Seasonal variations of concentrations and optical properties of water soluble HULIS collected in urban environments

Abstract

Abstract. Major contributors to the organic aerosol include water-soluble macromolecular compounds (e.g. HULIS WS : Water Soluble Humic LIke Substances). The nature and sources of HULIS WS are still largely unknown. This work is based on a monitoring in six different French cities performed during summer and winter seasons. HULIS WS analysis was performed with a selective method of extraction complemented by carbon quantification. UV spectroscopy was also applied for their chemical characterisation. HULIS WS carbon represent an important contribution to the organic aerosol mass in summer and winter, as it accounts for 12-22% of Organic Carbon and 34-40% of Water Soluble Organic Carbon. We found strong differences in the optical properties (specific absorbance at 250, 272, 280 nm and E2/E3 ratio) and therefore in the chemical structure between HULIS WS from samples of summer-and wintertime. These differences highlight different processes responsible for emissions and formation of HULIS WS according to the season, namely biomass burning in winter, and secondary processes in summer. Specific absorbance can also be considered as a rapid and useful indicator of the origin of HULIS WS in urban environment.

Chemical characterization of humic-like substances (HULIS) in PM2.5 in Lanzhou, China

“…ELSD is especially suitable for the quantification of HULIS (Zheng et al, 2013). Measurement methods of HULIS have been reported in many sorts of places, such as ocean environments (Cavalli et al, 2004), background areas (Samburova et al, 2005;Lukács et al, 2007), rural areas (Decesari et al, 2001;Kiss et al, 2002), and urban areas (Krivácsy et al, 2008;Baduel et al, 2010). The concentrations of HULIS varied from 0.15 to 25.6 μg/m 3 , with HULISc consisting of 9-72% of WSOC (Zheng et al, 2013).…”

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

“…These atmospheric HULIS materials are found ubiquitously in various environments, and are derived from various sources. Their possible sources include biomass burning (BB; Feczko et al, 2007;Baduel et al, 2010;Lin et al, 2010a), vehicular emissions (El Haddad et al, 2009), marine emissions (Krivacsy et al, 2008), the oxidation of soot Li et al, 2013Li et al, , 2015, and secondary processes via the transformation of gas-and condensed-phase species by chemical reactions (Salma et al, 2007;Baduel et al, 2010;Salma et al, 2013).…”

Aerosol formation and heterogeneous chemistry in the atmosphere

“…Their secondary origin, observed in summer in cities, is suspected to be principally aqueous phase reactions (Baduel et al 2010). Until recently, isoprene, accounting for about half of all natural VOC emissions, was not considered as a significant contributor to SOA.…”

“…Some of their physical and chemical properties resemble those of fulvic and humic acids found in soils and surface waters. HULIS can constitute an important fraction of SOA found in marine and terrestrial aerosols, and wood combustion aerosols (Graber et al 2006;Lukacs et al 2007;Feczko et al 2007;Baduel et al 2009;Baduel et al 2010;Stone et al 2009;Salma et al 2008;Reinhardt et al 2007), but their origins, and formation processes are still unknown.…”