Carbonaceous aerosols in PM_(10) and pollution gases in winter in Beijing

An intensive observation of organic carbon （OC） and element carbon （EC） in PM10 and gaseous materials （SO2, CO, and O3,） was conducted continuously to assess the characteristics of wintertime carbonaceous aerosols in an urban area of Beijing, China. Results showed that the averaged total carbon （TC） and PM10 concentrations in observation period are 30.2±120.4 and 172.6±198.3 μ/m^3 respectively. Average OC concentration in nighttime （24.9±19.6 μ/m^3 was 40% higher than that in daytime （17.7±10.9 μ/m^3. Average EC concentrations in daytime （8.8±15.2 μ/m^3 was close to that in nighttime （8.9±15.1 μ/m^3. The OC/EC ratios in nighttime ranging from 2.4 to 2.7 are higher than that in daytime ranging from 1.9 to 2.0. The concentrations of OC, EC, PM10 were low with strong winds and high with weak winds. The OC and EC were well correlated with PM10, CO and SO2, which implies they have similar sources. OC and EC were not well correlated with O3. By considering variation of OC/EC ratios in daytime and night time, correlations between OC and O3, and meteorological condition, we speculated that OC and EC in Beijing PM10 were emitted as the primary particulate form. Emission of motor vehicle with low OC/EC ratio and coal combustion sources with high OC/EC ratio are probably the dominant sources for carbonaceous aerosols in Beijing in winter. A simple method was used to estimate the relative contribution of sources to carbonaceous aerosols in Beijing PM10. Motor vehicle source accounts for 80% and 68%, while coal combustion accounts for 20% and 32% in daytime and nighttime, respectively in Beijing. Averagely, the motor vehicle and coal combustion accounted for 74% and 26%, respectively, for carbonaceous aerosols during the observation period. It points to the motor vehicle is dominant emission for carbonaceous aerosols in Beijing PM10 in winter period, which should be paid attention to control high level of PM10 in Beijing effectively.

A Modeling Study of the Climate Effects of Sulfate and Carbonaceous Aerosols over China

In this paper, the RIEMS 2.0 model is used to simulate the distribution of sulfate, black carbon, and organic carbon aerosols over China （16.2°-44.1°N, 93.4°-132.4°E） in 1998. The climate effects of these three anthropogenic aerosols are also simulated. The results are summarized as follows： （1） The regional average column burdens of sulfate, BC, OC, and SOC were 5.9, 0.24, 2.4, and 0.49 mg m-2, with maxima of 33.9, 1.48, 7.3, and 1.1 mg m-2, respectively. The column burden and surface concentration of secondary organic carbon accounted for about 20% and 7%, respectively, of the total organic carbon in eastern China. （2） The radiative forcings of sulfate, organic carbon, and black carbon at the top of the atmosphere were -1.24, -0.6, and 0.16 W m 2 respectively, with extremes of -5.25, -2.6, and 0.91 W m-2. （3） The surface air temperature changes caused by sulfate, organic carbon, and black carbon were -0.07, -0.04, and 0.01 K, respectively. The air temperature increase caused by black carbon at 850 hPa was higher than that at the surface. The net effect of the three kinds of anthropogenic aerosols together decreased the annual average temperature by -0.075 K; the maximum value was -0.3 K. （4） Black carbon can reduce the precipitation in arid and semi-arid areas of northern China and increase the precipitation in wet and semi-wet areas of southern China. The average precipitation increase caused by black carbon in China was 0.003 mm d^-1. The net effect of the three kinds of anthropogenic aerosols was to decrease the precipitation over China by 0.008 mmd ^-1.

