<div style="text-align:justify;"> Size-segregated of particulate matter (PM) including PM<sub>0.1</sub> at two different sites, i.e., educational (EA) and residential (RA) areas in Padang c...<div style="text-align:justify;"> Size-segregated of particulate matter (PM) including PM<sub>0.1</sub> at two different sites, i.e., educational (EA) and residential (RA) areas in Padang city, Indonesia were sampled by using a cascade type air sampler for 24 hours with the average flowrate 40 l/m throughout three weeks (March, 08<sup>th</sup>-25<sup>th</sup> 2018). Carbonaceous components were analyses by a carbon analyzer following the IMPROVE_TOR protocol. Average PM<sub>2.5</sub> and PM<sub>10</sub> concentrations in RA were higher than those in EA while being below the NAAQS of Indonesia. However, it was much higher compared to the WHO limit for 24 hours in RA. OC was the dominant fraction in TC. OC/EC ratio ranging from 2.4 to 33.0 was similar at both sites, suggesting the OC was emitted from various sources. Char-EC and soot-EC ratio were founded to be minimized for PM<sub>0.1</sub> (0.40 ± 0.27 and 0.39 ± 0.39, respectively at each site), indicating a more influence of burning of fossil fuel as vehicles exhaust and coal combustion. The transboundary influence of open biomass burning was not so significant although it cannot be ignored. </div>展开更多
Carbonaceous aerosols affect air quality adversely,affect global warming,and human health.However,our understanding of the impact of ultrafine(PM_(0.1))carbonaceous particulate matter is incomplete,particularly the ef...Carbonaceous aerosols affect air quality adversely,affect global warming,and human health.However,our understanding of the impact of ultrafine(PM_(0.1))carbonaceous particulate matter is incomplete,particularly the effects during haze episodes.This study monitored diurnal variations in PM_(0.1) in Chiang Mai,Thailand,from March to April 2020.We investigated carbonaceous PM_(0.1) collected by an ambient nano-sampler and evaluated their effect by using a carbon analyzer(IMPROVE_TOR).The results showed that burning large open areas in the dry season was crucial for increasing the particle mass concentration because of the large open burnings that occurred in this area.The majority of biomass fires near the sampling site occurred during the night,which would allow more particles to be released thus resulting in higher concentrations of PM_(0.1).Hence,the release of PM_(0.1) during the night would obviously result in higher concentrations than that during the day.In the eight carbon profiles,organic carbon 3(OC3)was predicted to be a marker of biomass fires.The carbon indices displayed that PM_(0.1) was influenced by biomass burning both daytime and nighttime.The findings reported herein should be of great impor-tance in terms of establishing biomass burning control policies for mitigating heavy haze pollution in Thailand and elsewhere.展开更多
Distribution of PM_(0.1),PM_(1) and PM_(2.5) particle-and gas-polycyclic aromatic hydrocarbons(PAHs)during the 2019 normal,partial and strong haze periods at a background location in southern Thailand were investigate...Distribution of PM_(0.1),PM_(1) and PM_(2.5) particle-and gas-polycyclic aromatic hydrocarbons(PAHs)during the 2019 normal,partial and strong haze periods at a background location in southern Thailand were investigated to understand the behaviors and carcinogenic risks.PM1 was the predominant component,during partial and strong haze periods,accounting for 45.1% and 52.9% of total suspended particulate matter,respectively,while during normal period the contribution was only 34.0%.PM_(0.1) concentrations,during the strong haze period,were approximately 2 times higher than those during the normal period.Substantially increased levels of particle-PAHs for PM_(0.1),PM_(1) and PM_(2.5) were observed during strong haze period,about 3,5 and 6 times higher than those during normal period.Gas-PAH concentrations were 10 to 36 times higher than those of particle-PAHs for PM_(2.5).Average total Benzo[a]Pyrene Toxic Equivalency Quotients(BaP-TEQ)in PM_(0.1),PM_(1) and PM_(2.5) during haze periodswere about 2–6 times higher than in the normal period.The total accumulated Incremental Lifetime Cancer Risks(ILCRs)in PM_(0.1),PM_(1) and PM_(2.5) for all the age-specific groups during the haze effected scenario were approximately 1.5 times higher than those in nonhaze scenario,indicating a higher potential carcinogenic risk.These observations suggest PM_(0.1),PM_(1) and PM_(2.5) were the significant sources of carcinogenic aerosols and were significantly affected by transboundary haze from peatland fires.This leads to an increase in the volume of smoke aerosol,exerting a significant impact on air quality in southern Thailand,as well as many other countries in lower southeast Asia.展开更多
