Abstract. Biomass burning emits significant quantities of intermediate-volatility and
semi-volatile organic compounds (I/SVOCs) in a complex mixture,
probably containing many thousands of chemical species. These components are
significantly more toxic and have poorly understood chemistry compared to
volatile organic compounds routinely quantified in ambient air; however,
analysis of I/SVOCs presents a difficult analytical challenge. The gases and particles emitted during the test combustion of a range of
domestic solid fuels collected from across Delhi were sampled and analysed.
Organic aerosol was collected onto Teflon (PTFE) filters, and residual
low-volatility gases were adsorbed to the surface of solid-phase extraction
(SPE) discs. A new method relying on accelerated solvent extraction (ASE)
coupled to comprehensive two-dimensional gas chromatography with
time-of-flight mass spectrometry (GC × GC–ToF-MS) was developed.
This highly sensitive and powerful analytical technique enabled over 3000
peaks from I/SVOC species with unique mass spectra to be detected.
A total of 15 %–100 % of gas-phase emissions and 7 %–100 % of particle-phase emissions were
characterised. The method was analysed for suitability to make quantitative
measurements of I/SVOCs using SPE discs. Analysis of SPE discs indicated
phenolic and furanic compounds were important for gas-phase I/SVOC emissions
and levoglucosan to the aerosol phase. Gas- and particle-phase emission
factors for 21 polycyclic aromatic hydrocarbons (PAHs) were derived,
including 16 compounds listed by the US EPA as priority pollutants.
Gas-phase emissions were dominated by smaller PAHs. The new emission factors
were measured (mg kg−1) for PAHs from combustion of cow dung cake
(615), municipal solid waste (1022), crop residue (747), sawdust (1236),
fuelwood (247), charcoal (151) and liquefied petroleum gas (56). The results of this study indicate that cow dung cake and municipal solid
waste burning are likely to be significant PAH sources, and further study is
required to quantify their impact alongside emissions from fuelwood
burning.
Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India
