scholarly journals Observation and analysis of spatio-temporal characteristics of surface ozone and carbon monoxide at multiple sites in the Kathmandu Valley, Nepal

2017 ◽  
Author(s):  
Khadak Singh Mahata ◽  
Maheswar Rupakheti ◽  
Arnico Kumar Panday ◽  
Piyush Bhardwaj ◽  
Manish Naja ◽  
...  
Keyword(s):  
Air Pollution ◽  
Forest Fires ◽  
Mountain Pass ◽  
Kathmandu Valley ◽  
Emission Flux ◽  
Mixing Ratio ◽  
Top Down ◽  
Monsoon Period ◽  
Temporal Characteristics ◽  
Mixing Ratios

Abstract. Residents of the Kathmandu Valley experience severe particulate and gaseous air pollution throughout most of the year, even during much of the rainy season. The knowledge base for understanding the air pollution in the Kathmandu Valley was previously very limited, but is improving rapidly due to several field measurement studies conducted in the last few years. Thus far, most analyses of observations in the Kathmandu Valley have been limited to short periods of time at single locations. This study extends on the past studies by examining the spatial and temporal characteristics of two important gaseous air pollutant (CO and O3) based on simultaneous observations over a longer period at five locations within the valley and on its rim, including a supersite (at Bode in the valley center, 1345 m above sea level) and four satellite sites (at Paknajol, 1380 m asl in the Kathmandu city center, at Bhimdhunga (1522 m asl), a mountain pass on the valley's western rim, at Nagarkot (1901 m asl), another mountain pass on the eastern rim, and Naikhandi, near the valley's only river outlet). CO and O3 mixing ratios were monitored from January to July 2013, along with other gases and aerosol particles by instruments deployed at the Bode supersite during the international air pollution measurement campaign SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley – endorsed by the Atmospheric Brown Clouds program of UNEP). The O3 monitoring at Bode, Paknajol and Nagarkot as well as the CO monitoring at Bode were extended beyond July 2013 to investigate their variability over a complete annual cycle. Higher CO mixing ratios were found at Bode than at the outskirt sites (Bhimdhunga, Naikhandi and Nagarkot), and all sites except Nagarkot showed distinct diurnal cycles of CO mixing ratio with morning peaks and daytime lows. Seasonally, CO was higher during the pre-monsoon and winter seasons, especially due to the emissions from brick kiln industries, which only operate during this period, as well as increased domestic heating during winter, and regional forest fires and agro-residue burning. It was lower during the monsoon due to rainfall, which reduces open burning activities within the valley and in the surrounding regions, and thus reduces the sources of CO. The meteorology of the valley also played a key role in determining the CO mixing ratios. Furthermore, there was evidence of some influence of pollution from the greater region around the valley. A top-down estimate of the CO emission flux was made by using the CO mixing ratio and mixing layer height (MLH) measured at Bode. The estimated annual CO flux at Bode was 4.92 μg m−2 s−1, which is 2–14 times higher than that in widely used emission inventory databases (EDGAR HTAP, REAS and INTEX-B). This difference in CO flux between Bode and other emission databases likely arises from large uncertainties in both the top-down and bottom-up approaches to estimating the emission flux. The O3 mixing ratio was found to be highest during the pre-monsoon season at all sites, while the timing of the seasonal minimum varied across the sites. The daily maximum 8 hour average O3 exceeded the WHO recommended guideline of 50 ppb on more days at the hilltop station of Nagarkot (159/357 days) than at the urban valley bottom sites of Paknajol (132/354 days) and Bode (102/353 days), presumably due to the influence of free-tropospheric air at the high-altitude site, as well as to titration of O3 by fresh NOx emissions near the urban sites. More than 78 % of the exceedance days were during the pre-monsoon period at all sites. This was due to both favorable meteorological conditions as well as contributions of precursors from regional sources such as forest fires and agro-residue burning. The high O3 mixing ratio observed during the pre-monsoon period is of a high concern for human health and ecosystems, including agroecosystems in the Kathmandu Valley and surrounding regions.

