Research Projects

Secondary inorganic aerosol (SIA) is formed in the atmosphere through chemical reactions and physical processes involving precursor gases. The production of secondary sulphates and/or nitrates is highly dependent on various factors, such as the level of gaseous precursors, atmospheric oxidizing agents, existing aerosol properties, and air-mass temperature and humidity. SIA contributes approximately 30-50% to PM2.5 in Europe and Asia, impacting air quality, cloud droplet formation, ambient visibility, and human health. Basic science questions related to SIA include the relative proportional/fractional contribution of known dominant components, preferred chemical transformational routes for thermodynamic evolution under different meteorological regimes, and the role of bio-mass, refuse, and solid-waste burning in SIA formation. To fill this gap, a research project has been proposed to monitor precursor gases (SO2, NOx, and NH3) simultaneously with PM1 aerosol sample collection in two spells of continuous sampling for 15 days in all four different seasons at two locations: Dharamshala – Urban and Village Salli – Rural and Remote. The study will analyze aerosol samples for water soluble ionic species (WSIS), use ambient concentrations of precursor gases and aerosol associated WSIS (NH4+ - SO42- - NO3-) as inputs to the ISORROPIA 2 thermodynamic model, and apply multivariate statistical analysis to discern the preferred chemical transformational routes for the thermodynamic evolution of SIA under different meteorological regimes and precursor gases' emission regimes.