Rate of volatilization

Volatilization of trichloroethylene from soil is slower than it is from water but more rapid than that of many other volatile organic compounds (Park et al. 1988). This study found that an average of 37% of the applied trichloroethylene was volatilized 168 hours after treatment at 12°C, and 45% was volatilized at 21°C. This study also concluded that soil t> pe had no effect on rate of volatilization, although this may simply be a reflection of the fact that the differences between soils used in the study, particularly in organic carbon content, were not very great. 

The mechanical rototilling method involves turning over soils to a depth of about 0.30 m (1 ft) below the surface to increase the rate of volatilization. Following treatment, the topsoil is moved to a nearby pile and rototilling is performed on the next 0.30 m (1 ft) of soil. The effectiveness of this mechanical rototilling method is highly dependent on weather conditions. High-speed rototillers and soil shredders can enhance the rate of volatilization. 

Mackay, D. (1981) Environmental and laboratory rates of volatilization of toxic chemicals from water. In Hazardous Assessment of Chemicals, Current Development. Volume 1, Academic Press. 

Qm be the evolution rate of volatile material (mass/time). 

Mass rate of volatile material resulting from evolution = Qm,... 

Equation 3-12 is used to estimate the vaporization rate of volatile from an open vessel or from a spill of liquid. 

It follows that rfVc is the volumetric rate of bulk vapor being displaced from the drum (vol-ume/time). Also, if pv is the density of the volatile vapor, rfVcpv is the mass rate of volatile displaced from the container (mass/time). Using the ideal gas law,... 

Volatilization loss can be a significant dissipation pathway for organics applied to land. The rate of dissipation of organics is governed by the vapour pressure of the compound, and on soil and environmental conditions. Losses to the atmosphere may take place immediately if the organics are applied at the soil surface if the organics are incorporated with the surface soil layer or injected below surface, the rate of volatilization loss is significantly reduced and is dependent on the rate of transport to the soil surface. As an example, 90% of Heptachlor applied on the soil surface may be lost in 2-7 days, in comparison to a 7% loss in 167 days when incorporated to 7.5cm [14]. 

Based on its very small calculated Henry s law constant of 4.0xl07-5.4xl0"7 atm-m3/mol (see Table 3-2) and its strong adsorption to sediment particles, endrin would be expected to partition very little from water into air (Thomas 1990). The half-life for volatilization of endrin from a model river 1 meter deep, flowing 1 meter per second, with a wind speed of 3 meters per second, was estimated to be 9.6 days whereas, a half-life of greater than 4 years has been estimated for volatilization of endrin from a model pond (Howard 1991). Adsorption of endrin to sediment may reduce the rate of volatilization from water. 

ISO 6179, Rubber, vulcanized or thermoplastic - Rubber sheets and rubber-coated fabrics - Determination of transmission rate of volatile liquids (gravimetric technique), 1998. 

Consideration of the air permeability of the soil, rate of biological degradation, and rate of volatilization of contaminants is important in the design of a bioventilation system. Reactions that take place in the soil are concentration, temperature, and time... 

The transport of disulfoton from water to air can occur due to volatilization. Compounds with a Henry s law constant (H) of <10 atm-m /mol volatilize slowly from water (Thomas 1990). Therefore, disulfoton, with an H value of 2.17x10" atm-m /mol (Domine et al. 1992), will volatilize slowly from water. The rate of volatilization increases as the water temperature and ambient air flow rate increases and decreases as the rate of adsorption on sediment and suspended solids increases (Dragan and Carpov 1987). The estimated gas- exchange half-life for disulfoton volatilization from the Rhine River at an average depth of 5 meters at 11 °C was 900 days (Wanner et al. ] 989). The estimated volatilization half-life of an aqueous suspension of microcapsules containing disulfoton at 20 °C with still air was >90 days (Dragan and Carpov 1987). 

