Chemical processing of water-soluble species and formation of secondary organic aerosol in fogs

Kim, Hwajin,Collier, Sonya,Ge, Xinlei,Xu, Jianzhong,Sun, Yele,Jiang, Wenqing,Wang, Youliang,Herckes, Pierre,Zhang, Qi Elsevier 2019 Atmospheric environment Vol.200 No.-

<P><B>Abstract</B></P> <P>A field study on fog chemistry and aqueous-phase processing of aerosol particles was conducted in Fresno, California's San Joaquin Valley (SJV) during wintertime. Fog droplets were collected while interstitial submicron aerosol was characterized in real time using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS). The fog samples were later analyzed using HR-AMS, ion chromatography (IC), and total organic carbon analyzer (TOC). Compared to interstitial aerosol, dissolved solutes in fog waters were composed of higher fractions of ammonium, nitrate, sulfate, methanesulfonic acid, and oxygenated organic compounds, likely due to aqueous formation of secondary species as well as enhanced gas-to-particle partitioning of water-soluble gases under humid conditions. The low-volatility dissolved organic matter in fog water (F-OA) was moderately oxidized with an average oxygen-to-carbon (O/C) ratio of 0.42. The chemical composition of F-OA appeared to be overall similar to that of oxygenated organic component in interstitial aerosol (OOA) and the HR-AMS mass spectra of F-OA and OOA are highly similar (r<SUP>2</SUP> > 0.95). However, there are also significant chemical differences as F-OA appeared to contain a larger fraction of carboxylic functional groups than OOA, indicating enhanced organic acid formation through aqueous-phase reactions. In addition, F-OA was composed of substantially more nitrogen-containing compounds, with an average N/C ratio ∼4 times that of OOA. Most strikingly was that the F-OA spectra showed substantial enhancements of the C<SUB>x</SUB>H<SUB>y</SUB>N<SUB>2</SUB> <SUP>+</SUP> (x ≥ 0; y ≥ 0) ions, which were likely contributed by imidazole- and/or pyrazine-based compounds formed from the aqueous reactions of aldehydes with amino compounds. The results of this study demonstrated that aqueous reactions in atmospheric droplets can significantly modify aerosol composition and contribute to the formation of oxygenated and nitrogen-containing organic compounds in atmospheric aerosol particles. This finding is important for understanding aerosol's effects on human health, air quality, and climate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HR-AMS study of fog processing of PM1 in San Joaquin Valley of CA during winter. </LI> <LI> Fog waters are enriched of secondary inorganic and organic aerosol species. </LI> <LI> Organic residuals in fog waters (FOM) is moderately oxidized (average O/C = 0.42). </LI> <LI> FOM has more abundant carboxylic acid and organic nitrogen compounds than OOA. </LI> <LI> This is evidence for forming imidazole- or pyrazine-based compounds in fog waters. </LI> </UL> </P>

