Potentially toxic elements determination and chemical-microbiological analysis of potable water in Taxco de Alarcon, Guerrero

Taxco de Alarcon is an important mining site in Mexico. The town is a well-known tourist destination where the potable water quality is important for guaranteeing the health of the users. Due to the altitude of the city, the surface and rain water are the main sources of water. Thus, the aims of this study were to characterize i) the composition and chemical speciation of particulate matter suspended in water to determine the content of potentially toxic elements, and ii) the chemical and bacteriological composition of the potable water of Taxco de Alarcon, Guerrero, Mexico, according to the Mexican official norm NOM-127-SSA1-1994. The analyzed representative samples were taken from the municipal water distribution network, the water treatment plant, the Chacuhalco spring and a mixture of the waters of the Chontalcuatlin river, the Teneria spring, and the San Marcos and El Sombrerito dams. According to the results, 94 % of the analyzed samples did not comply with the standard NOM-127-SSA1-1994.Moreover, the distribution of the analyzed elements in the different chemical fractions of the particulate matter showed that the highest concentration of Cd (4.17 mg.kg(-1)) is associated with the carbonate fraction. This means Cd is moderately bioavailable. On the other hand, the highest concentrations of Pb, Zn, Mn and Cu (62.2, 42.3, 243 and 1026 mg.kg(-1), respectively) were detected in the Fe-Mn oxyhydroxide fraction, also considered as moderately bioavailable, whereas the highest concentrations of As, Fe and V (24.0, 7583 and 31.3 mg.kg(-1), respectively) were associated with the residual fraction, considered as non-bioavailable. The results indicate that, to improve the quality of potable water, modifications must be incorporated along the water treatment processes, and in the distribution network and management.