放射性同位素^(14)C测年在岩溶地下水中的应用及研究进展

Application and Research Development of Radioisotope ^(14)C Dating in Karst Groundwater

放射性同位素^(14)C测年是获取岩溶地下水水文地质参数,探索岩溶地下水运移状态,评价其可持续利用的重要手段。搜集已公开发表的放射性同位素^(14)C文献资料和相关研究实例,对其主要来源、循环过程、测年原理、分析方法以及在岩溶地下水研究中的应用等内容进行系统论述。研究表明,目前放射性同位素^(14)C主要用于测定岩溶地下水年龄,通过地下水年龄分布和不同来源的同位素占比,科学识别地下水补给源、估算地下水补给速率、合理评估地下水的更新能力等,再现岩溶地下水运动过程,进而计算运移过程中同位素交换率,判断发生的岩溶作用程度,可示踪地下污染来源,揭示地下水污染质的迁移规律,可为水资源利用和环境评价提供关键性的依据。然而,在使用放射性同位素^(14)C测年的过程中,仍存在样品采集、处理流程不规范,仪器精度有限、测试价格昂贵、检测结果波动性大等问题。^(14)C测年范围有限,作为示踪剂指示作用单一,无法测定出过于“年轻”或者“古老”的岩溶地下水年龄。此外,地下水的运动过程中自然成因的“死碳”混入和人为因素的干扰也会造成测年结果的偏差,现有的校正模型暂时无法解决该问题,相关理论也缺乏研究,这给实际应用和进一步发展造成一定的困扰。该文指出放射性同位素^(14)C测年在未来仍需加强理论的研究,规范样品采集、处理流程,注重测试技术的开发,以解决“死碳”混入和人为因素的干扰造成的测年结果的偏差,多种示踪剂联合使用,提高测年精度和广度。

Radioisotope ^(14)C dating is an important means to obtain hydrogeological parameters of karst groundwater,explore its migration state of karst and evaluate its sustainable utilization.This paper collects the published documents and relevant case studies of radioisotope ^(14)C,and systematically discusses its main sources,cycle process,dating principle,analysis method and application in karst groundwater research.The research shows that the method is mainly used to determine the age of karst groundwater,scientifically identify the groundwater recharge source,estimate the groundwater recharge rate,reasonably assess the renewal capacity of groundwater,etc.,through the age distribution of groundwater and the proportion of isotopes from different sources.As a result,the migration process of karst groundwater can be reproduced,and the isotope exchange rate during the migration can be calculated.Determination of the degree of karst action can help trace the source of underground pollution and reveal the migration law of groundwater pollution,which can provide key evidence for water resources utilization and environment assessment.However,during the application of radioisotope ^(14)C dating,problems such as non-standard sample collection and processing process,expensive testing,time-consuming and labor-intensive testing,and large fluctuation of detection results still exist.Moreover,the range of radioisotope ^(14)C dating is quite limited,and has a single function as a tracer.In addition,the mix of“dead carbon”generated naturally in the process of groundwater migration and the interference of human factors also cause the deviation of dating results.The existing theoretical and technical research cannot solve these problems yet,which will cause certain confusions for practical application and further development of the method.This paper summarizes the above problems,points out that in the future,theoretical research of radioisotope ^(14)C dating still needs to be strengthened,sample collection and processing process need to be standardized,and the development of testing technology needs to be focused to solve the deviation of dating results caused by the mixing of“dead carbon”and interferences of human factors.The combined use of multiple tracers can improve the accuracy and breadth of dating,which is helpful to solve many problems in the application of radioisotope ^(14)C dating in karst groundwater research and provide references for future research.