Statistical analysis of Seoul air quality to assess the efficacy of emission abatement strategies since 1987

Chambers, Scott D.,Kim, Ki-Hyun,Kwon, Eilhann E.,Brown, Richard J.C.,Griffiths, Alan D.,Crawford, Jagoda Elsevier 2017 Science of the Total Environment Vol.580 No.-

<P><B>Abstract</B></P> <P>The combined influences of recent mitigation measures on urban air quality have been assessed using hourly observations of the criteria air pollutants (NO, NO<SUB>2</SUB>, O<SUB>3</SUB>, CO, and SO<SUB>2</SUB>) made from the Yongsan district of Seoul, Korea, over 26years (1987 to 2013). A number of data selection criteria are proposed in order to minimize variability associated with temporal changes (at diurnal, weekly, and seasonal timescales) in source strengths, their spatial distribution, and the atmospheric volume into which they mix. The temporal constraints required to better characterize relationships between observed air quality and changes in source strengths in Seoul were identified as: (i) a 5-hour diurnal sampling window (1300–1700h), (b) weekday measurements (Monday to Friday only), and (c) summer measurements (when pollutant fetch is mostly Korea-specific, and mean wind speeds are the lowest). Using these selection criteria, we were able to closely relate long-term trends identified in criteria pollutants to a number of published changes to traffic-related source strengths brought about by mitigation measures adopted over the last 10–15years.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Improved long-term analysis of urban air quality in the central Seoul region. </LI> <LI> We demonstrate the existence, magnitude, and temporal changes of ambient air pollutants. </LI> <LI> Improved analysis techniques for investigating long-term changes in urban air pollution. </LI> <LI> Clearly demonstrate the efficacy of mitigation measures on Seoul air quality since 1987. </LI> <LI> Identify causes of large inter-annual variability in Seoul air quality in summer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Photochemical Grafting of Organic Alkenes to Single-Crystal TiO₂ Surfaces: A Mechanistic Study

Franking, Ryan,Kim, Heesuk,Chambers, Scott A.,Mangham, Andrew N.,Hamers, Robert J. American Chemical Society 2012 Langmuir Vol.28 No.33

<P>The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor surfaces. Recent studies have shown that grafting reactions can be initiated by photoelectron emission into the reactant liquid as well as by excitation across the semiconductor band gap, but the relative importance of these two processes is expected to depend on the nature of the semiconductors, the reactant alkene and the excitation wavelength. Here we report a study of the wavelength-dependent photochemical grafting of alkenes onto single-crystal TiO<SUB>2</SUB> samples. Trifluoroacetamide-protected 10-aminododec-1-ene (TFAAD), 10-<I>N</I>-BOC-aminodec-1-ene (t-BOC), and 1-dodecene were used as model alkenes. On rutile (110), photons with energy above the band gap but below the expected work function are not effective at inducing grafting, while photons with energy sufficient to induce electronic transitions from the TiO<SUB>2</SUB> Fermi level to electronic acceptor states of the reactant molecules induce grafting. A comparison of rutile (110), rutile (001), anatase (001), and anatase (101) samples shows slightly enhanced grafting for rutile but no difference between crystal faces for a given crystal phase. Hydroxylation of the surface increases the reaction rate by lowering the work function and thereby facilitating photoelectron ejection into the adjacent alkene. These results demonstrate that photoelectron emission is the dominant mechanism responsible for grafting when using short-wavelength (∼254 nm) light and suggest that photoemission events beginning on mid-gap states may play a crucial role.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2012/langd5.2012.28.issue-33/la302169k/production/images/medium/la-2012-02169k_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la302169k'>ACS Electronic Supporting Info</A></P>

Variability of Atmospheric Radon-222 and Secondary Aerosol Components in Accordance with Air Mass Transport Pathways at Jeju Island, Korea, during 2011–2014

부준오,송정민,김원형,강창희,Scott D. Chambers,Alastair G. Williams,이철규 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.6

Real-time monitoring of hourly atmospheric Radon-222 concentration and three daily monitoring of the secondary aerosol components of PM10 were performed throughout 2011–2014 at Gosan station, Jeju Island, in order to characterize their background levels and temporal variation. The annual mean radon and PM10 mass concentrations were 2326 ± 1198 mBq/m3 and 37.1 ± 19.5 µg/m3, respectively. Based on cluster analyses of air mass back trajectories, the frequencies of air masses originating from continental China, the Korean Peninsula, and North Pacific Ocean routes were 53, 28, and 19%, respectively. When the air masses were transported to Jeju Island from continental China, the concentrations of radon and secondary aerosol components (nss-SO4 2 −, NO3 −, NH4 +) were relatively high: 2577 mBq/m3 and 14.4 µg/m3, respectively. In cases when the air masses have moved from the Korean Peninsula, the corresponding concentrations were 2247 mBq/m3 and 11.4 µg/m3, respectively. On the other hand, when the air masses came from the North Pacific Ocean, their radon and secondary aerosol concentrations decreased much further, 1372 mBq/m3 and 10.5 µg/m3, respectively. Consequently, the variability of atmospheric radon concentrations at Gosan station might be characterized by synoptic changes in air mass fetch as well as diurnal changes in atmospheric mixing depth.