Temporal Variability in Fine Carbonaceous Aerosol over Two Years in Two Megacities:Beijing and Toronto

Time-series of weekly total carbon （TC） concentrations of fine aerosol particles （PM2.5） in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August 2001 through July 2003. In addition to this comparison, differences in the factors contributing to the observed concentrations and their temporal variations are discussed. Based upon past knowledge about the two megacities with highly contrasting air pollutant levels, it is not surprising that the average TC concentration in Belling （31.5 μg C m^-3） was greater than that in Toronto by a factor of 8.3. Despite their large concentration differences, in both cities TC comprised a similarly large component of PM2.5. TC concentrations exhibited very different seasonal patterns between the two cities. In Beijing, TC experienced higher levels and greater weekly fluctuations in winter whereas in Toronto this behavior was seen in summer. As a result, the greatest gap in TC concentrations between Beijing and Toronto （by a factor of 12.7） occurred in winter, while the smallest gap （a factor of 4.6） was in summer. In Beijing, seasonal variations in the emissions probably played a greater role than meteorology in influencing the TC seasonality, while in Toronto during the warm months more than 80% of the hourly winds were recorded from the south, along with many potential anthropogenic sources for the days with high TC concentrations. This comparison of the differences provides insight into the major factors affecting carbonaceous aerosol in each city.

Chemical Characteristics of Carbonaceous Aerosols During Dust Storms over Xi'an in China

Characterization of carbonaceous aerosols including CC （carbonate carbon）, OC （organic carbon）, and EC （elemental carbon） were investigated at Xi＇an, China, near Asian dust source regions in spring 2002. OC varied between 8.2 and 63.7μgm^- 3, while EC ranged between 2.4 and 17.2 μ m^-3 during the observation period. OC variations followed a similar pattern to EC and the correlation coefficient between OC and EC is 0.89 （n=31）. The average percentage of total carbon （TC, sum of CC, OC, and EC） in PM2.5 during dust storm （DS） events was 13.6%, which is lower than that during non-dust storm （NDS） periods （22.7%）. CC, OC, and EC accounted for 12.9%, 70.7%, and 16.4% of TC during DS events, respectively. The average ratio of OC/EC was 5.0 in DS events and 3.3 in NDS periods. The OC-EC correlation （R^2=0.76, n=6） was good in DS events, while it was stronger （R^2=0.90, n=25） in NDS periods. The percentage of watersoluble OC （WSOC） in TC accounted for 15.7%, and varied between 13.3% and 22.3% during DS events. The distribution of eight carbon fractions indicated that local emissions such as motor vehicle exhaust were the dominant contributors to carbonaceous particles. During DS events, soil dust dominated the chemical composition, contributing 69% to the PM2.5 mass, followed by organic matter （12.8%）, sulfate （4%）, EC （2.2%）, and chloride （1.6%）. Consequently, CC was mainly entrained by Asian dust. However, even in the atmosphere near Asian dust source regions, OC and EC in atmospheric dust were controlled by local emission rather titan the transport of Asian dust.

Characteristics of Anthropogenic Sulfate and Carbonaceous Aerosols over East Asia: Regional Modeling and Observation

The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon （BC） and organic carbon compounds （OC）, including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion （especially in the aqueous phase） and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition （60%） and export （27%） being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition （60%） and export （30%）. The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.

Organic and Elemental Carbon in Atmospheric Fine Particulate Matter in an Animal Agriculture Intensive Area in North Carolina: Estimation of Secondary Organic Carbon Concentrations

Carbonaceous components contribute significant fraction of fine particulate matter (PM2.5). Study of organic carbon (OC) and elemental carbon (EC) in PM2.5 may lead to better understanding of secondary organic carbon (SOC) formation. This year-long (December 2008 to December 2009) field study was conducted in an animal agriculture intensive area in North Carolina of United States. Samples of PM2.5 were collected from five stations located in an egg production facility and its vicinities. Concentrations of OC/EC and thermograms were obtained using a thermal-optical carbon analyzer. Average levels of OC in the egg production house and at ambient stations were 42.7 μg/m3 and 3.26 - 3.47 μg/m3, respectively. Average levels of EC in the house and at ambient stations were 1.14 μg/m3 and 0.36 - 0.42 μg/m3, respectively. The OC to total carbon (TC) ratios at ambient stations exceeded 0.67, indicating a significant fraction of SOC presented in PM2.5. Principal factor analysis results suggested that possible major source of in-house PM2.5 was from poultry feed and possible major sources of ambient PM2.5 was from contributions of secondary inorganic and organic PM. Using the OC/EC primary ratio analysis method, ambient stations SOC fractions ranged from 68% to 87%. These findings suggested that SOC could appreciably contribute to total PM2.5 mass concentrations in this agriculture intensive area.

