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首页> 外文期刊>Environmental Science & Technology >Enhanced Dissolution of Manganese Oxide in Ice Compared to Aqueous Phase under Illuminated and Dark Conditions
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Enhanced Dissolution of Manganese Oxide in Ice Compared to Aqueous Phase under Illuminated and Dark Conditions

机译：与光照和黑暗条件下的水相相比，氧化锰在冰中的溶解度提高

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摘要

Manganese is one of the common elements in the Earth's crust and an essential micronutrient for all living things. The reductive dissolution of particulate manganese oxide is a dominant process to enhance mobility and bioavailability of manganese for the use of living organisms. In this work, we investigated the reductive dissolution of manganese oxides trapped in ice (at -20 ℃) under dark and light irradiation (visible: λ > 400 nm and UV: λ > 300 nm) in comparison with their counterparts in aqueous solution (at 25 ℃). The reductive dissolution of synthetic MnO_2, which took place slowly in aqueous solution, was significantly accelerated in ice phase both in the presence and absence of light: about 5 times more dissolution in ice phase than in liquid water after 6 h UV irradiation in the presence of formic acid. The enhanced dissolution in ice was observed under both UV and visible irradiation although the rate was much slower in the latter condition. The reductive dissolution rate of Mn(Ⅱ)_(aq) (under both irradiation and dark conditions) gradually increased with decreasing pH below 6 in both aqueous and ice phases, and the dissolution rates were consistently faster in ice under all tested conditions. The enhanced generation of Mn(Ⅱ)_(aq) in ice can be mainly explained in terms of freeze concentration of electron donors, protons, and MnO_2 in liquid-like ice grain boundaries. The outdoor solar experiment conducted in Arctic region (Ny-Alesund, Svalbard, 78°S5'N) also showed that the photoreductive dissolution of manganese oxide is enhanced in ice. The present results imply that the dissolution of natural minerals like manganese oxides can be enhanced in icy environments such as polar region, upper atmosphere, and frozen soil.
机译：锰是地壳中的常见元素之一，也是所有生物必需的微量营养素。颗粒状氧化锰的还原溶解是增强锰的迁移率和生物利用度的主要方法。在这项工作中，我们研究了锰氧化物在暗和光（可见光：λ> 400 nm，紫外线：λ> 300 nm）下与水溶液中的锰氧化物相比的还原溶解（可见光：λ> 400 nm和紫外线：λ> 300 nm）。在25℃）。在有光和无光条件下，在水溶液中缓慢发生的合成MnO_2的还原溶解在冰相中均显着加速：在存在紫外线6小时后，在冰相中的溶解度是在液态水中的约5倍甲酸。在紫外线和可见光照射下都观察到冰中溶解的增强，尽管在后者条件下速度要慢得多。在水相和冰相中，Mn（Ⅱ）_（aq）的还原溶出速率（在辐照和黑暗条件下）都随着pH值低于6逐渐增加，并且在所有测试条件下，在冰中的溶出速率始终较快。冰中Mn（Ⅱ）_（aq）的生成增强主要可以通过电子供体，质子和MnO_2在液态冰晶边界中的冻结浓度来解释。在北极地区（Ny-Alesund，斯瓦尔巴特群岛，北纬78°S5'N）进行的户外太阳能实验还表明，锰氧化物在冰中的光还原溶解作用增强。目前的结果表明，在冰冷的环境（例如极地，高层大气和冰冻的土壤）中，可以增强诸如氧化锰之类的天然矿物的溶解。

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  • 来源
    《Environmental Science & Technology》 |2012年第24期|13160-13166|共7页
  • 作者

    Kitae Kim; Ho-Il Yoon; Wonyong Choi;

  • 作者单位

    School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea;

    Korea Polar Research Institute, Incheon 406-840, South Korea;

    School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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