摘要
以三峡水库典型支流库湾小江和香溪河为例,通过2020年蓄水期不同阶段的野外监测,对比分析了两条支流库湾的水动力过程、热分层、溶解氧时空差异及其对蓄水过程的响应.结果表明:(1)蓄水初期,小江库湾表层受大气复氧和浮游植物影响溶解氧较高(7.00~13.00 mg·L^(-1)),其氧跃层出现在水深3~5 m处,5 m以下水域出现大面积缺氧(DO<2.00 mg·L^(-1)),甚至无氧现象.香溪河库湾溶解氧在垂向上大致可以分为3层:表层富氧水体(8.00~12.00 mg·L^(-1))、中层水体(6.00~8.00 mg·L^(-1))和底层低氧水体(4.00~6.00 mg·L^(-1)).(2)稳定的热分层为底层厌氧的形成提供了稳定的物理环境,而小江上游来流以及消落带植被分解增加了水体有机质的含量,可能是造成小江水体耗氧量增大、形成厌氧的内因;而香溪河因为长期存在的顺坡异重流补给,底层水体缺氧的风险较低.(3)持续的跟踪监测发现水库蓄水对支流库湾溶解氧起到了显著的补给作用,促使小江库湾厌氧现象在短期内得到有效改善.针对三峡水库,通过水库调度来改善支流库湾的缺氧和厌氧等水生态问题是可行的.结果进一步加深了对三峡水库不同支流库湾溶解氧分层特征及其差异的理解,从而为水库生态调度提供理论及技术支撑.
Taking the Xiaojiang and Xiangxi Rivers,two typical tributaries of the Three Gorges Reservoir,as examples,this study analyzed and compared the hydrodynamic,thermal stratification,and temporal and spatial differences in dissolved oxygen(DO)and their responses to the water storage process in the two tributaries through field monitoring at different stages of the 2020 impoundment period.The results showed that:(1)at the initial stage of water storage,the DO in the surface layer of the Xiaojiang River was higher(7.00-13.00 mg·L^(-1))due to atmospheric reoxygenation and phytoplankton photosynthesis,and the oxycline appeared in the water depth of 3-5 m.A large area of anoxia(DO<2.00 mg·L^(-1))or even an anaerobic sublayer occurred in the water below 5 m.The DO in the Xiangxi River could be divided into three layers vertically:oxygen-rich surface water(8.00-12.00 mg·L^(-1)),middle water(6.00-8.00 mg·L^(-1)),and low-oxygen bottom water(4.00-6.00 mg·L^(-1)).(2)Thermal stratification provided a stable physical environment,whereas the upstream inflow and vegetation decomposition in the water-level fluctuation zone increased the content of organic matter,which likely increased the oxygen consumption which was conducive to the formation of an anaerobic bottom layer.In the Xiangxi River,the risk of hypoxia in the bottom water body was low because of the oxygen replenishment from the long-term downslope-bottom density current.(3)Continuous monitoring also showed that the storage of the reservoir played a significant role in the replenishment of DO in tributaries,which effectively and rapidly improved the anaerobic phenomenon in the Xiaojiang River.In the Three Gorges Reservoir,it is feasible to ameliorate the water ecological problems such as anoxia and anaerobic conditions in the tributaries via reservoir operation.This study aids understanding of the characteristics and differences of DO stratification in different tributaries of the Three Gorges Reservoir,which can provide theoretical and technical support for reservoir ecological operation.
作者
纪道斌
方娇
龙良红
杨正健
赵星星
杨霞
郭亚丽
JI Dao-bin;FANG Jiao;LONG Liang-hong;YANG Zheng-jian;ZHAO Xing-xing;YANG Xia;GUO Ya-li(College of Hydraulic and Environment Engineering,China Three Gorges University,Yichang 443002,China;Hubei Field Observation and Scientific Research Stations for Water Ecosystem in Three Gorges Reservoir,Yichang 443002,China;CTG Operation and Administration Center for River Basin Hydro Complex,Yichang443133 China;Shanghai Investigation,Design and Research Institute Co.,Ltd.,shanghai200335.China;Yangtze River Ecological Environmental Engineering Research Center of China Three Gorges Corporation,Shanghai200335,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2022年第7期3543-3551,共9页
Environmental Science
基金
国家自然科学基金项目(U2040220,52079069,51909135,52009066,52179065)
中国长江三峡集团有限公司科研项目(202003082)。
关键词
溶解氧(DO)
厌氧
热分层
水动力
三峡水库
dissolved oxygen(DO)
anaerobic
thermal stratification
hydrodynamics
Three Gorges Reservoir
