Modeling the transport of 2,3,7,8‐TCDD and other low volatility chemicals in soils

Freeman, Raymond A.; Schroy, Jerry M.

doi:10.1002/ep.670050110

Cited by 19 publications

(6 citation statements)

References 16 publications

(3 reference statements)

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“…Although TCDD can persist in soil for decades, rain and wind induced erosion [41] or leaching to underlying soil horizons [42] can lead to a small amount of TCDD being lost from the soil. However, very little of dioxin is likely to leach from the soil profile into shallow groundwater.…”

Section: Fate Of Agent Orange and Dioxin Tcdd In Soilmentioning

confidence: 99%

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

Olson¹,

Morton²

2019

OJSS

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The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C 8 H 6 Cl 2 O 3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C 8 H 5 Cl 3 O 3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C 12 H 4 Cl 4 O 2 ) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems; however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa

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Section: Fate Of Agent Orange and Dioxin Tcdd In Soilmentioning

confidence: 99%

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

Olson¹,

Morton²

2019

OJSS

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“…PCDD/Fs are highly adsorbed to soil and are considered persistent and non-leachable (Freeman and Schroy, 1986;Yanders et al, 1989). However, because movement of PCDD/Fs through soil can be enhanced under the presence of organic phases as a free phase such as wood-preserving oil.…”

Section: Fate Behavior and Persistence Of Pcdd/fs In Soilsmentioning

confidence: 99%

Nature and Fate of Dioxin in Soil Environment

Park¹,

Kim²,

Lee³

et al. 2011

Korean Journal of Soil Science and Fertilizer

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The chlorinated dioxins and furans have attracted considerable scientific and public concern because of their environmental persistence and super-toxicity through the foodchain. Recent dioxin scandals in several military bases have also contributed to a higher awareness on the side of food consumers as well as foodwaste combustion. However, there is continuing uncertainty over the relative importance of different sources of dioxins and furans to the soil environment. In difference to those awareness there is a main influence of potential soil contamination on the dioxin contents in groundwater. It is, therefore, important to provide a sound scientific framework and basis by which to evaluate the significance of the presence of dioxin in soils. Consequently, we have to identify the characteristics and nature of dioxin released into the soil environment, especially in agricultural aspect.

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“…In winter, represented by the 1°C temperature, evaporation is an insignificant pathway for the loss of 2,3,7,8-TCDD from surfaces, but in the warmer months evaporation is a significant pathway. Vaporization appears to be the mechanism of the long-term loss of TCDD from surface soils in Arkansas [1], Missouri [10J and Florida [11]. present, the value can go as low as urfaces due to various physical and chemical tion 7.…”

Section: Reaction and Evaporation Half-lifementioning

confidence: 99%

“…Equation 11 is used to calculate the distribution of TCDD between air and soil. Table 2 contains calculated values of K* for four temperature values which span the range of winter and summer soil surface conditions.…”

Section: Reaction and Evaporation Half-lifementioning

confidence: 99%

“…Based on data of the partial pressure of pesticides in and on damp soils, Thibodeaux [5] developed the following relationship to estimate K* for chemicals on such surfaces: K* = 1.46E6 p/Ti ocS-443 (11) where T is temperature in K, p is chemical pure component vapor pressure, mm. Hg, to is the fraction organic matter in the soil.…”

Section: Half-life Of Reaction and Evaporationmentioning

confidence: 99%

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A Fate and Transport Model for 2,3,7,8-tetrachlorodibenzo-p-dioxin in Fly Ash on Soil and Urban Surfaces

Thibodeaux¹,

Lipsky²

1985

Hazardous Waste and Hazardous Materials

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Quantities of particle-bound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) that are emitted from elevated stacks during the burning of municipal solid waste settle onto nearby soil and urban surfaces. The quantity and concentration emitted is small, however due to the potential hazard of this very toxic substance means are needed to estimate steady-state concentrations on surfaces. A fate and transport model was developed to quantify the mechanisms known to dissipate TCDD from surfaces. These mechanisms include resuspension by wind, run-off by water, evaporation into air, photochemical reaction and bioturbation.A transient model was formulated, but the use of constant rates (yearly average) yields a simple algorithm for the TCDD concentration in the growing dust layer. The analytical solution reveals that the TCDD concentration in the dust layer is independent of time and that neither the wind driven particle resuspension rate nor the water run-off rate is needed to yield numerical results. Published rate data on ash-fall, dust-fall, reaction and evaporation along with bioturbation parameters are used to make quantitative estimates of annual average TCDD concentrations on soil and urban surfaces for a Brooklyn, New York site. For a stack emitting ash containing TCDD of concentration 8 ng/g calculated concentrations in surface dust ranged from a high of 0.5 pg/g to a low of 10 fg/g.

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Modeling the transport of 2,3,7,8‐TCDD and other low volatility chemicals in soils

Cited by 19 publications

References 16 publications

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots

Nature and Fate of Dioxin in Soil Environment

A Fate and Transport Model for 2,3,7,8-tetrachlorodibenzo-p-dioxin in Fly Ash on Soil and Urban Surfaces

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