Contribution of HUmic-LIke Substances Carbon (HULIS-C) in WSOC and their characteristics in aerosol

Abstract:

HULIS has a similar structure to humic substances including aromatic ring structures with hydrocarbon side chains, hydroxyl, carbonyl, and carboxyl groups (Lin et al., 2010) and is one of major fractions of water soluble organic carbon (WSOC) which affect climate change as cloud condensation neclei (CCN) due to their special physiochemical properties. Recently, the active studies for the characteristics of HULIS in the atmospheric particles have been progressed due to possibility of significant contribution to the climate change both directly and indirectly (Graber and Rudich, 2006 ; Dinar et al., 2008). However, still there is a lack of reliable information on the amount and characteristics of HULIS in the aerosol. In this study, we will study contribution of HULIS-C concentrations in WSOC of urban aerosol and characterize origin and formation of HULIS in aerosol.

Four sampling periods were selected for fall (4 October to 4 November in 2012), winter (9 January to 8 February in 2013), spring (1 April to 30 April in 2013), and summer (13 August to 10 September in 2013) to investigate characteristics of HULIS-C and WSOC. The measurements of PM2.5 using high volume air sampler was made at the Korea Institute of Science and Technology (37.60°N, 127.05°E) at Seoul, representative urban site, Korea. 15cm² of each PM2.5 sample filters were extracted with 40 mL of ultrapure water (18.2MΩ) in ultrasonic bath for 60 min. The extracts were filtered with a 0.20 mm Teflon filter (PTFE, Hydrophilic, Advantec). 20mL of extracts was used for the HULIS analysis and other was used for the WSOC analysis. HULIS fraction was extracted using the solid phase extraction and WSOC and HULIS-C were analyzed using total organic carbon (TOC) analyzer. More details on the analytical methods can be found in Lin et al. (2010) and Yang et al. (2003).