| 摘要: |
| 近年来，夏季高温气候频繁出现，改变了浅水湖泊沉积物性质。由于界面处沉积物具有独特的结构特性，可直接影响湖泊生态健康。结合高温前、后滆湖原位采样和室内模拟实验，旨在探明温度对界面处沉积物结构性质的影响。首先采样结果发现高温导致湖泊沉积物密度、屈服应力降低，促使浮泥（密度< 1.25 g/cm3）的形成。其次，模拟实验也呈现相同趋势。随着温度从25℃升高至35℃，界面处沉积物密度（R2=0.99）呈指数型下降趋势，由1.244 g/cm3降低至1.229 g/cm3。同时，粒径分布结果表明，温度升高导致沉积物的中值粒径从最初的17.22 μm增加至21.16 μm，可促使沉积物颗粒物絮凝和团聚。并且，胞外聚合物中多糖/蛋白比值升高，也表明温度升高会导致沉积物稳定性下降。此外，沉积物屈服应力（R2=0.99）与临界剪切应力（R2=0.94）随温度升高呈指数衰减趋势，且温度阈值为29℃。综上，研究表明高温会导致沉积物结构的疏松多孔性增加，且当温度高于29℃时，沉积物更容易发生起动、悬浮。因此，本研究加深了温度升高对沉积物性质影响的认识，为沉积物的修复治理提供数据支持。另外，对浮泥的特征和再悬浮潜力有了更深入的了解。 |
| 关键词: 浅水湖泊 温度 沉积物 密度 流变特性 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金（52209102， U2240208）；江苏省双创博士（JSSCBS20211393）； 江苏省科技创新项目（BK20220043）；江苏省“碳达峰碳中和”科技创新专项资金项目（BE2022805） |
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| The Effect of Temperature Rise in Summer on Sediment Properties at the Sediment-Water Interface of Shallow Lakes |
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Liu Xin,Zhou Xinyue,Jin Wei,Wu Xiangyang,Jiang Helong,Wang Chunliu
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1.College of Ecology and the Environment,Nanjing Forestry University;2.School of the Environment and Safety Engineering,Jiangsu University;3.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
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| Abstract: |
| In recent years, high temperature continued to occur in summer. influencing sediment properties in shallow lakes. The sediments located at the sediment-water interface (SWI) directly impact the lakes ecological health, due to its unique structural characteristics. In order to investigate the effect of temperature on sediment structural properties, this study conducted sampling in Lake Gehu before and after high temperature, complemented by indoor simulation experiments. Firstly, sampling results indicated that elevated temperatures induce a decline in the density and yield stress of lake sediments, promoting the formation of fluid sediments (density < 1.25 g/cm3). Secondly, the simulation experiment also showed the same trend. As the temperature rose from 25℃ to 35℃, the density of sediments at the SWI displayed an exponentially decreasing trend(R2=0.99) from 1.244 g/cm3 to 1.229 g/cm3. Meanwhile, the increase in temperature led an increase of the sediment median size from the initial 17.22 μm to 21.16 μm, resulting in the flocculation and aggregation of sediment particles. Additionally, increasing temperatures resulted in a higher polysaccharide/protein ratio in extracellular polymeric substances (EPSs), which decreased the stability of sediments. Rheological tests and calculation of critical shear stress showed that the yield stress (R2=0.99) and critical shear stress (R2=0.97) of sediments exponentially decreased with increasing temperature. Overall, this study demonstrated that high temperatures can lead a loose and porous sediment structures with a threshold at 29℃, which can cause sediment particle resuspension and suspension. Overall, this study has deepened the understanding of the impact of temperature rise on sediment properties and provided data supports for the restoration and management of sediments. And it has provided an in-depth understanding of the characteristics of fluid sediments and its potential for resuspension. |
| Key words: Shallow lakes Temperature Sediment Density Rheological properties |
