Trace elements and environmental isotopes as tracers of surface water–groundwater interaction: a case study at Xin’an karst water system, Shanxi Province, Northern China

Abstract

In this case study, silica concentration, oxygen and strontium isotopes of water samples were used to study surface water–groundwater interaction at the Xin’an karst water system. The silica concentration in rain water is commonly less than 1 mg/l. In the areas around the south tributary of the Zhuozhang River, silica concentrations in the groundwater in Quaternary aquifers range between 4.04 and 7.66 mg/l while that of the surface water varies from 1.49 to 6.9 mg/l. Silica concentrations of most surface water samples increase with TDS, indicating the effect of groundwater recharge on river water chemistry. On the contour map of silica concentration of groundwater in Quaternary aquifers, samples located close to surface water often have lower silica concentrations as a result of surface water recharge. Both overland flow and surface water have impact on karst water according to our hydrogeochemical study of stable oxygen isotope, Sr isotope and strontium contents. Calculation results of three end member mixing model show that the contribution of karst water, surface water and overland flow water is 45, 28 and 27%, respectively.