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<p>A comprehensive year-long 24-hourly PM<sub>2.5</sub> sampling was performed at five different land-use sites over urban environment of Jammu in the North-Western Himalayas using volume flow controlled high volume samplers. Approximately 600 PM<sub>2.5</sub> samples were analysed for their optical properties. Attenuation (ATN) at 678&#xa0;nm, Elemental Carbon surface density (EC<sub>sd</sub>) and absorption coefficient were measured using Lab Organic Carbon-Elemental Carbon Aerosol Analyzer followed by the estimation of EC Mass Absorption Efficiency (EC-MAE) using established protocol. Strong linear relationships (R²: 0.72–0.95 &amp; <i>p</i> &lt; 0.05) between ATN and EC<sub>sd</sub> were observed suggesting EC as the principal absorbing species in PM<sub>2.5</sub>. The ATN and EC<sub>sd</sub> were highest at kerbside site and lowest at background site. Conversely, annual average EC-MAE was highest at background site (15.99 ± 5.35&#xa0;m²/g) and lowest at kerbside site (7.13 ± 2.66&#xa0;m²/g), reflecting differences in emission source(s) and atmospheric processing. Statistically significant variations (<i>p</i> &lt; 0.05) both site-wise and season-wise were observed in EC-MAE. Season-wise, highest and lowest EC-MAE was observed during summer and spring seasons respectively. Plausible reasons for lower EC-MAE at kerbside site and during the spring season could be the emission of fresh EC; whereas higher EC-MAE at background site and in summer season indicated suspected coating of freshly emitted EC aerosols with other absorbing species viz. secondary organic aerosols during transport from high to low source(s) strength sites. Findings indicate that aged and/or coated fine atmospheric particles at background locations, may lead to higher radiative forcing effects per unit mass as compared to the emission hotspots.</p>

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Spatio-temporal dynamics in elemental carbon-mass absorption efficiency of fine atmospheric particles over urban environment in the North-Western Himalayas

  • 期刊论文

  • 发表日期：

    2026年2月14日

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  • Konika Sharma,
  • Shweta Yadav,
  • Ankit Tandon

摘要

A comprehensive year-long 24-hourly PM2.5 sampling was performed at five different land-use sites over urban environment of Jammu in the North-Western Himalayas using volume flow controlled high volume samplers. Approximately 600 PM2.5 samples were analysed for their optical properties. Attenuation (ATN) at 678 nm, Elemental Carbon surface density (ECsd) and absorption coefficient were measured using Lab Organic Carbon-Elemental Carbon Aerosol Analyzer followed by the estimation of EC Mass Absorption Efficiency (EC-MAE) using established protocol. Strong linear relationships (R²: 0.72–0.95 & p < 0.05) between ATN and ECsd were observed suggesting EC as the principal absorbing species in PM2.5. The ATN and ECsd were highest at kerbside site and lowest at background site. Conversely, annual average EC-MAE was highest at background site (15.99 ± 5.35 m²/g) and lowest at kerbside site (7.13 ± 2.66 m²/g), reflecting differences in emission source(s) and atmospheric processing. Statistically significant variations (p < 0.05) both site-wise and season-wise were observed in EC-MAE. Season-wise, highest and lowest EC-MAE was observed during summer and spring seasons respectively. Plausible reasons for lower EC-MAE at kerbside site and during the spring season could be the emission of fresh EC; whereas higher EC-MAE at background site and in summer season indicated suspected coating of freshly emitted EC aerosols with other absorbing species viz. secondary organic aerosols during transport from high to low source(s) strength sites. Findings indicate that aged and/or coated fine atmospheric particles at background locations, may lead to higher radiative forcing effects per unit mass as compared to the emission hotspots.