The geochemical (alkaline earth) characteristics of groundwater in the Taiyuan Formation limestone aquifer in Huaibei coalfield

摘要

To understand the characteristics and distribution of alkaline earth elements in groundwater in the Taiyuan Formation limestone aquifer in Huaibei coalfield, 29 groundwater samples were collected, and the concentrations of major ions and alkaline earth metals (beryllium, barium and strontium) determined. The results show that the groundwater is alkaline, with the sample pH values between 7.40 and 10.10. The total dissolved solids (TDS) concentration in the samples was between 123 and 5,520 mg/l. The concentration ranges of Be, Ba and Sr are 0.0001 to 0.03 μg/l, 2.43 to 215.21 μg/l, and 13.08 to 18,168.5 μg/l, respectively. The major ions are mainly controlled by carbonate dissolution, with some ion exchange. The Be content is influenced mainly by pH, while the Sr has the same source as Ca and Mg. A concentration contour diagram for groundwater TDS and Sr can be used to identify groundwater runoff conditions. The Zhahe and Suixiao coal-mining districts are the main groundwater recharge areas, and Linhuan district the discharge area. The Sr/Mg and Sr/Ca ratios are highest where the groundwater residence time in the aquifer is longest. The two highest Sr/Ca ratios are 340.1 and 116.6, and occur in the Haizi and Yuanyi coalmines, respectively, suggesting that groundwater residence times are long in them.