Temporal Variation of Atmospheric Radon-222 and Gaseous Pollutants in Background Area of Korea during 2013-2014

부준오,송정민,김원형,강창희,송상근,Alastair G. Williams,Scott D. Chambers 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.2

Real-time monitoring of hourly concentrations of atmospheric Radon-222 (222Rn, radon) and some gaseous pollutants (SO2, CO, O3) was performed throughout 2013-2014 at Gosan station of Jeju Island, one of the cleanest regions in Korea, in order to characterize their background levels and temporal variation trend. The hourly mean concentrations of radon and three gaseous pollutants (SO2, CO, O3) over the study period were 2216±1100 mBq/m3, 0.6±0.7 ppb, 211.6±102.0 ppb, and 43.0±17.0 ppb, respectively. The seasonal order of radon concentrations was as fall (2644 mBq/m3)≈winter (2612 mBq/ m3)>spring (2022 mBq/m3)>summer (1666 mBq/ m3). The concentrations of SO2 and CO showed similar patterns with those of radon as high in winter and low in summer, whereas the O3 concentrations had a bit different trend. Based on cluster analyses of air mass back trajectories, the air mass frequencies originating from Chinese continent, North Pacific Ocean, and the Korean Peninsula routes were 30, 18, and 52%, respectively. When the air masses were moved from Chinese continent to Jeju Island, the concentrations of radon and gaseous pollutants (SO2, CO, O3) were relatively high: 2584 mBq/m3, 0.76 ppb, 225.8 ppb, and 46.4 ppb. On the other hand, when the air masses were moved from North Pacific Ocean, their concentrations were much low as 1282 mBq/m3, 0.24 ppb, 166.1 ppb, and 32.5 ppb, respectively.

Airborne iron across major urban centers in South Korea between 1991 and 2012

Kim, Ki-Hyun,Hong, Yoon-Jung,Szulejko, Jan E.,Kang, Chang-Hee,Chambers, Scott,Feng, Xinbin,Deep, Akash,Kim, Yong-Hyun Elsevier 2016 Science of the Total Environment Vol.550 No.-

<P><B>Abstract</B></P> <P>In this study, the distribution of airborne iron (Fe), one of the most abundant heavy metals in the Earth's crust was investigated to describe the basic features of i'ts pollution in various urban locations. The spatiotemporal distribution of Fe concentrations in seven major South Korean cities exhibited unique patterns to reflect differences as to Fe sources reflected in the relative enrichment in coastal relative to inland areas. In addition, the analysis of long-term trends of different metal species indicated that Fe levels maintained a fairly constant trend, while there had been a noticeable decline in concentrations of other metals (Cd, Cr, Cu, Mn, and Ni). The relative robustness of our correlation analysis was assessed by comparing (1) the Fe concentrations among cities, and (2) Fe with other metals at a given city. Fe concentrations were also partly explainable by the frequency of Asian dust events in most cities, with the observed spatial gradients in such relationships.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The atmospheric metal levels reflect the intensity of industrial activities. </LI> <LI> Anthropogenic processes substantially increased emission of Fe. </LI> <LI> The atmospheric behavior of Fe is yet poorly known. </LI> <LI> The impact of various sources on Fe distribution was evaluated. </LI> <LI> The man-made sources influenced Fe more evidently than PM. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Temporal Variation of Atmospheric Radon-222 and Gaseous Pollutants in Background Area of Korea during 2013-2014

Bu, Jun-Oh,Song, Jung-Min,Kim, Won-Hyung,Kang, Chang-Hee,Song, Sang-Keun,Williams, Alastair G.,Chambers, Scott D. Korean Society for Atmospheric Environment 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.2

