Characterizing PAH emission concentrations in ambient air during a large-scale joss paper open-burning event

Seasonal differences in the spatial patterns of wildfire drivers and susceptibility in the southwest mountains of China

Wildfires directly affect global ecosystem stability and severely threaten human life. The mountainous areas of Southwest China experience frequent wildfires. Mapping the susceptibility patterns and analyzing the drivers of wildfires are crucial for effective wildfire management, especially considering that the inclusion of seasonal dimensions will produce more dynamic results. Using Yunnan Province of China as a case study area, a method was attempted to distinguish dependable wildfires by season, while possible wildfire drivers were obtained and refined within seasons. The patterns of wildfire susceptibility in different seasons were modeled based on the Maxent and random forest models. Then, the spatial relationships between wildfire and potential drivers were analyzed integrating with GeoDetector to evaluate the variable importance of drivers and the marginal effect of drivers. The results showed that the two models effectively depicted each season's wildfire susceptibility. The susceptible wildfire areas in spring and winter are located throughout Yunnan Province, with anthropogenic factors being the most significant drivers. During the summer and autumn, wildfire risk areas are relatively concentrated, showing a trend of dominant drought-driven and humid conditions. The differences in wildfire drivers across seasons reflect the lagged effect of climate factors on wildfires, leading to significant discrepancies in the marginal effects of how seasonal drivers affect wildfires. The findings improve our understanding of the effects of the interseasonal variability of environmental variables on wildfires and promote the development of specific seasonal wildfire management strategies.

Emissions Characteristics of Hazardous Air Pollutants from the Incineration of Sacrificial Offerings

The incineration of sacrificial offerings generates numerous hazardous air pollutants, including particulate matter (PM), CO, SO2, NOx and non-methane hydrocarbons (NMHC), which has significant effects on the environment and human health. However, due to the concealment of sacrificial offerings incineration, the emission of such pollutants has not received sufficient attention. Relevant quantification of the emission, emission factors and pollution control measures for this pollution source are lacking. To address these problems, herein, we quantified the particulate matter and its chemical composition and the emission levels of gaseous pollutants, including SO2, NOx, NMHC and CO, by performing incineration experiments of four typical sacrificial offerings (Joss paper, Funeral wreath, Taoist paper art and Yuanbao paper), and obtained the emission factors and emission characteristics for the incineration of sacrificial offerings. Therefore, this study lays the foundation and provides support for establishing an emission inventory of the air pollutants from the incineration of sacrificial offerings and introducing corresponding pollution control measures. The results show that the emission concentrations of CO and total suspended particulate (TSP) from the incineration of sacrificial offerings greatly exceed the emission standard, with averages of 621.4 mg m−3 and 142.9 mg m−3 at 11% oxygen content, respectively. The average emission factors of SO2, NOx, NMHC, CO, PM10 and PM2.5 for the incineration of the four offerings are (0.47 ± 0.17) kg t−1, (2.46 ± 0.35) kg t−1, (5.78 ± 2.41) kg t−1, (32.40 ± 8.80) kg t−1, (4.23 ± 0.71) kg t−1 and (2.62 ± 0.48) kg t−1, respectively, among which the emission intensities of NMHC and CO are relatively high. Among the different types of sacrificial offerings, the overall average emission factor of air pollutants generated from the incineration of Yuanbao paper is the highest, which is mainly due to the low burning efficiency and the coating material. For the chemical composition of the particulate matters, ions, OC, EC and metal elements account for proportions of the PM2.5 at (23.55 ± 10.37) %, (29.74 ± 9.95) %, (14.83 ± 6.55) % and (13.45 ± 4.88) %, respectively, indicating that the organic pollution is severe

Identifying Key Sources of City Air Quality: A Hybrid MCDM Model and Improvement Strategies

Improvements for air quality were prioritized according to gaps between criteria. Existing improvement strategies for air quality often focus on a single criterion, without considering associations among criteria. Moreover, solutions are often temporary, failing to provide long-term improvement. Therefore, this study employed a multiple-criteria decision-making model and a substitution method based on causal relationships to analyze potential improvement strategies for air quality in Kaohsiung, Taiwan. Results revealed that coal-fired power plants and factory emissions are the major sources of pollution in Kaohsiung. This study suggests that environmental authorities in Kaohsiung should facilitate plants to improve energy efficiency with anti-pollution facilities.

Destruction of naphthalene via ozone-catalytic oxidation process over Pt/Al2O3 catalyst

This study investigated the application of ozone in conjunction with Pt/Al(2)O(3) catalysts, called ozone-catalytic oxidation (OZCO) process, to destruct gaseous naphthalene (Nap). The experiments were carried out at various constant reaction temperatures (T), space velocities (SV) and inlet concentrations of ozone (C(O3,in)). The results indicate that the required T for the effective decomposition of Nap decreases with the increase in inlet concentration of ozone (C(O3,in)) at the same conversion level of Nap (X(Nap)). Further, the values of X(Nap) and mineralization extent of Nap (M(Nap)) increase linearly with the increase of C(O3,in.) Regarding the T at X(Nap)=50% (T(50)), there is about 20K reduction at SV=100,000 h(-1) for the case of OZCO process with C(O3,in) of 1750 ppmv (T(50)=460 K) compared to the process without ozone (T(50)=480 K). Further, the power law can be applied to describe the data by using the second order expression with respect to ozone and Nap concentration. The observed activation energy and frequency factor are 68.3 kJ mol(-1) and 5.36 x 10(12)L(2)mol(-1)g(-1)-cat.s(-1), respectively. The information obtained is useful for the rational design and operation of the treatment of Nap via the OZCO process.

Characterization of polychlorinated dibenzo-p-dioxin/dibenzofuran emissions from joss paper burned in a furnace with air pollution control devices

Burning joss paper, a common practice in temples in some Asian countries, can release toxic pollutants. This study investigated polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) emissions and profiles from burning joss paper in a temple furnace connected to two wet scrubbers. The mean total PCDD/F content and corresponding toxic equivalent quantity (TEQ) in joss paper were 193 ng kg(-1) and 0.645 ng I-TEQ kg(-1), respectively, whereas those in bottom ash from burned joss paper were 18.5 ng kg(-1) and 1.92 ng I-TEQ kg(-1), respectively. The wet scrubbers decreased individual PCDD/F emissions by 26.7-71.0% and those of total PCDD/Fs and I-TEQ by 47.2% and 66.0%, respectively. The total PCDD/F TEQ emission factors before and after the wet scrubbers were 8.14 and 3.42 microg I-TEQ ton-feedstock(-1), respectively. The estimated total PCDD/F and corresponding TEQ emissions were 5.29 g year(-1) and 0.462 g I-TEQ year(-1), respectively, in Taiwan. Burning joss paper in temple furnaces is a significant source of PCDD/F emissions.