SIMULATION OF SPATIO-TEMPORAL DISTRIBUTION CHARACTERISTICS AND RADIATIVE FORCING OF ORGANIC CARBON AEROSOLS IN CHINA

The International Centre for Theoretical Physics(ICTP,Italy) Regional Climate Model version 3.0(RegCM3) is used to simulate spatio-temporal distribution characteristics and radiative forcing(RF) of organic carbon(OC) aerosols in and around China.The preliminary simulation results show that OC aerosols are mostly concentrated in the area to the south of Yellow River and east of Tibetan Plateau.There is a decreasing trend of column burden of OC aerosols from south to north in China.The maximum value of column burden of OC aerosols is above 3 mg/m2 and located in the central and southern China,southeastern Tibet,and southwestern China's Yunnan,Guizhou,Sichuan provinces.The simulation on the seasonal variation shows that the maximum value of column burden of OC aerosols appears in winter and the secondary value is in spring and the minimum in summer.The RF of OC aerosols which varies seasonally is negative at the top of the atmosphere(TOA) and surface.The spatio-temporal characteristics of the RF of OC aerosols are basically consistent with that of IPCC,implying the high accuracy of the parameterization scheme for OC aerosols in RegCM3.

Determining the environmental and atmospheric effects of coronavirus disease 2019(COVID-19)quarantining by studying the total aerosol optical depth,black carbon,organic matter,and sulfate in Blida City of Algeria

Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.

Characteristics of carbonaceous aerosol in a two-week campaign at Ny-Alesund

The concentrations of organic carbon （OC） and elemental carbon （EC） in total suspended particle （TSP） were investigated at Ny-Alesund, Svalbard in a two-week campaign. The levels of PC and EC are 0.86±0. 27μm^-3 （mean± standard deviation） and 0. 19±0.10 μm^-3 , respectively. Back trajectory analysis of air masses arriving at Ny-Alesund reveals that long-range transport of pol- luted air play insignificant role in PC and EC levels, to which the potential influ- ence of the local contamination were ascribed. The average OC/EC ratio is 5.41, suggesting the presence of the secondary organic aerosols. The estimated secondary organic carbon （SOC） in TSP is 0.59μg/m^3 , accounting for 64% of the total organic carbon.

Seasonal variation of atmospheric elemental carbon aerosols at Zhongshan Station,East Antarctica

Elemental carbon(or black carbon)(EC or BC)aerosols emitted by biomass burning and fossil fuel combustion could cause notable climate forcing.Southern Hemisphere biomass burning emissions have contributed substantially to EC deposition in Antarctica.Here,we present the seasonal variation of EC determined from aerosol samples acquired at Zhongshan Station(ZSS),East Antarctica.The concentration of EC in the atmosphere varied between 0.02 and 257.81 ng·m^(-3)with a mean value of 44.87±48.92 ng·m^(-3).The concentration of EC aerosols reached its peak in winter(59.04 ng·m^(-3))and was lowest(27.26 ng·m^(-3))in summer.Back trajectory analysis showed that biomass burning in southern South America was the major source of the EC found at ZSS,although some of it was derived from southern Australia,especially during winter.The 2019–2020 Australian bush fires had some influence on EC deposition at ZSS,especially during 2019,but the contribution diminished in 2020,leaving southern South America as the dominant source of EC.

Characteristics of Carbonaceous Particles in Beijing During Winter and Summer 2003

Campaigns were conducted to measure Organic Carbon （OC） and Elemental Carbon （EC） in PM2.5 during winter and summer 2003 in Beijing. Modest differences of PM2.5 and PM10 mean concentrations were observed between the winter and summer campaigns. The mean PM2.5/PM10 ratio in both seasons was around 60%, indicating PM2.5 contributed significantly to PM10. The mean concentrations of OC and EC in PM2.5 were 11.2±7.5 and 6.0±5.0 μg m^-3 for the winter campaign, and 9.4±2.1 and 4.3±3.0 μg m^-3 for the summer campaign, respectively. Diurnal concentrations of OC and EC in PM2.5 were found high at night and low during the daytime in winter, and characterized by an obvious minimum in the summer afternoon. The mean OC/EC ratio was 1.87±0.09 for winter and 2.39±0.49 for summer. The higher OC/EC ratio in summer indicates some formation of Secondary Organic Carbon （SOC）. The estimated SOC was 2.8 μg m^-3 for winter and 4.2 μg m^-3 for summer.