Size-resolved aerosols were continuously collected by a Nano Sampler for 13 days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the N...Size-resolved aerosols were continuously collected by a Nano Sampler for 13 days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the Nano Sampler and an ACSM(Aerodyne Aerosol Chemical Speciation Monitor) were compared. Between the data sets,similar trends and strong correlations were observed,demonstrating the validity of the Nano Sampler. PM10 and PM2.5concentrations during the measurement were 150.5 ± 96.0 μg/m3(mean ± standard variation)and 106.9 ± 71.6 μg/m3,respectively. The PM2.5/PM10 ratio was 0.70 ± 0.10,indicating that PM2.5dominated PM10. The aerosol size distributions showed that three size bins of 0.5–1,1–2.5 and 2.5–10 μm contributed 21.8%,23.3% and 26.0% to the total mass concentration(TMC),respectively. OM(organic matter) and SIA(secondary ionic aerosol,mainly SO42-,NO3-and NH4+) were major components of PM2.5. Secondary compounds(SIA and secondary organic carbon) accounted for half of TMC(about 49.8%) in PM2.5,and suggested that secondary aerosols significantly contributed to the serious particulate matter pollution observed in winter. Coal burning,biomass combustion,vehicle emissions and SIA were found to be the main sources of PM2.5. Mass concentrations of water-soluble ions and undetected materials,as well as their fractions in TMC,strikingly increased with deteriorating particle pollution conditions,while OM and EC(elemental carbon) exhibited different variations,with mass concentrations slightly increasing but fractions in TMC decreasing.展开更多
Atmospheric nanoparticles(PM<0.1μm)are a major cause of environmental problems and also affect health risk.To control and reduce these problems,sources identification of atmospheric particulates is necessary.Combu...Atmospheric nanoparticles(PM<0.1μm)are a major cause of environmental problems and also affect health risk.To control and reduce these problems,sources identification of atmospheric particulates is necessary.Combustion of bituminous coal and biomass includ-ing rubber wood,palm kernel,palm fiber,rice stubble,rice straw,maize residue,sugarcane leaves and sugarcane bagasse,which are considered as sources of air quality problems in many countries,was performed.Emissions of particle-bound chemical components includ-ing organic carbon(OC),elemental carbon(EC),water-soluble ions(NH4^(+),Cl^(-),NO_(3)^(-),SO_(4)^(2-)),elements(Ca,K,Mg,Na)and heavy metals(Cd,Cr,Ni,Pb)were investigated.The results re-vealed that PM<0.1μm from all samples was dominated by the OC component(>50%)with minor contribution from EC(3%-12%).The higher fraction of carbonaceous components was found in the particulates with smaller sizes,and lignin content may relate to concentration of pyrolyzed organic carbon(PyOC)resulting in the differences of OC/EC values.PM emit-ted from burning palm fiber and rice stubble showed high values of OC/EC and also high PyOC.Non-carbonaceous components such as Cl^(-),Cr,Ca,Cd,Ni,Na and Mg may be useful as source indicators,but they did not show any correlation with the size of PM.展开更多
Mixed crude palm oil (MCPO), the mixture of palm fiber oil and palm kernel oil, has become of great interest as a renewable energy source. It can be easily extracted from whole dried palm fruits. In the present work...Mixed crude palm oil (MCPO), the mixture of palm fiber oil and palm kernel oil, has become of great interest as a renewable energy source. It can be easily extracted from whole dried palm fruits. In the present work, the degummed, deacidified MCPO was blended in petroleum diesel at portions of 30% and 40% by volume and then tested in agricultural diesel engines for long term usage. The particulates from the exhaust of the engines were collected every 500 hr using a four-stage cascade air sampler. The 50% cut-off aerodynamic diameters for the first three stages were 10, 2.5 and 1μm, while the last stage collected all particles smaller than 1 μm. Sixteen particle bounded polycyclic aromatic hydrocarbons (PAHs) were analyzed using a high performance liquid chromatography. The results indicated that the size distribution of particulate matter was in the accmnulation mode and the pattern of total PAHs associated with fine-particles (〈 1 μm) showed a dominance of larger molecular weight PAHs (4--6 aromatic rings), especially pyrene. The mass median diameter, PM and total PAH concentrations decreased when increasing the palm oil content, but increased when the running hours of the engine were increased. In addition, Commercial petroleum diesel (PB0) gave the highest value of carcinogenic potency equivalent (BaPeq) for all particle size ranges. As the palm oil was increased, the; BaPeq decreased gradually. Therefore the degununed-deacidified MCPO blends are recommended for diesel substitute.展开更多
