| 1. |
- Li, Jun, et al.
(författare)
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Hygroscopicity and Ice Nucleation Properties of Dust/Salt Mixtures Originating from the Source of East Asian Dust Storms
- 2022
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Dust storms are common meteorological events that occur frequently in the late spring and early summer in arid and semi-arid areas. The resulting lofted dust and salt mixtures can impact atmospheric chemistry and climate systems through the many pathways represented by aerosol-cloud-climate interactions. In this study, dust/salt samples were collected from important sources of the East Asian dust storm, including the Badain Jaran Desert, the Tengger Desert and the Ulan Buh Desert in northwestern China. Ion chromatography (IC) measurements were performed to determine the concentrations of cations and anions. The ionic concentrations, pH and dissolvable fractions of sand samples show a positive correlation, indicating that the dissolved content is rich in alkaline ions. A positive matrix factorization (PMF) receptor model was employed to analyze the IC results, and from the PMF solutions non-obvious connections to local geography emerge. The results of hygroscopic experiments of sand samples which were measured by a vapor sorption analyzer indicate that the hygroscopicity may be related to the soluble content of samples, and the observed hygroscopic behavior can be well described by a thermodynamic model. The morphology of individual particles was chemically mapped by the synchrotron-based scanning transmission X-ray microscopy, and needle-shaped CaCO3 particles were observed to adhere to more irregular high K-containing particles. Moreover, a continuous flow diffusion chamber was used to investigate the ice nucleation abilities of typical salts, with both homogeneous freezing and deposition nucleation being observed. The results indicate that the salts primarily act as cloud condensation nuclei but can also act as ice nucleating particles at low temperatures.
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| 2. |
- Liu, Wanyu, et al.
(författare)
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Chemical and Hygroscopic Characterization of Surface Salts in the Qaidam Basin: Implications for Climate Impacts on Planet Earth and Mars
- 2021
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Ingår i: ACS Earth and Space Chemistry. - : American Chemical Society (ACS). - 2472-3452. ; 5:3, s. 651-662
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Tidskriftsartikel (refereegranskat)abstract
- Salt particles play important roles in many atmospheric processes due to their high hygroscopicity. Saline lakes and playas are sources of salt particles, which are normally mixed with mineral dust that can be transported over long distances. In this study, salt samples collected from four saline lakes and surrounding playas in the Qaidam Basin are studied for their physicochemical properties, focusing on the chemical compositions and hygroscopicity. The salt samples include brines, lakebed salts, crust salts, and crystallized brines. Thermodynamic models are used to explain the precipitating and hygroscopic behaviors based on ionic compositions of dissolved saline solutions. Regarding the ionic compositions, the crystallized brines are similar to the complex mineral compositions of brines, while the natural solid salts, including lakebed salts and crust salts, show very distinct composition differences. The main difference between brines and natural solid salts is the presence of Mg2+ and SO42–, which are primarily found in brines but not in the solid phases. Moreover, all the crust salts are dominated by NaCl regardless of the chemical compositions of the nearby saline lakes. Positive matrix factorization is applied to the ionic concentrations, and the results show that solid salts and brines are governed by different factors. The pH of brines correlates with Mg2+ concentrations and is potentially influenced by ambient CO2 uptake. The hygroscopicity experimental results and thermodynamic model outcomes show that the water uptake of different salt types is controlled by different salt components, that is, crystallized brines are controlled by MgCl2 and natural salts are governed by NaCl and KCl. The characterizations of saline lake and playa salts improve the understandings of the roles that surface salts potentially play in the climate systems of both Planet Earth and Mars.
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