scholarly journals Observation and analysis of spatiotemporal characteristics of surface ozone and carbon monoxide at multiple sites in the Kathmandu Valley, Nepal

2018 ◽  
Vol 18 (19) ◽  
pp. 14113-14132 ◽  
Author(s):  
Khadak Singh Mahata ◽  
Maheswar Rupakheti ◽  
Arnico Kumar Panday ◽  
Piyush Bhardwaj ◽  
Manish Naja ◽  
...  
Keyword(s):  
Air Pollution ◽  
Mixing Layer ◽  
Mountain Pass ◽  
Kathmandu Valley ◽  
Emission Flux ◽  
Mixing Ratio ◽  
Top Down ◽  
Layer Height ◽  
Mixing Ratios ◽  
Mixing Layer Height

Abstract. Residents of the Kathmandu Valley experience severe particulate and gaseous air pollution throughout most of the year, even during much of the rainy season. The knowledge base for understanding the air pollution in the Kathmandu Valley was previously very limited but is improving rapidly due to several field measurement studies conducted in the last few years. Thus far, most analyses of observations in the Kathmandu Valley have been limited to short periods of time at single locations. This study extends the past studies by examining the spatial and temporal characteristics of two important gaseous air pollutants (CO and O3) based on simultaneous observations over a longer period at five locations within the valley and on its rim, including a supersite (at Bode in the valley center, 1345 m above sea level) and four satellite sites: Paknajol (1380 m a.s.l.) in the Kathmandu city center; Bhimdhunga (1522 m a.s.l.), a mountain pass on the valley's western rim; Nagarkot (1901 m a.s.l.), another mountain pass on the eastern rim; and Naikhandi (1233 m a.s.l.), near the valley's only river outlet. CO and O3 mixing ratios were monitored from January to July 2013, along with other gases and aerosol particles by instruments deployed at the Bode supersite during the international air pollution measurement campaign SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley – endorsed by the Atmospheric Brown Clouds program of UNEP). The monitoring of O3 at Bode, Paknajol and Nagarkot as well as the CO monitoring at Bode were extended until March 2014 to investigate their variability over a complete annual cycle. Higher CO mixing ratios were found at Bode than at the outskirt sites (Bhimdhunga, Naikhandi and Nagarkot), and all sites except Nagarkot showed distinct diurnal cycles of CO mixing ratio, with morning peaks and daytime lows. Seasonally, CO was higher during premonsoon (March–May) season and winter (December–February) season than during monsoon season (June–September) and postmonsoon (October–November) season. This is primarily due to the emissions from brick industries, which are only operational during this period (January–April), as well as increased domestic heating during winter, and regional forest fires and agro-residue burning during the premonsoon season. It was lower during the monsoon due to rainfall, which reduces open burning activities within the valley and in the surrounding regions and thus reduces sources of CO. The meteorology of the valley also played a key role in determining the CO mixing ratios. The wind is calm and easterly in the shallow mixing layer, with a mixing layer height (MLH) of about 250 m, during the night and early morning. The MLH slowly increases after sunrise and decreases in the afternoon. As a result, the westerly wind becomes active and reduces the mixing ratio during the daytime. Furthermore, there was evidence of an increase in the O3 mixing ratios in the Kathmandu Valley as a result of emissions in the Indo-Gangetic Plain (IGP) region, particularly from biomass burning including agro-residue burning. A top-down estimate of the CO emission flux was made by using the CO mixing ratio and mixing layer height measured at Bode. The estimated annual CO flux at Bode was 4.9 µg m−2 s−1, which is 2–14 times higher than that in widely used emission inventory databases (EDGAR HTAP, REAS and INTEX-B). This difference in CO flux between Bode and other emission databases likely arises from large uncertainties in both the top-down and bottom-up approaches to estimating the emission flux. The O3 mixing ratio was found to be highest during the premonsoon season at all sites, while the timing of the seasonal minimum varied across the sites. The daily maximum 8 h average O3 exceeded the WHO recommended guideline of 50 ppb on more days at the hilltop station of Nagarkot (159 out of 357 days) than at the urban valley bottom sites of Paknajol (132 out of 354 days) and Bode (102 out of 353 days), presumably due to the influence of free-tropospheric air at the high-altitude site (as also indicated by Putero et al., 2015, for the Paknajol site in the Kathmandu Valley) as well as to titration of O3 by fresh NOx emissions near the urban sites. More than 78 % of the exceedance days were during the premonsoon period at all sites. The high O3 mixing ratio observed during the premonsoon period  is of a concern for human health and ecosystems, including agroecosystems in the Kathmandu Valley and surrounding regions.

