Black carbon(BC)is associated with adverse human health and climate change.Mapping BC spatial distribution imperatively requires low-cost and portable devices.Several portable BC monitors are commercially available,bu...Black carbon(BC)is associated with adverse human health and climate change.Mapping BC spatial distribution imperatively requires low-cost and portable devices.Several portable BC monitors are commercially available,but their accuracy and reliability are not always satisfactory during continuous field observation.This study evaluated three models of portable black carbon monitors,C12,MA350 and DST,and investigates the factors that affect their performance.The monitors were tested in urban Beijing,where portable devices running for one month alongside a regular-size reference aethalometer AE33.The study considers several factors that could influence the monitors'performance,including ambient weather,aerosol composition,loading artifacts,and built-in algorithms.The results show that MA350and DST present considerable discrepancies to the reference instrument,mainly occurring at lower concentrations(0-500 ng/m^(3))and higher concentrations(2500-8000 ng/m^(3)),respectively.These discrepancies were likely caused by the anomalous noise of MA350 and the loading artifacts of DST.The study also suggests that the ambient environment has limited influence on the monitors'performance,but loading artifacts and accompanying compensation algorithms can result in unrealistic data.Based on the evaluation,the study suggests that C12 is the best choice for unsupervised field measurement,DST should be used in scenarios where frequent maintenance is available,and MA350 is suitable for research purposes with post-processing applicable.The study highlights the importance of assigning portable BC monitors to appropriate applications and the need for optimized real-time compensation algorithms.展开更多
To investigate the cause of fine particulate matter(particles with an aerodynamic diameter less than 2.5 um,PM2.5) pollution in the heating season in the North China Plain(specifically Beijing,Tianjin,and Langfang),wa...To investigate the cause of fine particulate matter(particles with an aerodynamic diameter less than 2.5 um,PM2.5) pollution in the heating season in the North China Plain(specifically Beijing,Tianjin,and Langfang),water-soluble ions and carbonaceous components in PM2.5were simultaneously measured by online instruments with 1-hr resolution,from November 15,2016 to March 15,2017.The results showed extreme severity of PM2.5 pollution on a regional scale.Secondary inorganic ions(SNA,i.e.,NO3-+So42+NH4+) dominated the water-soluble ions,accounting for 30%-40% of PM2.5,while the total carbon(TC,i.e.,OC+EC) contributed to 26.5%-30.1% of PM2.5 IN the three cities.SNA were mainly responsible for the increasing PM2.5 pollution compared with organic matter(OM).NO3-was the most abundant species among water-soluble ions,but SO42- played a much more important role in driving the elevated PM2.5 concentrations.The relative humidity(RH) and its precursor SO2 were the key factors affecting the formation of sulfate.Homogeneous reactions dominated the formation of nitrate which was mainly limited by HNO3 in ammonia-rich conditions.Secondary formation and regional transport from the heavily polluted region promoted the growth of PM2.5 concentrations in the formation stage of PM2.5 pollution in Beijing and Langfang.Regional transport or local emissions,along with secondary formation,made great contributions to the PM2.5 pollution in the evolution stage of PM2.5 pollution in Beijing and Langfang.The favourable meteorological conditions and regional transport from a relatively clean region both favored the diffusion of pollutants in all three cities.展开更多
基金supported by the National Natural Science Foundation of China(No.42075182)。
文摘Black carbon(BC)is associated with adverse human health and climate change.Mapping BC spatial distribution imperatively requires low-cost and portable devices.Several portable BC monitors are commercially available,but their accuracy and reliability are not always satisfactory during continuous field observation.This study evaluated three models of portable black carbon monitors,C12,MA350 and DST,and investigates the factors that affect their performance.The monitors were tested in urban Beijing,where portable devices running for one month alongside a regular-size reference aethalometer AE33.The study considers several factors that could influence the monitors'performance,including ambient weather,aerosol composition,loading artifacts,and built-in algorithms.The results show that MA350and DST present considerable discrepancies to the reference instrument,mainly occurring at lower concentrations(0-500 ng/m^(3))and higher concentrations(2500-8000 ng/m^(3)),respectively.These discrepancies were likely caused by the anomalous noise of MA350 and the loading artifacts of DST.The study also suggests that the ambient environment has limited influence on the monitors'performance,but loading artifacts and accompanying compensation algorithms can result in unrealistic data.Based on the evaluation,the study suggests that C12 is the best choice for unsupervised field measurement,DST should be used in scenarios where frequent maintenance is available,and MA350 is suitable for research purposes with post-processing applicable.The study highlights the importance of assigning portable BC monitors to appropriate applications and the need for optimized real-time compensation algorithms.
基金supported by the National Natural Science Foundation of China(No.91544226)the National Key Research and Development Plan of China(Nos.2017YFC0209503 and 2016YFC0206202)+1 种基金the National Research Program for Key Issues in Air Pollution Control in China(No.DQGG0107-03)the financial support from CSC(Chinese Scholorship Council)
文摘To investigate the cause of fine particulate matter(particles with an aerodynamic diameter less than 2.5 um,PM2.5) pollution in the heating season in the North China Plain(specifically Beijing,Tianjin,and Langfang),water-soluble ions and carbonaceous components in PM2.5were simultaneously measured by online instruments with 1-hr resolution,from November 15,2016 to March 15,2017.The results showed extreme severity of PM2.5 pollution on a regional scale.Secondary inorganic ions(SNA,i.e.,NO3-+So42+NH4+) dominated the water-soluble ions,accounting for 30%-40% of PM2.5,while the total carbon(TC,i.e.,OC+EC) contributed to 26.5%-30.1% of PM2.5 IN the three cities.SNA were mainly responsible for the increasing PM2.5 pollution compared with organic matter(OM).NO3-was the most abundant species among water-soluble ions,but SO42- played a much more important role in driving the elevated PM2.5 concentrations.The relative humidity(RH) and its precursor SO2 were the key factors affecting the formation of sulfate.Homogeneous reactions dominated the formation of nitrate which was mainly limited by HNO3 in ammonia-rich conditions.Secondary formation and regional transport from the heavily polluted region promoted the growth of PM2.5 concentrations in the formation stage of PM2.5 pollution in Beijing and Langfang.Regional transport or local emissions,along with secondary formation,made great contributions to the PM2.5 pollution in the evolution stage of PM2.5 pollution in Beijing and Langfang.The favourable meteorological conditions and regional transport from a relatively clean region both favored the diffusion of pollutants in all three cities.
