Genetic model of strontium-rich mineral waters in Guinan, Qinghai Province revealed by hydrochemistry and isotope

The scientific and efficient exploration of natural mineral water resources in the upper reaches of the Yellow River conservation area is of strategic importance for promoting high-quality development of the Yellow River Basin, supporting Qinghai’s “Four Zones” construction, and advancing rural revitalization. This study investigates strontium-rich mineral water in the Guinan area of Qinghai using hydrochemical and isotopic methods to analyze its chemical characteristics, formation processes, and development potential. The results show that the strontium (Sr) concentration ranges from 0.42 to 1.15 mg/L, and total dissolved solids (TDS) range from 272.63 to 686.04 mg/L in the natural mineral water of the study area. The dominant hydrochemical facies are HCO3-Ca and HCO3-Ca-Na, indicating low-mineralization, strontium-type mineral water. The recharge source is atmospheric precipitation (δ18O: –10.94‰ to –9.33‰), with a recharge age dating to the Holocene (14C age: 5.31 ka B.P.). The primary strontium sources are Triassic feldspathic sandstones (Sr abundance: 0.585‰ to 1.790‰) and Quaternary sediments derived from these rocks. Water-rock interaction is the main mechanism of strontium enrichment. The Sr concentration increase progressively from 0.41 to 0.86 mg/L along the groundwater flow path, reflecting a transport pattern of “bedrock fissure water-unconfined pore water in loose rocks-confined pore water in loose rocks”. Two enrichment mechanisms are identified: shallow-cycle fissure leaching and recharge-driven burial accumulation. Preliminary estimates suggest that the region contains 6.09×104 m3/day of natural strontium-type mineral water, of which 1.13×104 m3/day is exploitable. With high quality and abundant reserves, this water source has strong potential for development as both a premium urban water supply and a large-scale bottled mineral water resource. The findings provide a scientific foundation for the sustainable utilization of high-quality groundwater resources in the upper Yellow River region.