Advances in Earth Science ›› 2023, Vol. 38 ›› Issue (6): 610-618. doi: 10.11867/j.issn.1001-8166.2023.012
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Xumei MAO( ), Xixi ZHA
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Xumei MAO, Xixi ZHA. Novel Method Based Radiogenic 32P for Determining Groundwater Age from 50 to 1000 Years[J]. Advances in Earth Science, 2023, 38(6): 610-618.
Groundwater age is an important and widely used hydrogeological parameter. The environmental isotope method is the most reliable method of groundwater dating. Different environmental isotopic tracers have different dating ranges, and the determination of groundwater age from to 50~1 000 a is the “short board” of dating groundwater. The period of 50~1 000 a is a period of frequent human activity. Therefore, dating groundwater that is 50~1 000 years old is scientifically significant. Silicon-32 (32Si) can be used to determine the age of 50~1 000 a groundwater, but application of 32Si dating is hindered by the complex and time-consuming pretreatment. The decay of 32Si to radiogenic 32P, 32Si, and 32P will reach a radioactive balance within three months and achieve consistent radioactive activity. 32Si and 32P in 50~1 000 a groundwater have been in radioactive equilibrium, so direct enrichment of 32P in groundwater can be used for age determination of 50~1 000 a groundwater. Magnesium hydroxide co-precipitation is used for the enrichment of 32P in groundwater. This method is convenient and rapid. Therefore, 32P is expected to solve the dating deficiency of 50~1 000 a groundwater. The results of 32P dating of groundwater in the Jianghan Plain were roughly consistent with those of 32Si. Therefore, radiogenic 32P groundwater dating is feasible, convenient, and accurate.