Transboundary haze from biomass burning is one of the most important air pollutions in Southeast Asia.The most recent serious haze episode occurred in 2015.Southern Thailand was affected by the haze during September t...Transboundary haze from biomass burning is one of the most important air pollutions in Southeast Asia.The most recent serious haze episode occurred in 2015.Southern Thailand was affected by the haze during September to October when the particulate matter concentration hit a record high.We investigated physical and chemical characteristics of aerosols,including concentration and aerosol size distribution down to sub-micron sizes during haze episodes in 2013 and 2015 and,for reference,an insignificant haze period in 2017.The highest total suspended particulates and PM 10 levels in Hat Yai city were 340.1 and 322.5μg/m^3.The mass fractions were nanoparticles(<100 nm)3.1%-14.8%and fine particles(<1μm)54.6%-59.1%.Polycyclic aromatic hydrocarbon size distributions in haze periods peaked at 0.75μm and the concentrations are 2-30 times higher than the normal period.High molecular weight(4-6 ring)PAHs during the haze episode contribute to about 56.7%-88.0%for nanoparticles.The average values of benzo(a)pyrene toxic equivalency quotient were 3.34±2.54ng/m^3 in the 2015 haze period but only 0.89±0.17 ng/m^3 in 2017.It is clear that particles smaller than 1μm,were highly toxic.Nanoparticles contributed 19.4%-26.0%of total BaP-TEQ,whereas the mass fraction is 13.1%-14.8%.Thus the nanoparticles were more carcinogenic and can cause greater health effect than larger particles.The fraction of BaP-TEQ for nanoparticles during 2017 non-haze period was nearly the same,while the mass fraction was lower.This indicates that nanoparticles are the significant source of carcinogenic aerosols both during haze and non-haze periods.展开更多
The characteristics of the particles of the smoke that is emitted from the burning ofbiomass fuels were experimentally investigated using a laboratory-scale tube furnace and different types of biomass fuels: rubber w...The characteristics of the particles of the smoke that is emitted from the burning ofbiomass fuels were experimentally investigated using a laboratory-scale tube furnace and different types of biomass fuels: rubber wood, whole wood pellets and rice husks. Emitted amounts of particles, particle-bound polycyclic aromatic hydrocarbons (PAHs) and water-soluble organic carbon (WSOC) are discussed relative to the size of the emitted particles, ranging to as small as nano-size (〈70 nm), and to the rate of heating rate during combustion, differential thermal analysis (DTA) and thermogravimetric analysis (TG) techniques were used to examine the effect of heating rate and biomass type on combustion behaviors relative to the characteristics of particle emissions. In the present study, more than 30% of the smoke particles from the burning ofbiomass fuel had a mass that fell within a range of 〈 100 nm. Particles smaller than 0.43 μm contributed greatly to the total levels of toxic PAHs and WSOC. The properties of these particles were influenced by the fuel component, the combustion conditions, and the particle size. Although TC--DTA results indicated that the heating rate in a range of 10-20℃did not show a significant effect on the combustion properties, there was a slight increase in the decomposition temperature as heating rate was increased. The nano-size particles had the smallest fraction of particle mass and particle-bound PAHs, but nonetheless these particles registered the largest fraction of particle-bound WSOC.展开更多
Annual and monthly-based emission inventories in northern, central and north-eastern provinces in Thailand, where agriculture and related agro-industries are very intensive,were estimated to evaluate the contribution ...Annual and monthly-based emission inventories in northern, central and north-eastern provinces in Thailand, where agriculture and related agro-industries are very intensive,were estimated to evaluate the contribution of agricultural activity, including crop residue burning, forest fires and related agro-industries on air quality monitored in corresponding provinces. The monthly-based emission inventories of air pollutants, or, particulate matter(PM), NOx and SO2, for various agricultural crops were estimated based on information on the level of production of typical crops: rice, corn, sugarcane, cassava, soybeans and potatoes using emission factors and other parameters related to country-specific values taking into account crop type and the local residue burning period. The estimated monthly emission inventory was compared with air monitoring data obtained at monitoring stations operated by the Pollution Control Department, Thailand(PCD) for validating the estimated emission inventory. The agro-industry that has the greatest impact on the regions being evaluated, is the sugar processing industry, which uses sugarcane as a raw material and its residue as fuel for the boiler. The backward trajectory analysis of the air mass arriving at the PCD station was calculated to confirm this influence. For the provinces being evaluated which are located in the upper northern, lower northern and northeast in Thailand, agricultural activities and forest fires were shown to be closely correlated to the ambient PM concentration while their contribution to the production of gaseous pollutants is much less.展开更多
