Abstract
Aerosols, including mineral dust, are transported from China and Mongolia to Japan, particularly in spring. It has been recognized that calcium (Ca) carbonate is the main Ca species in aerosols, which reacts with acidic species such as sulfuric and nitric acids at the surface of mineral dust during its long-range transport, related to mitigation of acid depositions. The similar assumption that magnesium (Mg) originally takes the form of carbonate and contributes to the neutralization reaction and buffering effect on the acidity of aerosols has been suggested in various studies. However, few studies have confirmed this process by measuring actual Mg species in aerosols quantitatively. In this study, X-ray absorption near-edge structure (XANES) spectroscopy was employed to determine Mg species in size-fractionated aerosol samples, including mineral dust. The results showed that (i) most Mg in the mineral dust did not take the form of carbonate and its reacted species (e.g., sulfate and nitrate) produced by the neutralization reaction, but (ii) Mg was mainly found as Mg in the octahedral layer in phyllosilicates. Given that the reactivity of such Mg in phyllosilicates is much lower than those in carbonate minerals, the contribution of Mg to the neutralization reactions in the atmosphere must be lower than previously expected.
Highlights
Calcium carbonate is the most common Ca species in aerosols or mineral dust [1,2]. This mineral is an important component in aerosols because it is reactive with acidic species such as sulfuric acid, nitric acid, and organic acids in the atmosphere [3,4,5]
Many studies have assumed that most Mg in the atmosphere is present as Mg carbonate in aerosols [5,8], which can react with acidic species
Carbonate minerals can be buffers to control the acidity of aerosols, which in turn regulates the solubility of Fe, an important component in aerosols related to ocean productivity [9,10]
Summary
Calcium carbonate is the most common Ca species in aerosols or mineral dust (coarse particle-size fraction in aerosols usually over 1 μm) [1,2]. This mineral is an important component in aerosols because it is reactive with acidic species such as sulfuric acid, nitric acid, and organic acids in the atmosphere [3,4,5]. The amount of Mg species in aerosol have been indirectly estimated using the charge balances of soluble cations and anions and the water solubilities of various salts [5] From another aspect, carbonate minerals can be buffers to control the acidity of aerosols, which in turn regulates the solubility of Fe, an important component in aerosols related to ocean productivity [9,10]. The presence of Mg carbonate has been assumed (e.g., Myriokefalitakis et al [11])
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
