高温对长江下游大城市饮用水源地水库水质的影响：以南京为例

Effect of high temperature on water quality of drinking water source reservoirs in large cities in lower reaches of Yangtze River: A case study of Nanjing

摘要

【目的】在全球气候变暖背景下，高温事件频发对城市饮用水源地水质安全构成严重威胁。为了探明城市饮用水源地水库水质受高温事件影响的机理，探讨高温期间水库库容和调度策略对水质变化的影响，【方法】以长江下游大城市南京市的16个饮用水源地水库为对象，基于2000—2023年逐月的长序列水质24项理化指标与气象数据，通过Spearman相关分析揭示关键水质指标与气温的长期关联特征，并结合2022年极端高温事件解析水库水质响应机制及空间变化规律。【结果】结果表明：只有水温(T)、酸碱度(pH)、高锰酸盐指数(COD_Mn)、溶解氧(DO)、粪大肠菌群数(FC)、总磷(TP)、总氮(TN)、氨氮(NH₃-N)这8项指标在某些水库与气温存在显著的相关性(p<0.01)。典型高温事件(2022年8月)导致各水库T平均上升6.5%、DO下降5.9%,TP和TN分别增加18.8%和15.6%。空间变化分析显示，江北地区水库(平均库容小、水位降幅大)TN和TP增幅(21.8%、15.5%)显著高于江南区域，而江南地区水库(平均库容大)的DO、pH、COD_Mn、FC和NH₃-N变化更明显。【结论】高温通过改变水体热分层结构与生物地球化学过程加剧水质恶化，库容规模和水资源调度策略对水质响应具有显著调控作用，其中小库容、快降水位型水库更易受高温胁迫。建议建立基于调度功能-响应特征的分类管理模型，制定差异化调控策略提升大城市供水系统的气候韧性。

Abstract

[Objective] Under the background of global warming, the frequent occurrence of high-temperature events has posed a serious threat to the water quality safety of urban drinking water sources. The objective is to clarify the mechanisms by which high-temperature events affect the water quality of urban drinking water source reservoirs, and to explore the effects of reservoir storage capacity and scheduling strategies on water quality changes during high-temperature periods. [Methods] Taking 16 drinking water source reservoirs in Nanjing, a major city in the lower reaches of Yangtze River, as the research objects, the monthly long-term data from 2000 to 2023, on 24 physicochemical water quality indicators and meteorological data were used. Spearman correlation analysis was conducted to reveal the long-term associations between key water quality indicators and temperatures. The response mechanisms and spatial variation patterns of reservoir water quality were analyzed in combination with the extreme high-temperature event in 2022. [Results] The result showed that only 8 indicators—water temperature(T), pH, permanganate index(COD_Mn), dissolved oxygen(DO), fecal coliform(FC), total phosphorus(TP), total nitrogen(TN), and ammonia nitrogen(NH₃-N)—were significantly correlated with temperature in certain reservoirs(p<0.01). The typical high-temperature events in August 2022 led to an average increase of 6.5% in T and a decrease of 5.9% in DO across the reservoirs, while TP and TN increased by 18.8% and 15.6%, respectively. Spatial variation analysis revealed that reservoirs in northern Nanjing, characterized by smaller average storage capacity and greater water level decline, had significantly higher increases in TN and TP(21.8% and 15.5%) compared to those in the southern region. In contrast, reservoirs in southern Nanjing with larger average storage capacities showed more pronounced changes in DO, pH, COD_Mn, FC, and NH₃-N. [Conclusion] High temperatures exacerbate water quality deterioration by altering thermal stratification structures and biogeochemical processes in water bodies. Reservoir storage capacity and water scheduling strategies significantly regulate water quality response, with small-capacity and rapid water-level-declining reservoirs being more vulnerable to high-temperature stress. It is recommended that a classification-based management model should be established based on scheduling functions and response characteristics, and differentiated regulation strategies should be developed to enhance the climate resilience of water supply systems in large cities.

关键词

高温 / 饮用水水源地 / 水库 / 水质 / 长江下游 / 气候韧性 / 库容调节

Key words

high temperature / drinking water source / reservoir / water quality / lower reaches of the Yangtze River / climate resicience / reservior capacity regulation

基金资助

国家自然科学基金青年项目(32301373)

常州市应用基础研究专项一般指导性项目(CJ20241009)