Evolution of Organic Matter during cloud events at Whistler during WACS 2010

Project: Research project

Project Details


Evolution of Organic Matter during cloud events at Whistler during WACS 2010 Evolution of Organic Matter during cloud events at Whistler during WACS 2010 Evolution of Organic Matter during cloud events at Whistler during WACS 2010 PI: Pierre Herckes, Arizona State University Motivation Recent work including observations from the Whistler Aerosol and Cloud Study (WACS) showed that clouds can play an important role in secondary organic aerosol (SOA) generation by processing gaseous species and transforming them into non volatile material that remains in the particle phase after droplet evaporation. This has substantial impact in terms of particle mass, size and hygroscopicity and hence impacts both climate and air pollution. However the overall process and impact is still poorly understood and inadequately reflected in air quality models. Here we propose to do further analysis on the data and samples collected during WACS, in particular cloud time series samples and interpret observations on bulk carbon measurements using size exclusion chromatography coupled to inline organic carbon detection (SEC-TOC) as well as excitation emission fluorescence spectroscopy(EEFS). The goal is to improve our understanding of the processing of organic matter by clouds form a bulk perspective, looking at all carbon present rather than individual organic species. While most observational data is already available, the support will allow for laboratory studies, simulating conditions during WACS to help interpret the observations. This will be done in close collaboration with EC as we will rely on the observational database form WACS. Research Plan A study on the application of SEC-TOC samples including WACS samples was just published. Here we will focus on the time series data. While we have observational data, the interpretation is not straightforward. Therefore we propose laboratory experiments on archived samples as well as model compounds in realistic matrices, based on WACS conditions, to investigate changes in molecular weight distributions over time using SEC-TOC chromatography. Similarly we are using excitation emission fluorescence spectroscopy to characterize cloud organic matter as well as water soluble organic carbon in aerosol particles. While we have some of the data, the interpretation is again challenging and would need support by additional laboratory studies. Specifically we are going to perform time series experiments using model compounds (like biogenic oxidized species) in authentic (archived) or simulated cloud samples in a photochemical aqueous phase chemistry reactor and compare these observations to the field observations. Anticipated Outcomes The results of the study will provide an improved understanding of the processing of organic matter by clouds. It will be a unique comprehensive approach as both SEC-TOC and EEFS detect changes in the overall organic matter present. The results will be novel and might allow for holistic parameterization of organic matter change during cloud processing that could be integrated in cloud and air quality models. Milestones Detailed data analysis of cloud samples time series from WACS using SEC-TOC and EEFS Laboratory studies on model species under WACS conditions Preparation of 1 or 2 manuscripts of these studies (SEC-TOC and EEFS joined or separated) Budget (USD) Salaries, Benefits and tuition (students, postdocs and RAs) $24,221 Materials and supplies (small amounts of gases etc, for post campaign calibrations) $3,137 Overhead (54% of direct costs) $10,361 Total 37,719 USD (or 40,001 CAN)
Effective start/end date6/26/133/31/14


  • OTHER: Foreign Government: $40,000.00


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