Vol.:(0123456789) 1 3 Environmental Earth Sciences (2020) 79:433 https://doi.org/10.1007/s12665-020-09164-3 ORIGINAL ARTICLE Assessment of nitrate and heavy metal contamination of groundwater using the heavy metal pollution index: case study of Linares, Mexico Héctor de León‑Gómez 1  · Miguel A. Martin del Campo‑Delgado 1  · María V. Esteller‑Alberich 2  · Fernando Velasco‑Tapia 3  · Efraín Alva‑Niño 3  · Arquímedes Cruz‑López 1 Received: 9 March 2020 / Accepted: 3 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Groundwater contamination is a signifcant problem in Mexico and around the world. It can be infuenced by both natural and anthropogenic factors. In Linares, Mexico, we identifed several wells used to cover the water demand for diferent human activities with nearby potential sources of contamination, including urban, agricultural, and livestock activities, electrical and electronic waste disposal, and fuel storage tanks. We then explored groundwater contamination herein as a result of anthropogenic activities as well as the hydrodynamics of the porous and fractured aquifers in the region based on physiochemical analyses of water samples and the heavy metal pollution index (HPI). The fractured aquifer is composed of shales with a thickness of 70–400 m, while the porous aquifer is composed mainly of gravels, sands, silt, and moderately cemented clays with a thickness of 5 m. The groundwater level is on average 20 m deep, and the fow direction is west to east. The identifed water facies are mainly Ca–HCO 3 type, originating from the dissolution of diverse carbonated materi‑ als in the area. It was also possible to identify the mixing of groundwater and water infuenced by various agricultural and livestock activities, including the use of pesticides and fertilizers and the direct deposition of cattle excreta. The average nitrate concentration of the sampled wells was 80 mg/L, higher than the permissible limit set by the WHO and Mexican standards. The calculated HPI value was 470, well above the critical value of 100, mostly due to the presence of Cd, which is likely associated with the storage of electrical and electronic waste and fuel tanks in the area. These results show that the water wells sampled in Linares, Mexico, without further treatment, are unsuitable for human use. It is important to continue to monitor the contamination of groundwater by heavy metals in diferent areas of Mexico and to identify potential sources of contamination to create mitigation strategies and ensure the safety and sustainability of water resources in the future. Keywords Fractured aquifer · Contamination · Nitrates · Heavy metals · HPI Introduction Groundwater is intensively used because of its relative abundance, low cost, and ease of collection, transport, and use. However, human activities have greatly impacted water resources, resulting in a decrease in both the quantity and quality of surface water and groundwater, especially in areas dedicated to agricultural and livestock activities (Fet‑ ter 2001). Groundwater quality is mainly determined by the chemical and mineral composition of aquifer rocks, geo‑ chemical processes, residence time, and other factors related to groundwater fow in addition to efuents or wastes from human activities (Purushotham et al. 2017). Frequently, hydrogeological studies focus on the amount of available water. However, one of the main problems surrounding the use of groundwater, aside from * Héctor de León‑Gómez hector.deleongm@uanl.edu.mx 1 Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León (UANL), San Nicolás de Los Garza, Av. Universidad S/N, Ciudad Universitaria, 66455 San Nicolás de los Garza, Nuevo León, México 2 Instituto Interamericano de Tecnología y Ciencias del Agua (IITCA), Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca km. 14.5 San Cayetano Morelos, 50120 Toluca, México 3 Facultad de Ciencias de la Tierra, Universidad Autónoma de Nuevo León (UANL), Carretera a Cerro Prieto km. 8, Ex Hacienda de Guadalupe, 67700 Linares, NL, México