scholarly journals Potential Source Regions and Transportation Pathways of Reactive Gases at a Regional Background Site in Northwestern China

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Quanwei Zhao ◽  
Qing He ◽  
Lili Jin ◽  
Jianlin Wang
Keyword(s):  
Cluster Analysis ◽  
Diurnal Variation ◽  
Source Area ◽  
Northwestern China ◽  
Mixing Ratios ◽  
Source Regions ◽  
Potential Source ◽  
Regional Background ◽  
Reactive Gases ◽  
Reactive Gas

Reactive gases (O3, CO, NO2, and SO2) were collected hourly at the Akedala regional background station in northwestern China during September 2017 to August 2018. Wind rose, cluster analysis, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) methods were adopted for identifying the transport pathways and potential source regions of these atmosphere components at Akedala. The average O3, CO, NO2, and SO2 mixing ratios detected were 29.65 ± 11.44 ppb, 123.78 ± 73.35 ppb, 3.79 ± 0.98 ppb, and 4.59 ± 0.88 ppb during the observation period, and the statistical results of the monthly mean values revealed that there were differences during the highest pollution period, with O3 and CO mainly peaking in February, with mixing ratios of 38.03 ± 7.10 ppb and 208.50 ± 106.50 ppb, respectively. Meanwhile, NO2 peaked in March (4.51 ± 0.54 ppb) and SO2 in January (5.70 ± 1.92 ppb). The most obvious diurnal variation of CO and SO2 was observed in the winter, with maximum levels reaching between 13 : 00 and 14 : 00. The diurnal variations of O3 exhibited low values during the night and maximum values in the afternoon (16 : 00–18 : 00). Diurnal variation was not significant in the case of NO2. Cluster analysis showed that six main paths affected the Akedala atmosphere. In turn, the PSCF and CWT analysis results indicated that the Akedala reactive gas was affected by both local and foreign sources. The high PSCF value of the reactive gas potential source areas appeared in eastern Kazakhstan, northern Xinjiang, Western Mongolia, and Southern Russia. The WCWT (weighted concentration-weight trajectory) values of CO and SO2 in winter were the highest, totaling 180–240 ppb and 5–6.5 ppb, respectively. The WCWT value of O3 in the spring and summer was higher than that in the autumn and winter. The main source area of O3 was about 32–36 ppb in the spring and summer, and the main source area of NO2 in the summer had a low WCWT value of 3–3.5 ppb, whereas the NO2 WCWT value was concentrated at 4–4.5 ppb in the other seasons.

scholarly journals Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1299
Author(s):  
Jiebo Zhen ◽  
Minmin Yang ◽  
Jie Zhou ◽  
Fengchun Yang ◽  
Tao Li ◽  
...  
Keyword(s):  
Eastern China ◽  
Source Region ◽  
Mixing Ratios ◽  
Industrial Sites ◽  
Source Regions ◽  
Msw Landfill ◽  
Potential Source ◽  
Ambient Concentration ◽  
Global Background ◽  
Concentration Levels

Recent studies have indicated that Eastern China might be a potential source region of increased atmospheric chlorofluorocarbons (CFCs). To investigate this possibility, a field measurement was carried out from October to December 2017 for identifying the ambient concentration levels of representative trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trifluorotrichloroethane (CFC-113), and tetrafluorodichloroethane (CFC-114) at the residential and municipal solid waste (MSW) landfills and industrial sites in Eastern China. The ambient mixing ratios of CFCs at residential sites were almost within 20% enhancements of the global background sites. The highest levels of CFCs were observed at the MSW landfill sites. Moreover, CFC-11 and CFC-113 concentrations at MSW landfill, which was in service, were two times higher than that at completed MSW landfill. Mean concentrations of 322 pptv for CFC-11, 791 pptv for CFC-12, 91 pptv for CFC-113, and 16 pptv for CFC-114 at various industrial sites were higher than those at residential sites, but they were obviously lower than that at MSW landfill in use. A poor intercorrelation between the CFCs indicated that they did not come from the same source. Higher concentrations measured in this study compared with background sites indicates that MSW landfills could be an unintentional emission source and there are still substantial amounts of CFCs being stored in banks that may discharge CFCs into the atmosphere in Eastern China.

