Investigation of fungal spore characteristics in PM2.5 through organic tracers in Shanghai, China

In order to investigate the fungal spore tracers in fine particles (PM2.5), including mannitol and arabitol at an urban site in a Chinese megacity, PM2.5 samples were collected in Shanghai from May 22 to June 19, 2015. The analysis results showed that the average concentration of airborne mannitol and arabitol were 5.79 and 3.86 ng m−3, respectively. Mannitol and arabitol exhibited obvious positive correlations at ambient temperature, resulting from improving fungal spores formation rate and emission strength along with higher temperature. The concentrations of fungal spore tracers with Relative humidity-RH 70%-85% were higher than that RH>85% and RH<70%, which reflected that fungal spores released would be restrained under higher humidity. The concentrations between arabitol and mannitol showed negative correlation with wind speed, probably due to the dilution effect of wind. Three ions components (sulfate, nitrate and ammonium) exhibited poor correlations with fungal spore tracer. Based on the results, mannitol had a similar formation pathway with arabitol, resulting in strong correlation between them during our campaign. The number concentration of fungal spores was 10513.16 spores m−3, while fungal spores contributed about 1.91% for organic carbon OC using conversion factors.