Airborne volatile aromatic hydrocarbons at an urban monitoring station in Korea from 2013 to 2015

Khan, Azmatullah,Szulejko, Jan E.,Kim, Ki-Hyun,Brown, Richard J.C. Elsevier 2018 Journal of environmental management Vol.209 No.-

<P><B>Abstract</B></P> <P>The concentrations of C<SUB>6</SUB>-C<SUB>10</SUB> volatile aromatic hydrocarbons (AHCs) in air were measured at an urban air quality monitoring station in Jong-Ro, Seoul, Korea, between 2013 and 2015. Their temporal patterns (e.g., diurnal, intraweek, daily) were assessed individually and collectively as groups of benzene, toluene, ethylbenzene, styrene, and xylene (BTESX); total aliphatic hydrocarbon (TALHC: C<SUB>2</SUB>-C<SUB>12</SUB>); total aromatic hydrocarbon (TARHC: C<SUB>6</SUB>-C<SUB>10</SUB>); and total hydrocarbon (THC: C<SUB>2</SUB>-C<SUB>12</SUB>). The highest mean AHC concentrations over the 3-year study (in ppb (v/v)) were observed for toluene (6.0 ± 4.3), followed by the xylenes (1.5 ± 1.3), ethylbenzene (0.85 ± 0.93), benzene (0.73 ± 0.77), and styrene (0.16 ± 0.30) nL/L. The mean ppbC ((v/v), nL∙atm∙C/nL∙atm) values for BTESX, TALHC, TARHC, and THC were 65.8, 113, 77.7, and 191 ppbC, respectively. For most AHC species (e.g., toluene, styrene, and BTESX), only weak seasonal trends were observed in contrast to temporally varying species like nitric oxide (NO) (e.g., 26.3 ppb (January–February) vs. 8.5 ppb (July–August) during weekdays in 2013). Furthermore, toluene and NO concentrations were much higher (up to a factor 3) on weekdays than on Sunday for most weeks. This might reflect reduced anthropogenic activities on Sunday.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Toluene was the major BTESX. </LI> <LI> Propane was major hydrocarbon in all 56 hydrocarbons. </LI> <LI> Toluene and NO has strong correlation. </LI> <LI> Both toluene and NO showed much higher working day levels compare to Sunday. </LI> </UL> </P>

Fixed volume sequential standard addition calibration: Value assignment of impurities in zero gas

Brown, Richard J.C.,Brewer, Paul J.,Kim, Ki-Hyun Elsevier 2017 Chemometrics and intelligent laboratory systems Vol.164 No.-

<P><B>Abstract</B></P> <P>A fixed volume case of sequential standard addition calibration (S-SAC) for the value assignment of impurities in zero gas is described. A mathematical description of this technique has been derived and has been shown to exhibit a similar systematic bias during the extrapolation process to that seen for other S-SAC cases. The use of S-SAC in the gas phase has demonstrated that variation in the sample volume for S-SAC in the liquid phase is not the generalised cause of the bias experienced during extrapolation. Instead it is the variation in the volume of the original sample with respect to the overall volume of the mixture following the addition of standard. In addition, the requirement to perform a bias correction on the extrapolated values has been discussed and best practice solutions for correction proposed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fixed volume sequential standard addition calibration is described mathematically. </LI> <LI> This has been applied to the determination of impurities in blank gas. </LI> <LI> A systematic bias during the extrapolation process is observed. </LI> <LI> Best practice solutions for correction are proposed. </LI> </UL> </P>

Who should take responsibility for decisions on internationally recommended datasets? The case of the mass concentration of mercury in air at saturation

Brown, Richard J C,Brewer, Paul J,Ent, Hugo,Fisicaro, Paola,Horvat, Milena,Kim, Ki-Hyun,Qu?tel, Christophe R BUREAU INTERNATIONAL DES POIDS ET MESURES 2015 METROLOGIA -BERLIN- Vol.52 No.5

<P>This paper considers how decisions on internationally recommended datasets are made and implemented and, further, how the ownership of these decisions comes about. Examples are given of conventionally agreed data and values where the responsibility is clear and comes about through official designation or by common usage and practice over long time periods. The example of the dataset describing the mass concentration of mercury in air at saturation is discussed in detail. This is a case where there are now several competing datasets that are in disagreement with each other, some with historical authority and some more recent but, arguably, with more robust metrological traceability to the SI. Further, it is elaborated that there is no body charged with the responsibility to make a decision on an international recommendation for such a dataset. This has led to the situation where several competing datasets are in use simultaneously. Close parallels are drawn with the current debate over changes to the ozone absorption cross section, which has equal importance to the measurement of ozone amount fraction in air and to subsequent compliance with air quality legislation. It is noted that in the case of the ozone cross section there is already a committee appointed to deliberate over any change. We make the proposal that a similar committee, under the auspices of IUPAC or the CIPM's CCQM (if it adopted a reference data function) could be formed to perform a similar role for the mass concentration of mercury in air at saturation.</P>

