| 摘要: |
| 太湖蓝藻暴发与水体中溶解态总磷(DTP)密切相关，而底泥是否向水中释放DTP是一个重要的问题。由于太湖底泥间隙水与上覆水的DTP之间存在3~5倍的浓度差，Fick扩散成为一个具有常发条件的DTP释放过程。针对Fick 扩散计算仍然未能精确地考虑含有有机磷时的扩散系数等问题，本文在考虑有机磷的影响、孔隙率、温度等等变化的条件下进行了监测和计算。基于全湖30个采样点的现场调查数据，使用只有无机磷扩散系数20%左右的扩散系数计算太湖DTP年Fick扩散量约为127.8t t，占入湖DTP通量的14.6%；磷的Fick 扩散量与上覆水磷浓度相同具有西北高、东南低的特点。敏感性分析表明:相对于温度变化，有机磷的占比和孔隙率的取值对于Fick扩散量的计算值有更大的影响。而整个太湖的磷平衡中，有约为38%的溶解态总磷的转化方式和去向需要进一步明确。 |
| 关键词: 磷平衡 底泥释放 Fick扩散 有机磷扩散系数 底泥孔隙率 温度影响 |
| DOI： |
| 分类号: |
| 基金项目:国家重点基础研究发展计划（973计划） |
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| Fick diffusion release flux study of DTP at the sediment-water interface of Lake Taihu |
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liuhuan,zhuwei,houhao,tanzhengwei,jilang
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Hohai university
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| Abstract: |
| Algal blooms in Lake Taihu are intricately linked to Dissolved Total Phosphorus (DTP), and the critical question of whether sediment releases DTP into the water demands attention. Given the 3-5 times concentration disparity between DTP in the sediment and the overlying water of Lake Taihu, Fick diffusion emerges as a recurrent DTP release process. Notably, the calculation of Fick release has hitherto struggled to precisely account for the diffusion coefficient when organic phosphorus is present. This paper addresses this limitation by conducting monitoring and calculations, considering the influence of organic phosphorus, porosity, temperature, and other variables. Leveraging field investigation data from 30 sampling points across the entire lake, the annual Fick diffusion of DTP in Taihu Lake is estimated to be approximately 127.8 tons per year. This calculation employs a diffusion coefficient only about 20% of that for inorganic phosphorus, constituting 14.6% of the external DTP loading. The Fick release of phosphorus exhibits spatial characteristics, mirroring the phosphorus concentration in the overlaying water, with higher concentrations in the northwest and lower concentrations in the southeast. Sensitivity analysis underscores the greater impact of organic phosphorus percentage and porosity values on the calculated Fick diffusion compared to temperature changes. In the phosphorus balance of Lake Taihu, approximately 38% of DTP transformation modes and destinations remain unclear. |
| Key words: Phosphorus balance Sediment release Fick diffusion Organophosphorus diffusion coefficient Sediment porosity Temperature effect |
