Pollutants SVOC

The principal PIC for penta and penta-treated wood would include volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), dioxins and furans, as well as SOj, COj, NO, and HCl. Penta would be expected to have undergone a very high destruction efficiency (DRE) during the fire (> 99.99%). Among the VOC emissions, the following chemicals likely contributed to air pollution problems benzene, bromobenzene, chloromethane, 1,3-butadiene, iodomethane, acetone, chloroform, and 1,2-dichloroethane. 

Wilke, O., )ann, O. and Brodner, D. (2003) VOC and SVOC contribution of papers for hardcopy devices to indoor air pollution. Proceedings of the 7th International Conference Energy-Efficient Healthy Buildings, Singapore, Vol. 1, pp. 289-94. 

Many persistent organic pollutants (POPs) are semivolatile organic compounds (SVOCs) having vapour pressures (see Box 4.14) between 10 and 10 7Pa. At these vapour pressures SVOCs can evaporate (volatilize) from soil, water or vegetation into the atmosphere. However, as vapour pressure is temperature dependent (see Box 4.14), it follows that at lower temperatures (lower vapour pressures)... 

Indoor air measurements are often carried out on air polluting substances. However, the determination of the VOC and SVOC noxious emission situation is only the first stage in respect of achieving an effective reduction in emissions. Consequently the question must be raised regarding the specific emission sources and their contribution to the total pollution as a function of indoor concentration and climate influences such as temperature, humidity and air exchange. This is demonstrated in Fig. 1 for the example of a building product. 

The majority of research on lAQ sink effects has focused on vapor-phase organic compounds. These gases are often divided into two categories VOCs and semivolatile organic compounds (SVOCs). Much of the remainder of this chapter will deal with sorption phenomena associated with VOCs and SVOCs. However, other indoor pollutants that interact with indoor surfaces are also important. 

The use of dynamic, flow-through test chambers is common in the study of emissions from sources of indoor air pollution [39]. They are also widely used in the study of indoor sinks. Some of the earlier work on sinks examined the surfaces of the test chambers themselves and showed that chamber sink effects can be important [21]. Researchers routinely evaluate test chamber systems for sink effects [34,40]. A recent paper on the measurement of SVOC emissions showed how the chamber sink effect can be exploited [41]. In this study, SVOCs adsorbed on chamber walls were removed by heating, flushed out, and quantified to give SVOC emission rates. 

As discussed above, SVOCs are removed from the atmosphere and transported to the waters by precipitation scavenging of atmospheric vapors and particles, which are incorporated into the rain within or below the clouds. After SVOCs are deposited into the bulk seawater, partitioning in water column can affect the distribution of pollutants between the dissolved aqueous and the solid phases and eventually impact the fate of these compounds in oceans (Luo et al. 2004). In addition, air-sea exchange can make SVOCs diffuse across the air-sea interface however, the sea surface microlayer (SML), a unique compartment at the air-sea boundary defined operationally as the upper millimeter (1-1,000 pm)... 

A classical two-layer model, which has been previously apphed to the air-sea exchange of SVOCs (Achman et al. 1993 Zhang et al. 2007 Li et al. 2009), assumes that the rate of gas transfer is controlled by the pollutant s ability to diffuse across the air layer and sea surface water on either side of the air-water interface. The molecular diflusivity of the pollutant, dependent on the amount of resistance encountered in the hquid and gas films, describes the rate of transfer while the concentration gradient drives the direction of transfer (Totten et al. 2001). The flux F (ng m day ) is calculated by... 

In this study, DOC concentrations are in the range of 0.6-7.8 mg 1 . The predicted mean fractions adsorbed to DOC for individual PAH varied in the range of 0.1-40%. It clearly showed that HMW PAHs are more readily adsorbed to DOC (10-50%) than those LMW compounds (below 10%). a-, ) -, and y-HCH were adsorbed to DOC at a mean fraction of 0.26, 0.25 and 0.20%, consistent with the values ( 0.4%) reported by Wurl et al. (2006b), while the DOC fraction for DDXs was much higher in the range of 30-40%. This distribution pattern confirms the anticipation that the sorption of SVOCs onto DOC in the seawater is correlated with the chemical s Kqw. namely, pollutants with higher Kow are more easily sorbed onto DOC (Schwarzenbach et al. 2003). 

Among the major ubiquitous SVOC pollutants in the urban air worldwide are polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Their chemical structures are presented in Figs. 1, 2. Theoretically, there are 57 individual PAHs which contain 2-6 fused six-member benzenoid rings only (Harvey 1997). There are 209 individual PCB congeners and 209 individual PBDE congeners, varying in the number and positions of the substitutions by chlorine and bromine, respectively. 

Five VOCs that are commonly associated with pollution of drinking water are tetrachloroethylene (PCE), trichloroethylene (TCE), viityl chloride (VC), 1,2-dichlo-roethane (DCE), and carbon tetrachloride (CCU) Examples of SVOCs include cresol, phenol, pyrene, 1,2- dichlorobenzene, and 1,4-dichlorobenzene. 

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