A temperature-based approach to predicting lost data from highly seasonal pollutant data sets

Brown, Richard J. C.,Brown, Andrew S.,Kim, Ki-Hyun The Royal Society of Chemistry 2013 Environmental science Vol.15 No.6

<P>A new technique to predict concentrations of benzo[<I>a</I>]pyrene (B<I>a</I>P) in ambient air during periods of lost data has been developed and tested. This new technique is based on the relationship between ambient temperature and B<I>a</I>P concentration observed at individual monitoring stations over many years. The technique has been tested on monthly data of B<I>a</I>P concentrations in PM<SUB>10</SUB> at individual monitoring stations on the UK PAH Monitoring Network. The annual average concentration values produced with and without the use of predicted data have been compared to the actual annual averages in the absence of any data loss. The use of predicted data is a significant improvement when compared with the averages produced in the absence of any data prediction and outperforms previous prediction strategies associated with intra-year trends. Furthermore the technique is suitable for the prediction of long periods of missing data, which other prediction techniques have not been able to deal with satisfactorily.</P> <P>Graphic Abstract</P><P>A temperature-based approach to predicting lost data from highly seasonal pollutant data sets is presented. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3em00131h'> </P>

Memory Effects on Adsorption Tubes for Mercury Vapor Measurement in Ambient Air: Elucidation, Quantification, and Strategies for Mitigation of Analytical Bias

Brown, Richard J. C.,Kumar, Yarshini,Brown, Andrew S.,Kim, Ki-Hyun American Chemical Society 2011 Environmental science & technology Vol.45 No.18

<P>The short- and long-term memory effects associated with measurements of mercury vapor in air using gold-coated silica adsorption tubes have been described. Data are presented to quantify these effects and to determine their dependence on certain relevant measurement parameters, such as number of heating cycles used for each analysis, age of adsorption tube, mass of mercury on adsorption tube, and the length of time between analyses. The results suggest that the long-term memory effect is due to absorption of mercury within the bulk gold in the adsorption tube, which may only be fully liberated by allowing enough time for this mercury to diffuse to the gold surface. The implications of these effects for air quality networks making these measurements routinely has been discussed, and recommendations have been made to ensure any measurement bias is minimized.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2011/esthag.2011.45.issue-18/es201454u/production/images/medium/es-2011-01454u_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es201454u'>ACS Electronic Supporting Info</A></P>

Emerging Measurement Techniques for Airborne Pollutants

Kim, Ki-Hyun,Brown, Richard J. C. TheScientificWorldJOURNAL 2011 The Scientific World Journal Vol.11 No.-

Foliar Transfer of Dust and Heavy Metals on Roadside Plants in a Subtropical Environment

Triratnesh Gajbhiye,김기현,Sudhir Kumar Pandey,Richard J. C. Brown 한국대기환경학회 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.3

In this study, the contents of dust and associated heavy metals on roadside plants were investigated to assess their foliar transfer. The study was conducted at six different locations (four roadside and two industrial) near an industrial area in Bilaspur (Chhattisgarh), India. Six metals (Fe, Mn, Pb, Cu, Cr, and Cd) were examined in this study. The concentrations of heavy metals in foliar dust were found to be in the order of Fe>Mn>Pb>Cu>Cr>Cd. However, this relative order changed in the case of leaf concentrations to Fe>Mn>Cd>Cu>Pb>Cr. The metal concentrations in the dust and leaves can be attributed mainly to industrial and vehicular emissions. In contrast to other metals, Cd showed significant accumulation in the leaves compared to the respective dust samples. This study showed different patterns in the distributions of heavy metals between the dust deposited on the leaves and the metal accumulated in the leaves. These results suggest that the dust retention and heavy metal accumulation in native plant species should be explored in an attempt to manage these hazardous metallic elements.

Conditions for the optimal analysis of volatile organic compounds in air with sorbent tube sampling and liquid standard calibration: demonstration of solvent effect.