대기 중 PM2.5, 미세먼지 바로 알기

한진석 ( Jin-seok Han ) 한국환경농학회 2019 한국환경농학회 학술대회집 Vol.2019 No.-

본 연구에서는 요즘 이슈가 되고 있는 미세먼지, 그 중에서도 PM2.5에 대해 알아보고자 하였다. PM2.5의 농도현황과 배출원, 구성성분, 생성기작 등의 물리적인 특징과 화학적 특징에 대해 알아 보고, PM2.5가 인체에 미치는 영향, PM2.5의 현황에 대해 알아보고자 하였다. 미세먼지는 1차 입자상물질(Primary Aerosol)과, 2차 생성 입자상 물질 (Sencondary Aerosol)로 분류할 수 있다. 2차 생성 입자상 물질은 대기중으로 배출된 SO₂, NOx, VOCs와 같은 기체상 물질이 광화학반응과 같은 균질반응(Homogeneous Reaction)과 비균질반응(Heterogeneous Reaction)에 의하여 입자상으로 생성, 변화되어진 것이다. PM2.5 고농도 발생 시에는 일반적으로 1차 입자상 물질보다는 2차 생성 입자상물질의 기여율이 증가하는 특성을 나타낸다. 대기 중 PM2.5농도를 개선, 관리하기 위해서는 1차 입자상 물질의 발생원, 2차 생성 입자상 물질의 전구물질인 SO₂, NOx, VOCs에 대한 관리와 함께 대기 중 생성, 반응 기작의 이해를 바탕으로 개선 전략을 추진해야 할 것이다. In this study, We wanted know about PM2.5 of fine particle, and about physical, chemical characteristic such as concentration, configuration constituent and emission source. The fine particle can be classified into primary aerosol and secondary aerosol. The secondary aerosol were generated by heterogeneous, homogeneous reaction of gaseous materials such as SO₂, NOx, VOCs. When PM2.5 is generated at a high concentration, the contribution ratio of secondary aerosol increase rather than the primary aerosol. To improve and manage the concentration of PM2.5 in ambient air, it is necessary to manage for the emission source of primary aerosol, secondary aerosol(SO₂, NOx, VOCs), and development strategies base on understanding of generation in ambient air and reaction mechanism.

Volatility of methylglyoxal cloud SOA formed through OH radical oxidation and droplet evaporation

Ortiz-Montalvo, D.L.,Schwier, A.N.,Lim, Y.B.,McNeill, V.F.,Turpin, B.J. Pergamon Press ; Elsevier [distribution] 2016 Atmospheric environment Vol.130 No.-

<P>The volatility of secondary organic aerosol (SOA) formed through cloud processing (aqueous hydroxyl radical (OH) oxidation and droplet evaporation) of methylglyoxal (MGly) was studied. Effective vapor pressure and effective enthalpy of vaporization (Delta H-vap,H-eff) were determined using 1) droplets containing MGly and its oxidation products, 2) a Vibrating Orifice Aerosol Generator (VOAG) system, and 3) Temperature Programmed Desorption Aerosol-Chemical Ionization Mass Spectrometry (TPD Aerosol-CIMS). Simulated in-cloud MGly oxidation (for 10-30 min) produces an organic mixture of higher and lower volatility components with an overall effective vapor pressure of (4 +/- 7) x 10(-7) atm at pH 3. The effective vapor pressure decreases by a factor of 2 with addition of ammonium hydroxide (pH 7). The fraction of organic material remaining in the particle-phase after drying was smaller than for similar experiments with glycolaldehyde and glyoxal SOA. The Delta H-vap,H-eff of pyruvic acid and oxalic acid + methylglyoxal in the mixture (from TPD Aerosol-CIMS) were smaller than the theoretical enthalpies of the pure compounds and smaller than that estimated for the entire precursor/product mix after droplet evaporation. After 10 (even neutralized) will volatilize during droplet evaporation; neutralization and at least 80 min of oxidation at 10(-12) M (OH)-O-center dot (or >12 h at 10(-14) M) is needed before low volatility ammonium oxalate exceeds pyruvate. (C) 2015 Elsevier Ltd. All rights reserved.</P>

