Hydrogeochemical zoning characteristics of the strontium mineral spring in Xintian county, Hunan Province

Migration and transformation of the strontium element in groundwater in karst hilly regions are affected by the groundwater agent, and its enrichment and zoning characteristics have important hydrogeochemical significance. This paper addresses these issues using an example of a large strontium-rich mineral spring in Hunan Xintian county. Sampling, water chemical composition analysis, and data processing by ArcGIS and AquaChem software permit to reveal the horizontal and vertical zoning characteristics as well as chemical composition and types of this spring. Results show that the strontium element content in the gravity springs has good zoning characteristics, while such characteristics in the motor-pumped wells are not obvious. TDS is basically consistent with the strontium content. The variation coefficients of ions have good consistence in the gravity spring and well. Ca2+ and HCO3 - content are relatively stable, while Sr2+, Mg2+, Na+, SO4 2-, and Cl-concentrations change greatly. The hydrodynamic environments of the springs and motor-pumped wells vary intensively, or the water-bearing rocks are obviously different. The main ion microgram equivalent number in the gravity springs and motor-pumped wells has the same percentage rank, but the vertical variation range is larger. The hydrochemistry components in the wells are primarily influenced by water-bearing rocks and human activities. The hydrochemical type also changes from the single type in the surface karst springs to the well’s complex hydrochemical type, showing the upward geochemical zoning in the vertical direction. The vertical zoning of strontium is abnormal and reaches the maximum at 50-80 m depth.