| 长江河口及邻近海域表层沉积物中铁溶解和磷释放活性的动力学表征 |
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| 引用本文： | 肖丽,王迪,马伟伟,李文君,李铁,朱茂旭.长江河口及邻近海域表层沉积物中铁溶解和磷释放活性的动力学表征[J].海洋学报,2019,41(12):1-13. |
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| 作者姓名： | 肖丽 王迪 马伟伟 李文君 李铁 朱茂旭 |
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| 作者单位： | 1. 中国海洋大学 化学化工学院，山东 青岛 266100 |
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| 基金项目： | 国家自然科学基金（41576078，41776085）；国家重点研发计划项目（2016YFA0601301）。 |
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| 摘 要： | 运用溶解动力学实验及活性连续体模型表征了长江河口至东海邻近海域表层沉积物中铁(Fe)和磷(P)的活性。通过动力学数据拟合得到了活性组分的理论含量m0和表观速率常数k。结果表明，Fe(Ⅱ)普遍存在于表层沉积物中，这应是高活性有机络合态Fe(Ⅲ)絮凝/沉淀到沉积物中后快速还原的结果。沉积物中黏土及总有机碳（TOC）含量对Fe(Ⅱ)的m0及其k值起重要控制作用。从长江河口至邻近海域沉积物中Fe(Ⅱ)均以FeCO3形态为主，FeCO3的溶解及与之相结合磷(主要为交换态P和自生P)的释放导致Fe(Ⅱ)和P具有相似的溶解动力学特征。与吸附于Fe(Ⅱ)矿物相的P相比，与Fe(Ⅱ)矿物相共沉淀的P的m0较高，但k较低。与TOC含量较低的粗粒沉积物中的Fe(Ⅲ)相比，TOC含量较高的细粒沉积物中Fe(Ⅲ)的m0值较小，但k值较大。以上特征是Fe不同的氧化还原过程导致的。Fe(Ⅲ)氧化物的含量(m0)和活性(k)总体上控制着与之相结合P的含量(m0)及溶解活性(k)。虽然传统活性Fe形态分析未能揭示出长江河口沉积物中活性Fe的富集作用，但溶解动力学表征结果表明，Fe的絮凝/沉淀导致河口沉积物中活性Fe的明显富集，且该过程主要发生在盐度明显增加的低盐度河口区。
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| 关 键 词： | 铁 磷 活性 溶解动力学 絮凝 沉淀 长江河口 东海 |
| 收稿时间： | 2018/10/20 0:00:00 |
| 修稿时间： | 2019/12/17 0:00:00 |
Kinetic characterization of reactivity of iron dissolution and phosphorus release in surface sediments of the Changjiang (Yangtze) River Estuary and the adjacent East China Sea |
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| Xiao Li,Wang Di,Ma Weiwei,Li Wenjun,Li Tie and Zhu Maoxu.Kinetic characterization of reactivity of iron dissolution and phosphorus release in surface sediments of the Changjiang (Yangtze) River Estuary and the adjacent East China Sea[J].Acta Oceanologica Sinica (in Chinese),2019,41(12):1-13. |
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| Authors: | Xiao Li Wang Di Ma Weiwei Li Wenjun Li Tie and Zhu Maoxu |
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| Institution: | College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China |
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| Abstract: | Kinetic dissolution and the reactive continuum model were combined to characterize the reactivity of iron (Fe) and phosphorus (P) in surface sediments of the Changjiang (Yangtze) River Estuary and the adjacent East China Sea. Two kinetic parameters, i.e., theoretical amounts (m0) and apparent rate constant (k) of reactive Fe, were extracted by fitting kinetic dissolution data to the reactive continuum model. Results showed that Fe(Ⅱ) phases occurred in all surface sediments studies, which could be ascribed to rapid reduction of highly reactive organic-bound Fe(Ⅲ) flocculated/precipitated to the sediments. It is inferred that Fe(Ⅱ) occurs mainly as FeCO3 in both the Changjiang (Yangtze )River Estuarine sediments and the adjacent East China Sea sediments. The m0 and k values of Fe(Ⅱ) were controlled mainly by total organic carbon (TOC) contents and clay fractions. Simultaneous release of Fe(Ⅱ) and associated P (mainly exchangeable P and authigenic P) resulted in similar pattern of dissolution kinetics. Relative to P adsorbed on surfaces of Fe(Ⅱ) solid phases, coprecipitated P with Fe(Ⅱ) phases has higher m0 but lower k. In fine-grained sediments with high TOC contents, Fe(Ⅲ) oxides have lower m0 values but higher k in comparison with those in coarse-grained sediments with lower TOC contents, which is caused by different processes of Fe redox cycling. Overall, the dissolution reactivity of P associated with Fe(Ⅲ) phases is largely controlled by the reductive reactivity of Fe(Ⅲ) phases. Our kinetic characterization indicates that flocculation/precipitation has caused reactive Fe enrichment in the estuarine sediments, occurring mainly in a narrow zone of low salinity, but the enrichment could not be revealed by conventional Fe speciation. |
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| Keywords: | iron phosphorus reactivity dissolution kinetics flocculation precipitation Changjiang(Yangtze) River Estuary East China Sea |
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