Partitioning Of Polychlorinated Biphenyls Research Articles

Air–soil exchange of semi-volatile organic compounds (SOCs) in the UK

This paper describes (1) a field experiment in which the air–soil exchanges of a range of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured and (2) the use of the fugacity quotient concept to provide information on the equilibrium partitioning of PCBs, PAHs and polychlorinated dibenzo- p-dioxins (PCDDs) between the air and soil in the UK. In the field experiment aluminium foil trays containing thin layers (∼5 mm) of spiked and unspiked soil were placed under custom-built shelters at a meteorological station and exposed to outdoor air for periods of up to 9 months (281 days). Soil and air samples were taken periodically throughout the 9-month period and analysed for PCBs and PAHs. The results from the experiment showed that the PCBs and PAHs in the soils were moving towards equilibrium partitioning conditions. Statisitically significant losses of the majority of PCB/PAH compounds occurred in the spiked soils. Volatilisation was hypothesised to be the dominant loss mechanism. The PCBs in the unspiked soils were close to equilibrium with the air at the start of the experiment and there was, therefore, little change in their concentrations during the 9 months of exposure. For the PAHs there was also only a small change in the concentrations in the unspiked soils during the experiment, although there was a statistically significant loss of acenaphthene, fluorene and phenanthrene. Soil/air fugacity quotients were calculated using the air and soil concentrations measured in the field experiment and also using our database of UK air and soil survey data. The calculated soil/air fugacity quotients, together with the findings of the field experiment, indicate that the soil and air are close to equilibrium for PCBs. However, this study provides evidence that the soil may now be a source of some lighter weight PAHs to the atmosphere, whereas it appears to be still acting as a long-term sink for the heavier weight PAHs and the PCDDs.

Adsorption versus Absorption of Polychlorinated Biphenyls onto Solid-Phase Microextraction Coatings

Absorption-based polymeric solid-phase microextraction (SPME) fibers with poly(dimethylsiloxane) (PDMS) coatings were used to determine the partitioning coefficients of polychlorinated biphenyls (PCBs) between the sorptive fiber coatings and water. Previous models showing very good correlations between octanol-water partitioning coefficients (K(ow)) and absorption-based fiber-water partitioning coefficients (K(dv)) for low-molecular-weight analytes failed to predict K(dv) values for PCBs. In fact, K(dv) values for PCBs were 1-7 orders of magnitude lower than those predicted by K(ow) and actually showed a strong negative correlation between K(ow) and K(dv) for higher molecular weight analytes (MW >∼200). K(dv) values obtained using PDMS fibers with 7- and 100-μm coatings also disagree, demonstrating that K(dv) cannot be used to describe the partitioning behavior of PCBs between PDMS and water. However, when PCB partitioning coefficients were calculated on the basis of surface area (K(ds)), the K(ds) values obtained using 7- and 100-μm PDMS fibers agreed reasonably well, demonstrating that surface adsorption is the primary mechanism controlling PCB (and likely other higher molecular weight solutes) partitioning from water to SPME sorbents.

Gas-Particle Partitioning of PCBs and PAHs in the Chicago Urban and Adjacent Coastal Atmosphere: States of Equilibrium

Simultaneous air samples were taken in Chicago and over southern Lake Michigan as part of the AEOLOS Project (Atmospheric Exchange Over Lakes and Oceans). Gas and particle phase concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and total suspended particles (TSP) were measured over 12 h periods during July, 1994, and January, 1995. Partitioning of PCBs and PAHs between gas and particle phases was well correlated with the subcooled liquid vapor pressure (p°L) for individual samples, but the relationship differed among samples. For all but a few of the samples the slopes of the log Kp vs log p°L lines were statistically greater than −1. Other investigators who have found similar results have concluded that the PCBs/PAHs were not at equilibrium; however, other factors indicate that the PCBs and PAHs in the Chicago/Lake Michigan atmosphere are at equilibrium. Slopes of the regressions of log Kp vs log p°L from samples of continental background origin, and therefore assumed to have had sufficient atmospheric residence times to reach equilibrium, are among the shallowest measured (−0.70 to −0.53 and −0.16 to −0.56 for PAHs and PCBs, respectively). One pair of samples where the air mass is believed to have been sampled twice, once in the urban area and again ∼3.4 h downwind, shows no difference in partitioning. PCBs and PAHs measured in Chicago and over Lake Michigan were apparently at equilibrium between the gas and particle phases. A slope of −1 in the regression of log Kp vs log p°L is not necessary to describe equilibrium partitioning. Differences in particulate matter may be responsible for the shallow slopes observed.

