Potential risk reduction of Aroclor 1254 by microbial dechlorination in anaerobic Grasse River sediment microcosms

Abstract

Aroclor 1254 was the second most produced commercial PCB mixture and is found in soils, sediments and sewage throughout the globe. This commercial PCB mixture is considered particularly toxic because of the relatively high concentrations of congeners with dioxin-like properties. The potential for risk reduction by microbial reductive dechlorination of Aroclor 1254 (A1254) was investigated in sediment microcosms from Grasse River (GR), Massena, NY. The specificity of A1254 dechlorination was doubly- and singly-flanked chlorines in meta positions and to a less extent doubly-flanked para chlorines of 2345-substituted chlorobiphenyl rings. The average dechlorination rate of A1254 was 0.0153 Cl/biphenyl/day, and dechlorination rates of single congeners ranged between 0.001 and 0.0074 Cl/biphenyl/day. Potential risk associated with A1254 based on the toxic equivalency factors of the dioxin-like congeners was reduced by 83%. Additional potential risk associated with bioaccumulation in fish was reduced by 35% based on biota-sediment accumulation factor estimates for all detected congeners. Finally, the dechlorination end-products were tri- and tetra-chlorobiphenyls with unflanked chlorines, all of which are susceptible to further degradation by aerobic microorganisms. The combined results indicate that microbial reductive dechlorination has the potential for reducing risk associated with toxicity and bioaccumulation in fish in sites contaminated with A1254.

Effects of Ferric Oxyhydroxide on Anaerobic Microbial Dechlorination of Polychlorinated Biphenyls in Hudson and Grasse River Sediment Microcosms: Dechlorination Extent, Preferences, Ortho Removal, and Its Enhancement

“…Also, an easy approach to selectively enhance ortho dechlorination was provided. Most recently, a study in Grasse River sediment microcosms focusing on Aroclor 1254 detoxification used dioxin-like PCB 105 as a test congener, in which PCB 28 and PCB 25 were also the dominant dechlorination products after 180 days ( Kaya et al, 2017 ). Therefore, the ortho dechlorination preference with the potential for complete dechlorination of mono- ortho PCB congeners, including some dioxin-like congeners, might be crucial for further potential risk reduction in Grasse sediment.…”

“…General conclusions are difficult to draw due to the variety of experimental conditions considered. In some cases, researchers add the carbon sources at the initiation of incubation ( Pulliam Holoman et al, 1998 ; Fagervold et al, 2011 ; Ho and Liu, 2012 ; Kaya et al, 2017 ), while others add carbon periodically during incubation ( Alder et al, 1993 ; Zhen et al, 2014 ; Matturro et al, 2016 ). No study has considered long-term incubation of PCB spiked sediment microcosms prior to carbon addition.…”

Determination of Aroclor 1254 in Water Samples Using Polystyrene–Divinylbenzene Solid-Phase Extraction and Gas Chromatography

“…Indeed, PCBs have been detected at 141.09 ng/l in the International Anzali Wetland [3], and at concentrations ranging from 0.59 to 12.38 ng/g (dry weight) in sediments from Songhua River, China [4]. Aroclor 1254, the second most produced commercial PCB mixture [5], is particularly persistent due to the dozens of highly chlorinated congeners in the mix [6]. Research on Aroclor 1254 has increased in recent years [6][7][8] due to its hepatic, renal, thyroidal, developmental and reproductive toxicity in animals [9].…”

“…Aroclor 1254, the second most produced commercial PCB mixture [5], is particularly persistent due to the dozens of highly chlorinated congeners in the mix [6]. Research on Aroclor 1254 has increased in recent years [6][7][8] due to its hepatic, renal, thyroidal, developmental and reproductive toxicity in animals [9]. Thus, the detection of Aroclor 1254 in the environment has become very important, and a sensitive analytical method is necessary for the detection of Aroclor 1254 in water samples.…”

Aerobic Biodegradation of OCDD by P. Mendocina NSYSU: Effectiveness and Gene Inducement Studies

“…Aerobic microorganisms can co-metabolize chlorinated organic compounds, indicating that addition of primary substrates is required (Jeon et al, 2016;Stella et al, 2015;Urbaniak, 2013). The tri-and tetra-chlorobiphenyls with unflanked chlorines, all of which are susceptible to further degradation by aerobic microorganisms, less-chlorinated dioxins are susceptible to partial degradation via aerobic cometabolism, and monochlorinated congeners could be used as the carbon sources for the bacterial metabolism under certain conditions (Bastviken, 2013;Kaya et al, 2017;Peng et al, 2012).…”