Hydrochemical characteristics of underground fluid observation wells in ShandongLiyuan Wen, Zhen Jia, Zongbin Guo, Kaixuan Lian, Bingdun Yan, Yi Cao and Qifeng ChenE3S Web Conf., 520 (2024) 01010DOI: https://doi.org/10.1051/e3sconf/202452001010