Atar Singh Pipal

Carbonaceous aerosols and pollutants over Delhi urban environment: temporal evolution, source apportionment and radiative forcing.

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.

Study of mineral aerosols in fine (PM 2.5 ) and coarse (PM 10 ) atmospheric particles over a world heritage site at Agra, India

PM 2.5 and PM 10 samples were collected at different sites from Agra to see their monthly and seasonal trends along with associated mineral aerosols. Annual mean mass concentrations of PM 2.5 and PM 10 over Agra were 104.25 and 261.89 µg/m 3 respectively. The monthly average varied from 26.94 to 211.56 µg/m 3 and 126.05 to 474.31 µg/m 3 in fine and coarse particles at traffic site while at semirural site it varied from 50.44 to 275.99 and 93.86 to 528.33 µg/m 3 in fine and coarse respectively. Concentrations of crustal elements indicate that calcium was abundant among the elements in mineral dust. Significant correlation coefficient (r = 0.51–0.87) was observed among the crustal elements indicating the origin of these elements from similar type of sources at semirural site. Enrichment factor analysed found that the origin of these elements is from crust and anthropogenic activities as well as local and transported sources.