This study reports on an investigation of fine and coarse carbonaceous particulate matters(PM)in Tachileik,eastern Myanmar,during the dry and wet seasons of 2022.The carbon compositions,including organic carbon(OC)and...This study reports on an investigation of fine and coarse carbonaceous particulate matters(PM)in Tachileik,eastern Myanmar,during the dry and wet seasons of 2022.The carbon compositions,including organic carbon(OC)and elemental carbon(EC),in each size(PM10-2.5,PM2.5-1.0,and PM1.0-0.5)were determined by a carbon analyzer.The average total mass concentration of the three fractions of particle samples during the dry season was higher(51.23±23.86μg/m3)than that of the wet season(14.00±5.26μg/m3).The results indicate that OC and EC levels were highest for PM1.0-0.5 during the dry season and the sizes were similar for both seasons.The OC/EC ratios varied in different seasons,from 1.93 to 4.40 and 4.13 to 5.25 in the dry and wet seasons,respectively.EC was sub-divided into char-EC and soot-EC;the char-EC/soot-EC in the dry season was higher than in the wet season,signifying that biomass burning is the main particle source during the dry season.However,vehicle emissions dominated during the wet season.The effective carbon ratio(ECR)suggested that finer particles contributed more to global warming.This information is important in terms of air quality control and mitigation in Myanmar and elsewhere.展开更多
文摘<div style="text-align:justify;"> Size-segregated of particulate matter (PM) including PM<sub>0.1</sub> at two different sites, i.e., educational (EA) and residential (RA) areas in Padang city, Indonesia were sampled by using a cascade type air sampler for 24 hours with the average flowrate 40 l/m throughout three weeks (March, 08<sup>th</sup>-25<sup>th</sup> 2018). Carbonaceous components were analyses by a carbon analyzer following the IMPROVE_TOR protocol. Average PM<sub>2.5</sub> and PM<sub>10</sub> concentrations in RA were higher than those in EA while being below the NAAQS of Indonesia. However, it was much higher compared to the WHO limit for 24 hours in RA. OC was the dominant fraction in TC. OC/EC ratio ranging from 2.4 to 33.0 was similar at both sites, suggesting the OC was emitted from various sources. Char-EC and soot-EC ratio were founded to be minimized for PM<sub>0.1</sub> (0.40 ± 0.27 and 0.39 ± 0.39, respectively at each site), indicating a more influence of burning of fossil fuel as vehicles exhaust and coal combustion. The transboundary influence of open biomass burning was not so significant although it cannot be ignored. </div>
基金supported by the Office of the Permanent Secretary,Ministry of Higher Education,Science,Research and Innovation,Thailand (Grant No.RGNS 63-253)Moreover,this research work was partially supported by JICA-JST SATREPS (Grant No.JPMJSA2102)JSPS KAKENHI 21H03618。
文摘Carbonaceous aerosols affect air quality adversely,affect global warming,and human health.However,our understanding of the impact of ultrafine(PM_(0.1))carbonaceous particulate matter is incomplete,particularly the effects during haze episodes.This study monitored diurnal variations in PM_(0.1) in Chiang Mai,Thailand,from March to April 2020.We investigated carbonaceous PM_(0.1) collected by an ambient nano-sampler and evaluated their effect by using a carbon analyzer(IMPROVE_TOR).The results showed that burning large open areas in the dry season was crucial for increasing the particle mass concentration because of the large open burnings that occurred in this area.The majority of biomass fires near the sampling site occurred during the night,which would allow more particles to be released thus resulting in higher concentrations of PM_(0.1).Hence,the release of PM_(0.1) during the night would obviously result in higher concentrations than that during the day.In the eight carbon profiles,organic carbon 3(OC3)was predicted to be a marker of biomass fires.The carbon indices displayed that PM_(0.1) was influenced by biomass burning both daytime and nighttime.The findings reported herein should be of great impor-tance in terms of establishing biomass burning control policies for mitigating heavy haze pollution in Thailand and elsewhere.
