Citation: Ramírez-Javier, J.C.; Ramírez-Guzmán, A.H.; Hernández-Flores, G.; Hernández Hernández, M.A.; Talavera-Mendoza, O.; Salgado Souto, S.A.; Cortés-Silva, A. Heavy Metal Dispersion in a Hydrological Sub-Basin as Consequence of Mining Activity in Taxco, Guerrero (Southern Mexico). Water 2023, 15, 1950. https:// doi.org/10.3390/w15101950 Academic Editor: Lahcen Zouhri Received: 4 April 2023 Revised: 28 April 2023 Accepted: 18 May 2023 Published: 21 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). water Article Heavy Metal Dispersion in a Hydrological Sub-Basin as Consequence of Mining Activity in Taxco, Guerrero (Southern Mexico) Juan Carlos Ramírez-Javier 1 , Alejandro Hermelindo Ramírez-Guzmán 2, *, Giovanni Hernández-Flores 3, * , Mario Alberto Hernández Hernández 4 , Oscar Talavera-Mendoza 2 , Sergio Adrián Salgado Souto 2 and Alejandra Cortés-Silva 5 1 Facultad de Ecología Marina, Universidad Autónoma de Guerrero,Av. Gran Vía Tropical No. 20, Fracc. Las Playas, Acapulco 39390, Mexico 2 Escuela Superior de Ciencias de la Tierra, Universidad Autónoma de Guerrero, Ex hacienda de San Juan Bautista s/n, Taxco de Alarcón 40323, Mexico 3 CONACYT-Escuela Superior de Ciencias de la Tierra, Universidad Autónoma de Guerrero, Ex Hacienda San Juan Bautista s/n, Taxco de Alarcón 40323, Mexico 4 CONACYT-Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Delegación Coyoacán, Ciudad de México 04510, Mexico 5 Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Delegación Coyoacán, Ciudad de México 04510, Mexico * Correspondence: halessandro2@hotmail.com (A.H.R.-G.); ghernandez@conacyt.mx (G.H.-F.) Abstract: The mining industry generates high concentrations of heavy metals (HMs) susceptible to being released into surface and ground water. The objective of this work was to determine the concentration and dispersion of HMs in surface water and ground water in a hydrological sub-basin located in southwest Mexico. The samples were collected as following: 24 samples from streams, rivers, and one lake, and 15 samples from springs, located along the Taxco-Cocula sub-basin. A total of 78 samples were collected in the dry and rainy seasons. Physicochemical parameters, major ions, and HMs were analyzed. The pH, Eh, electrical conductivity, and total dissolved solids were analyzed in situ, while the concentrations of anions, cations, and HMs were measured in the laboratory. The results were treated with multivariate analysis and PHREEQC simulation. The highest recorded values (in mg/L) were in surface water, where the HMs in the dry season were Al (28.63), As (0.60), Cd (1.78), Cu (1.10), Fe (68.27), Mn (21.47), Pb (0.02), and Zn (208.80). These high concentrations exceed the limits established by national and international regulations for drinking water. The ground water did not indicate pollutants associated to the mining industry. On the other hand, in the rainy season, the surface water showed a decrease in the concentrations of the measured heavy metals. The hypsometric gradient and the hydrogeological and meteorological characteristics of the Taxco-Cocula sub-basin are the factors that contribute to the dilution and dispersion of the HMs along the 60 km of its length. Keywords: ground water; hydrogeochemistry; mining waste; surface water; Taxco mining district; water quality 1. Introduction Mining activity is an essential activity around the world. However, it is also an important source of hazardous pollutants, such as heavy metals (HMs), Pb, Cd, As, Sb, Cr, and Zn among others, which are non-biodegradable and difficult to remove. These pollutants can be incorporated into natural resources, such as water, soil, air, flora, and fauna [1–4]. Water plays a key role in the dispersion of HMs. It is considered to be a “transporting agent”, one of the most effective ways to disperse dissolved or non-dissolved materials in surface and ground water [5]. Through consumption of contaminated water in the food chain, Water 2023, 15, 1950. https://doi.org/10.3390/w15101950 https://www.mdpi.com/journal/water