PM2.5 EC/OC Analysis, Banizoumbou, Niger

Weekly integrated aerosol samples are collected using two automatic aerosol samplers specifically designed and developed for the INDAAF program (http://indaaf.obs-mip.fr). Each sampler is equipped with two independent air inlets connected with KNF pumps (N89 KNE-K 12V) operating at a flow rate of 9 L/min, Cole palmer ball flow meters with a micrometric valve (flow range adjustable from 0 to 10 L/min and NILU online filter holders. Each air inlet is surmounted with an aerosol cutting head corresponding to aerodynamic particles diameter. Two mini Partisol low air inlets PM2.5 and PM10 (Rupprecht and Patashnick) operates at a flow rate of 5 L/min and the air volume sample is measured with a GALLUS type G4 gas meter (accuracy ±0.01 m-3) (Ouafo-Luembe et al., 2017; Djoussou et al, 2018). Aerosol samples were collected on 47mm diameter filters on a weekly basis. Quartz fiber filters were used for carbonaceous analysis and the determination of Elemental Carbon (EC), Organic Carbon (OC) and Total Carbon (TC). Quartz fiber filters were cleaned by burning at 450°C for 48h before exposition. For each filter batch preparation, field blanks are included with the samplers sent into the field. Before and after collection, samples and blanks filters are conditioned in petri slides boxes and stored at 4°C. Weekly filter samples are analyzed at the Laboratoire d’Aérologie (LAERO) of Toulouse using thermo-optical methods. From 2005 to 2018, analysis were performed using the Desert Research Institute (DRI) instrument and the IMPROVE analytical protocol. Since 2018, analysis are performed using the Sunset instrument and the European EUSAAR2 protocol. All analytical results are converted to concentrations (in microgram per cubic meter).