scholarly journals Seasonal and diurnal variations of methane and carbon dioxide in the Kathmandu Valley in the foothills of the central Himalaya

2017 ◽  
Author(s):  
Khadak Singh Mahata ◽  
Arnico Kumar Panday ◽  
Maheswar Rupakheti ◽  
Ashish Singh ◽  
Manish Naja ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Monsoon Season ◽  
Winter Season ◽  
Diurnal Variations ◽  
The Other ◽  
Kathmandu Valley ◽  
Mixing Ratio ◽  
Monsoon Period ◽  
Mixing Ratios ◽  
Carbon Dioxide Co2

Abstract. The SusKat-ABC (Sustainable Amosphere for the Kathmandu Valley- Atmospheric Brown Clouds) international air pollution measurement campaign was carried out during December 2012–June 2013 in the Kathmandu Valley and surrounding regions in Nepal. The Kathmandu Valley is a bowl-shaped basin with a severe air pollution problem. This paper reports measurements of two major greenhouse gases (GHGs), methane (CH4) and carbon dioxide (CO2), that begun during the campaign and extended for a year at the SusKat-ABC’s supersite in Bode, a semi-urban location in the Kathmandu Valley. Measurements were also made at a nearby rural site (Chanban), ~ 25 km (aerial distance) to the southwest of Bode, on the other side of a tall ridge. The ambient mixing ratios of methane (CH4), carbon dioxide (CO2), water vapor, and carbon monoxide (CO) were measured with a cavity ring down spectrometer (Picarro G2401, USA), along with meteorological parameters for a year (March 2013–March 2014). Simultaneous measurements were also made at Chanban from 15 July to 3 October 2015. These measurements are the first of their kind in the central Himalayan foothills. At Bode, the annual average mixing ratios of CO2 and CH4 were 419.4 (±23.9) ppm and 2.193 (±0.224) ppm, respectively. These values are higher than the levels observed at background sites such as Mauna Loa, USA (CO2: 396.8 ppm, CH4: 1.831 ppm) and Waliguan, China (CO2: 397.7 ppm, CH4: 1.879 ppm) during the same period, and at other urban/semi-urban sites in the region such as Ahmedabad and Shadnagar (India) and Nanjing (China). They varied slightly across the seasons at Bode, with seasonal average CH4 mixing ratios being 2.157 (±0.230) ppm in the pre-monsoon season, 2.199 (±0.241) ppm in the monsoon, 2.210 (±0.200) ppm in the post-monsoon, and 2.214 (± 0.209) ppm in the winter season. The average CO2 mixing ratios were 426.2 (±25.5) ppm in pre-monsoon, 413.5 (±24.2) ppm in monsoon, 417.3 (±23.1) ppm in post-monsoon, and 421.9 (±20.3) ppm in winter season. The maximum seasonal mean mixing ratio of CH4 in winter was only 0.057 ppm or 2.6 % higher than the seasonal minimum during the pre-monsoon period, while CO2 was 12.8 ppm or 3.1 % higher during the pre-monsoon period (seasonal maximum) than during the monsoon (seasonal minimum). On the other hand, the CO mixing ratio at Bode was 191 % higher during the winter than during the monsoon season. The enhancement in CO2 mixing ratios during the pre-monsoon season is associated with additional CO2 emissions from forest fire and agro-residue burning in northern South Asia in addition to local emissions in the Kathmandu Valley. Published CO / CO2 ratios of different emission sources in Nepal and India were compared with the observed CO / CO2 ratios in this study. This comparison indicated that the major sources in the Kathmandu Valley were residential cooking and vehicle exhaust in all seasons except winter. In winter, the brick kiln emissions were a major source. Simultaneous measurement in Bode and Chanban (15 July–3 Oct 2015) revealed that the mixing ratio of CO2, CH4 and CO mixing ratios were 3.8 %, 12 %, and 64 % higher in Bode than Chanban. Kathmandu Valley, thus, has significant emissions from local sources, which can also be attributed to its bowl shaped geography that is conducive to pollution build-up. All three gas species in Bode showed strong diurnal patterns, whereas CH4 and CO at Chanban did not show any noticeable diurnal variations. These measurements provide the first insights into diurnal and seasonal variation of key greenhouse gases and air pollutants and their local and regional sources, which are important information for the atmospheric research in the region.

