Groundwater From Abandoned Mines of the Partizansk Coal Basin, Primorye: Isotope-Geochemical Features of Composition and Regularities of Formation

The underground waters from the abandoned mines of the Partizansk coal basin were subjected to isotope-geochemical study to investigate their compositional features and regularities of their formation. The study has shown that flooding of the mines caused origin in the natural and industrial structures of a succession of water solutions with changeable composition: HCO₃-Ca→HCO₃-Mg→HCO₃-Na→HCO₃-SO₄-Na→SO₄-Na. The sulfur variability here is conditioned by the amount and level of oxidation of pyrite inherent in coals, bacterial component is important as well. The natural and industrial structures under consideration demonstrate zonality of geochemical conditions. Deeper horizons are the place where aerobic systems transit into anaerobic ones, and predominantly deoxidizing environment stimulates generation of biochemical natural gases, such as CH₄, H₂S, CO₂, and H₂. It has been established also that transformation of groundwater composition influences the rare-earths behavior; distribution of the dissolved REE depends on the water type and is controlled by the water-rock interaction processes and equilibrium – non-equilibrium state. Mineralization of the waters under study correlates with δ¹O and δD parameters, and variation of their values can be used for estimation of the water-rock interaction degree.