Investigations of aerosol black carbon from a semi-urban site in the Indo-Gangetic Plain region

Joshi, H. P.; Naja, Manish; Singh, Krishna Pal; Kumar, Rajesh; Bhardwaj, Piyush; Babu, S. Suresh; Satheesh, S. K.; Moorthy, K. Krishna; Chandola, H. C.

doi:10.1016/j.atmosenv.2015.04.007

Cited by 69 publications

(24 citation statements)

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“…The ratio was calculated using the equation (BC − BC 0 )/(CO − CO 0 ), assuming the background values (BC 0 or CO 0 ) as 1.25 percentile of the data. The BC/ CO ratio in Lumbini is similar to that obtained at a suburban site, Pantnagar, in India (0.017) (Joshi et al, 2016) and in Maldives (0.017) (Dickerson et al, 2002), indicating the possibility of similar types of emission sources. However, the lower BC/ CO ratio obtained over megacities such as Beijing and Shanghai is due to the higher number of gasoline and diesel vehicles (Zhou et al, 2009).…”

Section: Meteorologysupporting

confidence: 60%

Pre-monsoon air quality over Lumbini, a world heritage site along the Himalayan foothills

et al. 2017

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Abstract. Lumbini, in southern Nepal, is a UNESCO world heritage site of universal value as the birthplace of Buddha. Poor air quality in Lumbini and surrounding regions is a great concern for public health as well as for preservation, protection and promotion of Buddhist heritage and culture. We present here results from measurements of ambient concentrations of key air pollutants (PM, BC, CO, O 3 ) in Lumbini, first of its kind for Lumbini, conducted during an intensive measurement period of 3 months (April-June 2013) in the pre-monsoon season. The measurements were carried out as a part of the international air pollution measurement campaign; SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley -Atmospheric Brown Clouds). The main objective of this work is to understand and document the level of air pollution, diurnal characteristics and influence of open burning on air quality in Lumbini. The hourly average concentrations during the entire measurement campaign ranged as follows: BC was 0.3-30.0 µg m −3 , PM 1 was 3.6-197.6 µg m −3 , PM 2.5 was 6.1-272.2 µg m −3 , PM 10 was 10.5-604.0 µg m −3 , O 3 was 1.0-118.1 ppbv and CO was 125.0-1430.0 ppbv. These levels are comparable to other very heavily polluted sites in South Asia. Higher fraction of coarsemode PM was found as compared to other nearby sites in the Indo-Gangetic Plain region. The BC / CO ratio obtained in Lumbini indicated considerable contributions of emissions from both residential and transportation sectors. The 24 h average PM 2.5 and PM 10 concentrations exceeded the WHO guideline very frequently (94 and 85 % of the sampled period, respectively), which implies significant health risks for the residents and visitors in the region. These air pollutants exhibited clear diurnal cycles with high values in the morning and evening. During the study period, the worst air pollution episodes were mainly due to agro-residue burning and regional forest fires combined with meteorological conditions conducive of pollution transport to Lumbini. Fossil fuel combustion also contributed significantly, accounting for more than half of the ambient BC concentration according to aerosol spectral light absorption coefficients obtained in Lumbini. WRF-STEM, a regional chemical transport model, was used to simulate the meteorology and the concentrations of pollutants to understand the pollutant transport pathways. The model estimated values were ∼ 1.5 to 5 times lower than the observed concentrations for CO and PM 10 , respectively. Model-simulated regionally tagged CO tracers showed that the majority of CO came from the upwind region of Ganges Valley. Model performance needs significant improvement Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Meteorologysupporting

confidence: 60%

Pre-monsoon air quality over Lumbini, a world heritage site along the Himalayan foothills

et al. 2017

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“…Figure 11 shows the comparison of normalized light absorption as a function of the wavelength for BC observed at Lumbini during cooking and non-cooking hours and also for both events. Our results are compared with the published data of Kirchstetter et al (2004) and that observed over a village site of Project Surya in the IGP (Praveen et al, 2012) (figure not shown). We discuss light absorption data from two distinct times of the day.…”

Section: Does Fossil Fuel or Biomass Influencesupporting

confidence: 52%

“…Two pollutants having biomass burning as the potential primary source, BC and CO, were taken in consideration. High AAE values during these two events are also an indication of the presence of BC of biomass burning origin (Praveen et al, 2012;Bergstrom et al, 2007;Kirchstetter et al, 2004), with the value being ∼ 1.6 for Lumbini. The chemical composition of TSP filter samples collected at Lumbini also showed higher concentration of Levoglucosan, a biomass burning tracer in Lumbini during the pre-monsoon season, compared to other seasons of the year (Wan et al, 2017).…”

Section: Identification Of Large-scale Forest Fire Influence Using Inmentioning

confidence: 88%

“…Observed CO vs. model open burning CO illustrating the contribution of forest fires during peak CO loading is shown in panel (k). enables to analyze the contributions of fossil fuel combustion and biomass burning contributions to the observed BC concentration (Kirchstetter et al, 2004). Besides BC, other light absorbing (in the UV region) aerosols are also produced in course of combustion, collectively termed organic aerosols (often also called brown carbon) (Andreae and Gelencsér, 2006).…”

Section: Does Fossil Fuel or Biomass Influencementioning

confidence: 99%

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Compiled Response to the reviewers comments

