DOI: 10.1594/pangaea.848522
title: Particle characterization at CVAO during the 2007 RHaMBLe intensive

description: The chemical characterization of filter high volume (HV) and Berner impactor (BI) samples PM during RHaMBLe (Reactive Halogens in the Marine Boundary Layer) 2007 shows that the Cape Verde aerosol particles are mainly composed of sea salt, mineral dust and associated water. Minor components are nss-salts, OC and EC. The influence from the African continent on the aerosol constitution was generally small but air masses which came from south-western Europe crossing the Canary Islands transported dust to the sampling site together with other loadings. The mean mass concentration was determined for PM10 to 17 µg/m**3 from impactor samples and to 24.2 µg/m**3 from HV filter samples. Non sea salt (nss) components of PM were found in the submicron fractions and nitrate in the coarse mode fraction. Bromide was found in all samples with much depleted concentrations in the range 1-8 ng/m**3 compared to fresh sea salt aerosol indicating intense atmospheric halogen chemistry. Loss of bromide by ozone reaction during long sampling time is supposed and resulted totally in 82±12% in coarse mode impactor samples and in filter samples in 88±6% bromide deficits. A chloride deficit was determined to 8% and 1% for the coarse mode particles (3.5-10 µm; 1.2-3.5 µm) and to 21% for filter samples.During 14 May with high mineral dust loads also the maximum of OC (1.71 µg/m**3) and EC (1.25 µg/m**3) was measured. The minimum of TC (0.25 µg/m**3) was detected during the period 25 to 27 May when pure marine air masses arrived. The concentrations of carbonaceous material decrease with increasing particle size from 60% for the ultra fine particles to 2.5% in coarse mode PM.Total iron (dust vs. non-dust: 0.53 vs. 0.06 µg/m**3), calcium (0.22 vs. 0.03 µg/m**3) and potassium (0.33 vs. 0.02 µg/m**3) were found as good indicators for dust periods because of their heavily increased concentration in the 1.2 to 3.5 µm fraction as compared to their concentration during the non-dust periods. For the organic constituents, oxalate (78-151 ng/m**3) and methanesulfonic acid (MSA, 25-100 ng/m**3) are the major compounds identified. A good correlation between nss-sulphate and MSA was found for the majority of days indicating active DMS chemistry and low anthropogenic influences.
description: Mass: Mettler-Toledo UMT2 after 48 h equilibration of the impactor foils at 20 °C and 50 % rel. humidity.Extraction: Parts of the Al impactor foils were extracted in 2 ml high purity water (&gt;18.1 ohm cm). 15 min: shaking - 15 min ultrasonic bath - 15 min shaking.IC (cations): Metrohm with WATERS IC-Pak C M/D Column; eluent: 0.1 mM EDTA, 3.0 mM HNO3IC (anions): To determine bromide along the high chloride concentrations of the sea salt, a special column Metrosep A Supp 5 (Metrohm) was used in a Compact IC 761 (Metrohm LTD, Switzerland) to measure the anions Chloride, Bromide, Nitrate, Sulfate, Oxalate (Eluent: 1mM NaHCO3/3.2 mMNa2CO3, flow rate:0.7 ml/min)CE: Spectra Phoresis 1000 (TSP, USA), equipped with fused silica capillary (length:70 cm, 63 cm to detector, ID: 75 µm) For separation of dicarboxylic acids and methane sulfonic acic, the capillary was filled with a background electrolyte consisting of 10 mmol/l p-aminobenzoic acid, 8 mmol/l diethylenetriamine, and 3.5 mmol/l aqueous sodium hydroxide (pH = 9.6). After hydrodynamic injection at 10.3 kPa for 34 s, a separation voltage of 30 kV was applied. Indirect detection was performed at 254 nm.OC/EC: modified VDI2465 Bl.2 using a C-mat 5500 at Tmax = 650 °C (OC: 8 min at 650 °C under high purity Nitrogen; EC: 8 min at 650 °C under high purity Oxygen)OM was calculated according to the paper of Turpin et al. 2000 (doi:10.1016/S1352-2310(99)00501-4) from OC using a factor of 2.TXRF: Bruker S2 Picofox on quartz wafers after 1.5 h cold plasma pyrolysis to eliminate the Nuclepore substrate.
description: Supplement to: Müller, Konrad; Lehmann, S; van Pinxteren, Dominik; Gnauk, T; Niedermeier, Nicole; Wiedensohler, Alfred; Herrmann, Hartmut (2010): Particle characterization at the Cape Verde atmospheric observatory during the 2007 RHaMBLe intensive. Atmospheric Chemistry and Physics, 10(6), 2709-2721