Influence of sampling approaches on physical and geochemical analysis of aeolian dust in source regions

Holdt, Johanna von; Eckardt, Frank D.; Baddock, Matthew C.; Hipondoka, Martin; Wiggs, Giles F.S.

doi:10.1016/j.aeolia.2021.100684

Cited by 9 publications

(6 citation statements)

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“…Based on an original design by Ganor (1975), we chose MDCOs due to the efficiency and popularity in desert research (e.g., Offer et al, 1992;Goossens and Offer, 1994;Goossens and Rajot, 2008). In general, the representation of dust in the sample depends on the selected sampling method, which may result in underestimation or overprediction of some important minerals (von Holdt et al, 2021). MDCOs (like many other dust catchers) are less efficient in dust collection in high-wind regimes (Goossens, 2005).…”

Section: Sample Collectionmentioning

confidence: 99%

Contrasting mineral dust abundances from X-ray diffraction and reflectance spectroscopy

2022

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Abstract. Mineral dust particles dominate aerosol mass in the atmosphere and directly modify Earth's radiative balance through absorption and scattering. This radiative forcing varies strongly with mineral composition, yet there is still limited knowledge on the mineralogy of atmospheric dust. In this study, we performed X-ray diffraction (XRD) and reflectance spectroscopy measurements on 37 different dust deposition samples collected as airfall in an urban setting to determine mineralogy and the relative proportions of minerals in the dust mixture. Most commonly, XRD has been used to characterize dust mineralogy; however, without prior special sample preparation, this technique is less effective for identifying poorly crystalline or amorphous phases. In addition to XRD measurements, we performed visible and short-wave infrared (VSWIR) reflectance spectroscopy for these natural dust samples as a complementary technique to determine mineralogy and mineral abundances. Reflectance spectra of dust particles are a function of a nonlinear combination of mineral abundances in the mixture. Therefore, we used a Hapke radiative transfer model along with a linear spectral mixing approach to derive relative mineral abundances from reflectance spectroscopy. We compared spectrally derived abundances with those determined semi-quantitatively from XRD. Our results demonstrate that total clay mineral abundances from XRD are correlated with those from reflectance spectroscopy and follow similar trends; however, XRD underpredicts the total amount of clay for many of the samples. On the other hand, calcite abundances are significantly underpredicted by SWIR compared to XRD. This is caused by the weakening of absorption features associated with the fine particle size of the samples, as well as the presence of dark non-mineral materials (e.g., asphalt) in these samples. Another possible explanation for abundance discrepancies between XRD and SWIR is related to the differing sensitivity of the two techniques (crystal structure vs. chemical bonds). Our results indicate that it is beneficial to use both XRD and reflectance spectroscopy to characterize airfall dust because the former technique is good at identifying and quantifying the SWIR-transparent minerals (e.g., quartz, albite, and microcline), while the latter technique is superior for determining abundances for clays and non-mineral components.

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Section: Sample Collectionmentioning

confidence: 99%

Contrasting mineral dust abundances from X-ray diffraction and reflectance spectroscopy

2022

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“…Specifically, we examined the immersion-mode IN ability of surface-derived material samples aerosolized in a cloud-simulation chamber and ambient OLLF dust sampled in the field through offline lab analysis. We focused on the immersion-mode freezing because recent modeling simulation and remote sensing studies suggest that immersion freezing is the most prominent heterogeneous IN mechanism, through which ice crystals are formed in mixedphase clouds, accounting for 85 % to 99 % of ice crystal formation (Hande and Hoose, 2017;Westbrook and Illingworth, 2011). To complement the immersion freezing results, we also attempted to investigate the presence of any known biological INPs by taxonomic identification of the microbiome.…”

Section: Introductionmentioning

confidence: 99%

Laboratory and field studies of ice-nucleating particles from open-lot livestock facilities in Texas

Hiranuma

Auvermann²,

Belosi

et al. 2021

Atmos. Chem. Phys.