Rupakheti¹

2017

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Lumbini, in southern Nepal, is a UNESCO world heritage site of universal value as the birthplace of Buddha. Poor air quality in Lumbini and surrounding regions is a great concern for public health as well as for preservation, protection and promotion of Buddhist heritage and culture. We present here results from measurements of ambient concentrations of key air pollutants (PM, BC, CO, O 3 ) in Lumbini, first of its kind for Lumbini, conducted during an intensive measurement period of 3 months (April-June 2013) in the pre-monsoon season. The measurements were carried out as a part of the international air pollution measurement campaign; SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley -Atmospheric Brown Clouds). The main objective of this work is to understand and document the level of air pollution, diurnal characteristics and influence of open burning on air quality in Lumbini. The hourly average concentrations during the entire measurement campaign ranged as follows: BC was 0.3-30.0 µg m −3 , PM 1 was 3.6-197.6 µg m −3 , PM 2.5 was 6.1-272.2 µg m −3 , PM 10 was 10.5-604.0 µg m −3 , O 3 was 1.0-118.1 ppbv and CO was 125.0-1430.0 ppbv. These levels are comparable to other very heavily polluted sites in South Asia. Higher fraction of coarsemode PM was found as compared to other nearby sites in the Indo-Gangetic Plain region. The BC / CO ratio obtained in Lumbini indicated considerable contributions of emissions from both residential and transportation sectors. The 24 h average PM 2.5 and PM 10 concentrations exceeded the WHO guideline very frequently (94 and 85 % of the sampled period, respectively), which implies significant health risks for the residents and visitors in the region. These air pollutants exhibited clear diurnal cycles with high values in the morning and evening. During the study period, the worst air pollution episodes were mainly due to agro-residue burning and regional forest fires combined with meteorological conditions conducive of pollution transport to Lumbini. Fossil fuel combustion also contributed significantly, accounting for more than half of the ambient BC concentration according to aerosol spectral light absorption coefficients obtained in Lumbini. WRF-STEM, a regional chemical transport model, was used to simulate the meteorology and the concentrations of pollutants to understand the pollutant transport pathways. The model estimated values were ∼ 1.5 to 5 times lower than the observed concentrations for CO and PM 10 , respectively. Model-simulated regionally tagged CO tracers showed that the majority of CO came from the upwind region of Ganges Valley. Model performance needs significant improvementPublished by Copernicus Publications on behalf of the European Geosciences Union. 11042 D. Rupakheti et al.: Pre-monsoon air quality over Lumbini in simulating aerosols in the region. Given the high air pollution level, there is a clear and urgent need for setting up a network of long-term air quality monitoring stations in the greater Lumbini region.

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“…Henriksson et al [2011] studied the seasonal cycle of aerosols in India and showed that their model qualitatively captures the differences in spatial patterns of sulfate and carbonaceous aerosols, and spatial distribution of aerosol optical depth, but they did not evaluate modeled BC quantitatively. The discrepancies between observations and models in these studies were mainly attributed to errors in boundary layer mixing/parameterization, uncertainties in BC emissions estimates, and coarse spatial resolution of the models [e.g., Nair et al, 2012;Moorthy et al, 2013;Michael et al, 2014;Joshi et al, 2014]. However, the knowledge of BC emissions since then has advanced with recent developments of high resolution anthropogenic (0.1°) [Janssens-Maenhout et al, 2015;Sadavarte and Venkataraman, 2014;Pandey et al, 2014] and biomass burning (1 km) [Wiedinmyer et al, 2011] emission inventories.…”

Section: Introductionmentioning

confidence: 99%

What controls the seasonal cycle of black carbon aerosols in India?

et al. 2015

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The seasonal variability of black carbon (BC) aerosols in India is studied using high resolution (10 km) BC simulations conducted using the Weather Research and Forecasting Model coupled with Chemistry. The model reproduces the observed seasonality of surface BC fairly well over most parts of India but fails to capture the seasonality in the Himalayas and deviates from the observed BC magnitude at several sites. The errors in modeled BC are attributed to uncertainties in BC emissions and their diurnal cycle, planetary boundary layer height underestimation, and aerosol processes. Model results show distinct but opposite seasonality of BC in the lower (LT) and free troposphere (FT) with BC showing winter maximum and summer minimum in the LT and vice versa in the FT. Our analysis shows that BC seasonality is not driven by seasonality of the anthropogenic emissions but by changes in the regional meteorology through weakening of the horizontal transport and strengthening of the vertical transport of BC during summertime compared to winter. BC in both the LT and FT comes mostly from anthropogenic emissions followed by biomass burning emissions except during winter when long-distant sources become more important in the FT. BC in the FT is significantly affected by anthropogenic emissions from all parts of India. The source-receptor relationship changes seasonally, but the regional transport remains a significant contributor to BC loadings in the LT of India, highlighting the necessity of considering nonlocal sources along with local emissions when designing strategies for mitigating BC impacts on air quality.

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Investigations of aerosol black carbon from a semi-urban site in the Indo-Gangetic Plain region

Cited by 69 publications

References 54 publications

Pre-monsoon air quality over Lumbini, a world heritage site along the Himalayan foothills

Pre-monsoon air quality over Lumbini, a world heritage site along the Himalayan foothills

Compiled Response to the reviewers comments

What controls the seasonal cycle of black carbon aerosols in India?

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