Ground-based off-line aerosol measurements at Praia, Cape Verde, during
                        the Saharan Mineral Dust Experiment: microphysical properties and
                        mineralogy

Kandler, Konrad; Schütz, L.; Jäckel, S.; Lieke, K.; Emmel, Carmen; Müller-Ebert, D.; Ebert, Martin; Scheuvens, Dirk; Schladitz, A.; Šegvić, Branimir; Wiedensohler, A.; Weinbruch, Stephan

doi:10.1111/j.1600-0889.2011.00546.x

Cited by 66 publications

(41 citation statements)

References 77 publications

(117 reference statements)

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“…It has now been shown that, when immersed in water, the feldspar component nucleates ice much more efficiently than the other main minerals that make up typical desert dust (Atkinson et al, 2013;Augustin-Bauditz et al, 2014;O'Sullivan et al, 2014;Niedermeier et al, 2015;Zolles et al, 2015). This is an important finding as it has been demonstrated that feldspar is a common component of aerosolized mineral dusts (Glaccum and Prospero, 1980;Kandler et al, 2009Kandler et al, , 2011Atkinson et al, 2013;Perlwitz et al, 2015). Feldspar particles in the atmosphere tend to be larger than clay particles and so will have shorter lifetimes in the atmosphere, however aerosol modelling work has suggested that feldspar particles can account for many observations of INP concentrations around the world (Atkinson et al, 2013).…”

Section: Introductionmentioning

confidence: 69%

Not all feldspars are equal: a survey of ice nucleating properties across the feldspar group of minerals

et al. 2016

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Abstract. Mineral dust particles from wind-blown soils are known to act as effective ice nucleating particles in the atmosphere and are thought to play an important role in the glaciation of mixed phase clouds. Recent work suggests that feldspars are the most efficient nucleators of the minerals commonly present in atmospheric mineral dust. However, the feldspar group of minerals is complex, encompassing a range of chemical compositions and crystal structures. To further investigate the ice-nucleating properties of the feldspar group we measured the ice nucleation activities of 15 characterized feldspar samples. We show that alkali feldspars, in particular the potassium feldspars, generally nucleate ice more efficiently than feldspars in the plagioclase series which contain significant amounts of calcium. We also find that there is variability in ice nucleating ability within these groups. While five out of six potassium-rich feldspars have a similar ice nucleating ability, one potassium rich feldspar sample and one sodium-rich feldspar sample were significantly more active. The hyper-active Na-feldspar was found to lose activity with time suspended in water with a decrease in mean freezing temperature of about 16 • C over 16 months; the mean freezing temperature of the hyper-active K-feldspar decreased by 2 • C over 16 months, whereas the "standard" K-feldspar did not change activity within the uncertainty of the experiment. These results, in combination with a review of the available literature data, are consistent with the previous findings that potassium feldspars are important components of arid or fertile soil dusts for ice nucleation. However, we also show that there is the possibility that some alkali feldspars may have enhanced ice nucleating abilities, which could have implications for prediction of ice nucleating particle concentrations in the atmosphere.

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Section: Introductionmentioning

confidence: 69%

Not all feldspars are equal: a survey of ice nucleating properties across the feldspar group of minerals

et al. 2016

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“…Kandler et al (2011b) observed the presence of 4 size distribution modes during the SAMUM-2 campaign, in January of 2008, at Praia airport, using a Differential Mobility Particle Sizer (DMPS) for the size range 26-800 nm and an Aerodynamic Particle Sizer (APS) for the aerodynamic size range of 570 nm-10 μm. The finest mode of the volume size distribution was found for D p of 200-300 nm and was attributed to sulfate.…”

Section: Size Distributionsmentioning

confidence: 99%

“…An intensive 1 month field experiment run in Praia during January 2008 integrated in the SAMUM-2 campaign revealed PM 10 values of the order of 29 μg.m −3 , during transport of maritime air masses, and of 223 μg.m −3 , during dust events with air masses transported directly from Africa (Kandler et al, 2011b); the mass ratio between PM 10 and PM 2.5 did not present a significant variation during the field experiment, with an average of 2.67, not very different from our annual average ratio of 2.53.…”

Section: Pm Concentrationsmentioning

confidence: 99%

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Pio

Cardoso

Cerqueira

et al. 2014

Front. Environ. Sci.

