title: Spatial and Temporal Trends of Polyhalogenated Carbazoles in Sediments of Upper Great Lakes: Insights into Their Origin.
abstract: Polyhalogenated carbazoles (PHCZs) have been increasingly detected in the environment. Their similarities in chemical structure with legacy pollutants and their potential toxicity have caused increasing concern. In this work, 112 Ponar grab and 28 core sediment samples were collected from Lakes Michigan, Superior, and Huron, and a total of 26 PHCZs were analyzed along with unsubstituted carbazole using gas chromatography coupled with single- or triple-quadrupole mass spectrometry. Our results show that the total accumulation of PHCZs in the sediments of the upper Great Lakes is >3000 tonnes, orders of magnitude greater than those of polychlorinated biphenyls (PCBs) and decabromodiphenyl ether (BDE209). The 27 individual analytes differ in spatial distribution and temporal trend. Our results showed that PHCZs with substitution patterns of -Br2-5, -Cl1-2Br2-4, or having iodine, were more abundant in sediment of Lake Michigan deposited before 1900 than those deposited more recently, implying a natural origin. Some "emerging" PHCZs have been increasingly deposited into the sediment in recent decades, and deserve further environmental monitoring and research. Other PHCZs with low halogen substitution may form from in situ dehalogenation of PHCZs having more halogens. Anthropogenic sources of PHCZs may exist, particularly for the emerging and low molecular mass congeners.
authors.forename: Jiehong
authors.initials: J
authors.lastname: Guo
authors.forename: Zhuona
authors.initials: Z
authors.lastname: Li
authors.forename: Prabha
authors.initials: P
authors.lastname: Ranasinghe
authors.forename: Solidea
authors.initials: S
authors.lastname: Bonina
authors.forename: Soheil
authors.initials: S
authors.lastname: Hosseini
authors.forename: Margaret B
authors.identifier: 0000-0002-9114-0230
authors.initials: MB
authors.lastname: Corcoran
authors.forename: Colin
authors.identifier: 0000-0002-9462-1531
authors.initials: C
authors.lastname: Smalley
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Rockne
authors.forename: Neil C
authors.initials: NC
authors.lastname: Sturchio
authors.affiliation: Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5C5, Canada.
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
authors.forename: An
authors.initials: A
authors.lastname: Li
mesh_terms: D002227:Carbazoles; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D006114:Great Lakes Region; D060106:Lakes / Q000737:chemistry*; D011078:Polychlorinated Biphenyls; D014874:Water Pollutants, Chemical
chemical_list: D002227:Carbazoles; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls