| 深型水库溶解氧分层规律及其机制探究——以万安水库为例 |
| Stratification of Dissolved Oxygen in Deep Reservoirs: A Case Study of Wan’an Reservoir |
| 投稿时间：2023-08-12 修订日期：2023-10-15 |
| DOI：10.15928/j.1674-3075.202308120217 |
| 中文关键词:溶解氧 水体热分层 缺氧状态 万安水库 |
| 英文关键词:dissolved oxygen thermal stratification anoxic state Wan’an reservoir |
| 基金项目:福建省水利科技项目(MSK202216)；福建省环保科技计划项目(2021R023，2022R013)；福建省厦门环境监测中心站环保科技项目(2022S01) |
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| 中文摘要: |
| 溶解氧（DO）是衡量生态状况的重要指标，对生态系统的平衡至关重要。为探究深型水库DO分层的规律及其影响机制，于2022年监测了九龙江万安水库的理化指标及营养元素的垂向分布，并分析库区的DO分层规律及影响因素。结果表明：2月属万安水库混合期，呈贫营养状态，DO垂向平均浓度高达6.70 mg/L，DO变化受浮游植物分布及“翻库”影响；5月属热分层形成期，处中营养状态，水体在内源产氧减少和原位DO消耗驱动作用下出现温跃层溶解氧极小值，36 m以下水体处于缺氧状态；8月为热分层稳定期，处中度富营养化，表层DO最大浓度达12.00 mg/L以上，在35 m深度出现DO极大值，水体热分层阻碍DO补充、内源产氧减弱是造成热分层稳定期水体上层大范围缺氧的主要原因；10月为热分层消退期，呈中营养状态，DO垂向平均浓度仅为0.77 mg/L，水深2.79 m以下水层皆处于缺氧状态。热分层时期DO垂向变化受到水体热分层、营养水平、污染状态及浮游植物生长分布等因素的影响，热分层从物理角度影响DO分层，营养水平及污染状态可以影响DO的产耗机制，而库区水体浊度通过影响浮游植物的垂向分布进而对DO浓度产生影响。研究探明了水层缺氧及变温层DO极小值等现象出现的原因，深入探讨了DO变化规律与营养元素生物地球化学循环间的关系，为维护库区水生态健康提供了科学依据。 |
| 英文摘要: |
| Dissolved oxygen (DO) is a key indicator for evaluating the ecological condition and balance of an aquatic ecosystem. We explored DO stratification and mechanisms producing variations in DO in deep reservoirs, using Wan’an Reservoir on Jiulong river as a case study. Depth profiles of physicochemical parameters and nutrients in Wan’an reservoir were recorded seasonally in February, May, August and October of 2022, and DO stratification patterns and influencing factors were analyzed. February was the mixing period of Wan’an reservoir, and the average vertical concentration of DO increased to a high of 6.70 mg/L. Changes in DO were driven by phytoplankton distribution and "reservoir turnover". Thermal stratification occurred in Wan’an reservoir during May, and the reservoir was in a mesotrophic state. In May, a local minimum DO at the thermocline appeared as oxygen production by photosynthesis decreases and in-situ DO was consumed by microbial decomposition, leading to anoxic water below 36 m. August was the period of stable thermal stratification, and the reservoir was moderately eutrophic. The maximum DO concentration at the surface exceeded 12.00 mg/L because of high algal production. Thermal stratification hinders DO replenishment, and decomposition of settling nonviable algal cells consume DO, resulting in large-scale DO depletion during the period of stable thermal stratification. October was the period when thermal stratification weakened, and the reservoir was in a mesotrophic state, with an average vertical DO concentration of 0.77 mg/L, and anoxic water below 2.79 m. The vertical change in DO during thermal stratification was affected by thermal stratification, nutrient levels, pollution status, and the vertical distribution of phytoplankton growth. Thermal stratification produces a physical barrier that affects DO stratification, nutrient levels and pollution affect DO production and consumption mechanisms, and water turbidity affect the vertical distribution of the phytoplankton and, consequently, the DO concentration. In conclusion, we explored the mechanisms leading to anoxic conditions and the occurrence of a DO minima near the thermocline, and analyzed the relationship between changes in the vertical distribution of DO and nutrient biogeochemical cycles. Our research provides a scientific basis for maintaining a healthy aquatic ecosystem in Wan’an reservoir. |
| 陈 侃,王飞飞,阮琪祯,吴旭春,曹文志.2024.深型水库溶解氧分层规律及其机制探究——以万安水库为例[J].水生态学杂志,45(2):20-30. |
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