| 大九湖泥炭沼泽源铁有机配合物的络合稳定性及其生态环境意义 |
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| 引用本文： | 黄玉冰,赵甜甜,向武,赵云鹏,刘洋. 大九湖泥炭沼泽源铁有机配合物的络合稳定性及其生态环境意义[J]. 地球科学, 2021, 46(5): 1862-1870. DOI: 10.3799/dqkx.2020.149 |
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| 作者姓名： | 黄玉冰 赵甜甜 向武 赵云鹏 刘洋 |
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| 作者单位： | 中国地质大学地球科学学院,湖北武汉 430074;中国地质大学地球科学学院,湖北武汉 430074;流域关键带演化湖北省重点实验室,湖北武汉 430074 |
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| 基金项目： | 国家自然科学基金项目41977263国家自然科学基金项目41472316 |
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| 摘 要： | 为了研究泥炭沼泽源铁有机配合物的络合稳定性，利用pH电位滴定法和荧光淬灭滴定法测定了大九湖泥炭沼泽中不同分子量段的DOM和Fe2+、Fe3+的络合稳定常数.pH电位滴定法结果（4.0~6.1）和荧光淬灭滴定法（1.5~4.1）差异较大，这与高pH条件下OH被脱质子化及Fe2+的氧化有关.相对而言，pH滴定法更适用于探究不同分子量段DOM与铁的络合稳定性，荧光淬灭法不改变样品酸碱条件，更适于研究不同价态铁与DOM的络合稳定性.研究结果表明:DOM与Fe3+的络合稳定常数大于Fe2+，低分子量段（< 3 kDa）的DOM与Fe2+、Fe3+的络合稳定常数更大.泥炭沼泽源铁有机配合物具有较好的络合稳定性，分子量相对较小的DOM与铁的络合能力更强.即便Fe2+氧化为Fe3+，仍能与DOM络合并保持较强的稳定性，这有利于陆源溶解性铁向水生态系统的输出.沼泽源铁有机配合物的络合稳定性还会影响铁的生物可利用性.
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| 关 键 词： | 络合稳定常数 pH电位滴定 荧光淬灭滴定 溶解性有机质 铁 环境地球化学 |
| 收稿时间： | 2020-11-07 |
Stability of Organic Iron Complexes in Dajiuhu Peats and Its Ecological Significance |
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| Huang Yubing,Zhao Tiantian,Xiang Wu,Zhao Yunpeng,Liu Yang. Stability of Organic Iron Complexes in Dajiuhu Peats and Its Ecological Significance[J]. Earth Science-Journal of China University of Geosciences, 2021, 46(5): 1862-1870. DOI: 10.3799/dqkx.2020.149 |
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| Authors: | Huang Yubing Zhao Tiantian Xiang Wu Zhao Yunpeng Liu Yang |
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| Abstract: | In order to study the complexing stability of organic iron complexes from peat, the stability of DOM-Fe2+, Fe3+ in different molecular weights of Dajiuhu peatland was determined by potentiometric titration and fluorescence quenching titration. There are obvious differences between the results of potentiometric titration (4.0-6.1) and fluorescence quenching titration (1.5-4.1), which can be explained by the deprotonation of OH in high pH value and the oxidation of Fe2+ during the experiments. Potentiometric titration is suitable for studying the complexing stability of different molecular weights of DOM-Fe; the pH would not change during the experiment using fluorescence quenching titration method. Thus, the fluorescence method can be well applied to the element of variable valency. The results show that the complexing stability constants of DOM-Fe3+ is higher than that of Fe2+, and that of low-molecular-weight DOM with Fe2+ and Fe3+ is higher. The experiment indicates that high stability of DOM-Fe in peat, and relatively low-molecular-weight DOM has stronger ability to complex iron. Even Fe2+ is oxidized to Fe3+, it can still complex with DOM stably, which is conducive to the output of terrestrial dissolved iron to aquatic ecosystem. The complexing stability of iron organic complexes from peat will also affect the bioavailability of iron. |
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