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DOI	10.5194/acp-22-9461-2022
	Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility
	Sakata, Kohei; Kurisu, Minako; Takeichi, Yasuo; Sakaguchi, Aya; Tanimoto, Hiroshi; Tamenori, Yusuke; Matsuki, Atsushi; Takahashi, Yoshio
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	9461
结束页码	9482
卷号	22 期号:14 页码:22
英文摘要	Atmospheric deposition is one of the main sources of dissolved iron (Fe) in the ocean surfaces. Atmospheric processes are recognized as controlling fractional Fe solubility (Fe-sol%) in marine aerosol particles. However, the impact of these processes on Fe-sol% remains unclear. One of the reasons for this is the lack of field observations focusing on the relationship between Fe-sol% and Fe species in marine aerosol particles. In particular, the effects of organic ligands on Fe-sol% have not been thoroughly investigated in observational studies. In this study, Fe species in size-fractionated aerosol particles in the Pacific Ocean were determined using X-ray absorption fine structure (XAFS) spectroscopy. The internal mixing states of Fe and organic carbon were investigated using scanning transmission X-ray microscopy (STXM). The effects of atmospheric processes on Fe-sol% in marine aerosol particles were investigated based on the speciation results. Iron in size-fractionated aerosol particles was mainly derived from mineral dust, regardless of aerosol diameter, because the enrichment factor of Fe was almost 1 in both coarse (PM>1.3) and fine aerosol particles (PM1.3). Approximately 80 % of the total Fe (insoluble + labile Fe) was present in PM>1.3, whereas labile Fe was mainly present in PM1.3. The Fe-sol% in PM>1.3 was not significantly increased (2.56 +/- 2.53 %, 0.00 %-8.50 %, n = 20) by the atmospheric processes because mineral dust was not acidified beyond the buffer capacity of calcite. In contrast, mineral dust in PM1.3 was acidified beyond the buffer capacity of calcite. As a result, Fe-sol% in PM1.3 (0.202 %-64.7 %, n = 10) was an order of magnitude higher than that in PM>1.3. The PM1.3 contained ferric organic complexes with humic-like substances (Fe(III)-HULIS, but not Fe-oxalate complexes), and the abundance correlated with Fe-sol%. Iron(III)-HULIS was formed during transport in the Pacific Ocean because Fe(III)-HULIS was not found in aerosol particles in Beijing and Japan. The pH estimations of mineral dust in PM1.3 established that Fe was solubilized by proton-promoted dissolution under highly acidic conditions (pH < 3.0), whereas Fe(III)-HULIS was stabilized under moderately acidic conditions (pH 3.0-6.0). Since the observed labile Fe concentration could not be reproduced by proton-promoted dissolution under moderately acidic conditions, the pH of mineral dust increased after proton-promoted dissolution. The cloud process in the marine atmosphere increases the mineral dust pH because the dust particles are covered with organic carbon and Na. The precipitation of ferrihydrite was suppressed by Fe(III)-HULIS owing to its high water solubility. Thus, the organic complexation of Fe with HULIS plays a significant role in the stabilization of Fe that was initially solubilized by proton-promoted dissolution.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000829853700001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273109
作者单位	National Institute for Environmental Studies - Japan; Japan Agency for Marine-Earth Science & Technology (JAMSTEC); High Energy Accelerator Research Organization (KEK); University of Tsukuba; Nagoya University; Japan Synchrotron Radiation Research Institute; Kanazawa University; University of Tokyo; Japan Agency for Marine-Earth Science & Technology (JAMSTEC)
推荐引用方式 GB/T 7714	Sakata, Kohei,Kurisu, Minako,Takeichi, Yasuo,et al. Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility[J],2022,22(14):22.
APA	Sakata, Kohei.,Kurisu, Minako.,Takeichi, Yasuo.,Sakaguchi, Aya.,Tanimoto, Hiroshi.,...&Takahashi, Yoshio.(2022).Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(14),22.
MLA	Sakata, Kohei,et al."Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.14(2022):22.