New Precipitation Method Sampling Procedure of 14C Dating of Groundwater and the Evaluation of the Formerly-obtained 14C Dating Results(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2016年第03期
- Page:
- 387-397
- Research Field:
- 水资源与环境
- Publishing date:
Info
- Title:
- New Precipitation Method Sampling Procedure of 14C Dating of Groundwater and the Evaluation of the Formerly-obtained 14C Dating Results
- Author(s):
- QI Ji-xiang; ZHANG Zhi-gan; PENG Yu-rong; GUO Hua-liang; DUAN Bao-qian
- 1. Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, Hebei, China; 2. Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, Guangxi, China
- Keywords:
- ground water; 14C dating; deviation; atmospheric CO2 pollution; sampling method; measurement method; upper limit of dating; Hebei Plain
- PACS:
- P641
- DOI:
- -
- Abstract:
- The precipitation method sampling procedure of 14C dating of groundwater recommended by IAEA is suffering from atmospheric CO2 pollution. As a result, the dating results tend to be much younger. After analyzing the possible sources of atmospheric CO2 pollution and related influencing factors, a state-of-the-art precipitation method sampling procedure of 14C dating of groundwater was developed to reduce the atmospheric CO2 pollution. This sampling procedure not only integrates various CO2 pollution controlling techniques, but also enjoys easy operation. A specially-designed sample bottle links the field sampling operation and the sample preparing operation effectively. After adopting the new procedure, the negative deviations of the dating results obtained by using benzene-synthesis-liquid-scintillation spectrometer (for the dating results below the upper limit of 50 000 years) are negligible. By comparing the previouslyobtained 14C dating results of ancient groundwater with the results obtained by adopting the new sampling procedure in Hebei Plain, the former exists significant negative deviations. For the groundwater with 14C apparent age of approximately 47×103 years, the dating results tend to be more than 20×103 years younger. Therefore, it is necessary to conduct new evaluations for the formerly-obtained 14C dating results of ancient groundwater and the research conclusions based on the dating results. The new precipitation method sampling procedure of 14C dating of groundwater makes researchers attach importance to the traditional radioactivity measurement method again. Because the sampling quantity is a thousand times more than accelerator mass-spectrometry, it is easier to control the atmospheric CO2 pollution during sample preparation, and the 14C dating results of ancient groundwater are more reliable.
Last Update: 2016-06-02