Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, China.
College of Environment, Hohai University, 1 Xikang road, Nanjing, 210098, China.
Environ Sci Pollut Res Int. 2017 Jul;24(21):17900-17911. doi: 10.1007/s11356-017-9374-x. Epub 2017 Jun 15.
Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.
浅水湖泊由于风致流速效应对内源营养负荷非常敏感。本研究以中国第三大淡水湖太湖的一个狭长型深湾为研究对象，调查了风致流速效应对营养物质悬浮的影响。测量了长狭湾中大风条件下垂向水柱的风生反向/补偿流和稳定流场的出现概率。风场与水流速度之间的概率分布在水面（80.6%）和底层（65.1%）具有很强的相关性。垂向流速剖面分析表明，底层水流对风场的响应存在时间延迟。西风（W）和西北风（WNW）产生的强风场导致水体向相反方向移动。当考虑风速作为控制因素时，水面和底层水流速度之间存在指数相关关系。建立了一个线性模型来关联风生流对水面和底层营养浓度的影响。结果表明，主导风向（ENE、E 和 ESE）分别对水面和底层营养物质再悬浮的贡献最大（营养物质再悬浮潜力），分别为 34.7%和 43.6%。在太湖东部湾的现场实验中，总悬浮固体（TSS）、总氮（TN）和总磷（TP）的平均浓度分别为 6.38、1.5 和 0.03mg/L。总的来说，风致低到中等水动力干扰对太湖东部湾的营养物质再悬浮贡献更大。本研究可以用来了解浅水湖泊（形态均匀且边缘较深）风致流速与营养浓度之间的关系，以便进行水质管理和进一步开发模型。