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Abstract. In this work, an abundance of ice-nucleating particles (INPs) from livestock facilities was studied through laboratory measurements from cloud-simulation chamber experiments and field investigation in the Texas Panhandle. Surface materials from two livestock facilities, one in the Texas Panhandle and another from McGregor, Texas, were selected as dust proxies for laboratory analyses. These two samples possessed different chemical and biological properties. A combination of aerosol interaction and dynamics in the atmosphere (AIDA) measurements and offline ice spectrometry was used to assess the immersion freezing mode ice nucleation ability and efficiency of these proxy samples at temperatures above −29 ∘C. A dynamic filter processing chamber was also used to complement the freezing efficiencies of submicron and supermicron particles collected from the AIDA chamber. For the field survey, periodic ambient particle sampling took place at four commercial livestock facilities from July 2017 to July 2019. INP concentrations of collected particles were measured using an offline freezing test system, and the data were acquired for temperatures between −5 and −25 ∘C. Our AIDA laboratory results showed that the freezing spectra of two livestock dust proxies exhibited higher freezing efficiency than previously studied soil dust samples at temperatures below −25 ∘C. Despite their differences in composition, the freezing efficiencies of both proxy livestock dust samples were comparable to each other. Our dynamic filter processing chamber results showed on average approximately 50 % supermicron size dominance in the INPs of both dust proxies. Thus, our laboratory findings suggest the importance of particle size in immersion freezing for these samples and that the size might be a more important factor for immersion freezing of livestock dust than the composition. From a 3-year field survey, we measured a high concentration of ambient INPs of 1171.6 ± 691.6 L−1 (average ± standard error) at −25 ∘C for aerosol particles collected at the downwind edges of livestock facilities. An obvious seasonal variation in INP concentration, peaking in summer, was observed, with the maximum at the same temperature exceeding 10 000 L−1 on 23 July 2018. The observed high INP concentrations suggest that a livestock facility is a substantial source of INPs. The INP concentration values from our field survey showed a strong correlation with measured particulate matter mass concentration, which supports the importance of size in ice nucleation of particles from livestock facilities.

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“…Following the Chinese load code [13] requirements, the 1/50 scale turbulent wind field of class B landform was simulated by arranging sharp splits and various rows of distributed harsh elements in the test section of the wind tunnel laboratory. The test arrangement is depicted in Figure 1b, in which class B landform generally refers to the suburban landform with sparse houses [21]. The equations for mean wind profile v(z) and turbulence profile I z (z) are presented as follows:…”

Section: Simulation Of Wind Fieldsmentioning

confidence: 99%

Wind-Induced Vibration Coefficient of Landscape Tower with Curved and Twisted Columns and Spiral Beams Based on Wind Tunnel Test Data

et al. 2022

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The complex aerodynamic shape and structural form affect the wind-induced vibration coefficient β of landscape towers with a twisted column and spiral beam (short for LTs). To clarify the β distribution characteristics, evaluate the applicability of existing load codes, and provide accurate design wind loads, wind tunnel tests and numerical simulations were carried out on a LT. The LT’s aerodynamic coefficients and wind-induced responses were measured using rigid sectional and aeroelastic models. Furthermore, the displacement wind-induced vibration coefficient βd and inertial load wind-induced vibration coefficient βi(z) of the LT were calculated from these measured data. Combined with test data and a finite element model, the impacts of the wind speed spectrum type, the structural damping ratio ξ, and the peak factor g on β of the LT are analyzed. The accuracy of β of the LT calculated by Chinese and American load codes was examined and given the correction method. The results showed that the wind yaw angle had a significant impact on βd of the LT, which cannot be neglected in current load codes. The abrupt mass increase at the platform location makes the distribution characteristics of βi(z) of the LT different from conventional high-rise structures. The values of ξ and g have a significant impact on the calculation results of β, which are the key to the accurate design wind loads of LTs. The existing load codes are not suitable for LTs, and the correction method proposed in this paper can be used to improve them.

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Influence of sampling approaches on physical and geochemical analysis of aeolian dust in source regions

Cited by 9 publications

References 100 publications

Contrasting mineral dust abundances from X-ray diffraction and reflectance spectroscopy

Contrasting mineral dust abundances from X-ray diffraction and reflectance spectroscopy

Laboratory and field studies of ice-nucleating particles from open-lot livestock facilities in Texas

Wind-Induced Vibration Coefficient of Landscape Tower with Curved and Twisted Columns and Spiral Beams Based on Wind Tunnel Test Data

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