Measurement of VOCs Emission From Freshwater Algae by Vocus PTR‐ToF‐MS

Volatile organic compounds (VOCs) are receiving more attention for their potential to form ozone and secondary organic aerosol (SOA). Considerable amounts of VOCs are released from freshwater algae, and their chemical compositions and release rates have not been well understood. In this work, chemical compositions and release rates of VOCs emitted from a dominant algae species ( Microcystis aeruginosa ) in freshwater phytoplankton community were investigated under various cultivation conditions (i.e., BG11 medium, BG11 + extra nitrogen nutrient, BG11 + extra phosphorus nutrient, and low pH). 238 VOC species were identified from the emission of M. aeruginosa , among which 40 were hydrocarbons (elemental composition: CH), 81 were oxygenated‐VOCs (elemental composition: CHO), 61 were nitrogen‐containing VOCs (elemental composition: CHN and CHNO), 56 were sulfur‐containing VOCs (elemental composition: CHS, CHSO, CHNS, CHNSO). The average release rates of hydrocarbons, oxygenated‐VOCs (CHO), sulfur‐VOCs (CHS and CHSO), and nitrogen‐VOCs (CHN and CHNO) across all cultivation conditions were 668.6 ± 431.6, 352.0 ± 244.7, 2562.5 ± 1347.3, and 12.3 ± 5.76 ng·m −2 ·h −1 , respectively, among which, sulfur‐VOCs were the dominant species. Adding NH 4 Cl or CO(NH 2 ) 2 as extra nitrogen nutrient significantly reduced total VOCs release. Hydrocarbons and nitrogen‐VOCs were mainly released during the growth stage of algae, while some oxygenated species and sulfur‐containing species were released during the decline phase. This study offers enhanced insight into the diversity and emission levels of VOCs produced by freshwater algae and underlying SOA and ozone formation over and around inland eutrophic lakes.