Real-time monitoring of hourly concentrations of atmospheric Radon-222 ($^{222}Rn$, radon) and some gaseous pollutants ($SO_2$, CO, $O_3$) was performed throughout 2013-2014 at Gosan station of Jeju Island, one of the cleanest regions in Korea, in order to characterize their background levels and temporal variation trend. The hourly mean concentrations of radon and three gaseous pollutants ($SO_2$, CO, $O_3$) over the study period were $2216{\pm}1100mBq/m^3$, $0.6{\pm}0.7ppb$, $211.6{\pm}102.0ppb$, and $43.0{\pm}17.0ppb$, respectively. The seasonal order of radon concentrations was as fall ($2644mBq/m^3$)$${\sim_\sim}$$winter ($2612mBq/m^3$)>spring ($2022mBq/m^3$)>summer ($1666mBq/m^3$). The concentrations of $SO_2$ and CO showed similar patterns with those of radon as high in winter and low in summer, whereas the $O_3$ concentrations had a bit different trend. Based on cluster analyses of air mass back trajectories, the air mass frequencies originating from Chinese continent, North Pacific Ocean, and the Korean Peninsula routes were 30, 18, and 52%, respectively. When the air masses were moved from Chinese continent to Jeju Island, the concentrations of radon and gaseous pollutants ($SO_2$, CO, $O_3$) were relatively high: $2584mBq/m^3$, 0.76 ppb, 225.8 ppb, and 46.4 ppb. On the other hand, when the air masses were moved from North Pacific Ocean, their concentrations were much low as $1282mBq/m^3$, 0.24 ppb, 166.1 ppb, and 32.5 ppb, respectively.

Toward a better understanding of the impact of mass transit air pollutants on human health

Kim, Ki-Hyun,Kumar, Pawan,Szulejko, Jan E.,Adelodun, Adedeji A.,Junaid, Muhammad Faisal,Uchimiya, Minori,Chambers, Scott Pergamon Press 2017 Chemosphere Vol.174 No.-

<P><B>Abstract</B></P> <P>Globally, modern mass transport systems whether by road, rail, water, or air generate airborne pollutants in both developing and developed nations. Air pollution is the primary human health concern originating from modern transportation, particularly in densely-populated urban areas. This review will specifically focus on the origin and the health impacts of carbonaceous traffic-related air pollutants (TRAP), including particulate matter (PM), volatile organic compounds (VOCs), and elemental carbon (EC). We conclude that the greatest current challenge regarding urban TRAP is understanding and evaluating the human health impacts well enough to set appropriate pollution control measures. Furthermore, we provide a detailed discussion regarding the effects of TRAP on local environments and pedestrian health in low and high traffic-density environments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Efficient transport system is an essential step toward sustainable urban development. </LI> <LI> The effect of traffic-related air pollutants (TRAP) on human health is significant. </LI> <LI> The overall health conditions of pedestrians in a localized area were assessed. </LI> </UL> </P>

Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO₃ Thin Films

Varga, Tamas,Droubay, Timothy C.,Kovarik, Libor,Nandasiri, Manjula I.,Shutthanandan, Vaithiyalingam,Hu, Dehong,Kim, Bumsoo,Jeon, Seokwoo,Hong, Seungbum,Li, Yulan,Chambers, Scott A. American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.26

<P>Polarization-induced weak ferromagnetism (WFM) was demonstrated a few years back in LiNbO3-type compounds, MTiO3 (M = Fe, Mn, Ni). Although the coexistence of ferroelectric polarization and ferromagnetism has been demonstrated in this rare multiferroic family before, first in bulk FeTiO3, then in thin-film NiTiO3, the coupling of the two order parameters has not been confirmed Here, we report the stabilization of polar, ferromagnetic NiTiO3 by oxide epitaxy on a LiNbO3 substrate utilizing tensile strain and demonstrate the theoretically predicted coupling between its polarization and ferromagnetism by X-ray magnetic circular dichroism under applied fields. The experimentally observed direction of ferroic ordering in the film is supported by simulations using the phase-field approach. Our work validates symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and WFM in MTiO3 transition metal titanates crystallizing in the LiNbO3 structure. It also demonstrates the applicability of epitaxial strain as a viable alternative to high-pressure crystal growth to stabilize metastable materials and a valuable tuning parameter to simultaneously control two ferroic order parameters to create a multiferroic. Multiferroic NiTiO3 has potential applications in spintronics where ferroic switching is used, such as new four-stage memories and electromagnetic switches.</P>

제주도 고산측정소의 대기 라돈농도 시계열 변화

고희정(Hee-Jung Ko),신승희(Seung-Hee Sin),허철구(Chul-Goo Hu),김원형(Won-Hyung Kim),강창희(Chang-Hee Kang),강동훈(Dong-Hun Kang),Scott Chambers 한국대기환경학회 2013 한국대기환경학회지 Vol.29 No.1