| 引用本文: | 唐钰婧，贾小红，黄承鹏，王甫，任燕，顾文君，李锐，张国华，唐明金.2023.典型含铁矿物的溶解特征[J].地球环境学报,14(2):136-144 |
| TANG Yujing, JIA Xiaohong, HUANG Chengpeng, WANG Fu, REN Yan, GU Wenjun, LI Rui, ZHANG Guohua, TANG Mingjin.2023.Dissolution characteristics of typical iron-containing minerals[J].Journal of Earth Environment,14(2):136-144 |
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| 摘要: |
| 气溶胶沉降是开阔大洋可溶性铁的重要来源。矿质颗粒物在大气传输后铁可溶性显著增加，然而尚缺乏大气化学反应对铁可溶性影响的系统研究。本文探究了pH值、不同酸以及草酸盐浓度对赤铁矿、针铁矿、伊利石和蒙脱石中铁可溶性的影响。在pH=2的硫酸溶液中，铁可溶性为：伊利石（2.18%±0.14%）＞针铁矿（1.68%±0.18%）＞赤铁矿（0.43%±0.06%）＞蒙脱石（0.20%±0.08%）。加入乙酸盐对铁可溶性无促进作用，而加入草酸盐后，铁可溶性明显增加，且草酸盐浓度增加对铁（氢）氧化物铁可溶性有促进作用，但对黏土矿物铁可溶性几乎无促进作用。在加入2 mmol·L−1草酸盐后，铁可溶性为：针铁矿（5.38%±1.76%）＞伊利石（4.19%±0.30%）＞赤铁矿（3.87%±0.24%）＞蒙脱石（1.83%±0.06%），草酸盐对铁（氢）氧化物中铁可溶性的促进作用大于黏土矿物。 |
| 关键词: 铁 溶解特征 铁（氢）氧化物 黏土矿物 |
| DOI：10.7515/JEE222007 |
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| 基金项目:国家自然科学基金项目（42022050）；中国博士后科学基金（2021M703222） |
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| Dissolution characteristics of typical iron-containing minerals |
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TANG Yujing, JIA Xiaohong, HUANG Chengpeng, WANG Fu, REN Yan, GU Wenjun, LI Rui, ZHANG Guohua, TANG Mingjin
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1. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences,
Guangzhou 510640, China
2. CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
4. Longhua Center for Disease Control and Prevention of Shenzhen, Shenzhen 518109, China
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| Abstract: |
| Background, aim, and scope Aerosol deposition is regarded as an important source of soluble iron in the open ocean. Atmospheric processing could significantly increase the aerosol iron fractional solubility. However, there is a lack of systematic studies for the effect of atmospheric processing on iron fractional solubility. This study aims to investigate the effects of atmospheric processing on iron fractional solubility of minerals, which are the main sources of iron in aerosol. Materials and methods In this work, we selected four typical minerals, including hematite, goethite, illite and montmorillonite. The minerals were dissolved in sulfuric acid, oxalate and acetate solution, and then the dissolved iron was determined by a 1, 10-phenanthroline method. Effects of pH, different acids and oxalate concentrations on iron fractional solubility of minerals were explored. Results In sulfuric acid solution (pH=2), the iron fractional solubility performed as follows: illite (2.18%±0.14%)＞goethite (1.68%±0.18%)＞hematite (0.43%±0.06%)＞montmorillonite (0.20%±0.08%). The addition of acetate to the sulfuric acid solution didn’t promote iron fractional solubility; however, when oxalate was added, iron fractional solubility was significantly elevated. In addition, fractional solubility of iron in iron (hydro)oxide increased with oxalate concentration; while the increase of oxalate concentration almost showed no effects on solubility of iron in clays. After adding 2 mmol·L−1 oxalate to the solution, the iron fractional solubility performed as follows: goethite (5.38%±1.76%)＞illite (4.19%±0.30%)＞hematite (3.87%±0.24%)＞montmorillonite (1.83%±0.06%). Oxalate showed more significant effects on iron solubility enhancement for iron (hydro)oxide compared to clay. Discussion Overall, iron (hydro)oxides had higher Fe solubility compared to clays in this work, indicating that not all iron (hydro)oxides have lower iron solubility compared to clays, some other factors might control the Fe solubility. In addition, with pH increased from 2 to 3, Fe solubility was significantly decreased in sulfuric acid while slightly decreased in oxalate solution. Acids and their pH significantly impact iron solubility in minerals, and the increase in pH value directly inhibits proton-promoted dissolution and indirectly inhibits ligand-promoted dissolution. Conclusions The main conclusions include the following: (1) pH significantly impacts iron solubility in minerals, the increase in pH directly inhibits proton-promoted dissolution and indirectly inhibits ligand-promoted dissolution. (2) The acetate showed no effects on iron solubility while the oxalate could promote the dissolution of iron in minerals. (3) Oxalate has a greater effect on promoting the iron solubility for iron (hydro)oxides compared to clays, and the iron solubility of hematite shows a positive correlation with oxalate concentrations. Recommendations and perspectives Overall, the dissolution characteristics of iron in ambient aerosols remain poorly understood. The dissolution characteristics of iron in desert dust and combustion aerosol should be further explored, and the correlations between iron solubility and iron speciation need to be investigated. |
| Key words: iron dissolution characteristics iron (hydro)oxide clay mineral |
