Geochemistry - Interdisciplinary Journal for Chemical Problems of the Geosciences and Geoecology xxx (xxxx) xxx Please cite this article as: Priyadarsi D. Roy, Geochemistry - Interdisciplinary Journal for Chemical Problems of the Geosciences and Geoecology, https://doi.org/10.1016/j.chemer.2021.125742 Available online 23 January 2021 0009-2819/© 2021 Elsevier GmbH. All rights reserved. Identifcation of sources and groundwater recharge zones from hydrochemistry and stable isotopes of an agriculture-based paleo-lacustrine basin of drought-prone northeast Mexico Priyadarsi D. Roy a, *, S. Selvam b , S. Venkatramanan c , Natarajan Logesh d , Chokkalingam Lakshumanan d , Jos´ e L. S´ anchez-Zavala a a Instituto de Geología, Universidad Nacional Aut´ onoma de M´ exico, Ciudad Universitaria, Ciudad de M´ exico, CP 04510, Mexico b Department of Geology, V.O. Chidambaram College, Tuticorin, Tamil Nadu, India c Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Viet Nam d Centre for Disaster Management and Coastal Research, Department of Remote Sensing, Bharathidasan University, Tiruchirappalli, 620023, India A R T I C L E INFO Handling Editor: M Barbieri Keywords: Shallow groundwater Hydrogen and oxygen isotope Mineral saturation index Hydrogeochemical process PHREEQC Semi-arid Mexico ABSTRACT Over exploitation for agricultural activities and consumption has depleted the groundwater resources of drought- prone northeast Mexico. Major ion concentrations along with δ 18 O H2O , δ 2 H H2O and d-excess values of shallow groundwater from the Cieneguilla Basin (near Tula) located at a distance of ~200 km from coast of the Gulf of Mexico helped to contribute new data about drought vulnerability in this region through identifcation of the moisture source and groundwater recharge zone. Different degrees of rock-water interaction through gypsum, anhydrite and halite dissolutions and minor silicate weathering controlled the hydrochemistry. Stable isotopes yielded a least square regression and slope similar to the local as well as global meteoric water lines, indicating minimal effect of evaporation during the recharge as well as in the subsoil. Isotopic fractionations along with a digital elevation model demarcated the recharge zones at north and east of the basin, with altitudinal difference of ≥1000 m, and indicated that the recharge occurred through warm season moisture sourced from the Gulf of Mexico. Less frequent landfalling of tropical storms caused by warmer sea surface temperature, however, has reduced this rainfall over the last few decades. If the trend of global warming continues unabated, the depleted groundwater resources would trigger reduction in agricultural activities in this drought-prone region and lead to enhanced socio-economic challenges. 1. Introduction In arid and semi-arid regions, the groundwater has been increasingly used for domestic, agricultural and industrial requirements, both in the rural and urban areas (Zaidi et al., 2015; Reyes-G´ omez et al., 2017). Over exploitation from growing population and the effects of anthro- pogenic global warming through higher temperature and reduced rainfall, however, create challenges to sustainability of this resource (e. g. Christensen et al., 2007; S´ aenz-Romero et al., 2010; Cavazos et al., 2013). The northeastern Mexico has always been drought prone and the tree ring registers show at least 18 different drought events over the last six centuries, some of them with over two decades of duration (Villa- nueva-Diaz et al., 2007; Stahle et al., 2016). Paleoclimate records have suggested continuance of aridifcation since the late Holocene, and increase in the abundance of desert shrubs and enhanced aeolian ac- tivity in surroundings of the paleo-lacustrine basins were due to more frequent El Ni˜ no Southern Oscillation (ENSO) and modifcation in tra- jectories of tropical storms from the Atlantic Ocean and Gulf of Mexico (e.g. Roy et al., 2013, 2019, 2020). Climate models project a tendency towards reduction in rainfall over the next century due to unabated greenhouse emissions and warmer ocean (Cai et al., 2015; Zhu et al., 2015; Cheng et al., 2016). Less amounts of rainfall along with warmer conditions would further aggravate the stress on limited water resources of this drought-prone region and Nawrotski et al. (2015) suggested that the adverse effects of climate change might cause more migration of rural population employed in the agricultural sectors. Feng et al. (2010) proposed that about 48 % of declined agricultural yield by the end of 21 st century would be forcing more than 6 million adult Mexicans to * Corresponding author. E-mail address: roy@geologia.unam.mx (P.D. Roy). Contents lists available at ScienceDirect Geochemistry journal homepage: www.elsevier.com/locate/chemer https://doi.org/10.1016/j.chemer.2021.125742 Received 8 September 2020; Received in revised form 25 December 2020; Accepted 18 January 2021