Levels and patterns of polychlorinated biphenyls in water collected from the San Francisco Bay and Estuary, 1993-95

Levels of polychlorinated biphenyls (PCBs) were measured in water (particulate and dissolved fractions) from various locations in the San Francisco Estuary over the years 1993–1995 during six cruises. Geometric mean levels of ΣPCBs (sum of 58 congeners) in the combined dissolved and particulate fractions for the six cruises ranged from 340 ng/L to 1600 ng/L. Comparing this data to previous data from 1975 and 1980 does not reveal any significant temporal trends. The partitioning of PCBs into the dissolved/particulate fraction were correlated with total suspended solids. Using the novel chemometric technique of polytopic vector analysis (PVA) on the data from cruise 8 (April 1995), five separate PCB congener fingerprints were identified in the data. Fingerprint 1 (or end-member 1) represents a slightly degraded source of Aroclor® 1260 in the northern part of the South Bay; the end-member (EM) 2 fingerprint is related to a predominantly Aroclor® 1260 source that has been moderately-severely degraded present in the highest proportions in the Pacific Ocean sample; EM-3 is interpreted as a slightly degraded Aroclor® 1242:1254:1260 mixture in southern San Pablo Bay; end-member 4 is interpreted as a moderately degraded source of multiple Aroclors® and is present in the river samples; EM-5 is interpreted as a slightly degraded Aroclor® 1254/1260 mixture present in northern San Pablo Bay and the South Bay.

Field Measurements of PCB Partitioning between Water and Planktonic Organisms: Influence of Growth, Particle Size, and Solute−Solvent Interactions

Due to long equilibration times, growth of planktonic organisms significantly dilutes cell concentrations of adsorbed highly hydrophobic organic compounds (HOCs). Behavior of polychlorinated biphenyls (PCBs) in field samples of 0.2−2, 2−25, and >100 μm particle size fractions confirmed this. The in-situ log Koc values showed a near linear relationship with hydrophobicity (log Kow) with a slope of 1.2 for the 0.2−2 μm size fraction, whereas the in-situ log Koc values remained within 1 log unit throughout the entire log Kow interval for the 2−25 μm size fraction. In the largest size fraction, there was a weak positive relationship between log Koc and log Kow with a linear regression slope of 0.28. The results imply that equilibrium concentrations in planktonic organisms cannot be used in food chain modeling. Observed high equilibrium log Koc values relative to log Kow values are discussed in terms of solute−solvent interactions in the octanol−water system as opposed to the organic carbon−water system in the field.

Micellar Solubility and Micelle/Water Partitioning of Polychlorinated Biphenyls in Solutions of Sodium Dodecyl Sulfate

An experimental method is described to determine enhanced solubilities and partitioning of extreme hydrophobics in micellar systems. Experimental data are presented on the enhanced solubilities, chemical activity coefficients and micelle/water partition coefficients of 14 polychlorinated biphenyls (PCBs) in solutions of sodium dodecyl sulfate (SDS) below and above the critical micellar concentration (cmc). The method described in this study proves to be highly accurate. Solubility data obtained are in accordance with data from other studies. Experimental micelle/water partition coefficients turn out to be sufficiently accurate to distinguish between isomers. Solubilities of PCBs in micellar solutions above the cmc depend linearly on SDS concentration, and the solubility enhancement is 2-4 orders of magnitude. PCB partition coefficients (log K mw ) are independent of SDS concentrations in this study and ranged from 4.61 to 6.62. The partitioning behavior of the pertinent extremely hydrophobics between the aqueous and micellar phases is not completely comparable with simple organic solvent/water systems, and the linear correlation between log K ow and log K mw no longer holds.

