The Wudalianchi UNESCO Global Geopark (Northeast China) is famous for its rare cold mineral springs and its associated five hydrologically connected barrier lakes. During this study, strontium (Sr) isotopes (87Sr/86Sr) were studied along with other geochemical data to determine the source of water within the region's deep and shallow mineral springs, shallow wells, and lakes. These waters were characterized by a relatively narrow range of 87Sr/86Sr ratios (0.70648-0.70816). Those ratios were not different in shallow and deep mineral spring waters, and probably reflect ratios associated with potassium volcanic rocks in the area as expected. When combined with 1/Sr ratios, it appears that the shallow mineral springs were derived from upwelling of deep mineral springs and had a composition as an endmember of other waters. Shallow mineral springs and wells exhibited large variations in Cl-/Sr2+ and NO3-/Sr2+ ratios, owing to the input of fertilizers. Farmland runoff and waters from Yaoquan Lake that drains an agricultural area also appear to have been influenced by fertilizers and showed 87Sr/86Sr ratios intermediate between wells and mineral springs. Sewage input is likely responsible for this difference and a slight elevation of the ratios in the wells. The Wudalianchi lakes had similar variations in 87Sr/86Sr and 1/Sr ratios, suggesting their rapid response to terrestrial runoff and the supply of shallow mineral springs. Strontium isotope data can be combined with water chemistry to emphasize water-rock interaction and refine the region's existing model of water interaction in surface and subsurface environments.
Keywords: Anthropogenic activities; Groundwater cycle; Sr isotope; Surface-groundwater interactions; Wudalianchi Region.
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