Long-term observation of black carbon aerosols at an urban location over the central Indo-Gangetic Plain, South Asia

Abstract

Se presentan las primeras mediciones a largo plazo de aerosoles de carbono negro (CN) en una ubicación urbana de la llanura indogangética media (IGP, por sus siglas en inglés). Tanto las variaciones a corto como a largo plazo en CN de 2009 a 2013 se analizan con énfasis específico en la variación de las fuentes de CN, la meteorología, la tendencia y el posible mecanismo de transporte a través de la IGP. Se observó una carga de CN excepcionalmente alta con una media (± DE) de 11.8 (± 8.6), con un patrón estacional fuerte y constante (mediana: 8.8; rango: 1.4-48.0 μg m -3 ). El aumento específico en el invierno (21.5 ± 9.9 μg m -3 ) y la temporada post monzón (17.4 ± 10.2 μg m -3 ) fue consistente con el aumento de las emisiones domésticas y la quema de residuos agrícolas. La masa de CN fue influenciada principalmente por fuentes locales, mientras que el cambio repentino en la concentración de CN fue consistente con el cambio en Delta-C, lo cual indica que las emisiones provienen principalmente de fuentes biogénicas de CN. Además de las fuentes, la altura de la capa límite atmosférica influyó considerablemente en la carga de CN. También se calculó una tendencia creciente monotónica estadísticamente significativa en la concentración de CN (0.9 μg m -3 yr -1 ) junto con sus correspondientes límites de incertidumbre de 95% (0.38-1.52 μg m -3 yr -1 ). Tal aumento gradual en CN fue consistente con el aumento potencial en sus fuentes. Además, se encontró evidencia clara del transporte local y regional de aerosoles de utilizando el modelo lagrangiano de partículas. ABSTRACTThe first ever long-term measurement of black carbon (BC) aerosols over an urban location at the central Indo-Gangetic Plain (IGP) is presented. Both short-and long-term variations in BC during the period 2009-2013 are discussed with specific emphasis on variation in BC sources, meteorology, trend and possible transport pathways across the IGP. High BC mass loading was noted with a 5-yr composite mean (± SD) of 11.8 (± 8.6) µg m -3 , having strong and consistent seasonal variations (median: 8.8; range: 1.4-48.0 µg m -3 ). Winter (21.5 ± 9.9µ gm -3 ) and post-monsoon (17.4 ± 10.2 µg m -3 ) specific rises in BC mass were consistent with the increase in household emissions, and from agricultural residue burning. The BC mass concentration was mostly influenced by local sources, while sudden change in BC was consistent with the change in Delta-C, indicating emissions primarily from biomass burning. Beside sources, atmospheric boundary layer height was noted to considerably influence short-term variations in BC concentration. A statistically significant monotonic increasing trend in BC concentration (0.9 µg m -3 yr -1 ) was computed along with its 95% uncertainty bounds (0.38-1.52 µ gm -3 yr -1 ). Increase in BC concentration was consistent with a rise in BC sources across the IGP and over India. Furthermore, clear evidence of local and regional scale transport of BC aerosols was found using the particle Lagrangian model.

Long-Term eBC Measurements with the Use of MAAP in the Polluted Urban Atmosphere (Poland)

“…During the entire 11-year measurement period, eBC concentrations in the urban atmosphere of Zabrze showed similar annual fluctuations. Temporal variations in daily eBC concentrations are common and have also been observed at other urban stations, e.g., at Varanasi (India, South Asia), where significantly higher eBC concentrations were recorded (1.4-48.1 µg•m −3 ) [41]. Maximum concentrations at a level similar to those in this study were recorded in the form of a single peak during long-term measurements of eBC at urban site in Beijing (BC max = 24.28 µg•m −3 ) [54].…”

“…A comparison of long-term eBC concentrations with the values from the 13-year period (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002) in the area of the Canadian Arctic shows a similar relationship; however, the peak concentrations of eBC were observed in the period from January to April [58]. Considering only measurement stations with similar characteristics, the average monthly eBC concentrations recorded at the urban station in Varanasi (Indo-Gangetic Plain, South Asia) (from ~5 to ~24 µg•m −3 ) were higher than those registered in Zabrze, but revealed similar variations, with a maximum falling in January [41]. High concentrations of eBC in the fall and winter months were also observed during long-term measurements carried out at urban background and industrial in Germany [46].…”

“…The eleven-year averaged concentration of eBC at the urban background station in Zabrze was 3.82 ± 4.23 µg•m −3 (Table 1), which was clearly lower compared to the average concentrations of eBC from long-term measurements (2006-2015) carried out at urban stations in China, e.g., Chengdu (9.97 µg•m −3 ), Beijing (7.17 µg•m −3 ), and Zhengzhou (9.59 µg•m −3 ) [39]. Higher eBC concentrations were also recorded at the urban station in Colombo (Sri Lanka) during five-year measurements (11.30 µg•m −3 ) [40] and at the urban station in Varanasi (India) (11.8 µg•m −3 ) (4-year period) [41]. Focusing only on the results of studies conducted in Europe, it was found that the concentrations of eBC observed in Zabrze are generally higher compared to the values recorded at most urban or urban background stations, e. [43].…”

“…The occurrence of an episodic increase in the diurnal course of eBC concentrations may therefore be characteristic and independent of the localization characteristics. Annual variability of eBC concentrations may be caused, on the one hand, by a change in the intensity of anthropogenic emission sources, and, on the other hand, by a change in meteorological conditions [41,56,57].…”

Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications

“…Here, it is important to note that BC trends over the urban/semi-urban coastal locations in southern India can be quite different, as compared to the high-altitude locations over northern India, which are in close proximity to the highly polluted IGP region. Interestingly, the BC trend over the urban location, Varanasi, over the central IGP has been reported to show an increasing trend in BC (Srivastava et al, 2019).…”