scholarly journals Seasonal and diurnal variations in methane and carbon dioxide in the Kathmandu Valley in the foothills of the central Himalayas

2017 ◽  
Vol 17 (20) ◽  
pp. 12573-12596 ◽  
Author(s):  
Khadak Singh Mahata ◽  
Arnico Kumar Panday ◽  
Maheswar Rupakheti ◽  
Ashish Singh ◽  
Manish Naja ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Monsoon Season ◽  
Winter Season ◽  
Diurnal Variations ◽  
Kathmandu Valley ◽  
Mixing Ratio ◽  
Monsoon Period ◽  
Mixing Ratios ◽  
Simultaneous Measurements ◽  
Carbon Dioxide Co2

Abstract. The SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley–Atmospheric Brown Clouds) international air pollution measurement campaign was carried out from December 2012 to June 2013 in the Kathmandu Valley and surrounding regions in Nepal. The Kathmandu Valley is a bowl-shaped basin with a severe air pollution problem. This paper reports measurements of two major greenhouse gases (GHGs), methane (CH4) and carbon dioxide (CO2), along with the pollutant CO, that began during the campaign and were extended for 1 year at the SusKat-ABC supersite in Bode, a semi-urban location in the Kathmandu Valley. Simultaneous measurements were also made during 2015 in Bode and a nearby rural site (Chanban)  ∼  25 km (aerial distance) to the southwest of Bode on the other side of a tall ridge. The ambient mixing ratios of methane (CH4), carbon dioxide (CO2), water vapor, and carbon monoxide (CO) were measured with a cavity ring-down spectrometer (G2401; Picarro, USA) along with meteorological parameters for 1 year (March 2013–March 2014). These measurements are the first of their kind in the central Himalayan foothills. At Bode, the annual average mixing ratios of CO2 and CH4 were 419.3 (±6.0) ppm and 2.192 (±0.066) ppm, respectively. These values are higher than the levels observed at background sites such as Mauna Loa, USA (CO2: 396.8 ± 2.0 ppm, CH4: 1.831 ± 0.110 ppm) and Waliguan, China (CO2: 397.7 ± 3.6 ppm, CH4: 1.879 ± 0.009 ppm) during the same period and at other urban and semi-urban sites in the region, such as Ahmedabad and Shadnagar (India). They varied slightly across the seasons at Bode, with seasonal average CH4 mixing ratios of 2.157 (±0.230) ppm in the pre-monsoon season, 2.199 (±0.241) ppm in the monsoon, 2.210 (±0.200) ppm in the post-monsoon, and 2.214 (±0.209) ppm in the winter season. The average CO2 mixing ratios were 426.2 (±25.5) ppm in the pre-monsoon, 413.5 (±24.2) ppm in the monsoon, 417.3 (±23.1) ppm in the post-monsoon, and 421.9 (±20.3) ppm in the winter season. The maximum seasonal mean mixing ratio of CH4 in winter was only 0.057 ppm or 2.6 % higher than the seasonal minimum during the pre-monsoon period, while CO2 was 12.8 ppm or 3.1 % higher during the pre-monsoon period (seasonal maximum) than during the monsoon (seasonal minimum). On the other hand, the CO mixing ratio at Bode was 191 % higher during the winter than during the monsoon season. The enhancement in CO2 mixing ratios during the pre-monsoon season is associated with additional CO2 emissions from forest fires and agro-residue burning in northern South Asia in addition to local emissions in the Kathmandu Valley. Published CO∕CO2 ratios of different emission sources in Nepal and India were compared with the observed CO∕CO2 ratios in this study. This comparison suggested that the major sources in the Kathmandu Valley were residential cooking and vehicle exhaust in all seasons except winter. In winter, brick kiln emissions were a major source. Simultaneous measurements in Bode and Chanban (15 July–3 October 2015) revealed that the mixing ratios of CO2, CH4, and CO were 3.8, 12, and 64 % higher in Bode than Chanban. The Kathmandu Valley thus has significant emissions from local sources, which can also be attributed to its bowl-shaped geography that is conducive to pollution build-up. At Bode, all three gas species (CO2, CH4, and CO) showed strong diurnal patterns in their mixing ratios with a pronounced morning peak (ca. 08:00), a dip in the afternoon, and a gradual increase again through the night until the next morning. CH4 and CO at Chanban, however, did not show any noticeable diurnal variations. These measurements provide the first insights into the diurnal and seasonal variation in key greenhouse gases and air pollutants and their local and regional sources, which is important information for atmospheric research in the region.

