishes from “Raoued” and 2.5 pg/g w wt for specimens from “Radès”.     

Fox River voluntary sediment cleanup plan stalled

Remediation.     

Enhanced reductive dechlorination of polychlorinated biphenyl impacted sediment by bioaugmentation with a dehalorespiring bacterium

Anaerobic reductive dehalogenation of commercial PCBs such as Aroclor 1260 has a critical role of transforming highly chlorinated congeners to less chlorinated congeners that are then susceptible to aerobic degradation. The efficacy of bioaugmentation with the dehalorespiring bacterium Dehalobium chlorocoercia DF1 was tested in 2-L laboratory mesocosms containing sediment contaminated with weathered Aroclor 1260 (1.3 ppm) from Baltimore Harbor, MD. Total penta- and higher chlorinated PCBs decreased by approximately 56% (by mass) in bioaugmented mesocosms after 120 days compared with no activity observed in unamended controls. Bioaugmentation with DF-1 enhanced the dechlorination of doubly flanked chlorines and stimulated the dechlorination of single flanked chlorines as a result of an apparent synergistic effect on the indigenous population. Addition of granulated activated carbon had a slight stimulatory effect indicating that anaerobic reductive dechlorination of PCBs at low concentrations was not inhibited by a high background of inorganic carbon that could affect bioavailability. The total number of dehalorespiring bacteria was reduced by approximately half after 60 days. However, a steady state level was maintained that was greater than the indigenous population of putative dehalorespiring bacteria in untreated sediments and DF1 was maintained within the indigenous population after 120 days. The results of this study demonstrate that bioaugmentation with dehalorespiring bacteria has a stimulatory effect on the dechlorination of weathered PCBs and supports the feasibility of using in situ bioaugmentation as an environmentally less invasive and lower cost alternate to dredging for treatment of PCB impacted sediments.     

Simultaneous release of metals and sulfide in lacustrine sediment

A single DGT (diffusive gradient in thin films) probe that could measure metals and sulfide simultaneously and at the same location was deployed in the surface sediment of a productive lake (Esthwaite Water). It contained a layer of AgI that binds sulfide overlying a layer of chelating resin that binds metals. Analysis for sulfide in two dimensions showed local sources of sulfide, 1-5 mm in diameter, at 8-11 cm depth within the sediment. A transect of trace metals measured at 100-microm intervals through the largest sulfide "hot spot" demonstrated concomitant release of Fe, Mn, Cu, Ni, and Co. Substantial supersaturation with respect to metal sulfides was observed for Fe and Co at the site of metal generation, but at a distance of less than 1 mm, solution concentrations were consistent with equilibration with amorphous FeS and CoS phases. Simple mass balance calculations were consistent with Fe being supplied from reductive dissolution of its oxides and with sulfide being supplied from reduction of sulfate. The observed concentrations of Cu, Ni, Co, and Mn could be accounted for by their release from iron oxides without invoking Mn reduction. The metals are removed rapidly (approximately 1 min) at the edge of the hot spot. These first observations of the simultaneous release of trace metals and sulfide are consistent with the known removal of metals by formation of their insoluble sulfides if the in situ kinetics of metal sulfide formation is on this time scale. The coproduction of reduced Fe and S suggests that iron- and sulfate-reducing bacteria may exist together in the same localized zone of actively decomposing organic matter.