GEOCHEMICAL REACTIVE TRANSPORT MODELING IN CONTAMINATED AQUIFERS, BEIJING AREA, CHINA ALFA-SIKA MANDE SEYF-LAYE 1,2,3* , TCHAKALA IBRAHIM 2 , DJANEYE-BOUNDJOU GBANDI 2 AND HONGHAN CHEN 1 1 Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, P.R. China 2 Water Chemistry Laboratory, Faculty of Science, University of Lome, BP. 1515, Togo, West Africa 3 Faculty of Science and Technology, University of Kara, BP. 404, Togo, West Africa (Received 19 October, 2016; accepted 19 June, 2017) Key words: Geochemical, PHT3D, Modeling, Nitrate, Transport ABSTRACT Water supplies, which are vital to economic development, are severely at risk through pollution. Problems relating to water are more serious for some countries, such as China, where water is relatively scarce. A three-dimensional multicomponent reactive transport model was developed to predict the future development of groundwater quality in aquifers in and around Beijing. PHT3D, which combines the three-dimensional transport simulator MT3DMS with the geochemical model PHREEQC-2, was used as the model code. The model results showed that although nitrate in the groundwater was partially reduced by denitrifcation, nitrate was still present in excessive levels. The coupled model was able to quantify the infuence of various land-use functions on groundwater quality, and it could identify the geochemical processes taking place in the aquifers. Finally, a novel conceptual model for an urban area that can be used to evaluate future site-remediation scenarios was developed as part of this study. Jr. of Industrial Pollution Control 33(1)(2017) pp 1085-1097 www.icontrolpollution.com Research Article *Corresponding authors email: seyf08@live.com INTRODUCTION Computer modeling and simulation are frequently applied to predict water movement and contamination migration in surface-water and groundwater regimes as well as to analyze the interaction between these two water sources. Groundwater simulation is more problematic than surface-water simulation; this is because subsurface monitoring of water and tracking the movements and hidden sources of water and various contaminants is a more complicated process. Modeling has long been used for groundwater investigation because of the diffculties involved with direct assessment and monitoring of underground reservoirs. Modeling methods have been shown to be reliable in determining groundwater fow and the transport of contaminants by means of mathematical equations based on certain simplifying assumptions (Kumar, 2007). The general lack of knowledge about historical source terms, the high cost of feld investigations, and the limited data density relative to the heterogeneity of the subsurface make it diffcult to determine reliably the risks from subsurface contaminants. In the present study, the MODFLOW/MT3DMS-based multicomponent reactive transport model PHT3D (Prommer, et al., 2003) was used to interpret the geochemical fngerprint produced by subsurface contamination and also to determine the history of such contamination. Analysis of the historical data provides an important insight into whether the