Environmental Fate. The fate of bromomethane in the environment is dominated by rapid evaporation into air, where it is quite stable (EPA 1986b). The rates of volatilization from soil and water have been studied and are known with reasonable precision (although such rates are typically site-specific) (Jury et al. 1984 Lyman et al. 1982). The rates of breakdown by hydrolysis, reaction with hydroxyl radical, and direct photolysis in the stratosphere have also been estimated (Castro and Belser 1981 Davis et al. 1976 Robbins 1976). Further studies to improve the accuracy of available rate constants for these processes would be helpful, but do not appear to be essential in understanding the basic behavior of bromomethane in the environment. 

ISO 1663 1999 Rigid cellular plastics - Determination of water vapour transmission properties ISO 2556 1974 Plastics - Determination of the gas transmission rate of films and thin sheets under atmospheric pressure - Manometric method ISO 6179 1998 Rubber, vulcanized or thermoplastic - Rubber sheets and rubber-coated fabrics - Determination of transmission rate of volatile liquids (gravimetric technique)... 

The work reported in this paper was part of a larger project whose principal objective was to measure the rate of volatilization of the herbicide trifluralin to the atmosphere from a field soil after surface application and incorporation to a depth of 7.5cm by cultivation with a disc harrow. In this experiment it was necessary to measure as accurately as possible the amount of the trifluralin residue in the soil on several days during the growing season and to calculate the rate of disappearance of the... 

Multiple publications (Pankow et al. 1997 Ingebrethsen et al. 2001 Pankow et al. 2003 Watson et al. 2004) have discussed measuring free-base nicotine directly, addressed the importance of free-base nicotine delivery, and examined the chemical properties of nicotine in cigarette smoke as an important determinant of the effective delivery and bioavailability of nicotine from cigarettes. Pankow et al. (1997) examined how ammonia influences nicotine delivery in tobacco smoke and concluded that conversion of nicotine to the free-base form could be facilitated by ammonia. Based on a theoretical treatment, Pankow et al. (1997) concluded that, under certain circumstances, up to 40% of the nicotine could be available as the volatile free-base form. These authors also concluded that the rate of volatilization was more rapid than that previously measured by Lewis et al. (1995) using denuder technology to examine the properties of mainstream cigarette smoke. 

The rate of volatilization will also increase with an increase in temperature, ten Hulscher et al. (1992) studied the temperature dependence of Henry s law constants for three chlorobenzenes, three chlorinated biphenyls, and six polynuclear aromatic hydrocarbons. They observed that within the temperature range of 10 to 55 °C, Henry s law corrstant doubled for every 10 °C increase in temperature. This temperature relationship should be corrsidered when assessing the role of chemical volatilization from large surface water bodies whose temperatines are generally higher than those typically observed in groimdwater. 

Mackay and Wolkoff (1973) estimated an evaporation half-life of 10.1 d from a surface water body that is 25 °C and 1 m deep. Singmaster (1975) studied the rate of volatilization of aldrin (1 ng/L) in a flask filled with 0.9 L water obtained from California. The flask was gently stirred and an air stream was passed over the air-water interface. He reported volatilization half-lives of 0.38, 0.59, and 0.60 h from San Francisco Bay, American River, and Sacramento River, respectively. 

Biological. Methanococcus thermolithotrophicus, Methanococcus deltae, and Methanobacterium thermoautotrophicum metabolized 1,2-dichloroethane releasing methane and ethylene (Belay and Daniels, 1987). 1,2-Dichloroethane showed slow to moderate biodegradative activity with concomitant rate of volatilization in a static-culture flask-screening test (settled domestic wastewater inoculum) conducted at 25 °C. At concentrations of 5 and 10 mg/L, percent losses after 4 wk of incubation were 63 and 53, respectively. At a substrate concentration of 5 mg/L, 27% was lost due to volatilization after 10 d (Tabak et al., 1981). 

In a static-culture-flask screening test, 1,1,2-trichloroethane was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. Biodegradative activity was slow to moderate, concomitant with a significant rate of volatilization (Tabak et al., 1981). 

Podoll, R.T., Jaber, H.M., and Mill, T. Tetrachlorodioxin rates of volatilization and photolysis in the environment. Environ. 

Spencer and Cliath (1969, 1973) studied the effect of organic matter and clay content on vapor density of various pesticides. In general, they found that subsurface organic matter content and partition coefficients are of primary importance in describing the rate of volatilization for compounds having a high affinity for organic matter. 

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