Characterisation of selected speciated organic compounds associated with particulate matter in London

Kendall, M., Hamilton, R.S., Watt, J. and Williams, I.D. (2001) Characterisation of selected speciated organic compounds associated with particulate matter in London. Atmospheric Environment, 35 (14), 2483-2495. (doi:10.1016/S1352-2310(00)00431-3).

Abstract

Total suspended particulate matter (TSP) was collected and analysed at two sites in central and north London during 1995/6 for particulate-associated total organic carbon (TOC), particulate elemental carbon (PEC), 16 polycyclic aromatic hydrocarbons (PAHs) and 23 n-alkanes. The analysis revealed slightly higher concentrations of all of these substances at the central London location and generally low correlations between variables. Overall, PEC was measured as 1-13% of TSP, whilst TOC was measured as 7-45 % of TSP. Seasonal differences in concentrations were identified at both sites, with higher concentrations of combustion related compounds occurring in winter and autumn. The dominant PAH compounds were found to be the higher molecular weight compounds, namely BghiP, BaA and Chrys. n-alkane compound distributions between C-10 and C-34 showed that the highest concentrations of compounds were between C-21 and C-29 Three methods were used to identify specific sources of particulate-associated organic compounds. Ratios of PAHs indicated a dominant petroleum source at both sites, with a higher diesel component at the central London site. Carbon preference index (CPI) values of 1.03 and 1.28 for the central and north London sites, respectively, indicated a stronger anthropogenic (vehicular) influence at the central London location. Using principal component analysis (PCA), key principal components (PCs) were extracted from each data set. These PCs collectively accounted for 76.4 and 78.1% of the total variations within the north and central London data sets, respectively, although differentiation of sources proved difficult because the organic compounds monitored may not be statistically independent.

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Contributors

Author: I.D. Williams

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