| Autor: |
Zhou L; School of Energy and Environment, City University of Hong Kong, Hong Kong, China., Salvador CM; Department of Chemistry and Molecular Biology, University of Gothenburg, 412 96 Gothenburg, Sweden., Priestley M; Department of Chemistry and Molecular Biology, University of Gothenburg, 412 96 Gothenburg, Sweden., Hallquist M; Department of Chemistry and Molecular Biology, University of Gothenburg, 412 96 Gothenburg, Sweden., Liu Q; School of Energy and Environment, City University of Hong Kong, Hong Kong, China., Chan CK; School of Energy and Environment, City University of Hong Kong, Hong Kong, China., Hallquist ÅM; IVL Swedish Environmental Research Institute, 400 14 Gothenburg, Sweden. |
| Abstrakt: |
Complying with stricter emissions standards, a new generation of heavy-duty trucks (HDTs) has gradually increased its market share and now accounts for a large percentage of on-road mileage. The potential to improve air quality depends on an actual reduction in both emissions and subsequent formation of secondary pollutants. In this study, the emissions in real-world traffic from Euro VI-compliant HDTs were compared to those from older classes, represented by Euro V, using high-resolution time-of-flight chemical ionization mass spectrometry. Gas-phase primary emissions of several hundred species were observed for 70 HDTs. Furthermore, the particle phase and secondary pollutant formation (gas and particle phase) were evaluated for a number of HDTs. The reduction in primary emission factors (EFs) was evident (∼90%) and in line with a reduction of 28-97% for the typical regulated pollutants. Secondary production of most gas- and particle-phase compounds, for example, nitric acid, organic acids, and carbonyls, after photochemical aging in an oxidation flow reactor exceeded the primary emissions (EF Aged /EF Fresh ratio ≥2). Byproducts from urea-selective catalytic reduction systems had both primary and secondary sources. A non-negative matrix factorization analysis highlighted the issue of vehicle maintenance as a remaining concern. However, the adoption of Euro VI has a significant positive effect on emissions in real-world traffic and should be considered in, for example, urban air quality assessments. |