基金financially supported by Thailand Science Research and Innovation (TSRI) and Electricity Generating Authority of Thailand (EGAT) under grant number RDG60D0002supported by the Interdisciplinary Graduate School of Energy Systems,Prince of Songkla University via student scholarships under grant number IGS-Energy 1-2018/09Equipment support from the East Asia Nanoparticle Monitoring Network (EA-Nano Net)
文摘Distribution of PM_(0.1),PM_(1) and PM_(2.5) particle-and gas-polycyclic aromatic hydrocarbons(PAHs)during the 2019 normal,partial and strong haze periods at a background location in southern Thailand were investigated to understand the behaviors and carcinogenic risks.PM1 was the predominant component,during partial and strong haze periods,accounting for 45.1% and 52.9% of total suspended particulate matter,respectively,while during normal period the contribution was only 34.0%.PM_(0.1) concentrations,during the strong haze period,were approximately 2 times higher than those during the normal period.Substantially increased levels of particle-PAHs for PM_(0.1),PM_(1) and PM_(2.5) were observed during strong haze period,about 3,5 and 6 times higher than those during normal period.Gas-PAH concentrations were 10 to 36 times higher than those of particle-PAHs for PM_(2.5).Average total Benzo[a]Pyrene Toxic Equivalency Quotients(BaP-TEQ)in PM_(0.1),PM_(1) and PM_(2.5) during haze periodswere about 2–6 times higher than in the normal period.The total accumulated Incremental Lifetime Cancer Risks(ILCRs)in PM_(0.1),PM_(1) and PM_(2.5) for all the age-specific groups during the haze effected scenario were approximately 1.5 times higher than those in nonhaze scenario,indicating a higher potential carcinogenic risk.These observations suggest PM_(0.1),PM_(1) and PM_(2.5) were the significant sources of carcinogenic aerosols and were significantly affected by transboundary haze from peatland fires.This leads to an increase in the volume of smoke aerosol,exerting a significant impact on air quality in southern Thailand,as well as many other countries in lower southeast Asia.
基金supported by the National Natural Science Foundation of China (No.41175018)the Ministry of Science and Technology of China (No.2013CB955804)the special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (Nos.13Z02ESPCP and 13K04ESPCP)
文摘Size-resolved aerosols were continuously collected by a Nano Sampler for 13 days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the Nano Sampler and an ACSM(Aerodyne Aerosol Chemical Speciation Monitor) were compared. Between the data sets,similar trends and strong correlations were observed,demonstrating the validity of the Nano Sampler. PM10 and PM2.5concentrations during the measurement were 150.5 ± 96.0 μg/m3(mean ± standard variation)and 106.9 ± 71.6 μg/m3,respectively. The PM2.5/PM10 ratio was 0.70 ± 0.10,indicating that PM2.5dominated PM10. The aerosol size distributions showed that three size bins of 0.5–1,1–2.5 and 2.5–10 μm contributed 21.8%,23.3% and 26.0% to the total mass concentration(TMC),respectively. OM(organic matter) and SIA(secondary ionic aerosol,mainly SO42-,NO3-and NH4+) were major components of PM2.5. Secondary compounds(SIA and secondary organic carbon) accounted for half of TMC(about 49.8%) in PM2.5,and suggested that secondary aerosols significantly contributed to the serious particulate matter pollution observed in winter. Coal burning,biomass combustion,vehicle emissions and SIA were found to be the main sources of PM2.5. Mass concentrations of water-soluble ions and undetected materials,as well as their fractions in TMC,strikingly increased with deteriorating particle pollution conditions,while OM and EC(elemental carbon) exhibited different variations,with mass concentrations slightly increasing but fractions in TMC decreasing.
