title: Carbonaceous aerosols and pollutants over Delhi urban environment: Temporal evolution, source apportionment and radiative forcing.
abstract: Particulate matter (PM2.5) samples were collected over Delhi, India during January to December 2012 and analysed for carbonaceous aerosols and inorganic ions (SO4(2-) and NO3(-)) in order to examine variations in atmospheric chemistry, combustion sources and influence of long-range transport. The PM2.5 samples are measured (offline) via medium volume air samplers and analysed gravimetrically for carbonaceous (organic carbon, OC; elemental carbon, EC) aerosols and inorganic ions (SO4(2-) and NO3(-)). Furthermore, continuous (online) measurements of PM2.5 (via Beta-attenuation analyser), black carbon (BC) mass concentration (via Magee scientific Aethalometer) and carbon monoxide (via CO-analyser) are carried out. PM2.5 (online) range from 18.2 to 500.6μgm(-3) (annual mean of 124.6±87.9μgm(-3)) exhibiting higher night-time (129.4μgm(-3)) than daytime (103.8μgm(-3)) concentrations. The online concentrations are 38% and 28% lower than the offline during night and day, respectively. In general, larger night-time concentrations are found for the BC, OC, NO3(-)and SO4(2-), which are seasonally dependent with larger differences during late post-monsoon and winter. The high correlation (R(2)=0.74) between OC and EC along with the OC/EC of 7.09 (day time) and 4.55 (night-time), suggest significant influence of biomass-burning emissions (burning of wood and agricultural waste) as well as secondary organic aerosol formation during daytime. Concentrated weighted trajectory (CWT) analysis reveals that the potential sources for the carbonaceous aerosols and pollutants are local emissions within the urban environment and transported smoke from agricultural burning in northwest India during post-monsoon. BC radiative forcing estimates result in very high atmospheric heating rates (~1.8-2.0Kday(-1)) due to agricultural burning effects during the 2012 post-monsoon season.
authors: Indian Institute of Tropical Meteorology, New Delhi, India.
authors: D S
authors: DS
authors: Bisht
authors: Aryabhatta Research Institute of Observational Sciences, Nainital, India. Electronic address: dumka@aries.res.in.
authors: U C
authors: UC
authors: Dumka
authors: School of Natural Sciences, Shiv Nadar University, Tehsil Dadri, India.
authors: D G
authors: DG
authors: Kaskaoutis
authors: Department of Chemistry, Savitribai Phule Pune University, Pune, India.
authors: A S
authors: AS
authors: Pipal
authors: Indian Institute of Tropical Meteorology, New Delhi, India.
authors: A K
authors: AK
authors: Srivastava
authors: India Meteorology Department, Lodhi Road, New Delhi, India.
authors: V K
authors: VK
authors: Soni
authors: India Meteorology Department, Lodhi Road, New Delhi, India.
authors: S D
authors: SD
authors: Attri
authors: India Meteorology Department, Lodhi Road, New Delhi, India.
authors: M
authors: M
authors: Sateesh
authors: Indian Institute of Tropical Meteorology, New Delhi, India.
authors: S
authors: S
authors: Tiwari
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis; D004784:Environmental Monitoring; D007194:India; D052638:Particulate Matter / Q000032:analysis*; D053260:Soot / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter; D053260:Soot; D002244:Carbon
keywords: Agricultural burning; Carbonaceous aerosols; Delhi; Inorganic ions; PM(2.5); Radiative impact