Atmospheric Degradation of Organic Substances

Klpffer, Walter; Wagner, Burkhard O.

doi:10.1002/9783527611638

Cited by 22 publications

(4 citation statements)

References 2 publications

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“…that a plot of ln( i cVMS , 0 / i cVMS , t ) versus ln( i cyclohexane,0 / i cyclohexane, t ) constructed using signal intensities collected at time t corresponding to each individual scan cycle of the mass spectrometer is linear with a slope of k cVMS / k cyclohexane . This calculation method has the advantage that it is valid if the OH concentration is not constant during the experiment and that covariant measurement errors of the cVMS and cyclohexane signal intensities will cancel out . Constructing plots according to Eq.…”

Section: Methodsmentioning

confidence: 99%

Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

Safron

Strandell

Kierkegaard

et al. 2015

Int J of Chemical Kinetics

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Reaction with hydroxyl radicals (OH) is the major pathway for removal of cyclic volatile methyl siloxanes (cVMS) from air. We present new measurements of second‐order rate constants for reactions of the cVMS octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) with OH determined at temperatures between 313 and 353 K. Our measurements were made using the method of relative rates with cyclohexane as a reference substance and were conducted in a 140‐mL gas‐phase reaction chamber with online mass spectrometry analysis. When extrapolated to 298 K, our measured reaction rate constants of D4 and D5 with the OH radical are 1.9 × 10−12 (95% confidence interval (CI): (1.7–2.2) × 10−12) and 2.6 × 10−12 (CI: (2.3–2.9) × 10−12) cm3 molecule−1 s−1, respectively, which are 1.9× and 1.7× faster than previous measurements. Our measured rate constant for D6 is 2.8 × 10−12 (CI: (2.5–3.2) × 10−12) cm3 molecule−1 s−1 and to our knowledge there are no comparable laboratory measurements in the literature. Reaction rates for D5 were 33% higher than for D4 (CI: 30–37%), whereas the rates for D6 were only 8% higher than for D5 (CI: 5–10%). The activation energies of the reactions of D4, D5, and D6 with OH were not statistically different and had a value of 4300 ± 2800 J/mol.

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Section: Methodsmentioning

confidence: 99%

Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

Safron

Strandell

Kierkegaard

et al. 2015

Int J of Chemical Kinetics

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“…Moreover, microorganisms preferentially decompose carbohydrates and protein‐like substances (Hansen et al., 2016), especially HMW components (Xu & Guo, 2018). Photodegradation may dominate the chemical composition of aging aerosol, mainly triggered by solar radiation in the atmosphere, compared to a relatively small degree in the pedosphere and hydrosphere, such as water surface (Walter & Wagner, 2007). In addition, the river sampling site is located in the estuary of the Yangtze River, which has complex hydrodynamic conditions.…”

Section: Resultsmentioning

confidence: 99%

Elucidating Dissolved Organic Sulfur in the Coastal Environment by Improved Online Liquid Chromatography Coupled to FT‐ICR Mass Spectrometry

Chen,

Qi,

Xie

et al. 2024

JGR Oceans

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Dissolved organic sulfur (DOS) is an important component of dissolved organic matter (DOM) and widely exists at the land‐atmosphere interface. However, the characterization of DOS at the molecular level among different environmental samples in coastal regions has not been sufficiently focused. Here, we investigated DOS in aerosol, rainwater, and river water samples in Shanghai using an improved method–online liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC‐FT‐ICR MS). This system is utilized to separate DOS from complicated environmental matrices. The results showed that the average relative abundance of DOS in three different environmental media (aerosol, rainwater, and river water samples) accounted for 16.8%, 21.9% and 13.1%, respectively. The common molecules of the three mediums in coastal Shanghai contain an abundance of aromatic and aliphatic DOS of anthropogenic origin in addition to the natural sources of sea spray. Notably, results from a new structural classification scheme for DOS demonstrate that anthropogenic sulfonates and their derivatives are widely spread, although their molecular diversity in different medium was recorded due to complex environmental conditions and diverse sources.

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“…The available experimental data for k OH have been compiled by Klopffer and Wagner [36]; this compilation shows that for most semivolatile organic compounds, k OH has not been measured. Therefore, estimation methods, such as the Atmospheric Oxidation Program Software (AOPWIN) [37] (http://www.epa.gov/oppt/exposure/pubs/episuite.htm), have to be used for SOCs.…”

Section: Environmental Fate Models and Drivers Of Lrtmentioning

confidence: 99%

“…In addition, the second‐order rate constants obtained with the AOPWIN method may be too high (see above). As pointed out by Klöpffer and Wagner [36], the advent of quantitative structure–activity relationship methods in the 1990s has caused a sharp reduction in experimental studies. This is unfortunate, because further experimental studies are crucial to broaden the empirical basis of methods such as AOPWIN, and measurements of OH reaction rate constants of complex substances are highly desirable.…”

Section: Environmental Fate Models and Drivers Of Lrtmentioning

confidence: 99%

Long‐range transport of organic chemicals in the environment

Scheringer

2009

Enviro Toxic and Chemistry

106

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Abstract-The long-range transport (LRT) of organic chemicals in the environment is reviewed, with particular focus on the role of environmental fate and transport models and the relationship between model results and field data. Results from generic multimedia box models, spatially resolved multimedia box models, and atmospheric transport models are highlighted, including conceptual investigations of cold-trap effect and global fractionation as well as results for particular chemicals, such as hexachlorocyclohexanes, DDT, polychlorinated biphenyls, perfluoroocctanoic acid, and polybrominated diphenyl ethers. Comparison of model results to field data shows that in many cases environmental fate models provide a good description of the distribution dynamics observed in the field, with deviations between measured and modeled concentrations around a factor of five. Sorption to atmospheric aerosols as a key process influencing the LRT of semivolatile organic chemicals (SOCs) is discussed, and the need for more measurements of the aerosol-air partitioning of SOCs and of the reactivity of particle-bound chemicals is pointed out. Key findings from field campaigns measuring legacy persistent organic pollutants (POPs) as well as new POPs are summarized. Finally, the relationship between science and politics in the field of POPs is addressed. Research into the LRT of organic chemicals has always occurred in interaction with political activities aiming to reduce the emissions of POPs. Since the late 1990s, the Stockholm Convention and the Aarhus Protocol on POPs have formed an important political context for research concerning POPs; the implementation of these international treaties creates a demand for ongoing research into the LRT of organic chemicals.

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Atmospheric Degradation of Organic Substances

Cited by 22 publications

References 2 publications

Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

Elucidating Dissolved Organic Sulfur in the Coastal Environment by Improved Online Liquid Chromatography Coupled to FT‐ICR Mass Spectrometry

Long‐range transport of organic chemicals in the environment

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