基金jointly funded by the Thailand Science Research and Innovation (TSRI) and the Electricity Generating Authority of Thailand (EGAT) under grant number RDG60D0002partially supported by the Graduate School,Prince of Songkla University,Thailandsupported by Scholarship Awards Thai PhD students under Thailand’s Education Hub for Southern Region of ASEAN Countries.
文摘Atmospheric nanoparticles(PM<0.1μm)are a major cause of environmental problems and also affect health risk.To control and reduce these problems,sources identification of atmospheric particulates is necessary.Combustion of bituminous coal and biomass includ-ing rubber wood,palm kernel,palm fiber,rice stubble,rice straw,maize residue,sugarcane leaves and sugarcane bagasse,which are considered as sources of air quality problems in many countries,was performed.Emissions of particle-bound chemical components includ-ing organic carbon(OC),elemental carbon(EC),water-soluble ions(NH4^(+),Cl^(-),NO_(3)^(-),SO_(4)^(2-)),elements(Ca,K,Mg,Na)and heavy metals(Cd,Cr,Ni,Pb)were investigated.The results re-vealed that PM<0.1μm from all samples was dominated by the OC component(>50%)with minor contribution from EC(3%-12%).The higher fraction of carbonaceous components was found in the particulates with smaller sizes,and lignin content may relate to concentration of pyrolyzed organic carbon(PyOC)resulting in the differences of OC/EC values.PM emit-ted from burning palm fiber and rice stubble showed high values of OC/EC and also high PyOC.Non-carbonaceous components such as Cl^(-),Cr,Ca,Cd,Ni,Na and Mg may be useful as source indicators,but they did not show any correlation with the size of PM.
基金supports from Prince of Songkla University(an annual research grant for fiscal years 2008-2010),the Center of Excellence for Innovation in Chemistry(PERCH-CIC),Office of the Higher Education Commission,Ministry of Education,Thailandthe Chaipattana Foundation under the support of the King of Thailand
文摘Mixed crude palm oil (MCPO), the mixture of palm fiber oil and palm kernel oil, has become of great interest as a renewable energy source. It can be easily extracted from whole dried palm fruits. In the present work, the degummed, deacidified MCPO was blended in petroleum diesel at portions of 30% and 40% by volume and then tested in agricultural diesel engines for long term usage. The particulates from the exhaust of the engines were collected every 500 hr using a four-stage cascade air sampler. The 50% cut-off aerodynamic diameters for the first three stages were 10, 2.5 and 1μm, while the last stage collected all particles smaller than 1 μm. Sixteen particle bounded polycyclic aromatic hydrocarbons (PAHs) were analyzed using a high performance liquid chromatography. The results indicated that the size distribution of particulate matter was in the accmnulation mode and the pattern of total PAHs associated with fine-particles (〈 1 μm) showed a dominance of larger molecular weight PAHs (4--6 aromatic rings), especially pyrene. The mass median diameter, PM and total PAH concentrations decreased when increasing the palm oil content, but increased when the running hours of the engine were increased. In addition, Commercial petroleum diesel (PB0) gave the highest value of carcinogenic potency equivalent (BaPeq) for all particle size ranges. As the palm oil was increased, the; BaPeq decreased gradually. Therefore the degununed-deacidified MCPO blends are recommended for diesel substitute.
基金This research was financially supported by Biodiversitybased Economy Development Office of Thailand under grant#ENG590707S.
文摘Transboundary haze from biomass burning is one of the most important air pollutions in Southeast Asia.The most recent serious haze episode occurred in 2015.Southern Thailand was affected by the haze during September to October when the particulate matter concentration hit a record high.We investigated physical and chemical characteristics of aerosols,including concentration and aerosol size distribution down to sub-micron sizes during haze episodes in 2013 and 2015 and,for reference,an insignificant haze period in 2017.The highest total suspended particulates and PM 10 levels in Hat Yai city were 340.1 and 322.5μg/m^3.The mass fractions were nanoparticles(<100 nm)3.1%-14.8%and fine particles(<1μm)54.6%-59.1%.Polycyclic aromatic hydrocarbon size distributions in haze periods peaked at 0.75μm and the concentrations are 2-30 times higher than the normal period.High molecular weight(4-6 ring)PAHs during the haze episode contribute to about 56.7%-88.0%for nanoparticles.The average values of benzo(a)pyrene toxic equivalency quotient were 3.34±2.54ng/m^3 in the 2015 haze period but only 0.89±0.17 ng/m^3 in 2017.It is clear that particles smaller than 1μm,were highly toxic.Nanoparticles contributed 19.4%-26.0%of total BaP-TEQ,whereas the mass fraction is 13.1%-14.8%.Thus the nanoparticles were more carcinogenic and can cause greater health effect than larger particles.The fraction of BaP-TEQ for nanoparticles during 2017 non-haze period was nearly the same,while the mass fraction was lower.This indicates that nanoparticles are the significant source of carcinogenic aerosols both during haze and non-haze periods.