광주 지역에서 2015년 10월에 발생한 PM2.5 고농도 사례 특성 분석

유근혜,박승식,정선아,조미라,임용재,신혜정,이상보,김영성 한국대기환경학회 2018 한국대기환경학회지 Vol.34 No.4

A severe haze event occurred in October 2015 in Gwangju, Korea. In this study, the driving chemical species and the formation mechanisms of PM2.5 pollution were investigated to better understand the haze event. Hourly concentrations of PM2.5, organic and elemental carbon, water-soluble ions, and elemental constituents were measured at the air quality intensive monitoring station in Gwangju. The haze event occurred was attributed to a significant contribution (72.3%) of secondary inorganic species concentration to the PM2.5, along with the contribution of organic aerosols that were strongly attributed to traffic emissions over the study site. MODIS images, weather charts, and air mass backward trajectories supported the significant impact of long-range transportation (LTP) of aerosol particles from northeastern China on haze formation over Gwangju in October 2015. The driving factor for the haze formation was stagnant atmospheric flows around the Korean peninsula, and high relative humidity (RH) promoted the haze formation at the site. Under the high RH conditions, SO4 2- and NO3 - were mainly produced through the heterogenous aqueous-phase reactions of SO2 and NO2, respectively. Moreover, hourly O3 concentration during the study period was highly elevated, with hourly peaks ranging from 79 to 95 ppb, suggesting that photochemical reaction was a possible formation process of secondary aerosols. Over the PM2.5 pollution, behavior and formation of secondary ionic species varied with the difference in the impact of LTP. Prior to October 19 when the influence of LTP was low, increasing rate in NO3 - was greater than that in NO2, but both SO2 and SO4 2- had similar increasing rates. While, after October 20 when the impact of haze by LTP was significant, SO4 2- and NO3 - concentrations increased significantly more than their gaseous precursors, but with greater increasing rate of NO3 -. These results suggest the enhanced secondary transformation of SO2 and NO2 during the haze event. Overall, the result from the study suggests that control of anthropogenic combustion sources including vehicle emissions is needed to reduce the high levels of nitrogen oxide and NO3 - and the high PM2.5 pollution occurred over fall season in Gwangju.

2차 무기 에어로졸 연구를 위한 상자모형의 적용: 질산염 생성을 중심으로

박성훈 한국대기환경학회 2024 한국대기환경학회지 Vol.40 No.1

More than a half of PM2.5 mass is composed of secondary inorganic aerosol (SIA) species in East Asia, with nitrate being the most abundant one, particularly during fine particulate matter pollution episodes. Although nitrate is produced from the oxidation of its precursor NOx, the reduction of NOx emissions does not always decrease the atmospheric nitrate concentration because of the non-linearity of the nitrate formation. Box models can be efficient tools to analyze the sensitivity of nitrate formation to the concentrations of its precursors and suggest appropriate policy directions to reduce SIA. This review article summarizes recent studies that developed and used various box models to investigate the principles and mechanisms of nitrate production in the air. Measurement of OH radical, ammonia, and trace species involved in the nitrate formation processes, sensitivity analyses of nitrate formation accounting for regional characteristics to deduce science-based policies, and integrated approach to manage ozone and SIA together are suggested as future directions for effective utilization of box models as a policy making tool.

광주 지역에서 2018년 1월 측정한 초미세먼지의 오염 특성

유근혜,박승식,정선아,조미라,장유운,임용재,김영성,Yu, Geun-Hye,Park, Seung-Shik,Jung, Sun A,Jo, Mi Ra,Jang, Yu Woon,Lim, Yong Jae,Ghim, Young Sung 한국입자에어로졸학회 2019 Particle and Aerosol Research Vol.15 No.3

In this study, hourly measurements of $PM_{2.5}$ and its major chemical constituents such as organic and elemental carbon (OC and EC), and ionic species were made between January 15 and February 10, 2018 at the air pollution intensive monitering station in Gwangju. In addition, 24-hr integrated $PM_{2.5}$ samples were collected at the same site and analyzed for OC, EC, water-soluble OC (WSOC), humic-like substance (HULIS), and ionic species. Over the whole study period, the organic aerosols (=$1.6{\times}OC$) and $NO_3{^-}$ concentrations contributed 26.6% and 21.0% to $PM_{2.5}$, respectively. OC and EC concentrations were mainly attributed to traffic emissions with some contribution from biomass burning emissions. Moreover, strong correlations of OC with WSOC, HULIS, and $NO_3{^-}$ suggest that some of the organic aerosols were likely formed through atmospheric oxidation processes of hydrocarbon compounds from traffic emissions. For the period between January 18 and 22 when $PM_{2.5}$ pollution episode occurred, concentrations of three secondary ionic species ($=SO{_4}^{2-}+NO_3{^-}+NH_4{^+}$) and organic matter contributed on average 50.8 and 20.1% of $PM_{2.5}$, respectively, with the highest contribution from $NO_3{^-}$. Synoptic charts, air mass backward trajectories, and local meteorological conditions supported that high $PM_{2.5}$ pollution was resulted from long-range transport of haze particles lingering over northeastern China, accumulation of local emissions, and local production of secondary aerosols. During the $PM_{2.5}$ pollution episode, enhanced $SO{_4}^{2-}$ was more due to the long-range transport of aerosol particles from China rather than local secondary production from $SO_2$. Increasing rate in $NO_3{^-}$ was substantially greater than $NO_2$ and $SO{_4}^{2-}$ increasing rates, suggesting that the increased concentration of $NO_3{^-}$ during the pollution episode was attributed to enhanced formation of local $NO_3{^-}$ through heterogenous reactions of $NO_2$, rather than impact by long-range transportation from China.

