PM10 Mineral 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. 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).

本研究采用两台专为INDAAF计划（http://indaaf.obs-mip.fr）定制开发的自动气溶胶采样器，采集每周整合式气溶胶样品。每台采样器配备两个独立进气口，分别连接KNF泵（型号N89 KNE-K 12V，工作流量设定为9 L/min）、带微调阀的Cole Palmer球式流量计（流量调节范围0~10 L/min）以及NILU在线滤膜支架。每个进气口上方均安装有对应空气动力学粒径的气溶胶切割头。两台Rupprecht与Patashnick品牌的mini Partisol型PM2.5及PM10低流量进气装置，工作流量为5 L/min；样品空气总体积采用GALLUS G4型气体流量计计量，测量精度为±0.01 m³（Ouafo-Luembe等，2017；Djoussou等，2018）。气溶胶样品采集于直径47 mm的滤膜上，采样周期为每周一次。本研究采用聚四氟乙烯（PTFE/Teflon）滤膜测定矿物类化合物组分，使用赛多利斯（SARTORIUS）MCS21型微量天平在采样前后对滤膜进行称重：该天平分辨率为1 μg，最大称量范围21 g，测量精度为±5 μg。每批次滤膜制备过程中，均设置现场空白样品，随采样器一同部署至采样现场。采样前后，样品滤膜与空白滤膜均置于培养皿盒中进行环境平衡处理，并于4℃条件下冷藏保存。2005年起，研究团队于大气气溶胶实验室（Laboratoire d’Aérologie，简称Laero）对每周采集的PM2.5或PM10滤膜样品开展分析，采用离子色谱法（Ion Chromatography，简称IC）测定矿物组分（可溶性主要离子）；2005年之前（1998-2005年），则采用特氟龙滤膜开展每周一次的全粒径气溶胶采样。