分层异重流对香溪河浮游植物叶绿素a空间分布的影响

曾一恒; 沈旭舟; 张佳磊; 张欢; 刘德富; 龚川; 翁传松

doi:10.12153/j.issn.1674-991X.20210808

分层异重流对香溪河浮游植物叶绿素a空间分布的影响

doi: 10.12153/j.issn.1674-991X.20210808

曾一恒^{1, 2,},
沈旭舟^{1, 2},
张佳磊^{1, 2, ,},
张欢^{1, 2},
刘德富^{1, 2},
龚川^{1, 2},
翁传松^{1, 2}

1.
湖北工业大学土木建筑与环境学院
2.
河湖生态修复与藻类利用湖北省重点实验室

基金项目: 国家水体污染控制与治理科技重大专项（2017ZX07101-003）

详细信息

作者简介:
曾一恒（1997—），男，硕士，主要从事水生态修复研究，yizzz1997@163.com

通讯作者:
张佳磊(1983—)，女，副教授，博士，主要从事水生态修复研究，zhangjialei2015@sina.com

中图分类号: X524
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- 文章访问数: 183
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- 被引次数: 0
出版历程
- 收稿日期: 2021-12-08
- 网络出版日期: 2022-04-02

Effects of stratified density flow on the spatial distribution of chlorophyll-a in phytoplankton in Xiangxi River

ZENG Yiheng^{1, 2
,},
SHEN Xuzhou^{1, 2},
ZHANG Jialei^{1, 2
, ,},
ZHANG Huan^{1, 2},
LIU Defu^{1, 2},
GONG Chuan^{1, 2},
WENG Chuansong^{1, 2}

1.
College of Civil and Environmental, Hubei University of Technology
2.
Key Laboratory of Ecological Remediation of Lakes and Rivers and Algal Utilization of Hubei Province

摘要

摘要: 基于三峡水库香溪河库湾汛期（2017年8月4—10日）水动力、气象和藻类漂移监测数据，运用数理统计方法，分析汛期香溪河浮游植物叶绿素a（Chla）浓度空间分布特征及其影响因素，探究分层异重流背景下藻类的水平输移和垂向掺混作用过程。结果表明：1)汛期香溪河库湾水动力具有明显的分层异重流特性，监测期间雷诺数均大于4 000，水体呈现紊流状态，对藻类的运动输移产生水平输运和垂向掺混2种影响。2)表层藻类水平漂移速度受到风速和水流流速的影响，响应关系式为V_藻=0.035V_风+0.461V_水+0.034 (R²=0.917，P<0.01)。3)分层异重流对高浓度藻细胞库湾原水的稀释作用和环流对高浓度藻细胞的携带作用，导致水柱Chla总浓度呈直线下降趋势，此时干流水体从中上层倒灌进库湾，上游来水以底部顺坡异重流方式流向河口，在中上游相遇形成环流，在库湾中部倒灌水体一分为二，分别从底部和表层输出库湾，Chla浓度分布特征为表层>底层>中层；当倒灌水体与库湾原水形成环流并从底部输出库湾时，Chla浓度分布特征为表层>中层>底层或者中层>底层>表层。因此，Chla浓度的水平分布主要受到风速和异重流的水平流速的影响，而垂向分布受到异重流所形成的水体循环模式的影响。
- 藻类漂移速度 /
- 紊流 /
- 水平输运 /
- 垂向掺混 /
- 三峡水库
Abstract: The spatial distribution characteristics of chlorophyll-a (Chla) in phytoplankton in the Xiangxi River during the flood season and their relevant affecting factors were analyzed by applying mathematical statistics methods and based on the monitoring data of hydrodynamics, meteorology and the drifting of the algae in Xiangxi River reservoir of the Three Gorges Reservoir during the flood season (August 4-10, 2017). The process of horizontal transport and vertical mixing of algae under the background of stratified density flow was explored. The results showed that: 1) The hydrodynamic data of Xiangxi River reservoir was featured with the obvious density-stratified flow. Reynolds numbers during the monitoring period were all above 4 000, and the water body got into the turbulent state, which produced two effects on the movement of the algae, i.e. horizontal movement and vertical mixing. 2) The horizontal drift velocities of the algae on the water surface was affected by wind speeds and water velocities with the response formula V_algae=0.035V_wind+0.461V_water+0.034 (R²=0.917, P<0.01). 3) The dilution effect of density-stratified flow on the raw water of high-concentration of algal cells in the reservoir and the carrying effect of circulations on high-concentration algal cells led to a linear downward trend of the total Chla concentrations of the water column. Meanwhile, the mainstream poured back into the reservoir at the upper and middle layers, and the upstream inflow flowed to the river mouth in the form of density current at the bottom along the slopes. The two flows met in the middle and upper sections of the river and thus a circulation was formed, and the pouring-back flow was divided into two parts in the middle of the reservoir, which were respectively discharged from the surface and the bottom. Chla concentrations presented such a sequence: surface > bottom > middle. When the circulation was formed as a result of the clash between the flow poured back and the raw water of the reservoir and discharged from the bottom to the reservoir bay, Chla concentrations presented this sequence: surface > middle > bottom, or middle > bottom > surface. The results suggested that the wind speeds and water horizontal velocities of density flow were key factors for the horizontal distribution of Chla, while the vertical distribution was affected by the water circulation mode formed by density flow.
- drift velocity of phytoplankton /
- turbulence /
- horizontal transport /
- vertical mixing /
- Three Gorges Reservoir

