eng Science and Education Publishing American Journal of Water Resources 2333-4819 2018-04-16 6 2 48 52 10.12691/ajwr-6-2-1 AJWR2018621 article Seyf-Laye Alfa-Sika Mande seyf08@live.com 1 2 3 Mingzhu Liu 3 Ibrahim Tchakala 3 Honghan Chen 3 Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, P.R. China Groundwater is the most important source of water supply in Beijing city. However, groundwater has undergone intensive total hardness pollution caused by water-rock interaction and by human activities. Analysis of monitoring data of 30 years shows that the high concentration of total hardness is relationship with carbonate mineral dissolution and cation exchange. But speciation calculations of two flow path using the hydrogeochemical modeling code PHREEQC indicated that the annual contribution of carbonate dissolution and cation exchange to concentration of Ca2+ and Mg2+ is less than 1 mg?L-1, which was far less than that observed. The results illustrated that carbonate mineral dissolution and cation exchange in aquifers play a small role in the contribution of groundwater chemical evolution, and also imply other anthropogenic sources exist indirectly. http://pubs.sciepub.com/ajwr/6/2/1/ajwr-6-2-1.pdf water-Rock Interaction hardness groundwater water supply pollution