Central Himalayas Face Aerosol Pollution Due to Dust from Northwest India, Pakistan and Arabian Sea

Apart from mineral dust and biomass burning, secondary sulphate and secondary nitrate from northwest India and Pakistan, polluted cities such as Delhi, the Thar desert, the Arabian Sea area, and long-range transported marine mixed particles also contribute to the aerosols in the central Himalayas.

This dust transport and forest fires are the main sources of total suspended particles (TSP), particularly in the pre-monsoon period (March-May) when TSP concentration peaks in the region, said the study on source apportionment of atmospheric pollution.

The study elucidates the atmospheric chemistry, emission source origins, and transport pathways of aerosol over the central Himalayan region. It will help assess contributions and temporal variability of sources that influence the area through regional transport and climate impacts assessment, a release from the Ministry of Science and Technology said on Thursday.

With a unique role in the Asian climate, the Himalayan region is considered a vulnerable environment. Several chemical speciation studies have been performed for carbonaceous aerosols and inorganic species over the western and central Himalayan areas during the last decade, reporting the dominance of transported aerosol plumes from the Indo-Gangetic plains.

However, there is a knowledge gap regarding the primary and secondary organic carbon fractions, along with a lack of statistical methods for identifying and quantifying the sources of air pollutants at a receptor location (receptor model) in the central Indian Himalayas.

The main source regions for aerosols at this remote background location (Nainital) were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar desert, and the Arabian Sea area.

The study revealed that the main aerosol sources in Nainital were mineral dust (34%), biomass burning (27%), secondary sulphate (20%), secondary nitrate (9%), and long-range transported marine mixed aerosols (10%), exhibiting distinct seasonal patterns.

There was a predominance of mineral dust in spring and summer and biomass burning and secondary sulphate in winter. The transported marine mixed aerosol source was mainly associated with SW monsoon air masses during the summer season.

The study's results published in the journal Atmosphere show that carbonaceous aerosols were the maximum in winter due to the intensification of biomass burning over the Indo Gangetic plains and the Himalayas because of domestic heating and shallower mixing layer.

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The above article has been published from a wire agency with minimal modifications to the headline and text.