Hsi-Hsien Yang

PAH emission from various industrial stacks

Abstract The emission of polycyclic aromatic hydrocarbons (PAHs) from various industrial stacks (blast furnace, basic oxygen furnace, coke oven, electric arc furnace, heavy oil plant, power plant and cement plant) in southern Taiwan were investigated. PAH concentrations ( μ g/N m 3 ) and PAH emission factors ( μ g/kg feedstock) were determined. In addition to these eight stationary industrial stacks, an industrial waste incinerator, a diesel engine and a gasoline-powered engine were selected and combined for the identification of source indicatory-PAHs in this study. The qualitative contribution of PAHs to the ambient air by various sources was estimated by factor analysis. Combustion of heavy oil produced considerably higher 4, 5 and 6+7-ring PAH concentration than other stacks. In addition, the HMW (higher molecular weight) PAH concentrations were significantly higher for the coke oven, the electric arc furnace and heavy oil combustion. Measured total-PAHs emission factors of eight stationary sources were between 77.0 and 3970 μ g/kg feedstock, while BaP (the most carcinogenic PAH) emission factors were between 1.87 and 15.5 μ g/kg feedstock. Among these eight emission sources, the heavy oil plant had both the highest total-PAH and the highest BaP emission factor. Indicatory PAHs of the cement plant were AcPy, Acp and Ant, which are all 3-ringed PAHs. However, the indicatory PAHs of the industrial waste incinerator were IND and CHR. For mobile sources (diesel- and gasoline-powered vehicles), the indicatory PAHs were mainly lower molecular weight PAHs (AcPy, FL and Flu). By using factor analysis, the cursorily qualitative analysis of PAH emission was found to be practicable.

Profiles of PAH emission from steel and iron industries

In order to characterize the polycyclic aromatic hydrocarbons (PAHs) emission from steel and iron industries, this study measured the stack emission of twelve steel and iron plants in southern Taiwan to construct a set of source fingerprints. The study sampled the emissions by the USEPAs sampling method 5 with the modification of Graseby for the gas and particulate phase PAH and, then, used Hewlett-Packard 5890 gas chromatograph equipped with mass spectrometer detector to analyze the samples. The steel and iron industries are classified into three categories on the basis of auxiliary energy source: Category I uses coal as fuel, Category II uses heavy oil as fuel and Category III uses electric arc furnace. The pollution source profiles are obtained by averaging the ratios of individual PAH concentrations to the total concentration of 21 PAHs and total particulate matter measured in this study. Results of the study show that low molecular weight PAHs are predominant in gas plus particulate phase for all three categories. For particulate phase PAHs, however, the contribution of large molecular weight compounds increases. Two-ring PAHs account for the majority of the mass, varying from 84% to 92% with an average of 89%. The mass fractions of 3-, 4-, 5-, 6-ring PAHs in Category I are found to be more than those of the other two categories. The mass of Category III is dominated by 7-ring PAHs. Large (or heavy) molecular weight PAHs (HMW PAHs) are carcinogenic. Over all categories, these compounds are less than 1% of the total-PAH mass on the average. The indicatory PAHs are benz[a]anthracene, benzo[k]fluoranthene, benzo[ghi]perylene for Category I, benzo[a]pyrene, acenaphthene, acenaphthylene for Category II and coronene, pyrene, benzo[b]chrycene for Category III. The indicatory PAHs among categories are very different. Thus, dividing steel and iron industry into categories by auxiliary fuel is to increase the precision of estimation by a receptor model. Average total-PAH emission factors for coal, heavy oil and electric arc furnace were 4050 microg/kg-coal, 5750 microg/l-oil, 2620 microg/kW h, respectively. Carcinogenic benzo[a]pyrene for gas plus particulate phase was 2.0 g/kg-coal, 2.4 microg/l-oil and 1.4 microg/kW h for Category I, II and III, respectively.