Solubility and micelle-water partitioning of polychlorinated biphenyls in solutions of bile salt micelles

Experimental data are presented on the enhanced solubilities and micelle/water partition coefficients of 14 polychlorinated biphenyls (PCBs) in solutions of the bile salts sodium taurocholate (TC) and sodium taurodeoxycholate (TDC) below and above the critical micellar concentration (CMC). Solubilities of PCBs in micellar solutions above the CMC depend linearly on bile salt concentration and the solubility enhancement is up to four orders of magnitude. PCB partition coefficients (log K mw) are independent of bile salt concentrations and are systematically higher in solutions of TDC than in solutions of TC, ranging from 4.26 to 6.24 and from 3.89 to 5.89 respectively. The partitioning behavior of the pertinent extremely hydrophobics between the aqueous and micellar phases is not completely comparable with simple organic solvent/water systems and the correlation between log K ow and log K mw is non-linear.

Partitioning of PCBs in the muscle and reproductive tissues of paddlefish, Polyodon spathula, at the Falls of the Ohio River.

The paddlefish, Polyodon spathula, is a primitive fish characterized by a predominantly cartilaginous skeleton, a virtually scaleless body, and a rostrum or paddle nearly one-third of the body length. At the Falls of the Ohio River near Louisville, KY, paddlefish are harvested for their roe used to produce domestic caviar. The persistence of this small but intensive fishery for the roe of female paddlefish may be slowing or even reversing the recovery of populations in the Falls area of the Ohio River. Residues of toxic substances harmful to humans are being detected in many fishes in the Ohio River. Organochlorine pollutants such as chlordane and polychlorinated biphenyls (PCBs) are being detected at levels as high as those of 10 yr ago. Recent data from studies conducted in the Missouri River on PCB levels in the tissues of the shovelnose sturgeon, a species closely related to the paddlefish, indicate that the concentration of PCBs in sturgeon roe is several times that of concentrations in flesh. This study examines the PCB content of the roe of paddlefish at the location of a commercial fishery. The study investigated the partitioning of PCBs into the muscle and reproductive tissues of paddlefish, considered possible correlationsmore » between PCB concentration and age and percent lipid, and looked at the existence of any differences in mean PCB concentrations between male and female paddlefish. 17 refs., 1 fig., 1 tab.« less

Changes in plasma lipoprotein metabolism in chicks in response to polychlorinated biphenyls (PCBs)

The results of the present study strongly suggest that the hypertriglyceridaemia in chicks treated with Aroclor 1254 is a result of reduction in VLDL clearance rather than an increase in rate of VLDL secretion. The decrease in post-heparin LPL activity responsible for reduced VLDL clearance may be mediated by cytokines produced by chronic activation of the immune system.

Polychlorinated biphenyls partitioning in waters from river, filtration plant and wastewater plant: the case for paris (france)

The partitioning of PCBs between the aqueous and particulate phases was studied from January to December 1987 in the Seine river at Paris, as well as the quality of the drinking water produced in the Orly plant. At the same time the concentrations in the influent and the effluent of the wastewater plant of Achéres were measured. Mean concentration in the Seine river at Paris was 115 ng 1 −1 in 1986, and 130 ng l −1 at Orly (upstream Paris) in 1987, which corresponds to the “heavily polluted” class of the WHO. Evolution of PCB concentration and speciation in waters were studied following the hydrological cycle, the suspended matter content, its mineralogy and particulate organic carbon content. At variance with the commonly accepted opinion, about three quarters of PCBs (73%) in the Seine were carried by the aqueous phase, with no notable influence of the hydrological cycle: suspended matters were insufficient (25 mg l −1 mean value) to adsorb the majority of PCBs and their adsorption capacity varied in opposition with their concentration. Therefore 67% of PCBs of the source water were not retained by the treatment plant, and the mean concentration of the drinking water was 79 ng l −1. However in most samples the concentration of PCBs was below the 100 ng 1 −1 norm of the EEC. In wastewaters the proportion of “particulate” PCBs was only 55%, probably due to their dissolution in greases and oils. The removal rate varied from 18 to 83% (mean 54%). Mean concentrations were 650 in wastewaters and 280 ng 1 −1 at the outlet of the secondary settling basin. The annual estimated flux was 95 mg per capita.