NGHIÊN CỨU ĐÁNH GIÁ TƯƠNG QUAN GIỮA HOẠT ĐỘ 14C VÀ HOẠT ĐỘ URANI TRONG MẪU NƯỚC DƯỚI ĐẤT TẠI ĐỒNG BẰNG NAM BỘ

Abstract

This study was conducted to investigate ¹⁴C activity and uranium isotope activities in six groundwater samples taken from six aquifers at Q602 station in Tien Giang, to evaluate the correlation between ¹⁴C activity and uranium activity in groundwater samples, thereby evaluating the applicability of ²³⁸U and ²³⁴U isotopes in determining the age of groundwater in Nambo Plain. Dissolved uranium in samples was extracted by ion exchange method, using C100 cation resin, and then measured ²³⁸U and ²³⁴U isotopic activities by alpha spectrometer system. The ¹⁴C radioactive isotope in samples was analyzed by a low-background liquid scintillation spectrometer after converting dissolved inorganic carbon in the samples to benzene. The results show that: 1) the ²³⁸U activity was from 0,970-6,771 mBq/L, and the ²³⁴U activity was from 1,250-13,461 mBq/L, in which qp₁ aquifer has the highest value. 2) In samples from Pleistocene aquifers, the correlation between ¹⁴C activity and depth, between ¹⁴C activity and the ²³⁸U or ²³⁴U activity are all negative. 3) In samples from Pliocene aquifers, the correlation between ¹⁴C activity and depth is also negative, while the correlation between ¹⁴C activity and the ²³⁸U or ²³⁴U activity are both positive.