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One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport) research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 μm. Time series of 5 min average PM 10 concentrations revealed peak values higher than 1000 μg.m −3 during winter dust storm events originating over Northern Africa. The 24 h average concentrations exceeded the World Health Organization (WHO) guidelines for PM 2.5 and PM 10 in 20 and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation) for PM 1 , PM 2.5 , and PM 10 were 5 ± 5, 19 ± 21, and 48 ± 64 μg.m −3 , respectively. The annual PM 2.5 and PM 10 values were also above the limits prescribed by the WHO (10 and 20 μg.m −3 , respectively). The aerosol mass size distribution revealed two main modes for particles smaller than 10 μm: a fine mode (0.7-0.8 μm), which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 μm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 and 10-12 μm were frequently present.

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“…The Anti-atlas mountains was also 25 suggested as a source of micronutrients to the North East Atlantic Ocean by Chavagnac et al (2007). In off-line filters collected at Praia Cabo Verde, Kandler et al (2011b) reported illite/kaolinite ratio of between 1:2 and 1:4 during winter transport of dust to Cabo Verde from coastal Mauritania and Mali respectively. In continuous long term measurements of elemental composition, Patey et al (2015) reported seasonal variation in Al content which was attributed to seasonal changes in dust transport, and reported illite as the most abundant.…”

mentioning

confidence: 99%

“…The traditional method for reporting the composition of aerosol particles involves the classification of particles into compositional groups using a variety of elemental ratios and boundary rules e.g Kandler et al (2007Kandler et al ( , 2011b ;Young et al (2016).…”

mentioning

confidence: 99%

Mineralogy and mixing state of North African mineral dust by on-line single-particle mass spectrometry

Marsden¹,

Ullrich²,

Möhler³

et al. 2018

Preprint

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Abstract. The mineralogy and mixing state of dust particles originating from the African continent influences climate and marine ecosystems in the North Atlantic due to its effect on radiation, cloud properties and biogeochemical cycling. Single-particle mineralogy and mixing state is particularly important in many processes but is difficult to predict because of large temporal and spatial variability and the lack of in-situ measurements of dust properties during emission, transport and deposition. This lack of measurements is in part due to the remoteness of potential source areas (PSA) and transport pathways, but also because of 5 the lack of an efficient method to report the mineralogy and mixing state of single particles with a time resolution comparable to atmospheric processes.In this work, the mineralogy and mixing state of the fine fraction (< 2.5µm) in laboratory suspended dust from the Sahara and Sahel were made using novel techniques with on-line single-particle mass spectrometry (SPMS) and traditional off-line scanning electron microscopy (SEM). A regional difference in mineralogy was detected, with material sourced from Morocco 10 contained a high number fraction of illite like particles in contrast to Sahelian material which contains potassium and sodium depleted clay minerals like kaolinite. Applying the same methods to ambient measurement of transported dust in the marine boundary layer at Cabo Verde in the remote North Atlantic enabled the number fractions of illite/smectite clay mineral (ISCM), non-ISCM, and calcium containing particles to be reported at a 1 hour time resolution over a 20 day period alongside internal mixing with nitrate, sulphate and organic/biological material. The ISCM and nitrate content was found to change significantly 15 between distinct dust events, indicating a shift in source and transport pathways which may not be captured in off-line composition analysis or remote sensing techniques.The results show SPMS and SEM techniques are complimentary and demonstrate that SPMS can provide a meaningful high resolution measurement of single-particle mineralogy and mixing state in laboratory and ambient conditions. In most cases, the mineralogy varies continuously between particles rather than a collection of discrete mineral phases. These techniques 20 will be useful in resolving the complexity of mineral dust transport and in obtaining atmospherically relevant test material for laboratory experiments of dust properties.

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Ground-based off-line aerosol measurements at Praia, Cape Verde, during the Saharan Mineral Dust Experiment: microphysical properties and mineralogy

Cited by 66 publications

References 77 publications

Not all feldspars are equal: a survey of ice nucleating properties across the feldspar group of minerals

Not all feldspars are equal: a survey of ice nucleating properties across the feldspar group of minerals

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Mineralogy and mixing state of North African mineral dust by on-line single-particle mass spectrometry

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