Potential source regions of air pollutants at a regional background station in Northern China

2018 ◽  
Vol 40 (26) ◽  
pp. 3412-3421 ◽  
Author(s):  
Weiwei Pu ◽  
Xuefeng Shi ◽  
Lili Wang ◽  
Jing Xu ◽  
Zhiqiang Ma
Keyword(s):  
Air Pollutants ◽  
Northern China ◽  
Source Regions ◽  
Potential Source ◽  
Regional Background

scholarly journals Enhanced Chlorinated very Short-Lived Substances in South East Asia: Potential Source Regions and Source Types

2020 ◽  
Vol 616 ◽  
pp. 012011
Author(s):  
Norfazrin Mohd Hanif ◽  
Claire E. Reeves ◽  
David E. Oram ◽  
Matthew J. Ashfold ◽  
Marios Panagi ◽  
...  
Keyword(s):  
East Asia ◽  
South East Asia ◽  
Source Regions ◽  
Potential Source

Investigation of potential source regions of atmospheric Black Carbon in the data deficit region of the western Himalayas and its foothills

2019 ◽  
Vol 10 (6) ◽  
pp. 1832-1842 ◽  
Author(s):  
Ashish Soni ◽  
Stefano Decesari ◽  
Vijay Shridhar ◽  
Vignesh Prabhu ◽  
Pooja Panwar ◽  
...  
Keyword(s):  
Black Carbon ◽  
Western Himalayas ◽  
Source Regions ◽  
Potential Source

Energetic Neutral Atoms from the Heliotail Direction and their Potential Source Regions

2010 ◽  
Author(s):  
M. Hilchenbach ◽  
R. Kallenbach ◽  
K. C. Hsieh ◽  
A. Czechowski ◽  
Jakobus le Roux ◽  
...  
Keyword(s):  
Neutral Atoms ◽  
Source Regions ◽  
Potential Source ◽  
Energetic Neutral Atoms

scholarly journals Identification of Long-Range Transport Pathways and Potential Source Regions of PM2.5 and PM10 at Akedala Station, Central Asia

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1183
Author(s):  
Hanlin Li ◽  
Qing He ◽  
Xinchun Liu
Keyword(s):  
Central Asia ◽  
Transport Pathways ◽  
Air Masses ◽  
Source Areas ◽  
Northern Xinjiang ◽  
Source Regions ◽  
Potential Source ◽  
Western Mongolia ◽  
Pm2.5 And Pm10 ◽  
Eastern Kazakhstan

Cluster analyses, potential source contribution function (PSCF) and concentration-weight trajectory (CWT) were used to identify the main transport pathways and potential source regions with hourly PM2.5 and PM10 concentrations in different seasons from January 2017 to December 2019 at Akedala Station, located in northwest China (Central Asia). The annual mean concentrations of PM2.5 and PM10 were 11.63 ± 9.31 and 19.99 ± 14.39 µg/m3, respectively. The air pollution was most polluted in winter, and the dominant part of PM10 (between 54 to 76%) constituted PM2.5 aerosols in Akedala. Particulate pollution in Akedala can be traced back to eastern Kazakhstan, northern Xinjiang, and western Mongolia. The cluster analyses showed that the Akedala atmosphere was mainly affected by air masses transported from the northwest. The PM2.5 and PM10 mainly came with air masses from the central and eastern regions of Kazakhstan, which are characterized by highly industrialized and semi-arid desert areas. In addition, the analyses of the pressure profile of back-trajectories showed that air mass distribution were mainly distributed above 840 hPa. This indicates that PM2.5 and PM10 concentrations were strongly affected by high altitude air masses. According to the results of the PSCF and CWT methods, the main potential source areas of PM2.5 were very similar to those of PM10. In winter and autumn, the main potential source areas with high weighted PSCF values were located in the eastern regions of Kazakhstan, northern Xinjiang, and western Mongolia. These areas contributed the highest PM2.5 concentrations from 25 to 40 µg/m3 and PM10 concentrations from 30 to 60 µg/m3 in these seasons. In spring and summer, the potential source areas with the high weighted PSCF values were distributed in eastern Kazakhstan, northern Xinjiang, the border between northeast Kazakhstan, and southern Russia. These areas contributed the highest PM2.5 concentrations from 10 to 20 µg/m3 and PM10 concentrations from 20 to 60 µg/m3 in these seasons.

