Search

A comprehensive sampling campaign was carried out around a municipal solid waste incinerator (MSWI) in central Taiwan in order to evaluate the impact of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) emissions on the ambient air and describe their spatial variation of gas–particle partitioning. Stack flue gas samples from the MSWI were also analyzed to investigate the relationship between the source and the impacted sites. Results showed that the PCDD/F emissions from the MSWI were a major source for PCDD/Fs in the ambient air. Moreover, PCDD/Fs in the ambient air tended to be distributed between the gaseous and particulate phases based on molecular weight; the higher chlorinated congener occupied a higher particulate fraction. There was an increase in the proportion of particle-bound PCDD/Fs with increasing distance from the MSWI. This observation supports the assumption that PCDD/Fs emitted were initially more associated with gaseous phase and the gaseous PCDD/Fs would gradually migrate to particles via either adsorption or absorption process. The results obtained were also applied and compared with the subcooled liquid vapor pressure (PL0)-based model and with the octanol–air partition coefficients (Koa)-based model. These two models were found to be excellent descriptors for the gas–particle partitioning of PCDD/Fs. Regressions for log partition coefficient (Kp) versus log PL0 and log Kp versus log Koa both demonstrated that PCDD/Fs were approaching equilibrium partitioning with increasing distance from the MSWI in the current study. [Copyright &y& Elsevier]

The atmospheric particle size distributions of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) between 0.056 and 100 μm in aerodynamic diameter (Dp) were measured at two sampling sites during January 2002. These sites were 1.1 and 2.1 km downwind from a municipal incinerator in central Taiwan, respectively. Size-segregated atmospheric particles were simultaneously collected by means of a cascade impactor and a rotary impactor. The results showed that PCDD/Fs were associated with the full size range of atmospheric particles. More than 80% of the ΣPCDD/Fs and toxic equivalents (TEQs) were found to be associated with fine particles of aerodynamic diameter, Dp<2.0 μm. Generally a smaller particle had a higher ΣPCDD/Fs content. The particle size distributions of ΣPCDD/Fs and TEQs were shifted to larger particles with increasing time and distance. It is noteworthy that PCDFs were found to distribute significantly among aerosol size fractions based on their chlorination level at both sampling sites. There was an increase in the proportion of the less chlorinated PCDFs in the coarse particles (Dp>2.0 μm). As for PCDDs, however, a relative enrichment of the less chlorinated congeners on coarse particles was found only at the farther sampling site (2.1 km). [Copyright &y& Elsevier]

Heavy metals are one of the concerned pollutants emitted by the municipal waste incineration system (MWIs). The objective of this study was to evaluate the potential impact on local airborne metals from the emissions of an MWI. Aerosol samples were simultaneously collected at eight different sites around the municipal waste incinerator using PS-1 sampler. The concentrations of 16 elements (Mg, Al, Fe, Cu, Zn, Pb, Ti, V, Cr, Mn, Co, Ni, As, Cd, Ba and Hg) were quantified by inductively coupled plasma-mass spectrometry (ICP–MS) and atomic absorption spectrometer (AA). The profiles of the 16 metals in the surroundings of a municipal incinerator in central Taiwan were compared with those of the emission sources. The results showed that the profiles of multiple metals obtained at all sampling sites were similar to those emitted from the MWI stack. These findings suggested that the local airborne metal pollutants might probably derive from the stack emission of the MWI. Using cadmium as an index metal, it was found that the metals like Mg, Ti, V, Cr, Mn, Co, Ni, As, and Hg are highly influenced by the stack emission from the municipal incinerator. Moreover, the ratio of other metals to Cd that were increased with the distance from the incinerator. This might be due to the additional sources contributed to airborne metals following the emission from the incinerator and a difference in particle size of each particle-bound metal. [Copyright &y& Elsevier]

Abstract: Atmospheric particulate and polycyclic aromatic hydrocarbon (PAH) size distributions were measured at a suburban area in central Taiwan during the rice straw burning and non-burning periods. Samples were acquired using a semi-volatile sampling train (PS-1 sampler) and a micro-orifice uniform deposit impactor (MOUDI). The collected materials were extracted and then analyzed by gas chromatograph/mass selective detector for 21 PAHs. The average total PAH concentrations of particulate and gaseous phases were 33.0 and 1160ngm−3, respectively, in the rice straw burning period, which were higher than those on the non-burning days. Potential sources of PAHs were identified using the characteristic ratios. Benzo[a]pyrene/benzo[ghi]perylene ratio indicates the burning of rice straw is a significant source for PAH contribution at the sampling area. It also suggests that the rice straw burning primarily contribute fine particulate PAHs. Bimodal size distributions are obtained with a predominance of total PAHs in the accumulation mode during rice straw burning periods and in ultra-fine mode during non-burning periods. The particulate and particulate phase PAHs from rice straw burning are coarser than those from vehicle exhaust. The results also suggest that the amounts of PAHs per unit mass of particulate are less for the burning of rice straw than those of vehicle emissions. [Copyright &y& Elsevier]

Abstract: Cooking exhausts may contribute significant organic compounds to the atmosphere. It has been shown that trans,trans-2,4-decadienal (tt-DDE) is an important toxic compound in cooking oil fumes (COF). In this study, the emissions of tt-DDE were quantified in both gaseous and particulate phases of three kinds of restaurant exhausts (Chinese, western and barbecue). Samples of exhausts were collected with a sampling system meeting the criteria of US EPA Modified Method 5. The tt-DDE was analyzed by HPLC–MS/MS. The results indicate that the emission factors of tt-DDE in terms of μgcustomer−1 were in sequence: barbecue (1990)>Chinese (570)>western (63.8). The average proportion of tt-DDE in the particulate phase of the exhausts was 83% for the 16 investigated restaurants. Evidently, the majority of tt-DDE in the exhausts was in the particulate phase. There was no evident correlation found between phase distribution of tt-DDE and exhaust temperature in the restaurants investigated. The efficiencies of removal of particulate tt-DDE by air pollution control devices (APCDs) were assessed. The removal efficiencies of electrostatic precipitator (ESP), ESP and activated carbon in series, and wet scrubber were 64.2%, 86.3% and 71.3%, respectively. [Copyright &y& Elsevier]