title: Global distribution of linear and cyclic volatile methyl siloxanes in air.
abstract: The global distribution of linear and cyclic volatile methyl silxoanes (VMS) was investigated at 20 sites worldwide, including 5 locations in the Arctic, using sorbent-impregnated polyurethane foam (SIP) disk passive air samplers. Cyclic VMS are currently being considered for regulation because they are high production volume chemicals that are potentially persistent, bioaccumulative, and toxic. Linear and cyclic VMS (including L3, L4, L5, D3, D4, D5, and D6) were analyzed for in air at all urban, background, and Arctic sites. Concentrations of D3 and D4 are significantly correlated, as are D5 and D6, which suggests different sources for these two pairs of compounds. Elevated concentrations of D3 and D4 on the West coast of North America and at high elevation sites suggest these sites are influenced by trans-Pacific transport, while D5 and D6 have elevated concentrations in urban areas, which is most likely due to personal care product use. Measured concentrations of D5 were compared to modeled concentrations generated using both the Danish Eulerian Hemispheric Model (DEHM) and the Berkeley-Trent Global Contaminant Fate Model (BETR Global). The correlation coefficients (r) between the measured and modeled results were 0.73 and 0.58 for the DEHM and BETR models, respectively. Agreement between measurements and models indicate that the sources, transport pathways, and sinks of D5 in the global atmosphere are fairly well understood.
authors: Environment Canada , Science and Technology Branch, 4905 Dufferin Street, Toronto, ON M3H 5T4, Canada.
authors: Susie
authors: S
authors: Genualdi
authors: Tom
authors: T
authors: Harner
authors: Yu
authors: Y
authors: Cheng
authors: Matthew
authors: M
authors: Macleod
authors: Kaj M
authors: KM
authors: Hansen
authors: Roger
authors: R
authors: van Egmond
authors: Mahiba
authors: M
authors: Shoeib
authors: Sum Chi
authors: SC
authors: Lee
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D000397:Air Pollution / Q000706:statistics & numerical data; D001272:Atmosphere / Q000737:chemistry; D004784:Environmental Monitoring; D008956:Models, Chemical; D012833:Siloxanes / Q000032:analysis* / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D012833:Siloxanes; D055549:Volatile Organic Compounds