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Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
PCBs are mixtures of chlorinated organic compounds called congeners (ATSDR 2021g). A congener is a related compound or compounds in a specific chemical family. There are a large number of congeners, with approximately 209 present in PCB mixtures (USEPA 2021f). PCBs were produced synthetically through electrophilic chlorination of a biphenyl molecule with chlorine gas. In the United States, PCBs are commonly known under the trade name aroclors. Aroclors are mixtures of PCBs distinguished by a four-digit numbering system. The first two digits refer to the number of carbon atoms in a PCB molecule, and the second two digits indicate the percentage of chlorine by mass in the mixture (USEPA 2021f). For example, PCB aroclor 1254 means the mixture contains 12 carbon atoms and is 54% chlorine by weight (ATSDR 2021g). As the degree of chlorination increases, the melting point increases and the vapor pressure and solubility decrease. Figure 3.7 shows the basic structure of a PCB molecule.
Chemistry of Contaminants
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
PCBs are mixtures of chlorinated organic compounds called congeners (ATSDR 2021g). A congener is a related compound or compounds in a specific chemical family. There are a large number of congeners, with approximately 209 present in PCB mixtures (USEPA 2021f). PCBs were produced synthetically through electrophilic chlorination of a biphenyl molecule with chlorine gas. In the United States, PCBs are commonly known under the trade name aroclors. Aroclors are mixtures of PCBs distinguished by a four-digit numbering system. The first two digits refer to the number of carbon atoms in a PCB molecule, and the second two digits indicate the percentage of chlorine by mass in the mixture (USEPA 2021f). For example, PCB aroclor 1254 means the mixture contains 12 carbon atoms and is 54% chlorine by weight (ATSDR 2021g). As the degree of chlorination increases, the melting point increases and the vapor pressure and solubility decrease. Figure 3.6 shows the basic structure of a PCB molecule.
Contamination
Published in Daniel T. Rogers, Urban Watersheds, 2020
PCBs are mixtures of chlorinated organic compounds called congeners (ATSDR 2019g). A congener is a related compound or compounds in a specific chemical family. There are a large number of congeners, with approximately 209 present in PCB mixtures (USEPA 2019f). PCBs were produced synthetically through electrophilic chlorination of a biphenyl molecule with chlorine gas. In the United States, PCBs are commonly known under the trade name aroclors. Aroclors are mixtures of PCBs distinguished by a four-digit numbering system. The first two digits refer to the number of carbon atoms in a PCB molecule, and the second two digits indicate the percentage of chlorine by mass in the mixture (USEPA 2019f). For example, PCB aroclor 1254 means the mixture contains 12 carbon atoms and is 54% chlorine by weight (ATSDR 2019g). As the degree of chlorination increases, the melting point increases and the vapor pressure and solubility decrease. Common PCB aroclors are listed in Table 7.3 (USEPA 2019f). Figure 7.7 shows the basic structure of a PCB molecule.
What should we know when choosing feather, blood, egg or preen oil as biological samples for contaminants detection? A non-lethal approach to bird sampling for PCBs, OCPs, PBDEs and PFASs
Published in Critical Reviews in Environmental Science and Technology, 2023
Studies performed by Zhao et al. (2019) showed that the major pesticides accumulated in eggshells were chlordanes and HCHs, possibly from soil. Although they found bioaccumulation potential to be higher for feathers than eggshells, the latter were still proven to be useful for predicting POPs pollution in the study area (Zhao et al., 2019). Matache et al. (2016) used chorioallantoid membrane to determine several OCPs. The prevalent contributors to the total organochlorine were DDT congeners, and gamma-HCH was the main congener from the HCH isomers. Also, concentrations were mostly higher than those from feathers, suggesting significant maternal transfer of pollutants to embryo. However, the difference was species dependent; for example, in Anas sp. the OC concentration was up to ten times higher in eggshells, whilst in a top predator, the seagull (Larus argentatus), feathers had higher concentrations of OCPs (Table 3).
New advance in the application of compound-specific isotope analysis (CSIA) in identifying sources, transformation mechanisms and metabolism of brominated organic compounds
Published in Critical Reviews in Environmental Science and Technology, 2022
Jukun Xiong, Guiying Li, Taicheng An
Based on the structure-activity relationship in fish with respect to debrominating PBDE congeners (Roberts et al., 2011), and the same isotope signature of BDE-100 in fish and in diet. It can be concluded that fish were directly exposed to BDE-100 through their diet. The δ13C values of BDE-99 in tiger barb were a little higher compared to DE71, and the discriminations were smaller than the total analytical uncertainty of 0.5‰. This demonstrates that no obvious isotope fractionation took place. This is because of the masking effect created by large amount of BDE-99 in tiger barb, which did not debrominate or dilute the other 11 carbons that did not participate in the reaction. However, δ13C values of BDE-99 decreased as trophic level increased (from −26.25‰ in DE71 to −27.76‰ in oscar fish and to −27.33‰ in tiger barb). Carbon isotope fractionation of BDE-47 in these fish species was a result of the debromination of highly brominated congeners, e.g., BDE-99 and 2,2′,3,4,4′-pentabromodiphenyl ether (BDE-85). A similar variation in δ13C values was also seen for BDE-28. The δ13C values of BDE-49 experienced no significant differences among DE71 within three fish species. Compared with δ13C values of PBDE congeners, the conservation of δ13C values of BDE-49 among fish species indicated that BDE-49 was not the intermediate of highly PBDE congeners.
Regional-temporal Trends and Risk Assessment of Polychlorinated Biphenyls (PCBs) in Olive Lands in Bursa, Turkey
Published in Soil and Sediment Contamination: An International Journal, 2022
Seyma Nur Erkul, Gizem Eker Sanli
The relationships between concentration with temperature, DM, and pH for each congener (43 congeners) were examined by correlation analysis. It was determined that there was a significant relationship between concentration, temperature, and DM in the same direction for PCB#89/101 (r = 0.42, p = .024 and r = 0.40, p = .019, respectively). For PCB#126 and PCB#170/190 there was a significant inverse relationship (r = −0.36, p = .021), and a significant relationship in the same direction between concentration, and DM measurements (r = 0.29, p = .038). For PCB#156/171/202, PCB#172 and PCB#135/144 species, the concentration measurements had a significant relationship with the temperature measurements in the same direction (r = 0.29, p = .037; r = 0.30, p = .049; and r = 0.33, p = .043, respectively).