scholarly journals Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

2016 ◽  
Vol 16 (6) ◽  
pp. 3979-4003 ◽  
Author(s):  
Chinmoy Sarkar ◽  
Vinayak Sinha ◽  
Vinod Kumar ◽  
Maheswar Rupakheti ◽  
Arnico Panday ◽  
...  
Keyword(s):  
Air Pollution ◽  
South Asia ◽  
Biomass Burning ◽  
Isocyanic Acid ◽  
Kathmandu Valley ◽  
Production Potential ◽  
Mixing Ratios ◽  
Brick Kilns ◽  
Ambient Concentrations ◽  
Tof Ms

Abstract. The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley–Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012–2013, a comprehensive study was carried out to characterise the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs, by deploying a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) – the first such deployment in South Asia. In the study, 71 ion peaks (for which measured ambient concentrations exceeded the 2σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m ∕ Δm  >  4200) and temporal resolution (1 min) of the PTR-TOF-MS. The concentration ranking in the average VOC mixing ratios during our wintertime deployment was acetaldehyde (8.8 ppb)  >  methanol (7.4 ppb)  >  acetone + propanal (4.2 ppb)  >  benzene (2.7 ppb)  >  toluene (1.5 ppb)  >  isoprene (1.1 ppb)  >  acetonitrile (1.1 ppb)  >  C8-aromatics ( ∼ 1 ppb)  >  furan ( ∼ 0.5 ppb)  >  C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m ∕ z  =  69.070) and furan (m ∕ z  =  69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde ( ∼  9 ppb), acetonitrile ( ∼  1 ppb) and isoprene ( ∼  1 ppb) to be among the highest reported to date. Two "new" ambient compounds, namely formamide (m ∕ z  =  46.029) and acetamide (m ∕ z  =  60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust), which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile, which correlated strongly with acetonitrile (r2 > 0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential. Based on known secondary organic aerosol (SOA) yields and measured ambient concentrations in the Kathmandu Valley, the relative SOA production potential of VOCs were benzene  >  naphthalene  >  toluene  >  xylenes  >  monoterpenes  >  trimethylbenzenes  >  styrene  >  isoprene. The first ambient measurements from any site in South Asia of compounds with significant health effects such as isocyanic acid, formamide, acetamide, naphthalene and nitromethane have been reported in this study. Our results suggest that mitigation of intense wintertime biomass burning activities, in particular point sources such biomass co-fired brick kilns, would be important to reduce the emission and formation of toxic VOCs (such as benzene and isocyanic acid) in the Kathmandu Valley.