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图 1 三峡库区香溪河采样断面分布

Figure 1. Location of sampling sites in Xiangxi River of the Three Gorges Reservoir

下载: 全尺寸图片幻灯片

图 2 三峡库区水位及入库流量变化过程

Figure 2. Variation of water level and inflow in the Three Gorges Reservoir area

下载: 全尺寸图片幻灯片

图 3 2017年8月4—10日香溪河库湾纵坡面流速分布

注：右箭头为干流流向上游方向，左箭头为上游流向河口方向，箭头长度表示流速。

Figure 3. Vertical profile of flow velocity of Xiangxi River Bay on August 4-10, 2017

下载: 全尺寸图片幻灯片

图 4 汛期香溪河水体混合模式

注：①为库湾原水，由于干流倒灌水体而阻塞，容易暴发水华；②为水温较低、密度较大的上游来水潜入库湾底部，输出库湾；③为库湾原水受到干流倒灌水体阻塞在中上游形成的环流；④为上游来水与干流倒灌水体的交汇面，在持续倒灌水体的作用下从底部输出；⑤为干流水体一分为二，改变流向从表层输出；⑥、⑦为干流倒灌水体。

Figure 4. Water mixing model of Xiangxi River Bay in flood season

下载: 全尺寸图片幻灯片

图 5 2017年8月4—10日香溪河库湾库湾风场、流场、藻类漂移速度、漂移面积和漂移生物量分布

Figure 5. Wind field, flow field, algae drift velocity, drift area and drift mass of Xiangxi River Bay on August 4-10, 2017

下载: 全尺寸图片幻灯片

图 6 藻类水平漂移速度与风速和流速的关系

Figure 6. Relationship between horizontal drift velocity of algae and wind speed and velocity

下载: 全尺寸图片幻灯片

图 7 2017年8月4—10日香溪河库湾纵坡面Chla浓度垂向分布特征

Figure 7. Vertical profile of distribution characteristics of Chl-a concentrations in Xiangxi River Bay on August 4-10, 2017

下载: 全尺寸图片幻灯片

表 1 2017年8月4—10日观测点雷诺数变化

Table 1. Reynolds numbers of observation points on August 4-10, 2017

参数	2017-08-04	2017-08-05	2017-08-06	2017-08-07	2017-08-08	2017-08-09	2017-08-10
V/(m/s)	0.074 1	0.007 5	0.002 7	0.002 0	0.002 4	0.012 5	0.022 0
h/m	6.0	5.0	4.0	8.0	6.0	4.0	5.0
Re	4.41×10⁵	3.72×10⁴	1.07×10⁴	1.59×10⁵	1.43×10⁴	4.96×10⁴	1.09×10⁵

下载: 导出CSV

表 2 藻类漂移速度与风速、流速影响因素的多元线性回归参数

Table 2. Multiple linear regression parameters among algae drift velocity and influencing factors of wind speed and flow velocity

参数	偏回归系数	标准误差	t	P
常数	0.034	0.002	20.437	1.76×10^−36**
风速	0.035	0.002	17.128	4.04×10^−32**
流速	0.461	0.031	14.976	6.55×10^−29**
注：**表示P<0.01。

下载: 导出CSV

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