基金supported by KAKENHI (No.22710073) from the Japan Society for the Promotion of Science (JSPS)the JENESYS Program of the Japan Student Services Organization (JASSO)
文摘The characteristics of the particles of the smoke that is emitted from the burning ofbiomass fuels were experimentally investigated using a laboratory-scale tube furnace and different types of biomass fuels: rubber wood, whole wood pellets and rice husks. Emitted amounts of particles, particle-bound polycyclic aromatic hydrocarbons (PAHs) and water-soluble organic carbon (WSOC) are discussed relative to the size of the emitted particles, ranging to as small as nano-size (〈70 nm), and to the rate of heating rate during combustion, differential thermal analysis (DTA) and thermogravimetric analysis (TG) techniques were used to examine the effect of heating rate and biomass type on combustion behaviors relative to the characteristics of particle emissions. In the present study, more than 30% of the smoke particles from the burning ofbiomass fuel had a mass that fell within a range of 〈 100 nm. Particles smaller than 0.43 μm contributed greatly to the total levels of toxic PAHs and WSOC. The properties of these particles were influenced by the fuel component, the combustion conditions, and the particle size. Although TC--DTA results indicated that the heating rate in a range of 10-20℃did not show a significant effect on the combustion properties, there was a slight increase in the decomposition temperature as heating rate was increased. The nano-size particles had the smallest fraction of particle mass and particle-bound PAHs, but nonetheless these particles registered the largest fraction of particle-bound WSOC.
基金supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI,253030003
文摘Annual and monthly-based emission inventories in northern, central and north-eastern provinces in Thailand, where agriculture and related agro-industries are very intensive,were estimated to evaluate the contribution of agricultural activity, including crop residue burning, forest fires and related agro-industries on air quality monitored in corresponding provinces. The monthly-based emission inventories of air pollutants, or, particulate matter(PM), NOx and SO2, for various agricultural crops were estimated based on information on the level of production of typical crops: rice, corn, sugarcane, cassava, soybeans and potatoes using emission factors and other parameters related to country-specific values taking into account crop type and the local residue burning period. The estimated monthly emission inventory was compared with air monitoring data obtained at monitoring stations operated by the Pollution Control Department, Thailand(PCD) for validating the estimated emission inventory. The agro-industry that has the greatest impact on the regions being evaluated, is the sugar processing industry, which uses sugarcane as a raw material and its residue as fuel for the boiler. The backward trajectory analysis of the air mass arriving at the PCD station was calculated to confirm this influence. For the provinces being evaluated which are located in the upper northern, lower northern and northeast in Thailand, agricultural activities and forest fires were shown to be closely correlated to the ambient PM concentration while their contribution to the production of gaseous pollutants is much less.
文摘This study reports on an investigation of fine and coarse carbonaceous particulate matters(PM)in Tachileik,eastern Myanmar,during the dry and wet seasons of 2022.The carbon compositions,including organic carbon(OC)and elemental carbon(EC),in each size(PM10-2.5,PM2.5-1.0,and PM1.0-0.5)were determined by a carbon analyzer.The average total mass concentration of the three fractions of particle samples during the dry season was higher(51.23±23.86μg/m3)than that of the wet season(14.00±5.26μg/m3).The results indicate that OC and EC levels were highest for PM1.0-0.5 during the dry season and the sizes were similar for both seasons.The OC/EC ratios varied in different seasons,from 1.93 to 4.40 and 4.13 to 5.25 in the dry and wet seasons,respectively.EC was sub-divided into char-EC and soot-EC;the char-EC/soot-EC in the dry season was higher than in the wet season,signifying that biomass burning is the main particle source during the dry season.However,vehicle emissions dominated during the wet season.The effective carbon ratio(ECR)suggested that finer particles contributed more to global warming.This information is important in terms of air quality control and mitigation in Myanmar and elsewhere.