scholarly journals Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

2015 ◽  
Vol 15 (17) ◽  
pp. 25021-25087 ◽  
Author(s):  
C. Sarkar ◽  
V. Sinha ◽  
V. Kumar ◽  
M. Rupakheti ◽  
A. Panday ◽  
...  
Keyword(s):  
Air Pollution ◽  
South Asia ◽  
Biomass Burning ◽  
Isocyanic Acid ◽  
Kathmandu Valley ◽  
Production Potential ◽  
Mixing Ratios ◽  
Brick Kilns ◽  
Ambient Concentrations ◽  
Tof Ms

Abstract. The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the Valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012–2013, a comprehensive study was carried out to characterize the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs by deploying a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS)–the first such deployment in South Asia. 71 ion peaks (for which measured ambient concentrations exceeded the 2 σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the Valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m/Δm > 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The highest average VOC mixing ratios during the measurement period were (in rank order): acetaldehyde (8.8 ppb), methanol (7.4 ppb), acetone (4.2 ppb), benzene (2.7 ppb), toluene (1.5 ppb), isoprene (1.1 ppb), acetonitrile (1.1 ppb), C8-aromatics (~ 1 ppb), furan (~ 0.5 ppb), and C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m/z = 69.070) and furan (m/z = 69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde (~ 9 ppb), acetonitrile (~ 1 ppb) and isoprene (~ 1 ppb) to be among the highest reported till date. Two "new" ambient compounds namely, formamide (m/z = 46.029) and acetamide (m/z = 60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust) which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene, and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile which correlated strongly with acetonitrile (r2 > 0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential. Based on known SOA yields and measured ambient concentrations in the Kathmandu Valley, the relative SOA production potential of VOCs were: benzene > naphthalene > toluene > xylenes > monoterpenes > trimethyl-benzenes > styrene > isoprene. The first ambient measurements from any site in South Asia of compounds with significant health effects such as isocyanic acid, formamide, acetamide, naphthalene and nitromethane have been reported in this study. Our results suggest that mitigation of intense wintertime biomass burning activities, in particular point sources such biomass co-fired brick kilns, would be important to reduce the emission and formation of toxic VOCs (such as benzene and isocyanic acid) in the Kathmandu Valley and improve its air quality.

scholarly journals Distribution of ozone and its precursors over Bay of Bengal during winter 2009: role of meteorology

2011 ◽  
Vol 29 (9) ◽  
pp. 1613-1627 ◽  
Author(s):  
L. M. David ◽  
I. A. Girach ◽  
P. R. Nair
Keyword(s):  
Bay Of Bengal ◽  
Forest Fires ◽  
Anthropogenic Activities ◽  
Mean Value ◽  
Radiation Budget ◽  
Mixing Ratio ◽  
Ozone Level ◽  
Back Trajectories ◽  
Mixing Ratios ◽  
The North

Abstract. Measurements of ozone and NO2 were carried out in the marine environment of the Bay of Bengal (BoB) during the winter months, December 2008–January 2009, as part of the second Integrated Campaign for Aerosols, gases and Radiation Budget conducted under the Geosphere Biosphere Programme of the Indian Space Research Organization. The ozone mixing ratio was found to be high in the head and the southeast BoB with a mean value of 61 ± 7 ppb and 53 ± 6 ppb, respectively. The mixing ratios of NO2 and CO were also relatively high in these regions. The spatial patterns were examined in the light of airflow patterns, air mass back trajectories and other meteorological conditions and satellite retrieved maps of tropospheric ozone, NO2, CO, and fire count in and around the region. The distribution of these gases was strongly associated with the transport from the adjoining land mass. The anthropogenic activities and forest fires/biomass burning over the Indo Gangetic Plains and other East Asian regions contribute to ozone and its precursors over the BoB. Similarity in the spatial pattern suggests that their source regions could be more or less the same. Most of the diurnal patterns showed decrease of the ozone mixing ratio during noon/afternoon followed by a nighttime increase and a morning high. Over this oceanic region, photochemical production of ozone involving NO2 was not very active. Water vapour played a major role in controlling the variation of ozone. An attempt is made to simulate ozone level over the north and south BoB using the photochemical box model (NCAR-MM). The present observed features were compared with those measured during the earlier cruises conducted in different seasons.