국내외 스모그 챔버 연구동향

이승복,김준태,이지원,김경환,김나진,김지민,김산,김환동,황민우,송예진,김진영,배귀남 한국대기환경학회 2023 한국대기환경학회지 Vol.39 No.5

The smog chamber is a research facility that simulates atmospheric phenomena such as secondary pollution of ozone and aerosols under different atmospheric conditions. It enables the investigation of photochemical reaction processes, yields, and products, as well as physicochemical properties of secondary aerosol. Since the beginning of smog chamber research under the 1950s, experiments mainly on ozone and particle formation have been conducted, depending on the chamber specification and research trends. Smog chamber research in Korea began in the early 2000s and has continued since 2010 due to growing interest in particulate matter pollution. This study covers the domestic and global history of smog chamber research, as well as significant recent research advancements, which provides recommendations for future studies in smog chamber research.

Simple quantification method for <i>N</i>-nitrosamines in atmospheric particulates based on facile pretreatment and GC-MS/MS

Hong, Youngmin,Kim, Kyung Hwan,Sang, Byoung-In,Kim, Hyunook Elsevier 2017 Environmental pollution Vol.226 No.-

<P><B>Abstract</B></P> <P>Nine <I>N</I>-nitrosamines (i.e., <I>N</I>-nitrosomethylamine, <I>N</I>-nitrosodiethylamine (NDEA), <I>N</I>-nitrosodimethylamine (NDMA), <I>N</I>-nitrosodi-n-propylamine (NDPA), <I>N</I>-nitrosomorpholine (NMor), <I>N</I>-nitrosopyrrolidine (NPyr), <I>N</I>-nitrosopiperidine (NPip), <I>N</I>-nitorosodi-n-butylamine (NDBA), and <I>N</I>-nitrosodiphenylamine (NDPhA) in atmospheric PM<SUB>2.5</SUB> collected in the fall season from an roadside site and a residential in Seoul, Korea have been analyzed using a newly developed method consisting of simple direct liquid extraction assisted by ultrasonication and subsequent quantification using a gas chromatography-triple quadrupole mass spectrometry (GC-TQMS). Excellent recovery values (92–100%) and method detection limits for the target compounds atmospheric PM samples could be achieved even without an evaporation step for sample concentration. The concentration of total <I>N</I>-nitrosamines in PM<SUB>2.5</SUB> was ranged from 0.3 to 9.4 ng m<SUP>−3</SUP> in this study; NDMA, NDEA, NDBA, NPyr, and NMor in PM<SUB>2.5</SUB> were found to be the most frequently encountered compounds at the sampling sites. Since no industrial plant is located in Seoul, vehicle exhausts were considered major cause of the formation of nitrosamines in this study. The mechanisms how these compounds are formed and detected in the atmosphere are explained from the viewpoint of secondary organic aerosol. Considering the concentrations of <I>N</I>-nitrosamines and their associated potential health risks, a systematic monitoring of nitrosamines present in both ambient air and PM<SUB>2.5</SUB> including seasonal and diurnal variations of selected sites (including potential precursor sources) should be carried out in the future. The proposed sample pretreatment method along with the analytical method will definitely help us perform the monitoring study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 9 nitrosamines in PMs of the air over Seoul, Korea were quantified. </LI> <LI> A newly developed easy analytical method was applied for the quantification. </LI> <LI> How nitrosamines are formed is explained. </LI> <LI> Nitrosamine levels detected are 4–31 times higher than the Norwegian guideline. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

