Mobilization Of Polychlorinated Biphenyls Research Articles

Plants radically change the mobility of PCBs in soil: Role of different species and soil conditions

The mobility of Polychlorinated Biphenyls (PCBs) in soil cultivated with different plant species was evaluated by means of a column experiment to investigate the specific plant influence on PCB environmental fate and the potential for leaching. The soil was collected at a National Relevance Site for remediation located in Northern Italy (SIN Brescia-Caffaro) and underwent a rhizoremediation treatment for 18 months with different plant species (Festuca arundinacea, Cucurbita pepo ssp pepo and Medicago sativa). The same but unplanted soil was also considered as control for comparison. The columns were leached with tap water and PCB concentrations were measured in the leachate after 7 days of soil/water contact. Soil previously cultivated with different plant species exhibited statistically different behavior in terms of chemical leaching among the different fractions. Total PCB bulk concentrations ranged from 24 to 219 ng/L. Leachate samples were enriched in tetra- to hepta-PCBs. While PCB concentrations in the dissolved phases varied within a factor of 2 between controls and treatments, PCB associated to particulate organic carbon (POC) differed by more than one order of magnitude. More specifically, Medicago sativa enriched the soil with POC doubling PCB leaching with respect to the other plant species and the unplanted controls.

Polychlorinated biphenyl behavior in soils amended with biosolids

Assessment of the mobility of polychlorinated biphenyls (PCBs) in soils, amended with biosolids at a rate of 30 Mg ha −1, was performed using an incubation process and leaching columns. The incubation process was carried out for 0, 30, and 60 d under field capacity conditions at 25 °C. The mobility of PCBs was assessed using solutions of 0.5 mol L −1 CaCl 2 and 25 mg L −1 linear alkylbenzenes sulfonate (LAS). Ultrasound-assisted pressurized solvent extraction (US-PSE) was utilized for compound separation from the solid matrix. Compounds were determined by gas chromatography coupled to mass spectrometry. The biosolids, containing a background PCB concentration about 300 μg kg −1, were spiked with the analytes at 300 mg kg −1 to obtain a clearer determination of their behavior when the biosolid was mixed with soil. In biosolid-amended soils, an increase was observed in the extractability of PCBs with increasing incubation time, which may be attributed to organic matter breakdown. The leaching column study showed that CaCl 2 was unable to mobilize the PCBs from the biosolid to the soil, whereas LAS mobilized these compounds within the time scale implicit in the experiment (30 d). The most mobilized congeners in the columns corresponded to those with the greatest molecular weight (hexa- and heptachlorinated), probably due to the higher hydrophobicity of these compounds. Results indicate that the presence of important concentrations of LAS in biosolids could mobilize PCBs from soil to the freatic level.

Local Sources of Polychlorinated Biphenyls (PCB) in Russian and Norwegian Settlements on Spitsbergen Island, Norway

Samples of surface soil, flaking paint, concrete, transformer oils, and small capacitors were collected from the three largest coal-mining settlements on Spitsbergen—Barentsburg (Russian), Pyramiden (Russian), and Longyearbyen (Norwegian)—to study the role of potential local sources of polychlorinated biphenyls (PCB) in the arctic areas (78° N). Median concentrations of PCB7 in soil from Barentsburg and Pyramiden were 0.268 and 0.172 mg/kg, respectively, with a maximum concentration of 28.7 mg/kg. High concentrations found in paint (3520 mg/kg) and small capacitors (114,000 mg/kg) indicated that these two are the main sources of local PCB contamination. Only traces of PCB were found in the Longyearbyen samples compared to the results from the other two settlements. Large amounts of building refuse, electrical waste, and scrap metals constitute major pollution sources in Barentsburg and Pyramiden. Weathering and general decay facilitate the mobilization of PCB from these sources to the local soil, which consequently is readily available for fluvial and eolian transport to the more vulnerable marine environment.

Mobilization of PCBs from blubber to blood in northern elephant seals ( Mirounga angustirostris) during the post-weaning fast

Northern elephant seals ( Mirounga angustirostris) are characterized by extended fasting during which they rely entirely on their own body reserves. During fasts, lipids are mobilized from blubber to match the energy requirements of the animal. This transfer frees toxic fat-soluble pollutants into the blood circulation, which may exert adverse health effects, especially in young and developing animals. We investigated the dynamics of mobilization of polychlorinated biphenyls (PCBs) from the blubber of northern elephant seal pups during the post-weaning fast. Longitudinal samples of blubber and serum were collected from free-ranging animals throughout the fast at Año Nuevo, California. Blubber biopsies were separated into inner and outer layers. The PCB profiles of blubber and serum consisted mainly of penta- (PCB-101, -110, -118), hexa- (PCB-138, -153) and hepta- (PCB-180, -183, -187) chlorobiphenyls, which accounted for almost 90% of the total PCB burden. Total PCB concentrations in inner blubber increased significantly between early and late fasting (563.6 ± 162.0 μg/kg lipids at early versus 911.6 ± 513.1 μg/kg lipids at late fasting) whereas they remained fairly constant in outer blubber (572.6 ± 134.8 μg/kg lipids at early versus 659.2 ± 158.8 μg/kg lipids at late fasting). A corresponding rise of PCB concentrations was observed in serum during the second half of the fast (3.8 ± 1.1 μg/l serum at early versus 7.2 ± 0.9 μg/l at late fasting). The longitudinal changes in circulating total PCBs could not be explained by the changes in serum lipid fractions (cholesterol, phospholipids, triacylglycerols and free fatty acids). The increases in total PCB concentrations in inner blubber and serum were more pronounced in leaner animals, which suggests that they might be more at risk to potential toxic effects.