scholarly journals Assessment of Tropospheric Concentrations of NO2 from the TROPOMI/Sentinel-5 Precursor for the Estimation of Long-Term Exposure to Surface NO2 over South Korea

2021 ◽  
Vol 13 (10) ◽  
pp. 1877
Author(s):  
Ukkyo Jeong ◽  
Hyunkee Hong
Keyword(s):  
South Korea ◽  
Spatial Resolution ◽  
Atmospheric Composition ◽  
Mixing Ratio ◽  
Mean Values ◽  
Mixing Ratios ◽  
Tropospheric No2 ◽  
Korean Ministry ◽  
Surface Mixing ◽  
Rural Sites

Since April 2018, the TROPOspheric Monitoring Instrument (TROPOMI) has provided data on tropospheric NO2 column concentrations (CTROPOMI) with unprecedented spatial resolution. This study aims to assess the capability of TROPOMI to acquire high spatial resolution data regarding surface NO2 mixing ratios. In general, the instrument effectively detected major and moderate sources of NO2 over South Korea with a clear weekday–weekend distinction. We compared the CTROPOMI with surface NO2 mixing ratio measurements from an extensive ground-based network over South Korea operated by the Korean Ministry of Environment (SKME; more than 570 sites), for 2019. Spatiotemporally collocated CTROPOMI and SKME showed a moderate correlation (correlation coefficient, r = 0.67), whereas their annual mean values at each site showed a higher correlation (r = 0.84). The CTROPOMI and SKME were well correlated around the Seoul metropolitan area, where significant amounts of NO2 prevailed throughout the year, whereas they showed lower correlation at rural sites. We converted the tropospheric NO2 from TROPOMI to the surface mixing ratio (STROPOMI) using the EAC4 (ECMWF Atmospheric Composition Reanalysis 4) profile shape, for quantitative comparison with the SKME. The estimated STROPOMI generally underestimated the in-situ value obtained, SKME (slope = 0.64), as reported in previous studies.

Associations Between Ambient Particulate Air Pollution and Cognitive Function in Indonesian Children Living in Forest Fire–Prone Provinces

2021 ◽  
pp. 101053952110317
Author(s):  
Bin Jalaludin ◽  
Frances L. Garden ◽  
Agata Chrzanowska ◽  
Budi Haryanto ◽  
Christine T. Cowie ◽  
...  
Keyword(s):  
Air Pollution ◽  
Cognitive Function ◽  
Forest Fire ◽  
Forest Fires ◽  
Regression Models ◽  
Individual Factors ◽  
Aerodynamic Diameter ◽  
Particulate Air Pollution ◽  
Multivariable Models ◽  
Particulate Matter 2.5

Smoke from forest fires can reach hazardous levels for extended periods of time. We aimed to determine if there is an association between particulate matter ≤2.5 µm in aerodynamic diameter (PM2.5) and living in a forest fire–prone province and cognitive function. We used data from the Indonesian Family and Life Survey. Cognitive function was assessed by the Ravens Colored Progressive Matrices (RCPM). We used regression models to estimate associations between PM2.5 and living in a forest fire–prone province and cognitive function. In multivariable models, we found very small positive relationships between PM2.5 levels and RCPM scores (PM2.5 level at year of survey: β = 0.1%; 95% confidence interval [CI] = 0.01% to 0.19%). There were no differences in RCPM scores for children living in forest fire–prone provinces compared with children living in non-forest fire–prone provinces (mean difference = −1.16%, 95% CI = −2.53% to 0.21%). RCPM scores were lower for children who had lived in a forest fire–prone province all their lives compared with children who lived in a non-forest fire–prone province all their life (β = −1.50%; 95% CI = −2.94% to −0.07%). Living in a forest fire–prone province for a prolonged period of time negatively affected cognitive scores after adjusting for individual factors.

