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| 筑坝河流水热盐情势变异下鱼类新污染物生态风险研究展望 |
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郭仕骞1, 李博1, 乔如霞2, 何术锋2, 冯韬2, 陈求稳2, 姜伟1
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1.长江经济带生态环境国家工程研究中心;2.水利部交通运输部国家能源局南京水利科学研究院
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| 摘要: |
| 河流生态系统保护是推进生态文明建设的核心环节。鱼类作为河流健康的关键指示物种,其生存状况受到筑坝工程与新污染物的双重胁迫。传统研究多关注单一胁迫因子,而忽视了筑坝引起的“水-热-盐”情势变化与新污染物之间的联合生态效应。本文旨在系统梳理筑坝河流关键环境因子的变异规律,阐明其与新污染物对鱼类的复合影响机制,以期为准确评估筑坝河流的生态风险并提供风险管理新思路。本文采用系统性文献综述的方法,首先总结了筑坝工程对河流水动力、水温及营养盐等关键环境因子的改变规律。进而,分别剖析了这些环境因子变化对鱼类生理机能、生长繁殖的影响,以及新污染物在鱼体内的富集、代谢过程及其毒性效应。在此基础上,本文重点探讨了环境因子变化如何通过三种途径调控新污染物的生态风险：1)改变新污染物在水体中的环境行为(分配、迁移、转化)；2)影响污染物在鱼体内的毒代动力学过程(摄食、代谢、免疫)；3)直接改变鱼类对新污染物的敏感性,从而产生协同或拮抗的联合毒性效应。筑坝河流中鱼类生态风险是环境因子胁迫与新污染物暴露共同作用的产物,二者存在不可忽视的联合效应。未来研究应重点关注：1)从致毒机制层面深入探究环境因子调控下新污染物的复合效应；2)从实际环境浓度和濒危物种角度开展更具生态相关性的长期低浓度暴露研究；3)探索通过水库生态调度优化环境因子,以增强水体自净能力和鱼类抗逆性的可行性。本研究为构建筑坝河流综合生态风险管理体系提供了重要的理论依据和前瞻性视角。 |
| 关键词: 筑坝河流 鱼类 生态风险 环境因子 新污染物 |
| DOI： |
| 分类号:Q89 |
| 基金项目:国家重点研发计划项目(2022YFC3203900)；国家自然科学基金项目(52500257,52400223)；江苏省自然科学基金资助项目(BK20240258)；中国长江三峡集团有限公司科研项目(NBWL202200489) |
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| Perspectives on ecological risks of emerging pollutants in fish under the variation of hydro-thermal-salinity regimes in dammed rivers |
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GUO Shiqian1, LI Bo1, QIAO Ruxia2, HE Shufeng2, FENG Tao2, CHEN Qiuwen2, JIANG Wei1
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1.National Engineering Research Center of Eco-Environment Protection for the Yangtze River Economic Belt,China Three Gorges Corporation;2.Nanjing Hydraulic Research Institute
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| Abstract: |
| The conservation of river ecosystems is fundamental to advancing ecological civilization. As key indicators of aquatic ecosystem health, fish populations face dual threats from dam construction and emerging pollutants. Traditional ecological risk assessments often focus on individual stressors, overlooking the critical combined effects arising from dam-induced alterations in hydrological, thermal, and ionic (hydro-thermal-salinity) regimes and concurrent emerging pollutants exposure. This review aims to synthesize the impact of damming on key environmental factors and elucidate the mechanisms of their combined effects with emerging pollutants on fish, thereby providing a scientific basis for comprehensive ecological risk assessment and novel insights for risk management in dammed rivers.This paper employs a systematic review methodology. It begins by summarizing the documented alterations in key environmental factors caused by dam construction, including hydrodynamics, water temperature, and nutrient regimes. Subsequently, it separately analyzes the impacts of these altered environmental factors on fish physiology, growth, and reproduction, as well as the processes of uptake, bioaccumulation, metabolism, and toxicity of various emerging pollutants in fish. Building upon this foundation, the review constructs a comprehensive analytical framework to explore how environmental factors modulate the ecological risks of emerging pollutants through three potential pathways: 1) modifying the environmental behavior of emerging pollutants; 2) influencing the toxicokinetics of emerging pollutants within fish bodies; and 3) directly altering the sensitivity of fish to emerging pollutants, leading to synergistic or antagonistic combined toxicity. The analysis reveals that dam construction profoundly transforms river ecosystems through multiple interconnected pathways. Hydrologically, projects significantly alter natural flow regimes, manifesting in reduced velocities, homogenized flow processes, and diminished extreme hydrological events. Thermally, reservoir operations induce stratification leading to downstream temperature inversion phenomena that can extend tens to hundreds of kilometers, accompanied by delayed thermal responses and flattened annual fluctuations. In nutrient cycling, reservoirs prolong hydraulic residence time, functioning as "biogeochemical reactors" that not only trap nitrogen and phosphorus but also promote their transformation into more bioavailable forms, with particularly pronounced effects in cascade systems. These environmental alterations directly impact fish at multiple biological levels. Specific flow velocities trigger spawning in drifting-egg species, while suitable vorticity ranges are crucial for juvenile behavior and adult reproduction. Water temperature regulates metabolism, growth and reproduction, with deviations from optimal ranges inducing oxidative stress and immune suppression. Regarding nutrients, while ammonia nitrogen may promote growth at low concentrations, elevated levels cause tissue lesions and impair reproductive capacity. Simultaneously, emerging pollutants accumulate in fish through dietary uptake, and following metabolic processing, some transform into more toxic compounds that disrupt endocrine function and inhibit development and reproduction. Critically, environmental alterations from damming interact with emerging pollutant exposure through multiple mechanisms. These dual stressors produce compounded ecological effects by simultaneously altering pollutant environmental behavior (including partitioning, transport, and transformation in the aquatic environment), modifying toxicokinetic processes in fish (affecting feeding, metabolic rates, immune competence, and thus uptake, distribution, metabolism, and excretion), and shifting organismal sensitivity, collectively amplifying ecological risks to fish populations.Future research should prioritize: 1) Mechanistic investigations into the combined effects of emerging pollutants under the influence of environmental factors, based on toxic mechanisms; 2) Studies conducted at environmentally relevant concentrations and focusing on endangered species, employing long-term, low-dose exposure scenarios for greater ecological relevance; 3) Exploring the feasibility of using optimized reservoir ecological operation strategies to manipulate environmental factors, thereby enhancing the self-purification capacity of water bodies and the resistance of fish to pollutants. This review provides a critical theoretical foundation and a forward-looking perspective for developing an integrated ecological risk management framework for dammed rivers. |
| Key words: Dammed river Fish Ecological risk Environmental factors Emerging pollutants |
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