Multiscale Chemical Composition of Carbonaceous particles and Coatings (MC4)

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences

Abstract

Black carbon (BC) particles are an important and highly relevant area of study in atmospheric science. These are produced in large quantities by human activities in the form of soot from fires and transport emissions. Concentrations of BC in the atmosphere have increased since pre-industrial times and the effect on global climate has been one of warming, as these particles can absorb incident radiation. In addition, these particles have the ability to alter regional climate and weather patterns through localised warming of the atmosphere. However, the exact effects of BC on the atmosphere are hard to predict, as the exact light-absorbing properties vary according to the exact source of the particles. In addition, atmospheric processes can cause the particles to become mixed with others and obtain coatings from gas phase reactions. These effects substantially change the absorption properties of the aerosol but are hard to predict. The study of these effects has traditionally been hampered by the lack of suitable instrumentation that can directly measure the chemical composition of BC and any coatings on the particles. To address these needs, the Soot Particle Aerosol Mass Spectrometer (SP-AMS) is being developed through a partnership between Aerodyne Research Inc., Droplet Measurement Technologies and the University of Manchester. This uses a near infra red laser to vaporise particles containing BC before the resultant vapours are analysed using mass spectrometry. Because particles that do not contain BC do not absorb the laser light, these are not detected. In this manner, the SP-AMS selectively measures only BC particles and their coatings, so therefore this instrument can be used to study the mixing state and the chemical composition of their coatings selectively. Multiscale Chemical Composition of Carbonaceous particles and Coatings (MC4) will use this novel instrument in conjunction with a suite of other measurements to study the sources and evolution of BC particles in the atmosphere, which will in turn lead to better model treatments and more accurate predictions of BC's climatic impacts. In addition, development work will take place in the laboratory to improve instrument sensitivity and data quality, accurately determine detection limits and formulate an operational protocol. This will maximise the effectiveness of subsequent experimental work. Measurements will take place in Los Angeles, Manchester and the Weybourne Atmospheric Observatory on the north Norfolk coast. A wide variety of sites is needed to characterise a broad range of aerosols. The measurements of coating and mixing will be compared with optical absorption measurements from automated filter-based methods. These will compared with estimates of the amount of chemical processing that the aerosol has undergone since emission based on gas phase VOC measurements. Different sources and types of BC particles will be identified and characterised using numerical factor analysis. The results from these studies will drive parameterisations that will be of use to the modelling community. This will allow the more accurate evaluation of the climatic impacts of BC particles over the course of their atmospheric lifetimes and lead to more accurate regional and global climate predictions in general.

Publications

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Bohnenstengel S (2015) Meteorology, Air Quality, and Health in London: The ClearfLo Project in Bulletin of the American Meteorological Society

 
Description This work has allowed black carbon in a number of polluted environments (such as London and Los Angeles) to be studied on new levels of detail. This includes the microphysical properties of soot particles produced from Diesel engines and domestic solid fuel burning. New analysis techniques were developed using state-of-the-art instruments such as the Soot Particle Aerosol Mass Spectrometer, Single Particle Soot Photometer (SP2) and Photoacoustic Soot Spectrometer. The detailed processes that govern the link between microphysical structure and optical properties (which have an impact on climate) were investigated using fundamental models. In addition, the evolution of hydrophobic soot particles within polluted plumes to hydrophilic particles was studied directly and was found to be mainly governed by the addition of nitrate to the particles. As part of a collaborative intercomparison exercise at the AIDA facility in Germany, best practices were developed for the SP2 instrument that have been adopted by the global user base. The data analysis techniques were applied to the analysis of the NERC BORTAS project, studying Canadian wildfire plumes. The UK aspects of this work contributed to the NERC ClearfLo project and a number of publications were arising from this, particularly with relevance to black carbon source apportionment. The data and modelling techniques developed directly contributed to a later high-impact publication (Liu et al., 2017) on black carbon morphology, mixing state and optical properties.
Exploitation Route The data on the discrimination and characterisation of the different soot sources in polluted environments will be of use to those interested in urban air quality and developing policies concerning emissions from transport and solid fuel burning in particular. Black carbon is increasingly being seen as having impacts on human health. The best practice developed during the AIDA intercomparison exercise is of use to other users of the SP2 instrument. The work measuring and modelling the optical properties of black carbon is useful to those investigating the role of aerosols in climate. Black carbon is known to have a strong forcing effect, particularly on local scales. The work investigating the transition of black carbon particles to being more hydrophilic in the atmosphere is of use to those interested in the lifetime of black carbon within the atmosphere. This is crucial to understand within the fields of global composition, climate and pollutant deposition.
Sectors Environment,Transport

 
Description Soot11
Amount £3,000 (GBP)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 11/2010 
End 12/2010
 
Description Soot11
Amount £3,000 (GBP)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 06/2010 
End 07/2010
 
Title CALNEX BC data 
Description The MC4 contributions to the CalNex campaign in California, 2010 
Type Of Material Database/Collection of data 
Year Produced 2010 
Provided To Others? Yes  
Impact Collaborations with other groups and numerous publications 
 
Title ClearfLo dataset 
Description MC4-funded measurements of black carbon, contributing to the NERC ClearfLo project, London, 2012 
Type Of Material Database/Collection of data 
Year Produced 2012 
Provided To Others? Yes  
Impact Multiple publications regarding black carbon work during this project 
 
Title Weybourne MC4 dataset 
Description Intensive atmospheric Aerosol Measurements made during 2011 at the Weybourne Atmospheric Observatory, specifically focusing on black carbon 
Type Of Material Database/Collection of data 
Year Produced 2012 
Provided To Others? Yes  
Impact This has been used in publications and conference presentations 
 
Description CalNex partnerships 
Organisation University of California, Los Angeles (UCLA)
Country United States 
Sector Academic/University 
PI Contribution Worked very closely with other groups in the CalNex project, in particular those involved in the Pasadena supersite. These involved a large number of academic and non-academic groups from across the USA. We contributed data to the project database and are involved in the collaborative authoring of papers.
Start Year 2010
 
Description Soot11 SP2 intercomparison exercise 
Organisation Paul Scherrer Institute
Country Switzerland 
Sector Public 
PI Contribution Participation in the Soot11 intercomparison exercise and publication of findings
Start Year 2010