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Assessment of carbonaceous aerosols at Mukteshwar: A high-altitude (~2200 m amsl) background site in the foothills of the Central Himalayas

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  • معلومة اضافية
    • Contributors:
      orcid:0000-0001-7938-071X; orcid:0000-0002-6135-4473; orcid:0000-0003-4874-7552; orcid:0000-0002-9694-4844; Ilmatieteen laitos; Finnish Meteorological Institute
    • بيانات النشر:
      Elsevier
    • الموضوع:
      2023
    • Collection:
      Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto
    • نبذة مختصرة :
      The present study examined the equivalent black carbon (eBC) mass concentrations measured over 10.5 years (September 2005–March 2016) using a 7-wavelength Aethalometer (AE-31) at Mukteshwar, a high-altitude and regional background site in the foothills of Indian central Himalayas. The total spectral absorption coefficient (babs) was divided into three categories: black carbon (BC) and brown carbon (BrC); fossil fuels (FF) and wood/biomass burning (WB/BB); and primary and secondary sources. At the wavelength of 370 nm, a significant BrC contribution (25 %) to the total babs is identified, characterized by a pronounced seasonal variation with winter (December–January-February) maxima (31 %) and post-monsoon (October and November) minima (20 %); whereas, at 660 nm, the contribution of BrC is dramatically less (9 %). Climatologically, the estimated BCFF at 880 nm ranges from 0.25 ± 0.19 μg m−3 in July to 1.17 ± 0.80 μg m−3 in May with the annual average of 0.67 ± 0.63 μg m−3, accounting for 79 % of the BC mass. The maximum BCFF/BC fraction reaches its peak value during the monsoon (July and August, 85 %), indicating the dominance of local traffic emissions due to tourism activities. Further, the highest BCWB concentration observed during pre-monsoon (March–May) suggests the influence of local forest fires along with long-range transported aerosols from the low-altitude plains. The increased contribution of BrC (26 % at 370 nm) and WB absorption (61 % at 370 nm) to the total absorption at the shorter wavelengths suggests that wood burning is one of the major sources of BrC emissions. Secondary BrC absorption accounts for 24 % [91 %] of the total absorption [BrC absorption] at 370 nm, implying the dominance of secondary sources in BrC formation. A trend analysis for the measured BC concentration shows a statistically significant increasing trend with a slope of 0.02 μgm−3/year with a total increase of about 22 % over the study period. A back trajectory-based receptor model, potential source contribution function ...
    • File Description:
      application/pdf
    • ISSN:
      0048-9697
      1879-1026
    • Relation:
      Science of the total environment; 866; 88158; http://hdl.handle.net/10138/566115; URN:NBN:fi-fe20231005138958
    • الدخول الالكتروني :
      http://hdl.handle.net/10138/566115
    • Rights:
      CC BY 4.0
    • الرقم المعرف:
      edsbas.F8BD399B