Kim, Ki-Hyun,Kim, Yong-Hyun,Brown, Richard J C Springer-Verlag 2013 Analytical and bioanalytical chemistry Vol.405 No.26

<P>The combined use of sorbent tubes (ST) and thermal desorption (TD) has become the common practice for the trace-level analysis of gaseous volatile organic compounds (VOCs). In this research, the potential bias in VOC analysis due to the solvent introduced into the system as a liquid standard (LS) is examined in three stages by analyzing LSs of 19 VOCs in methanol solvent against a three-bed ST (Tenax TA, Carbopack B, and Carboxen 1000). In experimental stage 1, LS made at four concentration levels (between 10 and 150 ng μL(-1)) were each analyzed at four injection volumes (1, 2, 5, and 10 μL) based on a vaporization method. In experimental stage 2, calibration was also conducted by direct injection over an extended concentration range at two volumes, 1 and 10 μL. In experimental stage 3, the response factors (RF) of a single analyte mass were compared across the four injection volumes and between two injection methods. These results were analyzed to explore the complex relationship between variables such as LS volume, target/solvent chemical type, sorbent strength, and prepurge condition. There was no change in the ST/TD performance up to 2 μL of LS. However, as the injection volume increased up to 5 μL, a notable shift in RF and retention time occurred (e.g., for benzene and methyl ethyl ketone). At the maximum injection volume (10 μL), a significant reduction in sensitivity is evident for all compounds, e.g., 50 % drops relative to 1 μL injection. As such, the TD performance tends to deteriorate with increasing volume of methanol initially loaded on the ST. Although the dominant fraction of solvent was removed by two prepurge steps, residue caught in the strong sorbent fraction is still found to exert an effect on the subsequent analysis, e.g., delayed retention, sensitivity reduction, or disappearance of certain compounds.</P>

Investigation of the relationship between atmospheric mercury and concentrations of key greenhouse gases at a mountainous monitoring site

Kim, Ki-Hyun,Pandey, Sudhir Kumar,Brown, Richard J. C.,Sheu, Guey Rong,Jeon, Eui-Chan,Jung, Kweon,Kang, Chang-Hee The Royal Society of Chemistry 2015 Environmental science Vol.17 No.3

<P>The concentration of total gaseous mercury (TGM) was monitored, together with some key greenhouse gases (GHGs: carbon dioxide (CO<SUB>2</SUB>), methane (CH<SUB>4</SUB>), and water (H<SUB>2</SUB>O) vapor) at hourly intervals at a mountainous monitoring site close to the highly industrialized city of Seoul, Korea. Correlations between the concentrations of Hg and those of the greenhouse gases were examined to assess their source characteristics and responses to changes in meteorological conditions. The mean Hg levels in this study (3.58 ± 2.13 ng m<SUP>−3</SUP>) were considerably lower (by, <I>e.g.</I>, 24.3%) than those measured previously in other comparable sites during 1999–2006 (4.73 ± 1.34 ng m<SUP>−3</SUP>). Accordingly, such a reduction in Hg levels suggests the effectiveness of the regulatory measures enforced over the years. The mean Hg level observed in this study is also lower (by approximately 5%) than those in other Asian locations. In contrast, the mean concentrations of the two most important GHGs (CO<SUB>2</SUB> and CH<SUB>4</SUB>) were moderately higher than those of other locations across the world (by approximately 4–9%). The results of our analysis indicate that the behavior of Hg is strongly correlated with water vapor and CH<SUB>4</SUB> in terms of their source characteristics, despite notable differences in their diurnal patterns.</P> <P>Graphic Abstract</P><P>The study at Mt. Gwan-ak (Seoul, Korea) revealed that the behavior of Hg was strongly correlated with water vapor and CH<SUB>4</SUB>, suggesting good similarities in their source characteristics. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4em00663a'> </P>

Recent developments in analytical quantitation approaches for parabens in human-associated samples

Raza, Nadeem,Kim, Ki-Hyun,Abdullah, Muhammad,Raza, Waseem,Brown, Richard J.C. Elsevier 2018 Trends in analytical chemistry Vol.98 No.-

<P>Parabens are an important class of antimicrobial compounds used as preservatives. Although they are considered to be safe when used within specified concentration limits, concerns about their potential toxicity have been raised due to their presence in cancerous breast tissues and their association with estrogenic activity, various kinds of allergies, and the malfunctioning of reproductive organs. The small quantities of parabens in human samples and complex nature of biological matrices make it difficult to determine free and/or conjugated forms of parabens and their metabolites. Consequently, it is desirable to develop sophisticated approaches for their sample pretreatments and subsequent determination. This review presents recent developments in the extraction, pre-concentration, and instrumental detection methods needed for the accurate quantification of parabens in human samples. This review is thus expected to help readers assess the potential impacts of parabens on human health through proper description of their exposure routes to human. (C) 2017 Elsevier B.V. All rights reserved.</P>