scholarly journals Cluster analysis of European surface ozone observations for evaluation of MACC reanalysis data

2016 ◽  
Vol 16 (11) ◽  
pp. 6863-6881 ◽  
Author(s):  
Olga Lyapina ◽  
Martin G. Schultz ◽  
Andreas Hense
Keyword(s):  
Cluster Analysis ◽  
Statistical Tests ◽  
Surface Ozone ◽  
Atmospheric Composition ◽  
Regional Differentiation ◽  
Mixing Ratio ◽  
Data Set ◽  
Diurnal Cycles ◽  
Mixing Ratios ◽  
Weekly Cycles

Abstract. The high density of European surface ozone monitoring sites provides unique opportunities for the investigation of regional ozone representativeness and for the evaluation of chemistry climate models. The regional representativeness of European ozone measurements is examined through a cluster analysis (CA) of 4 years of 3-hourly ozone data from 1492 European surface monitoring stations in the Airbase database; the time resolution corresponds to the output frequency of the model that is compared to the data in this study. K-means clustering is implemented for seasonal–diurnal variations (i) in absolute mixing ratio units and (ii) normalized by the overall mean ozone mixing ratio at each site. Statistical tests suggest that each CA can distinguish between four and five different ozone pollution regimes. The individual clusters reveal differences in seasonal–diurnal cycles, showing typical patterns of the ozone behavior for more polluted stations or more rural background. The robustness of the clustering was tested with a series of k-means runs decreasing randomly the size of the initial data set or lengths of the time series. Except for the Po Valley, the clustering does not provide a regional differentiation, as the member stations within each cluster are generally distributed all over Europe. The typical seasonal, diurnal, and weekly cycles of each cluster are compared to the output of the multi-year global reanalysis produced within the Monitoring of Atmospheric Composition and Climate (MACC) project. While the MACC reanalysis generally captures the shape of the diurnal cycles and the diurnal amplitudes, it is not able to reproduce the seasonal cycles very well and it exhibits a high bias up to 12 nmol mol−1. The bias decreases from more polluted clusters to cleaner ones. Also, the seasonal and weekly cycles and frequency distributions of ozone mixing ratios are better described for clusters with relatively clean signatures. Due to relative sparsity of CO and NOx measurements these were not included in the CA. However, simulated CO and NOx mixing ratios are consistent with the general classification into more polluted and more background sites. Mean CO mixing ratios are within 140–145 nmol mol−1 (CL1–CL3) and 130–135 nmol mol−1 (CL4 and CL5), and NOx mixing ratios are within 4–6 nmol mol−1 and 2–3 nmol mol−1, respectively. These results confirm that relatively coarse-scale global models are more suitable for simulation of regional background concentrations, which are less variable in space and time. We conclude that CA of surface ozone observations provides a powerful and robust way to stratify sets of stations, being thus more suitable for model evaluation.

A Gas Diluter for Measuring Nanometer-Sized Particles in Oxygen or Hydrogen

1998 ◽  
Vol 41 (4) ◽  
pp. 17-23
Author(s):  
Wayne McDermott
Keyword(s):  
Laminar Flow ◽  
Turbulent Mixing ◽  
Particle Concentration ◽  
Molecular Diffusion ◽  
Experimental Tests ◽  
Inert Gas ◽  
Contaminant Particle ◽  
Reactive Gases ◽  
Percent Efficiency ◽  
Reactive Gas

A laminar flow diluter tube was designed and tested. The tube dilutes reactive gas aerosols in nitrogen using molecular diffusion. No turbulent mixing of the gases occurs in the tube. The gases are diluted without substantially changing the particle concentration of the sample. The diluted gas can then be measured using an inert gas particle counter. A numerical model predicted the molecular diffusion and particle transport behavior of the tube. Experimental tests confirmed the predictions. The tube diluted sample hydrogen to a concentration of 6.5 percent and oxygen to a concentration of 17 percent. The same tube transported particles smaller than 10 nm with greater than 78 percent efficiency. Therefore, the diluter can be used with particle counters designed for nanometer-size sensitivity. The laminar flow diluter can be used to measure contaminant particle concentrations in filtered reactive gases. Such filtered gases are typically used in microcircuit fabrication.

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