Organic Constituents of Atmospheric Aerosols in a Hemi-boreal Forest



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Tartu Ülikool


Atmospheric aerosols have been demonstrated to be a highly dynamic system, playing a significant role in climate change and human health. In nature, ecosystems like boreal forests can modify the atmospheric particles producing a warming or cooling effect on climate. However, the regional and global impact of boreal forest on climate is still difficult to determine, especially due to the heterogeneous chemistry of aerosol samples, the need for multiple instruments for identification, and their limited library of compounds. In this thesis, to overcome these issues, we used a molecular networking technique based on the Global Natural Products Social web platform in combination with Nuclear Magnetic Resonance (NMR) to perform a screening of organic aerosols during the winter spring, and summer seasons from a Hemi-boreal forest. The aerosol samples were recollected in a glass filter weekly from SMEAR Station (Estonia) and analyzed by Gas Chromatography Mass spectrometry and NMR. A variety of chemical functional groups including carboxylic acids, phthalates, and organophosphate among the most abundant were annotated in the studied seasons. Furthermore, it was analyzed the presence of n-alkanol, carboxylic acid, and nalkane to evaluate any hydrocarbon contamination. Phthalates-based compounds like Dibutyl phthalate (~20.59% in winter), and Bis(2-ethylhexyl) phthalate (~3.87% in summer), altogether with organophosphates like Tris(2,4-di-tert-butylphenyl) phosphate (~24.13% in spring) and tris(2,4-di-tertbutylphenyl) phosphite (~5.13% in summer) were annotated as a possible air pollutant. Besides that, conifer burning tracers such as 7-Oxodehydroabietic (~1.18% in spring) and dehydroabietic acid (~0.49% in summer) were annoted. These finding presented in this work gives an insightful impact on the atmospheric aerosol composition presented in a Hemi-boreal forest using a straightforward and versatile technique such as molecular networking.



NMRfilter, Molecular networking, NMR, GNPS, GC/MS/EI, Organic aerosols