中国岩溶2025，Vol.44Issue(1)：38-47,10.DOI:10.11932/karst20250102
基于氚同位素的济南泉域地下水更新能力研究
Research on groundwater renewal capacity in Jinan spring area based on tritium isotopes
摘要
Abstract
The study area is located in Jinan City,Shandong Province,China,and belongs to the inland mid-latitude zone with a temperate monsoon climate.The average annual rainfall is 672 mm,and atmospheric precipitation is the main source of spring water recharge.The overall terrain of Jinan spring area is higher in the south and lower in the north,with the stratum of Archaean Taishan Group as the foundation,covered by the Cambrian and Ordovician strata.The strata incline to the north,forming a monoclinic structure.The karst development is weak.The water bearing medium is dominated by pores and fissures,supplemented by large fissures and pipelines.Groundwater tends to migrate northward along the strata and forms a karst spring group when encountering intrusion rocks from the Yanshan Period in the north.Under natural conditions,spring water is the main discharge form of karst water systems. Due to the intensification of human activities in recent years,the water levels of springs have decreased,and some springs have even cease to flow.In order to explore the groundwater renewal capacity of the Jinan karst spring area and to propose effective recommendations for spring water protection,this paper established a tritium isotope attenuation model for the study area.Previous experiments on mercury intrusion and karst aquifer seepage simulation in the study area have shown that the pore structure of the aquifer in the spring area and the hydraulic characteristics of different aquifer layers exhibit distinct spatial zoning.Moreover,drilling and hydraulic tests conducted in the direct and indirect recharge areas of the spring area have demonstrated that some areas are highly developed with karst fissures.These areas mainly consist of karst fissures and large fissures,which create advantageous seepage channels.Therefore,groundwater can be divided into karst water from karst fissures and large fissures and water from karst fissures and pores based on the characteristics of the medium in which groundwater is located.The piston flow model(PFM)is applicable to groundwater where the aquifer medium is predominantly composed of karst fissures and large fissures.In contrast,the entirely mixed flow model(EM)is suitable for groundwater where the aquifer medium is primarily characterized by a combination of fissures and pores.Since these two models cannot simultaneously account for the hydrogeological characteristics of the study area,this study proposes a new piston flow-entirely mixed flow model(PFM-EM)to facilitate a more accurate analysis of spring water renewal time. The model results show as follows:(1)The age of groundwater in the Cambrian Period ranges from 22 to 85 years,while the age of groundwater in the Ordovician Period ranges from 3 to 22 years.Additionally,and the annual water age of Baotu Spring is 15 years.When combined with previous EM model data,it is evident that the age of spring water gradually decreased during the abundant water period from 1989 to 2022.The decrease in the age of spring water indicates a gradual shift in the supply of spring water towards shallower strata.More importantly,it reflects an increased sensitivity in the response time of spring water to external influences.As urban built-up areas continue to expand,the hardening of urban surfaces has resulted in a reduction in the infiltration area of precipitation.To maintain a continuous flow of spring water,it is essential to limit the extraction of Ordovician karst water while simultaneously replenishing groundwater sources.(2)The age of groundwater increases with the depth of the aquifer,indicating that spring water is supplied by different water-bearing rock formations of the Cambrian and Ordovician strata.Given that the groundwater renewal capacity of the Cambrian strata is relatively limited and they exist within an open system,atmospheric precipitation and human activities directly or indirectly affect the deep aquifers.Therefore,it is also advisable to avoid intensive exploitation of the Cambrian aquifers to prevent a reduction in the proportion of deep Cambrian groundwater contributing to spring water replenishment.While the existing replenishment effects have yielded some positive results,it remains essential to continue replenishing groundwater.Furthermore,the regular monitoring of water sources should be conducted in the spring replenishment area to prevent contamination of groundwater and spring water by surface sewage.关键词
岩溶泉域/氚浓度/衰减模型/地下水年龄/循环特征Key words
karst spring area/tritium concentration/attenuation model/age of groundwater/cycle feature分类
地质学引用本文复制引用
孟庆晗,邢立亭,彭凯,朱文峰,刘连,何强,徐冰,潘潍艳,宋其峰..基于氚同位素的济南泉域地下水更新能力研究[J].中国岩溶,2025,44(1):38-47,10.基金项目
国家自然科学基金项目(42272288,42307083) （42272288,42307083）
山东省第一地质矿产勘查院青年科技创新基金(QN202203) （QN202203）
