Determining Atmospheric Sources, Sinks and Processing of Organic Aerosol (DIASPORA)

Lead Research Organisation: NERC Centre for Ecology and Hydrology
Department Name: Billett

Abstract

Fine particles (aerosols) in the atmosphere have major impacts on human health and interact with the climate system through a range of different effects, either directly (by reflecting and scattering sun-light) or indirectly (e.g. by affecting the formation of cloud). The chemical composition of atmospheric aerosol is complex, especially the important contribution from organic aerosol, which itself is composed of thousands of different chemical compounds. These are either emitted directly (from fossil fuel combustion) or formed in the atmosphere (from gases either of biogenic or anthropogenic origin). In this project we are proposing to develop a new measurement system that can quantify the vertical fluxes (i.e. emission, deposition and formation) of organic aerosols. This system will be based on a recently developed Aerosol Mass Spectrometer system, incorporating a time-of-flight mass spectrometer, capable of detecting the full organic aerosol composition of atmospheric particles. By correlating this information with the vertical wind speed, we will be able to quantify organic aerosol fluxes and to derive information on the nature of the organic components that are moving up or down. We will deploy this instrument during four campaigns in three different environments, to (a) probe formation of organic aerosol above a Californian pine forest, (b) study fluxes of primary organic aerosol and the formation of secondary organic aerosol in the urban environment (through measurements from the BT Tower in London) and (c) to characterise organic aerosol formation above rain forest in Malaysian Borneo. The data will be analysed in the context of associated measurements of emissions of gases that may be involved in aerosol production (precursor gases), meteorological parameters and aerosol physical properties. From these data we will characterise the aerosol, quantify SOA formation and identify aerosol production mechanisms together with associated chemical time scales.

Publications

10 25 50

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Farmer D (2013) Chemically Resolved Particle Fluxes Over Tropical and Temperate Forests in Aerosol Science and Technology

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Kimmel J (2011) Real-time aerosol mass spectrometry with millisecond resolution in International Journal of Mass Spectrometry

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Langford B.; Farmer D.; Phillips G.J.; Di Marco C.F.; Kimmel J.R.; Jimenez J.L.; Canonaco F.; Nemitz E. Organic aerosol source apportionment through factor analysis of aerosol mass spectrometer flux measurements

 
Description Until recently, surface / atmosphere exchange fluxes (emission / deposition) of particles could only be derived from particle number measurements (without information on chemical composition) or from gradient measurements, with is an indirect approach, subject to large errors. Under the NERC COSMAS programme we started the development of the first eddy-covariance system for chemical components, based on aerosol mass spectrometry and succeeded in measuring fluxes of nitrate, sulphate and some organic compounds. Following the introduction of a new generation of aerosol mass spectrometer, based on time-of-flight mass spectrometer, we have now completed the development of the next generation flux instrument and associated data processing routines. This has led to a much improved signal / noise ratio and additional capability of measuring fluxes of ammonium, fully quantitative organic aerosol fluxes and providing information on organic aerosol sources. Beneficiaries: The researcher benefited immediately, by being able to conduct research with this setup. Several flux datasets have been acquired and are being processed with the new data analysis package. A prototype has led to two papers and the new system will lead to many more. The scientific findings from the instrument will lead to a much improved understanding of the deposition of aerosols. First results have already led to the revision of the nitrate aerosol deposition velocity in the EMEP Chemical Transport Model, which is underpins European policy on emissions and ecosystem protection.
First Year Of Impact 2015
Sector Environment
Impact Types Cultural

 
Title Eddy-covariance flux measurement system for aerosol chemical components 
Description Development of the Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) into a flux measurement system for PM1 chemical components, including hardware modifications, development of a fast data acquisition mode and flux processing routines. 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2014 
Impact Underpinned flux measurements to quantify urban emissions and controls of dry deposition velocities of particles. 
 
Description Contribution to NERC 50th anniversary celebration abaord RRS Discovery 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact We presented a poster on the verification of pollutant emissions from London at the CEH stall during the NERC 50th anniversary celebration aboard the RRS Discovery, which was based on NERC grant research. Depending on the day the audience included local and national policy makers, school children and other members of the public.
Year(s) Of Engagement Activity 2015