Measurement of Atmospheric Black Carbon Concentration in Rural and Urban Environments: Cases of Lamto and Abidjan

Black carbon is one of the primary aerosols directly emitted from biomass known to have strong absorbing properties. The INDAAF and PASMU observational field campaigns which took place (2018) in Abidjan (urban area) and Lamto (rural area) allow the analysis of Black carbon concentration at different time scales through real-time measurements using an analyzer named Aethalometer AE-33. Results presented here show at Lamto: 1) for the diurnal scale an average of 1.71 ± 0.3 μg⋅m-3 (0.34 ± 0.09 μg⋅m-3) in the dry (wet) season;2) for the monthly scale an average of 1.14 ± 0.84 μg⋅m-3;3) on the seasonal scale, an average of 2.2 ± 0.02 μg⋅m-3 (0.6 ± 0.19 μg⋅m-3) in the dry (wet) season. The black carbon variation at Lamto is seasonal with an amplification factor of 85.6. Regarding the urban area of Abidjan, due to sampling issues, our analyses were limited to daily, diurnal and weekly time scales. We observed: a) at a daily scale an average of 5.31.± 2.5 μg⋅m-3, b) diurnal scale, an average ranging from 6.87 to 13.92 μg⋅m-3. The analysis indicated that emissions from urban areas are more related to social and economic activities, with weekday concentrations (7.24 μg⋅m-3) higher than concentrations over the weekend (e.g. Saturday 6.59 μg⋅m-3 and Sunday 6.00 μg⋅m-3). Moreover, BC concentration in Abidjan is quite noticeable compared to that of rural areas (Lamto). The ratio between the maximum values of the two areas is of the order of 5.86. In addition, concentrations in some urban areas are slightly above the daily threshold set by the WHO (10 μg⋅m-3). Therefore, the levels of urban BC concentrations are alarming whilst rural BC concentrations remain below daily WHO thresholds and are of the same magnitude as those of West African megacities. This study underlies that BC concentrations at Lamto are mainly related to biomass combustion sources while those from urban areas are related to traffic sources. The latter is permanently active, unlike those in rural Lamto, which is seasonal.

Carbonaceous aerosol transport from the Indo-Gangetic Plain to the Himalayas:Carbon isotope evidence and light absorption characteristics

The Indo-Gangetic Plain(IGP)is a major regional and global emitter of atmospheric pollutants,which adversely affect surrounding areas such as the Himalayas.We present a comprehensive dataset on carbonaceous aerosol(CA)composition,radiocarbon(D14C)-based source apportionment,and light absorption of total suspended particle(TSP)samples collected over a 3-year period from high-altitude Jomsom in the central Himalayas.The 3-year mean TSP,organic carbon(OC),and elemental carbon(EC)concentrations were 92.0±28.6,9.74±6.31,and 2.02±1.35 lg m^(3),respectively,with the highest concentrations observed during the pre-monsoon season,followed by the post-monsoon,winter,and monsoon seasons.The △^(14)C analysis revealed that the contribution of fossil fuel combustion(ffossil)to EC was 47.9%±11.5%,which is consistent with observations in urban and remote regions in South Asia and attests that EC likely arrives in Jomsom from upwind IGP sources via long-range transport.In addition,the lowest f_(fossil)(38.7%±13.3%)was observed in winter,indicating large contributions in this season from local biomass burning.The mass absorption cross-section of EC(MACEC:8.27±1.76 m^(2)/g)and watersoluble organic carbon(MACWSOC:0.98±0.45 m^(2)/g)were slightly higher and lower than those reported in urban regions,respectively,indicating that CA undergo an aging process.Organic aerosol coating during transport and variation of biomass burning probably led to the seasonal variation in MAC of two components.Overall,WSOC contributed considerably to the light absorption(11.1%±4.23%)of EC.The findings suggest that to protect glaciers of the Himalayas from pollution-related melting,it is essential to mitigate emissions from the IGP.

