Atmospheric Fate of Volatile Methyl Siloxanes

McLachlan, Michael S.

doi:10.1007/698_2018_371

Cited by 3 publications

(6 citation statements)

References 42 publications

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“…35 Variation in solar irradiation clearly has the most influence on seasonal variability of cVMS concentrations at higher latitudes, because a higher solar irradiance increases the concentration of photooxidants such as the hydroxyl radical. As oxidation by photooxidants is the major process known to remove cVMSs from the atmosphere, 4 one could anticipate that seasonal differences in concentrations would be related to the seasonal variation in the day length. The average day length during the deployments followed the order of winter < fall < spring < summer.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 It is also well established from measurements in the remote atmosphere 3 that cVMSs are globally dispersed. Although the bulk of the results, as compiled by McLachlan, 4 suggest that cVMSs do not undergo atmospheric deposition in notable amounts, some researchers have suggested otherwise. 5 Resolving this question is key to establishing whether cVMSs possess the potential for long-range transport in the sense of the Stockholm Convention.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seasonal and latitudinal variability in the atmospheric concentrations of cyclic volatile methyl siloxanes in the Northern Hemisphere

Wania

Warner

McLachlan

et al. 2023

Environ. Sci.: Processes Impacts

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seasonal and latitudinal variability in the atmospheric concentrations of cyclic volatile methyl siloxanes in the Northern Hemisphere

Wania

Warner

McLachlan

et al. 2023

Environ. Sci.: Processes Impacts

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“…They are very volatile and will not associate with atmospheric particles to any significant extent . It is clearly established that cVMS can be widely dispersed as vapors in the atmosphere, especially in winter . Should the cVMS also become a precedent, then not only involatile chemicals but any chemical with an atmospheric half-life longer than 2 days and less volatile than D4 would have to be considered to fulfill the LRET screening criterion (Figure ).…”

Section: Recent Nominations Stretch the Notion Of What Constitutes A Popmentioning

confidence: 99%

“…cVMS are proposed for nomination although there is considerable evidence that airborne cVMS cannot be deposited from the atmosphere in notable amounts . The absence of notable deposition makes it difficult to establish the likelihood of adverse effects as a result of LRET, as the potential for human and wildlife exposure to atmospherically transported cVMS is miniscule .…”

Section: Recent Nominations Stretch the Notion Of What Constitutes A Popmentioning

confidence: 99%

The Stockholm Convention at a Crossroads: Questionable Nominations and Inadequate Compliance Threaten Its Acceptance and Utility

Wania,

McLachlan

2024

Environ. Sci. Technol.

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Twenty years since coming into force, the Stockholm Convention has become a "living" global agreement that has allowed for the addition of substances that are likely, as a result of their long-range environmental transport (LRET), to lead to significant adverse effects. The recent listing of the phenolic benzotriazole UV-328 in Annex A and a draft nomination of three cyclic volatile methylsiloxanes (cVMS) for Annex B draw attention to the fact that many chemicals are subject to LRET and that this can lead to questionable nominations. The nomination of UV-328 and the draft nomination of cVMS also raise the spectre of regrettable substitutions. At the same time, atmospheric monitoring across the globe reveals that environmental releases of several unintentionally produced POPs listed in Annex C, such as hexachlorobenzene and hexachlorobutadiene, are continuing unabated, highlighting shortcomings in the enforcement of the minimum measures required under Article 5. There is also no evidence of efforts to substitute a chemical whose use has been known for three decades to unintentionally produce polychlorinated biphenyls. These developments need to be rectified to safeguard the long-term viability and acceptance of a global treaty of undeniable importance.

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“…The overall atmospheric fate of VMS can be simplified to 3 complex processes: emissions, advection, and reaction with OH radicals (McLachlan, 2018). Since D5 is present in the atmosphere almost exclusively in the gas phase, the latter process is predominant in its degradation.…”

Section: Modeling Strategy and Parameterizationmentioning

confidence: 99%

Characterizing the regional concentrations and seasonality of the emerging pollutant decamethylcyclopentasiloxane (D5) using a WRF+CHIMERE modeling approach

Jiménez‐Guerrero

Ratola

2021

Elementa: Science of the Anthropocene

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In this study, the results from two passive air sampling campaigns (winter and summer) performed previously in 8 different urban sites allowed the inclusion of the volatile methyl siloxane (VMS) D5 in a chemistry transport model (WRF+CHIMERE modeling system) to assess its performance in describing the concentrations and seasonal distribution of this emergent contaminant in a domain covering the western Iberian Peninsula. The model estimations were evaluated using the available field-based data, and the WRF+CHIMERE approach showed, in general, errors under 50% for all sampling sites and seasons, with a slight tendency to underestimations of D5 concentrations when using the lowest emission factor among those selected from the literature and to very large overestimations when using the highest emission factor available. The greatest errors are found for remote sampling points (substantial overestimations of the models at Midões, by even a factor of 3) and for coastal ones (where population and therefore emissions exhibit strong seasonality). The results also indicate that the chemical sinks by OH degradation play a negligible role on the ground-level concentrations of D5 at the scale of the investigated domain, with average contributions under 0.5%. Despite the lack of data regarding D5 emissions in the area, which led to the assumption of emission rates taken from other countries (and a constant population in the domain), the results of this first study are excellent and highlight the skill of WRF+CHIMERE in reproducing D5 concentrations. Indeed, the nature of the proposed modeling tool is helpful for understanding the processes conditioning the present and future behavior of contaminants like D5. Moreover, the model is bound to allow the future inclusion of D5 (and other VMSs) in regulatory scenarios, since restrictions on the use of these chemicals have just started to be introduced.

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Atmospheric Fate of Volatile Methyl Siloxanes

Cited by 3 publications

References 42 publications

Seasonal and latitudinal variability in the atmospheric concentrations of cyclic volatile methyl siloxanes in the Northern Hemisphere

Seasonal and latitudinal variability in the atmospheric concentrations of cyclic volatile methyl siloxanes in the Northern Hemisphere

The Stockholm Convention at a Crossroads: Questionable Nominations and Inadequate Compliance Threaten Its Acceptance and Utility

Characterizing the regional concentrations and seasonality of the emerging pollutant decamethylcyclopentasiloxane (D5) using a WRF+CHIMERE modeling approach

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