scholarly journals One-Year Characterization and Reactivity of Isoprene and Its Impact on Surface Ozone Formation at A Suburban Site in Guangzhou, China

Atmosphere ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 201 ◽  
Author(s):  
Yu Zou ◽  
Xue Jiao Deng ◽  
Tao Deng ◽  
Chang Qin Yin ◽  
Fei Li
Keyword(s):  
Surface Ozone ◽  
Atmospheric Composition ◽  
Anthropogenic Factors ◽  
Mixing Ratio ◽  
Night Time ◽  
Subtropical Zone ◽  
Guangzhou City ◽  
Mixing Ratios ◽  
One Year ◽  
Suburban Site

Isoprene has a potentially large effect on ozone (O3) formation in the subtropical, highly polluted city of Guangzhou. Online measurements of isoprene in Guangzhou city are scarce; thus, isoprene levels were monitored for one year at the Guangzhou Panyu Atmospheric Composition Station (GPACS), a suburban site in Guangzhou, using an online gas chromatography-flame ionization detector (GC–FID) system to investigate the characterization and reactivity of isoprene and its effect on the O3 peak profile in different seasons. The results showed that the daily average mixing ratios of isoprene at GPACS were 0.40, 2.20, 1.40, and 0.13 mixing ratio by volume (ppbv) in spring, summer, autumn, and winter, respectively. These values were considerably higher than the mixing ratios of isoprene in the numerous other subtropical and temperate cities around the world. Furthermore, isoprene ranked first with regard to O3 formation potential (OFP) and propylene-equivalent mixing ratio among 56 measured non–methane hydrocarbons (NMHCs). The ratios of isoprene to cis-2-butene, an exhaust tracer, were determined to estimate the fractions of biogenic and anthropogenic emissions. The results revealed a much greater contribution from biogenic than anthropogenic factors during the daytime in all four seasons. In addition, night-time isoprene emissions were mostly associated with vehicles in winter, and the residual isoprene that remained after photochemical loss during the daytime also persisted into the night. The high levels of isoprene in summer and autumn may cause the strong and broad peaks of the O3 profile because of its association with the most favorable meteorological conditions (e.g., high temperature and intense solar radiation) and the highest OH mixing ratio, which could affect human health by exposing people to a high O3 mixing ratio for prolonged periods. The lower mixing ratios of isoprene resulted in a weak and sharp peak in the O3 profile in both spring and winter. The high level of isoprene in the subtropical zone could accentuate its large impact on atmospheric oxidant capacity and air quality in Guangzhou city.

Climate change and its impact on the development of allergic diseases

2021 ◽  
Vol 17 (4) ◽  
pp. 7-18
Author(s):  
Evgeniya V. Nazarova
Keyword(s):  
Air Pollution ◽  
Respiratory System ◽  
Forest Fires ◽  
Negative Impact ◽  
Allergic Diseases ◽  
Developed Countries ◽  
Dust Storms ◽  
International Studies ◽  
Treatment And Prevention ◽  
Earth Temperature

Since the middle of the twentieth century, there has been a widespread increase in the prevalence of allergic diseases, especially in developed countries. Much attention is paid to the changing climate and its influence on the development of allergies, mainly of the respiratory system. In many countries, studies are intensifying to study the relationship of various weather phenomena, air pollution, Earth temperature with the course of certain allergic diseases of the respiratory tract. Global strategies for the treatment and prevention of allergic diseases are being developed. This review provides data from international studies demonstrating the negative impact on human health and the development of allergic diseases of the respiratory system, in particular asthma: a global rise in Earth temperature, air pollution, dust storms, forest fires, dampness in rooms and atmospheric mold, thunderstorms and floods.

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