Toxic gas clouds: Effects and implications of dry deposition on concentration

Jonsson, Lage; Karlsson, Edvard; Thaning, Lennart

doi:10.1016/j.jhazmat.2005.04.018

Cited by 12 publications

(8 citation statements)

References 41 publications

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“…2). This conclusion suggests that the prior analyses of Jonsson et al [12] and the HGSYS-TEM deposition module (both of which neglect the reduction in dense-gas turbulence) may significantly overestimate the losses to the earth's surface. However due to the importance of deposition to environmental objects (which was not included in the prior analyses), the current analysis supports the prior conclusions that deposition is most important for stable, low-wind conditions in which the plume is confined to be relatively low to the ground.…”

Section: Comparison To Prior Workmentioning

confidence: 97%

“…The higher loss rates near the surface are offset by the lofting of hazardous material above the deposition zone (which can then mix back down to the surface further downwind). For example, deposition reduced a passive-gas cloud concentration by 50% at 6 km downwind from the release for a case similar to the illustrative plume discussed above [12]. 9 For context, the cloud concentration in the illustrative dense-gas 9 Deposition to environmental objects was not considered in [12].…”

Section: Impact Of Neglected Factorsmentioning

confidence: 99%

“…We are aware of only three analyses that have directly considered dense-gas deposition effects: Jonsson et al [12]; the deposition module within the HGSYSTEM dense-gas model [6]; and the greenbelt design guidance provided by Kahn and Abbasi [13] (and references therein). None of these cases include the well-known suppression of vertical turbulence 1 within dense-gases [14,15], which would significantly reduce the actual deposition rate relative that assumed in these studies.…”

Section: Introductionmentioning

confidence: 99%

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The role of deposition in limiting the hazard extent of dense-gas plumes

Dillon

2009

Journal of Hazardous Materials

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Accidents that involve large (multi-ton) releases of toxic industrial chemicals and form dense-gas clouds often yield far fewer fatalities, casualties and environmental effects than standard assessment and emergency response models predict. This modeling study, which considers both dense-gas turbulence suppression and deposition to environmental objects (e.g. buildings), demonstrates that dry deposition to environmental objects may play a significant role in reducing the distance at which adverse impacts occur--particularly under low-wind, stable atmospheric conditions which are often considered to be the worst-case scenario for these types of releases. The degree to which the released chemical sticks to (or reacts with) environmental surfaces is likely a key parameter controlling hazard extents. In all modeled cases, the deposition to vertical surfaces of environmental objects (e.g. building walls) was more efficient in reducing atmospheric chemical concentrations than deposition to the earth's surface. This study suggests that (1) hazard extents may vary widely by release environment (e.g. grasslands vs. suburbia) and release conditions (e.g. sunlight or humidity may change the rate at which chemicals react with a surface) and (2) greenbelts (or similar structures) may dramatically reduce the impacts of large-scale releases. While these results are demonstrated to be qualitatively consistent with the downwind extent of vegetation damage in two chlorine releases, critical knowledge gaps exist and this study provides recommendations for additional experimental studies.

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Section: Comparison To Prior Workmentioning

confidence: 97%

Section: Impact Of Neglected Factorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of deposition in limiting the hazard extent of dense-gas plumes

Dillon

2009

Journal of Hazardous Materials

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“…In addition, note that the effective rate of Cl − appearance is initially fast and slows as [Cl 2 ]t is increased. This demonstrates that a constant deposition velocity for Cl 2 cannot be universally applied to large-scale releases, though constant deposition velocities were used in prior modeling studies [11,20,21]. Second, the inset to Fig.…”

Section: Chloride Measurementsmentioning

confidence: 99%

Cl2 deposition on soil matrices

Hearn¹,

Eichler

Hare³

et al. 2012

Journal of Hazardous Materials

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“…Estos experimentos concluyen que los modelos aseguran resultados cercanos a los reales. Actualmente los modelos de dispersión de gases densos son utilizados para mostrar el comportamiento de nubes de gases tóxicos (Dandrieux-Bony et al, 2005;Jonsson et al, 2005;Sklavounos y Rigas, 2004;Yegnan et al, 2002).…”

Section: Introduccionunclassified

Determinación de los Factores del Peor Escenario en la Emisión de Gases Tóxicos

2009

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*autor a quien debe ser dirigida la correspondencia ResumenSe analizan modelos de dispersión convencionales para determinar los factores que incrementan el riesgo de muerte durante una emisión de gases tóxicos. El análisis se basa en la determinación de la concentración del gas tóxico en función de la distancia con respecto al punto de emisión. Así, el daño sobre una persona depende de esta concentración y del tiempo de contacto. Se muestra que el viento es un factor importante en la determinación del peor escenario. Además, las características del terreno modifican de manera importante la dispersión del gas. Los resultados indican que el peor escenario se tiene con viento en calma y con condición atmosférica estable en terreno rural. Los modelos de Pasquill-Gifford en dispersión pasiva y Germeles en dispersión de gas denso tienden a sobreestimar la concentración lo cual permite hacer estimaciones más seguras. Palabras clave: dispersión de gases, factores de dispersión, modelos de dispersión, velocidad del viento, condición atmosférica Determination of the Factors for the Worst Scenario in Toxic Gas Release AbstractConventional dispersion models are analyzed to determine the factors that increase the risk of death during gas toxic release. The analysis is based in determining the toxic gas concentration as a function of the distance from the emission point. Thus, the injury in a person would depend on this concentration and the exposure time. It is shown here that the wind is an important factor to define the worst scenario. In addition, terrain characteristics substantially modify the gas dispersion. The results suggest that the worst scenario appears with calm wind and with stable atmospheric condition on rural terrain. The Pasquill-Gifford model in passive dispersion and Germeles model in gas dense dispersion tend to overestimate the concentration yielding safer estimations.

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Toxic gas clouds: Effects and implications of dry deposition on concentration

Cited by 12 publications

References 41 publications

The role of deposition in limiting the hazard extent of dense-gas plumes

The role of deposition in limiting the hazard extent of dense-gas plumes

Cl2 deposition on soil matrices

Determinación de los Factores del Peor Escenario en la Emisión de Gases Tóxicos

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