第十四届全运会大气污染物减排措施对西安市气溶胶中水溶性离子和含碳组分的影响

人为源密集的城市是空气污染影响的主要区域,厘清城市地区排放源的变化与大气污染物浓度之间的影响作用机制,有助于协调我国大气污染防控与城市社会经济发展之间的关系。为研究第十四届全运会期间大气污染物减排措施对西安市大气污染物(PM_(2.5)、PM_(10)、SO_(2)、NO_(2)、O_(3)和CO)的影响,于2021年8月6日至10月1日使用在线监测仪器观测了环境六要素、气象要素和PM_(2.5)中的气溶胶化学组分(有机碳、元素碳和水溶性离子)。结果表明:大气污染物减排措施对主要污染物O_(3)和PM_(2.5)浓度日变化的影响不同,主要由温度对光化学过程的影响和扩散条件差异导致。O_(3)在减排措施实施期间晴天峰值浓度更高、持续时间更长、浓度变化更迅速。PM_(2.5)在减排措施实施前晴天白天的峰值浓度较高,并在减排措施实施期间晴天夜间的峰值浓度较高。大气污染物减排措施对PM_(2.5)中化学组分的影响不同,尤其是对有机碳的组成影响较大。与减排措施实施前晴天相比,减排措施实施期间晴天NO_(3)^(-)、SO_(4)^(2-)、NH_(4)^(+)、Cl^(-)、Ca^(2+)、Na^(+)和NO_(2)^(-)浓度降低了17.9%~71.8%,K^(+)、Mg^(2+)和元素碳浓度增加了1.9%~13.6%,有机碳浓度仅降低了1.0%,但是一次有机碳浓度增加了13.6%,二次有机碳浓度降低了4.7%。NO_(3)^(-)/SO_(4)^(2-)值在减排措施实施期间晴天(0.53)远低于减排措施实施前晴天(1.66),表明减排措施实施期间交通源的贡献显著降低。降雨对NO_(3)^(-)和NH_(4)^(+)的清除较弱,反而会增加其浓度,但对K^(+)、Mg^(2+)、Ca^(2+)和Na+的清除作用较强。NO_(3)^(-)、SO_(4)^(2-)和NH_(4)^(+)在减排措施实施前后均是水溶性离子最重要的组成,在水溶性离子中的占比为90.8%(减排措施实施前的晴天)~95.8%(减排措施实施期间的雨天)。二次有机碳是有机碳的主要组成,占比为75.5%(减排措施实施期间的雨天)~79.9%(减排措施实施前的晴天)。不同阶段的水溶性离子和含碳气溶胶浓度日变化特征不同。NO_(3)^(-)、SO_(4)^(2-)和NH_(4)^(+)浓度晴天的日变化为单峰型分布,雨天为多峰型分布。

拉萨市夏季含碳气溶胶的浓度水平与组成特征研究

利用颗粒物采样器采集拉萨市夏季(2021年8月30日~2021年9月23日)大气细颗粒物(PM_(2.5))样品,并对不同含碳气溶胶组分进行测定和探讨。根据碳组分挥发性的强弱,将有机碳(OC)分为易挥发组分(HOC)、中等挥发组分(MOC)和难挥发组分(LOC),元素碳(EC)分为焦碳(char)和烟炱(soot)。结果显示,拉萨市夏季大气环境白天OC和EC的平均浓度分别为4.39±0.98μg/m^(3)和1.09±0.69μg/m^(3),夜晚OC和EC的平均浓度分别为4.39±1.43μg/m^(3)和1.17±0.57μg/m^(3)。系统比较OC/EC和char/soot源示踪指标在源辨识上的差异,发现char/soot值比OC/EC值可以更准确地识别关键排放源对含碳气溶胶的影响,说明char/soot值是一个可靠的源解析工具。本研究测定的char/soot平均值为0.20,符合机动车尾气污染特征,远小于生物质燃烧和煤炭燃烧特征值,说明拉萨夏季大气环境主要受机动车尾气排放影响。LOC是拉萨夏季含碳气溶胶最丰富的OC组分,在所有碳组分中的占比为47.7%,其次为MOC(18.2%)和HOC(10.8%)。不同碳组分之间的相关性分析表明,HOC主要通过大气化学反应生成,未来可成为评估二次有机气溶胶的一个潜在指标。

