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| 溶解性多聚磷酸盐（poly-P）在太湖竺山湾湖区底泥-水界面的迁移和水解机制初探 |
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张云帆1,2, 蔡健霞1, 童丞飞1, 周梓怡1, 郑尚杰3,1, 郭柳佳2,1, 古小治4
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1.中国科学院南京地理与湖泊研究所;2.中国科学院大学;3.南京师范大学;4.中国科学院南京地理与湖泊研究所，湖泊与环境国家重点实验室
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| 摘要: |
| 多聚磷酸盐（poly-P，简称聚磷）作为一种生物体普遍存在且生物活性高的磷组分，在富营养化水体的磷生物地球化学循环中至关重要。为探明聚磷在湖体沉积物-水界面及水体降解转化过程及其与湖底关键环境因子响应过程，采集太湖竺山湾水域原位样品模拟近自然条件下聚磷在湖体降解与转化过程。结果表明，在近自然条件下，溶解性聚磷的短期水解没有明显的受限，随浓度提高而增高，2d后高浓度聚磷水解产生的溶解性磷酸盐（SRP）浓度增长可达到0.1±0.01mg·L-1/d。聚磷的水解主要以生物降解为主，影响其降解速率的主要因素为溶解氧、碳源、温度以及水动力扰动导致的底泥再悬浮过程，低溶解氧浓度能够加速聚磷的水解进程，并使得SRP浓度提前12h达到峰值；碳源的添加能够略微增加聚磷的水解速率，并能够再培养周期内持续促进SRP的释放，净增长量达到对照组的2倍；低温能够显著减缓聚磷的水解速率，但整体SRP浓度仍然处于升高状态；扰动导致的底泥再悬浮能够增加聚磷的水解速率，并能够提高SRP浓度峰值。聚磷在沉积物主要以强结合态存在于Al-P组分中并不断释放和进一步水解，仅微量以游离态赋存于沉积物和间隙水。溶解性聚磷在近自然条件能够在48h内迅速沉降水解，并对水体SRP升高持续贡献。本研究水体聚磷的赋存特性及快速水解周转部分成果，为厘清夏秋季节的湖体藻细胞指数增殖期的活性磷供给源，以及阐明多聚磷参与水体磷循环的生物地球化学过程提供了支撑。 |
| 关键词: 多聚磷酸盐(poly-P)、水解、沉积物、太湖、溶解性活性磷（SRP） |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Preliminary Study on the Migration and Hydrolysis Mechanism of Dissolved Polyphosphate at the Sediment-Water Interface in the Zhushan Bay Area of Lake Taihu |
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zhangyunfan,caijianxia,tongchengfei,zhouziyi,zhengshangjie,guoliujia,guxiaozhi
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Nanjing Institute of Geography and Limnology, Chinese Academy of Science
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| Abstract: |
| Polyphosphate (poly-P), a phosphorus component that is widely present in organisms and exhibits high biological activity, plays a critical role in the biogeochemical cycling of phosphorus in eutrophic water bodies. To elucidate the degradation and transformation processes of poly-P at the sediment-water interface and within the water column, as well as its response to key environmental factors in lake sediments, in situ samples were collected from the Zhushan Bay area of Lake Taihu. These samples were used to simulate near-natural conditions for studying the degradation and transformation of poly-P. The results indicated that under near-natural conditions, the short-term hydrolysis rate of dissolved poly-P showed no obvious upper limit and increased with rising concentrations. After two days, the SRP (soluble reactive phosphorus) concentration generated by the hydrolysis of high-concentration poly-P could reach 0.1 ± 0.01 mg·L?1/d. The hydrolysis of poly-P was primarily driven by biological degradation, with key factors influencing the degradation rate including dissolved oxygen, carbon sources, temperature, and sediment resuspension caused by disturbances. Low dissolved oxygen concentrations accelerated the hydrolysis of poly-P and brought the SRP concentration to its peak 12 hours earlier. The addition of carbon sources slightly increased the hydrolysis rate and promoted sustained SRP release throughout the incubation period, with a net increase reaching twice that of the control group. Low temperatures significantly reduced the hydrolysis rate, although the overall SRP concentration continued to rise. Disturbances that led to sediment resuspension increased both the hydrolysis rate of poly-P and the peak SRP concentration. In the sediment, poly-P mainly existed in a strongly bound form within the Al-P fraction, undergoing continuous release and further hydrolysis, while only trace amounts were present as free poly-P in the sediment and pore water. Dissolved poly-P could rapidly settle and hydrolyze within 48 hours under near-natural conditions, contributing to the sustained supply of SRP to the water column. This study on the occurrence and rapid hydrolytic turnover of poly-P in the water column provides insights into tracing and clarifying the sources of active phosphorus that fuel algal cell proliferation during the summer and autumn seasons. It also sheds light on the biogeochemical processes involving polyphosphate in the phosphorus cycle of water bodies. |
| Key words: Polyphosphate, Hydrolysis, Sediment, Lake Taihu, Soluble Reactive Phosphorus(SRP) |
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