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 Formationlimestone aquifer in Huaibei coalfield, 29 groundwater samples were collected, and the concentrations ofmajor ions and alkaline earth metals (beryllium, barium and strontium) determined. The results show that thegroundwater is alkaline, with the sample pH values between 7.40 and 10.10. The total dissolved solids (TDS) concentrationin the samples was between 123 and 5,520 mg/l. The concentration ranges of Be, Ba and Sr are 0.0001to 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 bycarbonate dissolution, with some ion exchange. The Be content is influenced mainly by pH, while the Sr has thesame source as Ca and Mg. A concentration contour diagram for groundwater TDS and Sr can be used to identifygroundwater runoff conditions. The Zhahe and Suixiao coal-mining districts are the main groundwater rechargeareas, and Linhuan district the discharge area. The Sr/Mg and Sr/Ca ratios are highest where the groundwaterresidence time in the aquifer is longest. The two highest Sr/Ca ratios are 340.1 and 116.6, and occur in theHaizi and Yuanyi coalmines, respectively, suggesting that groundwater residence times are long in them.