Journal article
Modeled Global Impacts of Chlorine Oxidation and Temperature Dependence on the Atmospheric Lifetime and Concentrations of Volatile Methyl Siloxanes
Environmental science & technology, Vol.60(1), pp.873-886
01/13/2026
DOI: 10.1021/acs.est.5c08897
PMCID: PMC12810245
PMID: 41406986
Appears in UI Libraries Support Open Access
Abstract
Volatile methyl siloxanes (VMS) are high production volume chemicals found in a wide range of consumer items such as personal care products. VMS have attracted scrutiny due to long-range environmental transport (LRET) concerns. However, their emissions, lifetimes, and concentrations remain uncertain, in part because of limitations in previous atmospheric modeling. Herein, we describe the global modeling of siloxanes: D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane), and D6 (dodecamethylcyclohexasiloxane) in the Community Earth System Model (CESM2-SLH) using an updated chemical mechanism that includes chlorine radical oxidation and temperature-dependent reaction rates. With these previously unconsidered factors, we predicted VMS lifetimes ranging between 2.7 and 6.7 days and annual average D5 near-surface concentrations as high as 4.5 ng m
in the remote Arctic and 160 ng m
in urban areas. These lifetimes and the degree of LRET were significantly lower than previously reported. OH remained the largest loss pathway, although it decreased at low temperatures relative to previous modeling. The temperature-induced lifetime increase was outweighed by the previously unconsidered chlorine oxidation channel. Model results and previous measurements agreed relatively well but exhibited negative normalized biases (-0.55 to -0.88), particularly in urban areas not well-resolved at global model resolution, and for passive sampler measurements.
Details
- Title: Subtitle
- Modeled Global Impacts of Chlorine Oxidation and Temperature Dependence on the Atmospheric Lifetime and Concentrations of Volatile Methyl Siloxanes
- Creators
- Christopher E Brunet - University of IowaSaeideh Mohammadi - University of IowaBehrooz Roozitalab - University of IowaNora K Gibson - University of IowaRafael P Fernandez - Instituto Interdisciplinario de Ciencias BásicasAlfonso Saiz-Lopez - Instituto de Química Física Blas CabreraKeri C Hornbuckle - University of Iowa, IIHR--Hydroscience and EngineeringCharles O Stanier - University of Iowa, Chemical and Biochemical Engineering
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.60(1), pp.873-886
- DOI
- 10.1021/acs.est.5c08897
- PMID
- 41406986
- PMCID
- PMC12810245
- NLM abbreviation
- Environ Sci Technol
- ISSN
- 1520-5851
- eISSN
- 1520-5851
- Publisher
- American Chemical Society
- Grant note
- National Institute of Environmental Health Sciences: P42ES013661 NASA: ACCDAM program award # 80NSSC21K1439 Division of Atmospheric and Geospace Sciences: 2028764 Argentine Ministry of Science: REMATE IF-2023-85161983-APN
This study was supported by the National Science Foundation (grant: 2028764) and the National Institute of Environmental Health Sciences of the National Institutes of Health (NIEHS/NIH) under award number P42ES013661. B.R. thanks financial support from the NASA ACCDAM program (Award # 80NSSC21K1439). R.P.F thanks financial support from the Argentine Ministry of Science (REMATE IF-2023-85161983-APN). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the National Science Foundation. We thank the members of the organosilicon research team not listed as coauthors: Elizabeth Stone, Eleanor Browne, Rachel Marek, Josie Welker, Jeewani Meepage, Hanalei Lewine, and Jim Hall for their advice in developing this study and their previous research which informed this modeling project. We also thank lab director Chris Knutson for his technical and compliance support of our facilities and equipment and Brian Westra for his help in the publication of the data associated with this work. The CESM project is supported primarily by the U.S. National Science Foundation (NSF). Computing and data storage resources, including the Derecho supercomputer (doi:10.5065/qx9a-pg09) and Casper system (https://ncar.pub/casper), were provided by the Computational and Information Systems Laboratory (CISL) at the NSF National Center for Atmospheric Research. We thank all the scientists, software engineers, and administrators who contributed to the development of CESM.
- Language
- English
- Electronic publication date
- 12/17/2025
- Date published
- 01/13/2026
- Academic Unit
- Civil and Environmental Engineering; Occupational and Environmental Health; IIHR--Hydroscience and Engineering; Interdisciplinary Graduate Program in Human Toxicology; Chemical and Biochemical Engineering
- Record Identifier
- 9985092371902771
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