西安市燃煤锅炉颗粒物中有机碳和元素碳的排放特征研究

燃煤锅炉是城市地区含碳气溶胶的重要来源之一,本研究采集分析了西安市9个燃煤锅炉的PM_(10)和PM_(2.5)样品中的有机碳(OC)和元素碳(EC)。结果表明:燃煤锅炉颗粒物中OC在PM_(2.5)中的质量占比高于在PM_(10)中质量占比,而EC在PM_(10)中的质量占比高于在PM_(2.5)中质量占比。OC、EC和总碳气溶胶(TC)在PM_(10)中的质量占比分别为4.35%±1.09%、4.25%±1.02%和8.60%±1.87%,在PM_(2.5)中的质量占比分别为6.91%±1.09%、2.62%±0.41%和9.53%±1.40%。不同锅炉类型的OC/EC(二者浓度比)差异较大。链条炉、循环流化床和煤粉炉的OC/EC在PM_(10)中分别为1.50±0.96、0.89±1.06和12.03±8.48,在PM_(2.5)中分别为6.72±5.70、1.19±0.65和11.62±5.83。不同锅炉排放的PM_(10)和PM_(2.5)中含碳气溶胶的主导成分不同,通过含碳气溶胶的成分组成可以准确区分锅炉排放来源。PM_(10)中TC和EC的质量占比均呈链条炉(10.64%±5.13%和5.79%±4.78%)>循环流化床(7.25%±2.23%和4.15%±1.14%)>煤粉炉(4.85%±1.84%和0.50%±0.25%),OC的质量占比呈链条炉(4.85%±2.33%)>煤粉炉(4.35%±2.09%)>循环流化床(3.10%±3.37%)。PM_(2.5)中TC和OC的质量占比均呈链条炉(12.97%±5.57%和9.25%±5.63%)>煤粉炉(5.57%±1.86%和5.02%±1.79%)>循环流化床(4.92%±5.41%和2.94%±3.53%),EC的质量占比呈链条炉(3.71%±3.84%)>循环流化床(1.97%±1.88%)>煤粉炉(0.55%±0.07%)。不同锅炉类型对PM_(10)中的EC影响较大,对PM_(2.5)中的OC影响较大,主要是由于不同类型锅炉燃煤燃烧方式和燃烧效率差异所致。

乌鲁木齐市PM_(2.5)中碳组分污染特征及来源解析

为研究乌鲁木齐市主要大气污染物PM_(2.5)中的碳组分的浓度、污染特征及来源,于2023年7月3日—12月31日在市区按照监测规范采集PM_(2.5)样品,并按照实验规程进行分析。结果表明:(1)乌鲁木齐市PM_(2.5)的平均浓度为20.1±8.1μg·m^(-3),有机碳(OC)和元素碳(EC)的平均浓度分别为:3.2±1.0μg·m^(-3)和0.6±0.2μg·m^(-3),数值上呈现出采暖期大于非采暖期的趋势。(2)各时段OC和EC均呈现出较好的相关性,表明OC和EC具有相似的来源。(3)通过估算得到总碳气溶胶(TCA)浓度均值为7.52±3.66μg·m^(-3),占PM_(2.5)浓度比重约为16%;而二次有机碳SOC浓度为2.11±1.43μg·m^(-3),且SOC/OC比值为47.47%±12.69%,表明乌鲁木齐市大气中二次有机碳(SOC)占OC的比重接近50%。(4)通过主成分分析得出,PM_(2.5)中碳组分主要来源于燃煤排放和机动车尾气的排放。综合来看,采暖期大气环境污染依然严峻。

