Measurements provided completely new and detailed information about the composition of soot particles in Norther India. This information can be used to identify soot particle sources and quantify their transport from source areas.
High soot concentrations are often seen in Northern India and especially in the densely populated Gangetic Plain. This is due to the local emissions and prevailing meteorological conditions which reduce the dilution of pollutions. Soot particles are produced during incomplete burning and the unburnt carbon in these particles is called black carbon.
The new instrument is capable of measuring the fraction of soot particles from all particles and also the composition of soot containing particles. The measurements showed that almost half of the fine particles contain black carbon. These soot particles have two main types. Fresh soot particles have irregular shapes and are almost pure black carbon while aged soot particles are more spherical and have lower black carbon content.
Measurements were conducted at two sites which were made in cooperation with local partners. One site is the representative of densely populated Gangetic Plain and the other is a regional background site at the foothills of the Himalayas. Although soot concentrations were significantly lower at the Himalayan foothill site, structurally similar soot particles were observed at both sites. This indicates that a large fraction of the soot at the background site is originating from the Gangetic Plain.
Senior scientist Tomi Raatikainen, tel. +358 40 779 1782, email@example.com
Raatikainen, T., Brus, D., Hooda, R. K., Hyvärinen, A.-P., Asmi, E., Sharma, V. P., Arola, A., and Lihavainen, H.: Size-selected black carbon mass distributions and mixing state in polluted and clean environments of northern India, Atmos. Chem. Phys., 17, 371-383, doi:10.5194/acp-17-371-2017, 2017.
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