| 厦门西溪河口沉积物活性磷的分布特征及迁移转化机制 |
| 摘要点击 1722 全文点击 1162 投稿时间：2022-06-01 修订日期：2022-07-19 |
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| 中文关键词 活性磷 磷-铁-硫耦合 河口沉积物 氧化还原地球化学 吸附/解吸动力学 |
| 英文关键词 labile phosphorus P-Fe-S coupling estuarine sediments redox geochemistry kinetics of adsorption/desorption |
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| 中文摘要 |
| 为探索不同河口区域锰、铁和硫地球化学行为对活性磷分布的影响，选择厦门西溪河口，应用薄膜扩散梯度（DGT）采样技术，对沉积物DGT有效态磷（DGT-P）、锰、铁和硫进行原位和高分辨监测.结果表明，在垂向剖面中，DGT-P的分布与铁和硫的氧化还原转化以及沉积物活性磷背景值关系密切，磷的钝化/活化主要受控于铁氧化物对磷的氧化吸附和还原溶解，以及硫酸盐还原和硫化物积累引发的磷活化；沿采样点分布，DGT-P的浓度平均值差异大（0.075~0.80 mg ·L-1），与盐度无关，而是与氧化还原条件密切相关，即氧化带越深磷浓度平均值越低；模型模拟结果表明，表层沉积物对孔隙水磷的再补给能力与DGT-P浓度及氧化还原条件相关，即氧化环境不利于沉积物磷的解吸再补给，而还原环境中与铁和硫地球化学的耦合有利于维持高活性磷浓度以及磷的持续释放. |
| 英文摘要 |
| To explore the effect of manganese, iron, and sulfur geochemistry on the distribution of labile phosphorus in different estuarine areas, the diffusion gradient in thin-film (DGT) sampling technique was used for in-situ high-resolution monitoring of available phosphorus (DGT-P), manganese, iron, and sulfur in sediments from Xixi River estuary in Xiamen. The results showed that the distribution of DGT-P in the vertical profile was closely related to the redox transformation of iron and sulfur and the background value of active phosphorus in sediments. The passivation/activation of phosphorus was mainly controlled by the oxidative adsorption/reductive dissolution of phosphorus by iron oxides and the activation of phosphorus induced by sulfate reduction and sulfide accumulation. Along the sampling sites, the average concentration of DGT-P varied greatly (0.075-0.80 mg·L-1), which was not related to salinity but closely related to redox conditions, that is, the deeper the oxidation zone, the lower the average concentration of DGT-P. The simulation results showed that the phosphorus resupply capacity from surface sediments to porewater was correlated with DGT-P concentration and redox conditions, that is, the oxidative environment was unconducive to the desorption and resupply of sediment phosphorus, whereas the coupling with iron and sulfur geochemistry in the reducing environment was conducive to the maintenance of high labile phosphorus concentration and the continuous release of phosphorus. |
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