汾河平原城市秋冬季PM_(2.5)中碳质组分特征及来源解析

碳质组分是PM_(2.5)中的重要组成部分,对气溶胶辐射强迫、全球温室效应、能见度和人体健康等方面都有重要影响,因此对其特征及来源进行分析具有重要意义.本研究以汾河平原城市为研究对象,采集2020年11月—2021年1月PM_(2.5)样品,采用热/光分析仪分析PM_(2.5)中的碳质组分,并通过PMF模型对该地区碳质组分的来源进行解析.结果表明,采样期间PM_(2.5)浓度较高的为晋中(82.1μg·m^(-3)),运城(79.6μg·m^(-3))和临汾(74.4μg·m^(-3));有机碳(OC)浓度较高的为运城(11.2μg·m^(-3))和临汾(11.0μg·m^(-3)),元素碳(EC)浓度较高的为晋中(6.0μg·m^(-3))和运城(4.7μg·m^(-3)).各城市二次有机碳(SOC)浓度较高的为运城(3.0μg·m^(-3)),三门峡(2.5μg·m^(-3))和临汾(2.5μg·m^(-3)),但三门峡(40.3%)和吕梁(32.4%)的SOC占OC比例较高.相关性分析表明,采样期间汾河平原城市的OC、EC和SOC与污染物SO_(2)、NO_(2)和CO浓度呈显著正相关,说明采样期间汾河平原城市受到燃煤、工业以及机动车排放的影响.源解析结果显示,汾河平原城市碳质组分主要污染源的贡献最大为燃煤源(25.5%),其次是柴油车排放源(22.5%)、汽油车排放源(22.3%)和扬尘源(18.3%),生物质燃烧源(11.4%)贡献最小.燃煤源是汾河平原城市碳质组分的主要贡献源,是该地区的重点管控源;此外机动车对汾河平原城市碳质组分的影响不容小觑,尤其是柴油车.本研究从浓度特征、城市变化及来源解析等方面揭示了汾河平原各城市碳组分的污染特征和污染来源情况,为在区域层面对PM_(2.5)的控制提供了数据支撑和管控思路.

沈阳市秋冬季PM_(2.5)中有机碳和元素碳污染特征及来源分析

通过分析沈阳市环境空气秋冬季PM_(2.5)中有机碳(OC)和元素碳(EC)质量浓度,研究环境空气PM_(2.5)中OC,EC的污染特征。研究结果表明:沈阳城区秋季环境空气EC和OC质量浓度较高;秋冬季二次有机碳(SOC)平均质量浓度分别达到8.28~14.81μg/m^(3)和6.98~11.59μg/m^(3),二次污染程度较为严重;通过碳组分进行主成分分析,秋冬季碳组分主要来源于生物质燃烧、燃煤排放和汽油车尾气;冬季K^(+)与OC,EC,SOC之间的相关性较好,K^(+)与OC,EC,SOC具有一定的同源性;冬季OC与EC相关性较好,冬季碳质气溶胶污染源来源相对一致。

Pollution characteristics of organic and elemental carbon in PM_(2.5) in Xiamen,China

Xiamen, located on the southeastern coastal line of China, is undergoing rapid urbanization and industrialization, so its air quality has a trend of degradation. However, studies on level, temporal and spatial changes of fine particles （PM2.5） and their carbonaceous fractions are scarce. In this article, abundance, sources, seasonal and spatial variations, distribution of organic carbon （OC） and elemental carbon （EC） in PM2.5, were studied at suburban, urban and industrial sites in Xiamen during four season-representative months in 2009-2010. PM2.5 samples were collected with middle volume sampler and were analyzed for OC and EC with thermal optical transmittance （TOT） method. Results showed that the annual average PM2.5 concentrations were 63.88-74.80 Ixg/m3 at three sites. While OC and EC concentrations were in the range of 15.81-19.73 [xg/m3 and 2.74-3.49 ~tg/m3, respectively, and clearly presented the summer minima and winter maxima in this study. The carbonaceous aerosol accounted for 42.8%-47.3% of the mass of PMzs. The annual average of secondary organic carbon （SOC） concentrations in Xiamen were 9.23-11.36 ~g/m3, accounting for approximately 56% of OC. Strong correlations between OC and EC was found in spring （R2 = 0.50） and autumn （R2 = 0.73）, suggesting that there were similar emission and transport processes for carbonaceous aerosols in these two seasons, while weak correlations were found in summer （R2 = 0.33） and winter （R2 = 0.41）. The OCI＇EC ratios in PM2.5 varied from 2.1 to 8.7 with an annual average of 5.7, indicating that vehicle exhaust, coal smoke and biomass burning were main source apportionments of carbonaceous fractions in Xiamen.