Coprecipitation of Organic Matter, Phosphate With Iron: Implications for Internal Loadings of Phosphorus in Algae-Dominated and Macrophyte-Dominated Lakes
Coprecipitation of Organic Matter, Phosphate With Iron: Implications for Internal Loadings of Phosphorus in Algae-Dominated and Macrophyte-Dominated Lakes
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DOI：
10.3389/fenvs.2022.953509
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
Jiaru Dai;Qiaoying Zhang;J. Liu;Shuailong Wen;Yufeng Zhang;Ding He;YingXun Du
中科院分区：
文献类型：
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作者：
Jiaru Dai;Qiaoying Zhang;J. Liu;Shuailong Wen;Yufeng Zhang;Ding He;YingXun Du
铁（Fe）共沉淀在湖泊有机碳（OC）和磷（P）的生态地球化学循环中起着至关重要的作用。有机质（OM）的来源和组成介导其与铁的结合，从而影响磷的固定。在这项研究中，水溶性有机质从两个典型的国家的浅水湖泊沉积物，水生植物为主的区域（M-WSOM）和藻类为主的区域（A-WSOM），提取，和WSOM，磷酸盐与Fe（III）的三元共沉淀进行了研究。随着Fe（III）浓度的增加或pH值的降低，三元共沉淀过程增强。发现6.5的pH比7.5或8.5的pH更有利于共沉淀。在pH6.5时，低Fe（III）输入时，WSOM与Fe（III）发生络合，而当Fe（III）输入达到40 μM时，磷酸盐WSOM与Fe（III）发生共沉淀。A-WSOM对磷酸盐共沉淀的抑制作用强于M-WSOM。A-WSOM形成的三元共沉淀物的C/Fe比（0.13-2.78）低于M-WSOM形成的三元共沉淀物的C/Fe比（1.28-4.05），这是因为A-WSOM的芳香度低于M-WSOM。此外，A-WSOM中更多的官能团可以与Fe（III）络合，导致在A-WSOM、磷酸盐和Fe（III）的共沉淀过程中OC和P的固定较少。研究结果表明，在藻类占优势的区域，三元共沉淀过程中更多的磷保持在溶解状态，这对浮游植物的生长具有正反馈作用，为富营养化湖泊难以恢复提供了新的解释.
Coprecipitation with iron (Fe) plays an essential role in the biogeochemical cycles of organic carbon (OC) and phosphorus (P) in lakes. The sources and composition of organic matter (OM) mediate its association with iron, which could thus influence the immobilization of phosphorus. In this study, water-soluble organic matter from the sediments of two typical states of shallow lakes, macrophyte-dominated zones (M-WSOM) and algae-dominated zones (A-WSOM), was extracted, and the ternary coprecipitation of WSOM, phosphate with Fe(III), was investigated. The ternary coprecipitation process was enhanced with increasing Fe(III) or decreasing pH value. It was found that pH of 6.5 was more favorable for coprecipitation than a pH of 7.5 or 8.5. At pH 6.5, the complexation between WSOM and Fe(III) occurred at the low Fe(III) inputs, while the coprecipitation of phosphate, WSOM with Fe(III) took place when Fe(III) inputs reached 40 μM. The presence of A-WSOM showed stronger inhibition on the coprecipitation of phosphate than that by M-WSOM. The formed ternary coprecipitates with A-WSOM had lower C/Fe ratios (0.13–2.78) than those with M-WSOM (1.28–4.05), which was because A-WSOM had lower aromaticity than M-WSOM. In addition, more functional groups in A-WSOM could complex with Fe(III), resulting in less immobilization of OC and P during the coprecipitation of A-WSOM, phosphate, and Fe(III). Our results demonstrated that in algae-dominated zones, more phosphorus remained soluble during the ternary coprecipitation, which could perform positive feedback on the growth of phytoplankton and provide a novel explanation for the difficulty in restoring eutrophic lakes.