The aim of this work was to determine Ni, Cr, Cu, Zn, Pb, and As levels in raw milk and Oaxaca and ranchero type cheeses, produced in areas irrigated with waste water from Puebla in Mexico. Milk results showed a mean Pb level of 0.03 mg kg⁻¹, which is above the maximum limit as set by Codex Alimentarius and the European Commission standards. For As a mean value of 0.12 mg kg⁻¹ in milk was obtained. Mean As and Pb levels in milk were below the Mexican standard. Milk whey and ranchero cheese had mean Pb levels of 0.07 and 0.11 mg kg⁻¹, respectively. As was higher in Oaxaca and ranchero cheese at 0.17 and 0.16 mg kg⁻¹, respectively. It was concluded that cheeses made from cow’s milk from areas irrigated with waste water are contaminated with Pb and As, which may represent a health risk.

The aim of this study was to determine the hazard ratio (HQ), the risk index (HI), and the cancer risk index (CRI) for populations of adults and children exposed to ingestion, dermal contact and inhalation of heavy metals in agricultural soil. For these, the contents of Cd, Pb, Ni, Cu, Co, Cr, Zn, and the metalloid As were determined in soils of four zones of the sub-basin of Alto Balsas, during two different periods of the year. The average content of metals in the soil was 1.24, 14.77, 14.80, 13.06, 5.50, 17.65, 22.89, and 5.32 mg kg-1 for Cd, Pb, Ni, Cu, Co, Cr, Zn, and As, respectively. The highest risk in terms of HQ and HI was for adults, especially for men who are affected through the skin, with Cd and Cr being the most dangerous. CRI values were within the allowable range, without posing problems for adult and child populations.

The Atoyac River crosses the metropolitan area of Puebla-Tlaxcala in Mexico and presents a state of pollution that has been scarcely studied. In 2016, the water quality of the river was evaluated based on physicochemical and bacteriological parameters, under the guidelines established for the Maximum Permissible Limit (MPL) for Aquatic Life Protection (ALP) and Agricultural Irrigation (AI). The sampling sites were the Covadonga Dam, the Echeverría Dam, and an irrigation canal. Water from wells and a spring in the Emilio Portes Gil (EPG) population that uses Atoyac water for agricultural irrigation was also analyzed. The data obtained from the river were compared with the 2011 data published in the declaration of classification of Atoyac and Xochiac or Hueyapan and its tributaries. There was a notable increase in hemical oxygen demand (COD) (49%) and in heavy metals with varying percentages. The anoxic condition of the river (mean 1.47 mg of O₂/L) with large populations of coliform bacteria was demonstrated, 11 pathogenic members of the Enterobacteriaceae were found, and high organic pollution concentrations were shown, particularly during droughts. Irrigation and well water was contaminated with fecal bacteria (104–549 NMP/100 mL), which included pathogens.

NIVEL DE CONTAMINACIÓN DE METALES Y ARSÉNICO EN AGUAS RESIDUALES Y SUELOS EN LA SUBCUENCA DEL ALTO BALSAS EN TLAXCALA Y PUEBLA, MÉXICO

Identifying degraded lands and degradation trends is essential to determine measures that contribute to avoiding, reducing, and reversing the rate of deterioration of natural resources. In this study, we assessed the state and trend of degradation in Ixtacamaxtitlan, Puebla, Mexico, by determining the spatial and temporal changes of three indicators, Land Cover (LC), Land Productivity Dynamics (LPD), and Soil Organic Carbon (SOC), during the period 2000–2015, using global data proposed by the Convention to Combat Desertification for the implementation of Land Degradation Neutrality (LDN). The results showed increases in croplands (6.89%) and a reduction in grasslands (9.09%), with this being the transition that presents the most significant extension in the territory. The LPD is the indicator where the most deterioration was observed, and due to negative changes in LC, SOC losses were estimated at more than 7000 tons in the study period. The proportion of degraded land was 19% of approximately 567.68 km² of Ixtacamaxtitlan’s surface. Although the municipality presents incipient degradation and only a tiny part showed improvement, identifying areas with degradation processes in this work will favor degradation monitoring and the adequate planning and application of restoration measures in the local context to promote the path towards LDN.

La desertificación es un problema ambiental que amenaza la producción alimentaria a nivel mundial, México es uno de los países más afectados por este fenómeno y, a su interior, el estado de Puebla no escapa a esta problemática nacional, pocos son los estudios encaminados a conocer los niveles de desertificación actual, y aún menores, son los enfocados a prevenir este proceso dada la susceptibilidad de los territorios para desarrollarla o agravarla, por lo que el objetivo de este trabajo fue evaluar la susceptibilidad ambiental a la desertificación de la microcuenca San Andrés Azumiatla, Puebla, México. Se definieron áreas ambientalmente sensibles a la desertificación (AASD), agrupando indicadores en cuatro índices que definen la calidad del suelo, clima, vegetación y manejo. Se calificaron los atributos: textura de suelo, material parental, fragmentos de rocas en superficie, pendiente, profundidad del suelo, precipitaciones, riesgo de incendio, protección de la flora contra la erosión, resistencia de la vegetación a la sequía, cobertura, intensidad y uso del suelo, así como la aplicación de políticas para su protección. Se utilizó un sistema de información geográfica para generar el mapa final de las AASD, así como, los mapas de los índices calculados. Los resultados muestran que el 84.6% del área presenta niveles críticos de sensibilidad a la desertificación, mientras que el 15.4% presenta fragilidad a la desertificación; siendo las pendientes inclinadas con suelos someros, la siembra de cultivos intensivos anuales y la deforestación, las causas que promueven la degradación del suelo en la microcuenca.