Assessment of ecotoxicity of atmospheric humic-like substances using the Vibrio fischeri bioluminescence inhibition bioassay

Humic-like substances are ubiquitous constituents of atmospheric aerosol worldwide. Their sources, formation processes, physical and chemical properties have been studied thoroughly but hardly any information is available on the ecotoxicity of this complex organic mixture. In this study the ecotoxicity of HULIS isolated from winter rural aerosol was determined using the kinetic version of Vibrio fischeri bioluminescence inhibition bioassay. The EC50 values of the HULIS fractions varied between 38 and 178 mg L-1 (average: 90 mg L-1, SD: 45 mg L-1) in the aerosol samples which was found to be comparable to the ecotoxicity of terrestrial humic substances (EC50: 45-74 mg L-1). The ecotoxicity of HULIS isolated from winter rural aerosol was lower than that of biomass burning aerosol but higher than that of winter urban aerosol. An aromatic tracer of biomass burning (4-nitrocatechol) and BB SOA tracers were detected in the HULIS fractions. The ecotoxicity of 4-nitrocatechol was measured and found to be 15 times more ecotoxic than the HULIS fractions on average.

Automated summary

Humic-like substances are common in atmospheric aerosols worldwide, with ecotoxicity potentially falling between biomass burning aerosols and winter urban aerosols.