Impact assessment of terrestrial and marine air-mass on the constituents and intermixing of bioaerosols over coastal atmosphere

Abstract. Coastal environments provide an ideal setting for investigating the intermixing processes between terrestrial and marine aerosols. Fine particulate matter (PM_2.5) samples collected from a coastal location in Northern China were categorized into terrestrial, marine and mixed air masses. Chemical and biological constituents during the winter heating season in 2018, including the water-soluble ions (WSIIs), metallic elements, and bacterial and fungal aerosols, were investigated. Terrestrial air masses constituted a larger proportion of 59.94 %, particularly during severe air pollution episodes (up to 90 %), exhibiting higher concentrations of PM_2.5 (240 μg/m³) and carrying more water-soluble ions and metal elements. A relative shift towards marine air-mass with respect to pollution elimination stage was observed. The terrestrial air mass harbors more animal parasites or symbionts, and human pathogens from anthropogenic emission, such as Deinococcus, Sphingomonas, Lactobacillus, Cladosporium and Malassezia. In comparison, saprophytic bacteria and fungi, such as hydrocarbon degradation and gut bacteria from Comamonas, Streptococcus, Novosphingobium, and Aerococcus, saprophytic Aspergillus, were the most prevalent species in marine air mass. Mixed air-mass revealed the intermixing processes of terrestrial and marine sources. This is a consequence of the amalgamation of microorganisms from both terrestrial soils, animals, plants, and marine environments during transportation. Correlation analysis suggested a higher correlation between microorganisms and continental air mass, such as K⁺, Mg²⁺, and Ca²⁺ from soil dust. Present study on constituents and amalgamation of bioaerosols over coastal atmosphere encompassing distinct airmasses presume critical importance in comprehending the terrestrial and marine air mass transport, intermixing processes and health implications.