This study, based on fluid sample data from seven wells in the Tangshan region collected in 2018, 2021, and 2025, investigates the geochemical migration characteristics and their relationship with tectonic activity in the area. The analysis employed methods including the examination of well water chemical components and hydrogen-oxygen isotope testing, integrated with the known geological structure of Tangshan. The results indicate:① Temporal and Spatial Trends:Time Dimension: Ion concentrations in each well have remained relatively stable over time. However, \(\text{HCO}_{3^{-}}\) shows a fluctuating downward trend. Space Dimension: The spatial distribution of various ion components is generally consistent. Na+ gradually increases from the southern Luannan region towards the eastern Linxi Well. In 2025, two high-value areas for K+ appeared. High-value zones for Ca2+ are concentrated in northern Tangshan, while those for Mg2+ have shifted northward. High Cl- values are found in Tangshan City and the eastern Linxi mining area. The spatial distribution of SO42− has varied considerably. The maximum value point for HCO3− has migrated northeastward.② Piper Trilinear Diagram Analysis:The Piper diagram reveals that Tangshan well and Linxi Well well water samples are characterized by high Na+ and Cl− concentrations. Yutian well and Fengrun well samples are dominated by Ca2+. The Majiagou well and Luoxian well samples exhibit higher SO42− levels. HCO3− is generally high across all wells and is the dominant ion.③ Na-K-Mg Triangle Diagram Analysis:The Na-K-Mg triangle diagram indicates that the water-rock system in the Tangshan region has not yet reached equilibrium, suggesting that water-rock reactions are still ongoing.④ Hydrogen-Oxygen Isotope and Elevation Effect Analysis:Based on hydrogen-oxygen isotope results and the elevation effect, the primary source of the well water is determined to be atmospheric precipitation. The precipitation recharge rate in the Tangshan region is approximately 29.72%, with the recharge area located in the northern mountainous region of Tangshan.⑤ Impact of the 2020 Tangshan Guye Earthquake:Affected by the magnitude 5.1 earthquake in Tangshan Guye on July 12, 2020, the ion concentrations in the Yutian well and Majiagou well water subsequently exhibited a pattern of first increasing and then decreasing. This change may be related to increased and enhanced fracture connectivity in the aquifer after the earthquake, leading to the mixing of low-temperature water from the overlying layer into the aquifer, thereby altering the water chemistry of these two wells. The measured rise and fall of water levels in the study area wells generally correspond to the regional stress state of compression and tension, further indicating that moderate to strong earthquakes may cause changes in both well water levels and water quality.
