Mineral dust and biomass burning from northwest India and Pakistan polluted cities like Delhi and the Arabian Sea area, a new study has found.

The Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, an autonomous research institute under the Department of Science and Technology (DST), along with Indian and foreign collaborators, studied the chemical composition and source apportionment of the total suspended particulate (TSP), which includes all the aerosols and air pollution in the central Himalayan region.

Mineral dust, biomass burning, secondary sulfate, secondary nitrate from northwest India and Pakistan polluted cities like Delhi, the Thar Desert, and the Arabian Sea area, and long-range transported marine-mixed aerosols are the main sources of aerosols in the central Himalayan region,” said the Ministry of Science and Technology which shared the findings of the study. “This dust transport and forest fires are the main sources of TSP particularly in pre-monsoon period (March-May) when TSP concentration peaks in the region,” it said.

An aerosol is a collection of solid particles or liquid droplets dispersed in air. The study on source apportionment of atmospheric pollution, which elucidates the atmospheric chemistry, emission source origins, and transport pathways of aerosol over the central Himalayan region, will help in assessment of contributions and temporal variability of sources that influence the area through regional transport as well as climate impacts assessment, the study said.

The study also found that with a unique role in the Asian climate, the Himalayan region is considered a vulnerable environment.

“There is a knowledge gap regarding the primary and secondary organic carbon (POC, SOC) fractions, along with a lack of statistical methods for identifying and quantifying the sources of air pollutants at a receptor location in the central Indian Himalaya,” the study noted.

The study revealed that the main aerosol sources in Nainital were

*mineral dust (34 per cent)
*biomass burning (27 per cent)
*secondary sulfate (20 per cent)
*secondary nitrate (9 per cent)
*long-range transported marine mixed aerosols (10 per cent)

There was predominance of mineral dust in spring and summer and biomass burning and secondary sulfate in winter.

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