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This study set out to identify possible PCDD/F emission sources for different atmospheric environments in a highly industrialized city located in southern Taiwan. We collected stack flue gas samples from five main stationary emission sources of the municipal solid waste incinerators (MSWIs), medical waste incinerators (MWIs), electric arc furnaces (EAFs), secondary aluminum smelters (ALSs), and sinter plants to assess the characteristics of their PCDD/F emissions. For mobile sources, congener profiles reported in U.S. EPA's database for unleaded gas-fueled vehicles (UGFV) and diesel-fueled vehicles (DFV) were directly adopted owing to lack of local data. The congener profiles of the 2,3,7,8-substituted PCDD/Fs were selected as the signatures of these PCDD/F emission sources. We conducted PCDD/F samplings on atmospheric environments of four categories, including background, residential area, traffic area, and industrial area. Through PCA and cluster analyses, we found that traffic areas were most influenced by PCDD/F emissions from UGFV and DFV, while those of industrial areas were mainly influenced by metallurgical facilities and MWIs. The above results were further examined by using the methodology of the indicatory PCDD/Fs. We confirmed that traffic areas were contributed by traffic sources, but industrial areas were simply affected by metallurgical facilities rather than MWIs. In conclusion, besides the use of PCA and cluster analyses, the methodology of the indicatory PCDD/Fs should be conducted for further validation in order to prevent misjudgment.

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Polycyclic aromatic hydrocarbons are a class of semi-volatile organic carbons that are emitted from both natural and anthropogenic sources therefore are ubiquitous in nature. Their main sources are both fossil and biomass fuels as well as other feedstocks used in chemical and combustion processes. Mostly the combustion processes are PAH depletion processes rather than PAH generating processes. PAHs are emitted from both stationary and mobile sources at varying levels depending on the operation conditions such as fuels, feedstock, and control devices in use as well as process parameters for example combustion temperatures.After emission from sources, the fates of PAHs in the atmosphere include partitioning between gas and particulate phases, particle size distribution, long range transport, dry and wet deposition on to water bodies, soil, vegetation and other receptor surfaces as well as resuspension from receptor surfaces back to the atmosphere. These processes are controlled by their physiochemical properties. Additionally, it is through these processes that human beings are exposed to PAHs via inhalation, ingestion and dermal contact.Dry deposition is the major process through which PAHs from the atmosphere are made available to receptor surfaces including the human respiratory system. From studies with cumulative fractions of dry deposition and size distribution for particulate PAHs, it is evident that the coarse particles are majorly responsible for the highest fraction of deposition fluxes. This is especially true for the high molecular weight PAHs, since the low molecular weight PAHs are majorly in the gas phase, which have lower dry deposition velocities. On the other hand, the highest risk for human being comes in the form of fine particles, whose mean aerodynamic diameter is below 2.5 µm. This is because the particle bound content results and particle size distributions of PAHs indicate that the fine particles have the most PAH content owing to their large surface areas and high organic carbon content. For the wet deposition of PAHs, more research is recommended for measurement of scavenging ratios of individual PAHs, since there is a scarcity of studies focusing on this issue.PAH mutagenic activity and exposure risk of humans can be estimated using the deposition rates, toxicity levels based on benzo(a)pyrene, or biomarkers such as urinary 1-hydroxypyrene. Other parameters that have been used to evaluate the risks of various exposure groups include inhalation exposure levels (IEL), incremental lifetime cancer risk (ILCR), and estimation of maximum consumption time (t max ). Highway toll workers, back carbon workers and food vendors in night markets are among susceptible groups identified using these biomarkers and exposure parameters.To reduce exposure to human beings, PAH emissions need to be controlled at the sources. Control and reduction of PAH emissions from various sources involves largely altering the fuel and feedstock characteristics, using air pollution control devices and/or adjustin...

This study investigated the characteristics of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in the stack flue gases of the metallurgical processes. An examination of the PBDEs existing in the stack flue gases of sinter plants revealed that PBDEs can form during the combustion processes through the similar formation conditions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The PBDD/F and PBDE emission rates of the metallurgical facilities were 0.446-3.19 µg TEQ/h and 4470-27000 µg/h, correspondingly. Both emission rates could reach several orders higher than those of the reported sources, revealing that the metallurgical facilities are not only important PCDD/F but also significant PBDD/F and PBDE emission sources to the environment. BDE-209 is the most abundant PBDE congener in the emissions of metallurgical facilities and is found to be dominant in the atmosphere and soils. However, few studies have considered metallurgical facilities as potential PBDE contributors to the environment. Because PBDEs could form or not be completely destroyed in the feeding materials in the combustion system, PBDE contributions from combustion emission sources to the atmosphere should not be ignored and need further investigation.

As yet, very little is known about the polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) characteristics in the stack flue gases of incinerators. In this study, nine large-scale continuous municipal solid waste incinerators (MSWIs), two small-scale batch MSWls, and nine industrial waste incinerators (IWIs) were investigated for 2,3,7,8-substituted PBDD/Fs. The elevated PBDD/F concentrations (18.2 pg/Nm3, 4.17 pg TEQ/Nm3) of the IWIs, which were eight times higher than those of MSWIs (2.28 pg/Nm3, 0.557 pg TEQ/Nm3), are accompanied by PCDD/ Fs that are in the same range as those measured from MSWIs (0.0171-1.98 ng I-TEQ/Nm3). The obtained TEQ ratios (in percentage) of the PBDD/F to the PCDD/F concentration in the stack flue gases of the MSWls (0.72%), batch MWIs (0.18%), and IWIs (5.4%) are useful for the future estimate of PBDD/F emission quantity based on the well-established PCDD/F inventory. In addition, a significantly high correlation was found between the PBDD/F and PCDD/F concentrations, and the PBDD/F and PCDD/F congener profiles of the same emission source were similar, indicating a similar formation and substitution mechanism of bromine and chlorine in the combustion system.

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