PM Aerosol Mineral Analysis, Katibougou, Mali

Weekly integrated aerosol samples are collected using two automatic aerosol samplers specifically designed and developed for the INDAAF program (indaaf.obs-mip.fr). Each sampler is equipped with two independent air inlets connected with KNF pumps (N89 KNE-K 220V) 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. PTFE or teflon filters were used for to determine mineral compounds. PTFE filters are weighed before and after sampling using a SARTORIUS MCS21 microbalance (1 µg resolution for a maximum range of 21 g - Measuring accuracy of ± 5 µg). 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. From 2005, we performed PM2.5 or PM10 weekly filter samples analysis at the Laboratoire d’Aérologie (Laero) to determine mineral composition (soluble major ions) using Ion Chromatography (IC). Before this date, weekly bulk aerosol sampling on teflon filters was performed (1998-2005).