Abstract
Abstract. A positive matrix factorization model (US EPA PMF version 5.0) was applied for the source apportionment of the dataset of 37 non-methane volatile organic compounds (NMVOCs) measured from 19 December 2012 to 30 January 2013 during the SusKat-ABC international air pollution measurement campaign using a proton-transfer-reaction time-of-flight mass spectrometer in the Kathmandu Valley. In all, eight source categories were identified with the PMF model using the new constrained model operation mode. Unresolved industrial emissions and traffic source factors were the major contributors to the total measured NMVOC mass loading (17.9 and 16.8 %, respectively) followed by mixed industrial emissions (14.0 %), while the remainder of the source was split approximately evenly between residential biofuel use and waste disposal (10.9 %), solvent evaporation (10.8 %), biomass co-fired brick kilns (10.4 %), biogenic emissions (10.0 %) and mixed daytime factor (9.2 %). Conditional probability function (CPF) analyses were performed to identify the physical locations associated with different sources. Source contributions to individual NMVOCs showed that biomass co-fired brick kilns significantly contribute to the elevated concentrations of several health relevant NMVOCs such as benzene. Despite the highly polluted conditions, biogenic emissions had the largest contribution (24.2 %) to the total daytime ozone production potential, even in winter, followed by solvent evaporation (20.2 %), traffic (15.0 %) and unresolved industrial emissions (14.3 %). Secondary organic aerosol (SOA) production had approximately equal contributions from biomass co-fired brick kilns (28.9 %) and traffic (28.2 %). Comparison of PMF results based on the in situ data versus REAS v2.1 and EDGAR v4.2 emission inventories showed that both the inventories underestimate the contribution of traffic and do not take the contribution of brick kilns into account. In addition, the REAS inventory overestimates the contribution of residential biofuel use and underestimates the contribution of solvent use and industrial sources in the Kathmandu Valley. The quantitative source apportionment of major NMVOC sources in the Kathmandu Valley based on this study will aid in improving hitherto largely un-validated bottom-up NMVOC emission inventories, enabling more focused mitigation measures and improved parameterizations in chemical transport models.
Highlights
Non-methane volatile organic compounds (NMVOCs) are important atmospheric constituents and are emitted from both natural and anthropogenic sources (Hewitt, 1999)
We report the application of the Positive matrix factorization (PMF) model for source apportionment of non-methane volatile organic compounds (NMVOCs) using the NMVOC data measured in the Kathmandu Valley, Nepal, which have been reported and analyzed in detail in Sarkar et al (2016)
Tain as there has been no validation using in situ measurements of these mostly bottom-up inventories that rely on fuel and source emission factors measured in other technologically different regions of the world
Summary
Non-methane volatile organic compounds (NMVOCs) are important atmospheric constituents and are emitted from both natural and anthropogenic sources (Hewitt, 1999). They are important as precursors of surface ozone and secondary organic aerosol (SOA) and affect atmospheric oxidation capacity, climate and human health (IPCC, 2013). Source apportionment of NMVOCs can be achieved by applying source-receptor models to measured ambient datasets. Source apportionment of non-methane hydrocarbons (NMHCs) and oxygenated VOCs (OVOCs) using PMF source–receptor models has been carried out in several previous studies (Shim et al, 2007; Leuchner and Rappenglück, 2010; Gaimoz et al, 2011; Bon et al, 2011; Chen et al, 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