Budget calculations for polychlorinated biphenyls (PCBs) in the Northern Hemisphere — a single-box approach

Numerous studies show that the environmental concentrations of PCBs have been decreasing since the production and use of PCBs in most industrialised countries was banned in the 1970s. However, most of these studies have been conducted close to historical sources. The few studies conducted in remote locations detect no trend of decreasing concentrations over the past 20–30 years. These observations suggest that PCBs may be removed more slowly from the environment, when viewed from a global or hemispheric perspective. The present study estimates the mass fluxes of individual PCB congeners in the Northern Hemisphere in order to elucidate the most important removal processes and the rate of decrease one may expect with complete cessation of emissions. Atmospheric reaction lifetimes, open-ocean settling fluxes and the pools and mobility of PCBs in the terrestrial environment are shown to be crucial parameters. However, the calculations identify important gaps of knowledge regarding predictions of environmental half-lives of PCBs. The results suggest that highly chlorinated congeners such as PCB 153 and 180 may be persistent in the global environment with annual rates of decrease of less than 1%. The compiled environmental data also highlight large differences between the different PCB congeners. Although this paper is based on more than 800 PCB measurements it should be considered a starting point for further research aiming to quantify the global fate of toxic and persistent organic substances such as the PCBs.

Mobilization of PAH and PCB from contaminated soil using a digestive tract model

Environmental contaminants are mainly incorporated by ingestion. In general only those contaminants mobilized by the digestive juices are available for absorption in the digestive tract, while pollutants still fixed to indigestible particles leave the body without any effect. To evaluate the different health risks arising from the ingestion of individual types of polluted soil or other materials, we developed an in vitro test system which simulates the transition of pollutants from contaminated materials into digestive juices by means of a standardized artificial gastro-intestinal model. The test system simulates the influence of the acidic environment of the stomach (gastric model) followed by the neutral or slightly alkaline environment of the small intestine (gastro-intestinal model). Investigations on small amounts of polluted soil, sewage sludge, asphalt, metal scrap and blast sand showed that the mobilization of polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) by artificial gastric juice reaches 3% up to 22% of the pollutant concentration introduced into the test system. Elutions of the contaminated materials under gastric and subsequently under intestinal conditions with bile concentrations of 3 g/1 resulted in PAH- and PCB-mobilizations in the range of 5% up to 40%. The degree of mobilization depends considerably on supplementary food material added to the test system. Lyophilized milk increased the fraction of mobilized PAH and PCB to 40%–85%. Application of the test system on 22 different contaminated soils showed that the mobilization of PAH under gastro-intestinal conditions with the addition of lyophilized milk ranged from 7% up to 95%, and the mobilization of PCB ranged from 32% up to 83%. This indicates that the test system can be a useful tool for evaluating the individual health risks arising from polluted soil or other materials.

Growth of an estuarinePseudomonas sp. on polychlorinated biphenyl

In the course of a study of the microbial degradation of polychlorinated biphenyls (PCB), 16 cultures, representing 5 genera of bacteria, were isolated. APseudomonas sp. was found to degrade mixtures of PCB (Aroclor 1254) and pure isomers, i.e., hexachlorobiphenyl (HCB). Degradation was found to be variable, depending on length of incubation, purity, and degree of chlorination of the biphenyl molecule. In addition to apparent degradation of PCB, it was observed that PCB stimulated growth and oxygen uptake. Bioaccumulation of PCB residues was suggested since(14)-Clabeled material derived from(14)C-PCB accumulated on or in the bacterial cells. The potential degradation and utilization of PCB by microorganisms suggests that this may be an important mechanism for removal or mobilization of PCB into food chains in the estuarine environment.

Studies on a Calculation Method for Polychlorinated Biphenyl (PCB) Isomers

For the quantitative analysis of the environmental contamination of polychlorinated biphenyls (PCBs), the authors reported several methods, i. e. gas chromatographic (GC) pattern method, comparative relative response method, GC-MCD (microcoulometric detector) and mass fragmentography methods.By means of conventional GC separation (OV-1, 2mm×1.5m column) we separated approx. only 25 peaks, in which more than two components were suspected to be contained.So this makes it difficult to qualify the residue of PCBs biodegradated in the environment.Recently Jensen et al. reported more effective GC column separation by the use of 5m Apiezon (purified) column and identified each peak to synthesized reference substances (almost 60 components) of PCB isomers.It was certified that there was no difference in patterns between Clophen series and Japanese Kaneclors by GC analysis. Applying this technique for Japanese products (KC300-600), the authors determined chlorine numbers by GC-MS analysis and chlorobiphenyl contents (%) in each peak by means of comparative relative response method.From these data, we clarified the difference of PCB components in blood between a healthy man and a Yusho patient. It is uncleared yet whether it depends on PCB itself or polychlorinated dibenzofuran (PCDF).The application of this calculation method makes it possible not only to measure the absolute quantity of individual peaks, but also to elucidate the mobility of PCBs in the animal tissue.