실리콘-탄소-그래핀 복합체 제조 및 리튬이온 이차전지 응용

김선경,김찬미,장한권,장희동,Kim, SunKyung,Kim, ChanMi,Chang, Hankwon,Jang, Hee Dong 한국입자에어로졸학회 2019 Particle and Aerosol Research Vol.15 No.4

Recently, high electrochemical performance anode materials for lithium ion secondary batteries are of interest. Here, we present silicon-carbon-graphene (Si-C-GR) composites for high performance anode materials of lithium ion secondary battery (LIB). Aerosol process and heat-treatment were employed to prepare the Si-C-GR composites using a colloidal mixture of silicon, glucose, and graphene oxide precursor. The effects of the size of the silicon particles in Si-C-GR composites on the material properties including the morphology and crystal structure were investigated. Silicon particles ranged from 50 nm to 1 ㎛ in average diameter were employed while concentration of silicon, graphene oxide and glucose was fixed in the aerosol precursor. Morphology of as-fabricated Si-C-GR composites was generally the shape of a crumpled paper ball and the Si particles were well wrapped in carbon and graphene. The size range of composites was about from 2.2 to 2.9 ㎛. The composites including silicon particles larger than 200 nm in size exhibited higher performance as LIB anodes such as capacity and coulombic efficiency than silicon particles less than 100 nm, which were about 1500 mAh/g at 100 cycles in capacity and 99% in coulombic efficiency, respectively.

Effects of chemical aging on global secondary organic aerosol using the volatility basis set approach

Jo, D.S.,Park, R.J.,Kim, M.J.,Spracklen, D.V. Pergamon Press ; Elsevier [distribution] 2013 Atmospheric environment Vol.81 No.-

A global 3-D chemical transport model (GEOS-Chem) is used with the volatility basis set (VBS) approach to examine the effects of chemical aging on global secondary organic aerosol (SOA) concentrations and budgets. We present full-year simulations and their comparisons with the global aerosol mass spectrometer (AMS) dataset, the Interagency Monitoring of Protected Visual Environments (IMPROVE) dataset from the United States, the European Monitoring and Evaluation Programme (EMEP) dataset from Europe, and water-soluble organic carbon observation data collected over East Asia. Using different chemical aging constants, we find that the model results with 4 x 10<SUP>-11</SUP> cm<SUP>3</SUP> molecule<SUP>-1</SUP> s<SUP>-1</SUP> are in better agreement with all observations relative to the model results with other aging constants, without aging, and with the two-product approach. The model simulations are improved when chemical aging is considered, especially for rural regions. However, the simulations still underestimate observed oxygenated organic aerosol (OOA) in urban areas. Two sensitivity simulations including semi-volatile primary organic aerosol (POA) were conducted. We find that including semi-volatile POA improves the model in terms of the hydrogen-like organic aerosol (HOA) to OOA ratio. However, the total OA concentrations are not improved. The total SOA production is considerably increased by 53%, from 26.0 to 39.9 Tg yr<SUP>-1</SUP>, after considering chemical aging, remaining lower than top-down estimates of SOA production. Direct radiative forcing (DRF) increases by -0.07 W m<SUP>-2</SUP> due to the chemical aging of SOA, which is comparable to the mean DRF (-0.13 W m<SUP>-2</SUP>) of OA from the AeroCom multi-model study. This result indicates considerable global and, more importantly, regional climate implications. For example, the regional DRF change due to chemical aging of SOA in the eastern US is -0.29 W m<SUP>-2</SUP>, which is 4 times greater in magnitude than the global mean value.