北京市岩溶地下水质量评价及其生态环境效应

郭高轩; 代垠东; 许亮; 朱琳; 戚琦; 欧志亮; 沈媛媛

doi:10.12029/gc20230423001

北京市岩溶地下水质量评价及其生态环境效应

Assessment of karst groundwater quality and its ecological environmental effects in Beijing

摘要

摘要:
研究目的 岩溶地下水是北京市重要的供水水源，在城市供水安全保障中发挥着难以替代的作用，同时又具有重要的生态功能。
研究方法 本文以2021年6月在北京市系统采集的278件岩溶地下水样化验数据为基础，以岩溶水系统为单元，开展了岩溶水单因子质量评价和综合质量评价，并首次对有机指标进行了统计和分析。
研究结果 （1）北京市岩溶水的pH、TDS和TH平均值分别为7.69、334.77 mg/L和262.01 mg/L，具有弱碱性、低盐度和低硬度的特点，地下水质量总体良好。（2）非常规指标的检出率从大到小为：苯并a芘（4.32%）、三溴甲烷（3.60%）和二甲苯（总量）（2.52%），应当引起足够重视。（3）北京市岩溶水水质Ⅰ~Ⅲ类总占比为82.01%，Ⅳ和Ⅴ类总占比为17.99%，超标点主要集中在山区与平原分界线处，超标指标主要有Fe、TH、NH₃−N、Mn、SO₄²⁻、F⁻、NO₃−N等。
结论北京市生态涵养区是重要的水源补给区和生态保护区，区内岩溶水对于保障首都供水安全和保护生态环境具有重要意义，今后应通过提高植被覆盖率加强水源涵养以增加补给量，应严格控制点源和面源污染减少污染物输入，持续优化监测网络进行预警，广泛宣传增强公众生态环保意识，共同保护岩溶水的生态环境。

Abstract:
This paper presents the results of hydrogeological survey engineering.
Objective As an important water supply source in Beijing, karst groundwater plays an irreplaceable role in the security of the urban water supply and the improvement of the ecological environment.
Methods Based on the analysis of 278 karst groundwater samples systematically collected in Beijing in June 2021, both single-factor quality evaluation and comprehensive quality evaluation of karst water were carried out in different karst water systems. Additionally, the organic indicators were statistically counted and analyzed for the first time.
Results (1) The average values of pH, TDS, and TH of karst water in Beijing are 7.69, 334.77 mg/L, and 262.01 mg/L, respectively. These results indicate that the groundwater is weakly alkaline, with low salinity and low hardness, suggesting generally good water quality. (2) The detection rates for unconventional indicators, in descending order, were benzoapyrene (4.32%), tribromomethane (3.60%), and total xylene (2.52%). These contaminants warrant significant attention. (3) The results of groundwater quality evaluation show that the overall proportion of karst water quality falling within Classes I−III is 82.01%, while Classes IV and V constitute 17.99%. The exceedance points are primarily located at the interface between mountainous and plain areas, with the primary exceedance indicators being Fe, TH, NH₃-N, Mn, SO₄²⁻, F⁻, and NO₃-N.
Conclusions As the important water source supply area and ecological protection zone in Beijing's ecological conservation area, karst groundwater in the study area plays a very important role for ensuring the safety of the capital's water supply and protecting the ecological environment. In the future, to practically protect karst groundwater, measures such as increasing vegetation cover to enhance water conservation and recharge capacity, strictly controlling point source and non-point source pollution to reduce pollutant inputs, continuously optimizing the monitoring network for early warning, and broadly promoting public awareness and education on ecological protection should be implemented systematically.

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