Diesel-related hydrocarbons can dominate gas phase reactive carbon in megacities

Abstract

Article:Dunmore, R. E. orcid.org/0000-0002-9114-1823, Hopkins, J. R., Lidster, R. T. et al. (5 more authors) (2015) Diesel-related hydrocarbons can dominate gas phase reactive carbon in megacities. Atmospheric Chemistry and Physics. pp. 9983-9996. ISSN 1680-7324 Abstract. Hydrocarbons are key precursors to two priority air pollutants, ozone and particulate matter. Those with two to seven carbons have historically been straightforward to observe and have been successfully reduced in many developed cities through air quality policy interventions. Longer chain hydrocarbons released from diesel vehicles are not considered explicitly as part of air quality strategies and there are few direct measurements of their gaseous abundance in the atmosphere. This study describes the chemically comprehensive and continuous measurements of organic compounds in a developed megacity (London), which demonstrate that on a seasonal median basis, diesel-related hydrocarbons represent only 20-30 % of the total hydrocarbon mixing ratio but comprise more than 50 % of the atmospheric hydrocarbon mass and are a dominant local source of secondary organic aerosols. This study shows for the first time that 60 % of the winter primary hydrocarbon hydroxyl radical reactivity is from diesel-related hydrocarbons and using the maximum incremental reactivity scale, we predict that they contribute up to 50 % of the ozone production potential in London. Comparing real-world urban composition with regulatory emissions inventories in the UK and US highlights a previously unaccounted for, but very significant, under-reporting of diesel-related hydrocarbons; an underestimation of a factor ∼ 4 for C 9 species rising to a factor of over 70 for C 12 during winter. These observations show that hydrocarbons from diesel vehicles can dominate gas phase reactive carbon in cities with high diesel fleet fractions. Future control of urban particulate matter and ozone in such locations requires a shift in policy focus onto gas phase hydrocarbons released from diesels as this vehicle type continues to displace gasoline world-wide. PM load (Robinson et al.

Analysis of long‐term observations of NOx and CO in megacities and application to constraining emissions inventories

“…However, in contrast to the predominance of gasoline fuel in U.S. light‐duty vehicles, European nations have incentivized the use of light‐duty diesel vehicles (LDDVs) to increase fuel economy and decrease CO 2 emissions. There are now similar numbers of LDGVs and LDDVs in the UK [ Carslaw et al ., ], where overall diesel currently accounts for the majority of transportation fuel burned [ Dunmore et al ., ]. France and other European countries have similarly high diesel usage in their vehicle fleets [ Weiss et al ., ; Dunmore et al ., ].…”

“…There are now similar numbers of LDGVs and LDDVs in the UK [ Carslaw et al ., ], where overall diesel currently accounts for the majority of transportation fuel burned [ Dunmore et al ., ]. France and other European countries have similarly high diesel usage in their vehicle fleets [ Weiss et al ., ; Dunmore et al ., ]. European vehicle fleets have correspondingly higher NO x emissions and lower CO emissions than in the U.S., as demonstrated by the London and Paris observations (Figure b).…”

“…Ozone predictions from different models in response to improved emissions estimates will also likely depend on model VOC emissions speciation and chemical mechanisms [ von Schneidemesser et al ., ]. Recent observations suggest that there are higher VOC emissions from UK diesel vehicles than inventories report [ Dunmore et al ., ], further complicating efforts to accurately model ozone in global megacities.…”

Seasonality of Formic Acid (HCOOH) in London during the ClearfLo Campaign

“…Isoprene measurements were made using a dual channel GC‐flame ionization detector and was operated by the National Centre for Atmospheric Science (NCAS) Facility for Ground Atmospheric Measurements (FGAM) (now the Atmospheric Measurements Facility (AMF)) with the instrument set up and calibration described in Hopkins et al () and its deployment during ClearfLO described in detail by Dunmore et al ().…”

TRP channels and traffic-related environmental pollution-induced pulmonary disease

“…Some of the main producers of PMs and PAHs in traffic-related air pollutants are diesel engines. Diesel-related PAHs may represent a major source of gaseous hydrocarbons in urban environments [7]. In this review, we will discuss data on how diesel exhaust (DE) and two major toxic constituents, PM and PAHs, could involve transient receptor potential channels (TRPs) to regulate multiple cellular pathways and produce airway inflammation, which is considered a critical event in the mechanistic pathway leading to human pulmonary disease.…”