Adsorption characteristics of lead onto soils

Abstract The metal adsorption characteristics of fifteen Taiwan soils, exemplified by Pb (II), were evaluated using pH as the major variable. The soil samples were thoroughly characterized for their physical chemical properties and composition, particularly organic matter and metal oxides. The adsorption of Pb (II) followed the Langmuir relation and increased with increasing pH between pH 3.0 and 8.5. The greater adsorption was found for soils with a higher organic matter content at constant pH and metal concentration. To better understand the mechanism of adsorption, the experimental results for Pb (II) were tested in a partition coefficient model to relate the adsorption of the Pb (II) by the different soils with soil components: organic matter, iron oxide, aluminum oxide and manganese oxide. This model was not successful when applied to measurements at the natural soil pH because of the competition of protons with lead for available sites. However, partition coefficients obtained from experimental data were highly correlated with those calculated for a partition coefficient between lead and organic matter alone. Normalization of the partition coefficients, K d , for the organic matter content of the soils, K om , greatly improved the correlation between the partition coefficient and pH ( R 2 increased from 0.602 to 0.855). This suggests that the surficial adsorption sites are principally due to organic matter. For the 24-h equilibration period employed, diffusion of Pb through this superficial organic matter coating to underlying sorptive materials, including metal oxides, is not important in the partitioning of Pb.

Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine

Polycyclic aromatic hydrocarbons (PAHs) emission tests for a heavy-duty diesel engine fueled with blend base diesel fuel by adding batch fractions of poly-aromatic and mono-aromatic hydrocarbons, Fluorene and Toluene, respectively, were simulated to five steady-state modes by a DC-current dynamometer with fully automatic control system. The main objective of this study is to investigate the effect of total aromatic content and poly-aromatic content in diesel fuels on PAH emission from the HDD engine exhaust under these steady-state modes. The results of this study revealed that adding 3% and 5% (fuel vol%) Fluorene in the diesel fuel increases the amount of total-PAH emission by 2.6 and 5.7 times, respectively and increases the amount of Fluorene emission by 52.9 and 152 times, respectively, than no additives. However, there was no significant variation of PAH emission by adding 10% (vol%) of Toluene. To regulate the content of poly-aromatic content in diesel fuel, in contrast to the total aromatic content, will be more suitable for the management of PAH emission.

Size distribution and dry deposition of road dust PAHs

Abstract The size distribution of polycyclic aromatic hydrocarbons (PAHs) for road dust and for the engine exhaust of both gasoline-powered cars and motorcycles was investigated. In addition, by using the measured size distribution data, monitoring and modeling the PAH dry deposition, the contribution fraction of road dust on the dry deposition materials was also studied. Twenty-one PAHs were analyzed primarily by using a gas chromatograph/mass spectrometer (GC/MS). The mass median diameters (MMDs) of 21 individual PAHs for resuspendable road dust (cut size

Effects of biodiesel, engine load and diesel particulate filter on nonvolatile particle number size distributions in heavy-duty diesel engine exhaust

Diesel engine exhaust contains large numbers of submicrometer particles that degrade air quality and human health. This study examines the number emission characteristics of 10-1000 nm nonvolatile particles from a heavy-duty diesel engine, operating with various waste cooking oil biodiesel blends (B2, B10 and B20), engine loads (0%, 25%, 50% and 75%) and a diesel oxidation catalyst plus diesel particulate filter (DOC+DPF) under steady modes. For a given load, the total particle number concentrations (N(TOT)) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the N(TOT) and mode diameters increase modestly with increasing load of above 25%. The N(TOT) at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC+DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The N(TOT) post the DOC+DPF are comparable to typical ambient levels of ≈ 10(4)cm(-3). This implies that, without concurrent reductions of semivolatile materials, the formation of semivolatile nucleation mode particles post the after treatment is highly favored.

PAH emissions influenced by Mn-based additive and turbocharging from a heavy-duty diesel engine

A manganese-based additive was used in this study to investigate the effects on the polycyclic aromatic hydrocarbons (PAHs) emission from a natural-aspirated heavy-duty diesel-powered engine. A similar turbocharged engine was tested and compared with the natural-aspirated one for the PAH emission. The concentrations of 21 individual PAHs (gas + particle phases) and the metal element (Mn) of the particulate from the engine exhaust and in the diesel fuel, respectively, were determined. Engine exhaust (PAHs and Mn) was collected over the modified JAMA J-13 mode by a PAH sampling system. By adding 400 mg/kg of Mn-based additive in the diesel, the reduction fraction of mean total-PAH (gas plus particle phase) emission was 37.2%, while for the 10 higher molecular weight (HMW) PAHs, the mean reduction fraction was 64.5%. These results indicate that the Mn-based additive in the diesel engine can act as a catalyst enhancing the oxidation process and reducing a considerable amount of PAH emission. In addition, the amount of 10 HMW PAH emission from the turbocharged engine averaged 92.4% of magnitude lower than that of the natural-aspirated engine. This result revealed that the turbocharged engine has higher pressure and temperature and thus makes a more complete combustion of the fuel.

