Snow – a photobiochemical exchange platform for volatile and semi-volatile organic compounds with the atmosphere

Abstract

Environmental context Recent research has been directed towards the exchange of microorganisms and chemical compounds between snow and air. We investigate how microorganisms and chemical species in snow from the Arctic and temperate regions are transferred to the atmosphere and altered by the sun's energy. Results suggest that snow photo-biochemical reactions, in addition to physical-chemical reactions, should be considered in describing organic matter in air–snow exchanges, and in investigations of climate change. Abstract Field and laboratory studies of organic compounds in snow (12 species; concentrations =17 µg L–1) were conducted and microorganisms in snow and aerosols at urban and Arctic sites were investigated (snow: total bacteria count =40000 colony forming units per millilitre (CFU mL–1), fungi =400 CFU mL–1; air: bacteria =2.2 × 107 CFU m–3, fungi =84 CFU m–3). Bio-organic material is transferred between snow and air and influence on snow-air exchange processes is demonstrated. Volatile organic compounds in snow are released into the air upon melting. In vitro photochemistry indicated an increase of =60 µg L–1 for 1,3- and 1,4-dimethylbenzenes. Bacillus cereus was identified and observed in snow and air with ice-nucleating being P. syringae absent. As a result snow photobiochemical reactions should be considered in describing organic matter air–snow exchanges, and the investigation of climate change.