The Mezquital Valley system is the world's oldest and largest example with regard to use of untreated wastewater for agricultural irrigation. Because of the artificial high recharge associated with the Mezquital Valley aquifers, groundwater is extracted for human consumption, and there are plans to use this groundwater as a water resource for Mexico City. Thus, this study analyzed 218 organic micro-contaminants in wastewater, springs, and groundwater from Mezquital Valley. Five volatile organic compounds (VOCs) and nine semi-volatile organic compounds (SVOCs) were detected in the wastewater used for irrigation. Only two SVOCs [bis-2-(ethylhexyl) phthalate and dibutyl phthalate] were detected in all the wastewater canals and groundwater sources, whereas no VOCs were detected in groundwater and springs. Of the 118 pharmaceutically active compounds (PhACs) and 7 reproductive hormones measured, 65 PhACs and 3 hormones were detected in the wastewater. Of these, metformin, caffeine, and acetaminophen account for almost sixty percent of the total PhACs in wastewater. Nevertheless, 23 PhACs were detected in groundwater sources, where the majority of these compounds have low detection frequencies. The PhACs sulfamethoxazole, N,N-diethyl-meta-toluamide, carbamazepine, and benzoylecgonine (primary cocaine metabolite) were frequently detected in groundwater, suggesting that although the soils act as a filter adsorbing and degrading the majority of the organic pollutant content in wastewater, these PhACs still reach the aquifer. Therefore, the presence of these PhACs, together with the high levels of the endocrine disruptor bis-2-(ethylhexyl) phthalate, indicate that water sources derived from the recharge of the studied aquifers may pose a risk to consumer health.

No abstract

We analyzed two contrasting catchments located among the world's largest unspoiled tropical rainforests impacted by mining in the northeastern coastlands of South America. We used the following: (a) mining, agricultural, and urbanized areas to compare the land use evolution with suspended sediments and sediment yields; (b) field monthly river suspended sediments in the two catchments (2004–2015: n = 154); (c) MODIS remote sensing water color technique in the Maroni basin to complete (n = 387) and extend field suspended sediment sampling from 2000 to 2015; (d) hydroclimatic statistical analysis conditions and sediment concentrations to identify the long‐term trends, the abrupt changes in time series and to analyze if the environmental and anthropogenic factors control sediment yield regional variations. No significant long‐term changes were observed in precipitation or water discharge with the Mann–Kendall test. However, the mean suspended sediment concentration has increased significantly (239%) in the Maroni River with a breakpoint in 2009 and decreased (33%) in the Oyapock River (breakpoint in 2008). These differences are explained by the larger percentage of deforestation because of mining activities in the Maroni (0.37%) than in the Oyapock (0.06%) catchment. In the Maroni River, the increasing sediment yield trend (2000–2015) coincide significantly (r2 = 0.97; p < 0.0001) with the increase of 400% of mining areas, whereas no significant relationship with the runoff was found. In the Oyapock River, the runoff explains the sediment yield decreasing trend (r2 = 0.82; p < 0.0001) and no relationship with the land use change was found.

No abstract

No abstract

No abstract

The Monterrey metropolitan area (MMA) is the third greatest urban area and the second largest economic city of Mexico. More than four million people living in this megacity use groundwater for drinking, industrial and household purposes. Thus, major ion and trace element content were assessed in order to investigate the main hydrochemical properties of groundwater and determine if groundwater of the area poses a threat to the MMA population. Hierarchical cluster analysis using all the groundwater chemical data showed five groups of water. The first two groups were classified as recharge waters (Ca-HCO3) coming from the foothills of mountain belts. The third group was also of Ca-HCO3 water type flowing through lutites and limestones. Transition zone waters of group four (Ca-HCO3-SO4) flow through the valley of Monterrey, whereas discharge waters of group 5 (Ca-SO4) were found toward the north and northeast of the MMA. Principal component analysis performed in groundwater data indicates four principal components (PCs). PC1 included major ions Si, Co, Se, and Zn, suggesting that these are derived by rock weathering. Other trace elements such as As, Mo, Mn, and U are coupled in PC2 because they show redox-sensitive properties. PC3 indicates that Pb and Cu could be the less mobile elements in groundwater. Although groundwater supplied to MMA showed a high-quality, high mineralized waters of group 5 have NO3 − concentrations higher than the maximum value proposed by international guidelines and SO4 2−, NO3 −, and total dissolved solid concentrations higher than the maximum levels allowed by the Mexican normative.

Palabras clave: minería, mercurio, Sudamérica, contaminación RESUMENEn este estudio se determinaron las concentraciones de Al, Co, Cu, Fe, Hg, Ni, Mn, Pb y Zn en muestras de sedimentos de fondo del río Puyango y de algunos de sus tributarios con el objeto de conocer los factores de enriquecimiento de estos elementos en los sedimentos. Las muestras de sedimento fueron sometidas a digestión ácida utilizando el método EPA 3050B, para luego ser analizadas por espectrofotometría de absorción atómica. Las muestras para el análisis de Hg total fueron digeridas con una mezcla de HNO 3 , HCl y KMNO 4 y determinadas con la técnica de arrastre de vapor frío. Las mayores concentraciones de metales pesados fueron encontradas en los sedimentos colectados en el sector localizado después de la confluencia entre los ríos Calera y Amarillo. Los altos niveles de metales pesados y las bajas concentraciones de Al en los sedimentos de este sector indican que estos últimos están compuestos principalmente de mineral polimetálico, el cual ha sido descargado por las plantas procesadoras de mineral después del proceso de extracción de oro. Los sedimentos de las secciones media y baja del río Puyango se encuentran severamente contaminados con los elementos Hg, Cu, Pb, Zn y Mn, así como moderadamente contaminados con Co y Fe. Las altas concentraciones de Hg, Cu, Pb, Zn, Mn y Fe en los sedimentos de estos ríos pueden tener un efecto adverso para la biota acuática, de acuerdo con los criterios establecidos en normas internacionales.Key words: mining, mercury, South America, contamination ABSTRACTIn this study the concentrations of Al, Co, Cu, Fe, Hg, Mn, Ni, Pb and Zn were determined in bottom sediment samples of the Puyango River and its tributaries with the goal to know the enrichment factors of these elements in the sediments. Bulk sediment samples were digested using the EPA method 3050B and then analyzed by atomic absorption spectrometry. The samples for Hg determinations were digested with a mixture of HNO 3 , HCl y KMNO 4 and then analyzed by the cold-vapor generation technique. The highest concentrations of heavy metals in sediments were found in the sector located after the Calera-Amarillo rivers confluence. The high levels of heavy metals and the low concentrations of Al in the bottom sediments of this sector indicate