Carcinogenic potencies of polycyclic aromatic hydrocarbons for back-door neighbors of restaurants with cooking emissions

In the present study, 21 polycyclic aromatic hydrocarbon (PAH) congeners were measured in the exhaust stack of 3 types of restaurants: 9 Chinese, 7 Western, and 4 barbeque (BBQ). The total PAH concentration of BBQ restaurants (58.81 ± 23.89 μg m(-3)) was significantly higher than that of Chinese (20.99 ± 13.67 μg m(-3)) and Western (21.47 ± 11.44 μg m(-3)) restaurants. The total benzo[a]pyrene potency equivalent (B[a]P(eq)) concentrations, however, were highest in Chinese restaurants (1.82 ± 2.24 μg m(-3)), followed by Western (0.86 ± 1.43 μg m(-3), p<0.01) and BBQ-type restaurants (0.59 ± 0.55 μg m(-3), p<0.01). We further developed a probabilistic risk model to assess the incremental lifetime cancer risk (ILCR) for people exposed to carcinogenic PAHs. Because the exhaust stack directly affected the back-door neighbors of these restaurants, we were concerned with the real exposure of groups near the exhaust stack outlets of these restaurants. The ILCRs for total exposure of the neighbors (inhalation+dermal contact+ingestion) were 2.6-31.3, 1.5-14.8, and 1.3-12.2 × 10(-6) in Chinese, Western, and BBQ restaurants, respectively. We suggest that the maximum acceptable exposure time to the exhaust stack outlet area for Chinese, Western, and BBQ restaurants ranges between 5-19, 17-42, and 18-56 h month(-1), respectively, based on an ILCR of less than 10(-6).

Risk assessment of gaseous/particulate phase PAH exposure in foundry industry

Thirty-seven air samplings in different working areas of two foundry industries were collected to assess polycyclic aromatic hydrocarbon (PAH) levels. The average PAH level inside Foundry A was 19.56 microg/m(3), which was higher than that in Foundry B (8.26 microg/m(3)), whereas for the benzo[a]pyrene toxic equivalent (BaPeq) level (38.81 ng/m(3) vs. 46.52 ng/m(3)). A higher PAH level was found for big moulding process than for the small one, and the chemical binder in the different size moulds was hypothesized to be the main cause. The higher PAH levels were found in the painting area (95.51 microg/m(3)), pouring area (18.42 microg/m(3)), and inside the office (16.48 microg/m(3)); as well as the higher BaPeq level was in the painting area (152.3 ng/m(3)), and the furnace for melting iron (96.9 ng/m(3)). The gas phase (over 90%) was the major contributor of total PAHs in the manufacturing areas. Moreover, health risk assessment of PAHs exposure showed that lung cancer risks were 9.06x10(-4) and 1.09x10(-3) in Foundries A and B, respectively. This study suggests that the workers shall use appropriate respiratory masks in painting, melting, and pouring areas to prevent their occupational exposure to PAHs.

Simultaneous determination of N7-alkylguanines in DNA by isotope-dilution LC-tandem MS coupled with automated solid-phase extraction and its application to a small fish model

In the present study, we report the development of a sensitive and selective assay based on LC (liquid chromatography)-MS/MS (tandem MS) to simultaneously measure N7-MeG (N7-methylguanine) and N7-EtG (N7-ethylguanine) in DNA hydrolysates. With the use of isotope internal standards (15N5-N7-MeG and 15N5-N7-EtG) and on-line SPE (solid-phase extraction), the detection limit of this method was estimated as 0.42 fmol and 0.17 fmol for N7-MeG and N7-EtG respectively. The high sensitivity achieved here makes this method applicable to small experimental animals. This method was applied to measure N7-alkylguanines in liver DNA from mosquito fish (Gambusia affinis) that were exposed to NDMA (N-nitrosodimethylamine) and NDEA (N-nitrosodiethylamine) alone or their combination over a wide range of concentrations (1-100 mg/l). Results showed that the background level of N7-MeG in liver of control fish was 7.89+/-1.38 mmol/mol of guanine, while N7-EtG was detectable in most of the control fish with a range of 0.05-0.19 mmol/mol of guanine. N7-MeG and N7-EtG were significantly induced by NDMA and NDEA respectively, at a concentration as low as 1 mg/l and increased in a dose-dependent manner. Taken together, this LC-MS/MS assay provides the sensitivity and high throughput required to evaluate the extent of alkylated DNA lesions in small animal models of cancer induced by alkylating agents.