Natural volatile organic compounds (NVOCs) and airborne microorganisms in different stands of urban forests.

Natural volatile organic compounds (NVOCs) and airborne microorganisms are important elements in urban forest air that affect air quality and human health. In this study, the Zhuyu Bay urban forest in Yangzhou was selected as the research object, and gas chromatography-mass spectrometry (GC-MS) was used to detect the composition of NVOCs in different forest stands. Terpenes, heterocyclic compounds, and esters accounted for the highest proportions. We then explored the effects of NVOCs on the physiological health of each forest stand and used Kyoto Encyclopedia of Genes and Genome enrichment analysis to identify beneficial secondary metabolites. Among the identified compounds, alpha-phellandrene 1, azulene, and other terpenoids were found to possess antibacterial, anti-inflammatory, and antioxidant properties. Heterocyclic compounds, such as 4-Pyridinecarboxylic acid and visnagin, showed significant effects in the treatment of diseases. In addition, we collected and analyzed culturable airborne microorganisms in different forest stands and found that the bamboo forest had the lowest number of culturable airborne microorganisms. To further explore the influence of urban microclimates on air microorganisms and NVOCs, a partial least squares path modelling (PLS-PM) analysis was conducted. Air negative oxygen ion is an important factor affecting NVOCs, and Air moisture has a significant positive effect on bacteria proportion.