Particle and VOC emission factor measurements for anthropogenic sources in West Africa

Sekou Keita (1) , Cathy Liousse (2) , Véronique Yoboué (1) , Pamela Dominutti (3, 4) , Benjamin Guinot (5) , Eric-Michel Assamoi (2) , Agnès Borbon (6) , Sophie Haslett (7) , Laetitia Bouvier (8) , Aurélie Colomb (4) , Hugh Coe (9) , Aristide Akpo (10) , Jacques Adon , Julien Bahino , Madina Doumbia , Julien Djossou , Corinne Galy-Lacaux (2) , Eric Gardrat (2) , Sylvain Gnamien , Jean Leon (11) , Money Ossohou , E. Touré N'Datchoh , Laurent Roblou (2)

1 Laboratoire de Physique de l’Atmosphère [Abidjan]
2 LAERO - Laboratoire d'aérologie
3 WACL - Wolfson Atmospheric Chemistry Laboratories
4 LaMP - Laboratoire de Météorologie Physique
5 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
6 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
7 SEES - School of Earth and Environmental Sciences [Manchester]
8 LaMP - Laboratoire de météorologie physique
9 CAS - Centre for Atmospheric Science [Manchester]
10 NCAS - National Centre for Atmospheric Science [Leeds]
11 Centre de recherches Géodynamiques

A number of campaigns have been carried out to establish the emission factors of pollutants from fuel combustion in West Africa, as part of work package 2 ("Air Pollution and Health") of the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) FP7 program. Emission sources considered here include wood (hevea and iroko) and charcoal burning, charcoal making, open trash burning, and vehicle emissions, including trucks, cars, buses and two-wheeled vehicles. Emission factors of total particulate matter (TPM), elemental carbon (EC), primary organic carbon (OC) and volatile organic compounds (VOCs) have been established. In addition, emission factor measurements were performed in combustion chambers in order to reproduce field burning conditions for a tropical hardwood (he-vea), and obtain particulate emission factors by size (PM 0.25 , PM 1 , PM 2.5 and PM 10). Particle samples were collected on quartz fiber filters and analyzed using gravimetric method for TPM and thermal methods for EC and OC. The emission factors of 58 VOC species were determined using offline sampling on a sorbent tube. Emission factor results for two species of tropical hardwood burning of EC, OC and TPM are 0.98 ± 0.46 g kg −1 of fuel burned (g kg −1), 11.05 ± 4.55 and 41.12 ± 24.62 g kg −1 , respectively. For traffic sources, the highest emission factors among particulate species are found for the two-wheeled vehicles with two-stroke engines (2.74 g kg −1 fuel for EC, 65.11 g kg −1 fuel for OC and 496 g kg −1 fuel for TPM). The largest VOC emissions are observed for two-stroke two-wheeled vehicles, which are up to 3 times higher than emissions from light-duty and heavy-duty vehicles. Isoprene and monoterpenes, which are usually associated with biogenic emissions, are present in almost all anthropogenic sources investigated during this work and could be as significant as aromatic emissions in wood burning (1 g kg −1 fuel). EC is primarily emitted in the ultrafine fraction, with 77 % of the total mass being emitted as particles smaller than 0.25 µm. The particles and VOC emission factors obtained in this study are generally higher than those in the literature whose values are discussed in this paper. This study underlines the important role of in situ measurements in deriving realistic and representative emission factors.

Domaines: Chimie analytique; Environnement et Société; Milieux et Changements globaux; Ingénierie de l'environnement

Sekou Keita, Cathy Liousse, Véronique Yoboué, Pamela Dominutti, Benjamin Guinot, et al.. Particle and VOC emission factor measurements for anthropogenic sources in West Africa. Atmospheric Chemistry and Physics, 2018, 18 (10), pp.7691-7708. ⟨10.5194/acp-18-7691-2018⟩. ⟨hal-02169151⟩