Bioavailability and hence bioaccumulation of heavy metals in fish species depends on seasonal conditions causing different risks levels to human health during the lifetime. Mercury, cadmium and lead contents in fish from Chihuahua (Mexico) water reservoirs have been investigated to assess contamination levels and safety for consumers. Muscle samples of fish were collected across the seasons. Lead and cadmium were analyzed by inductively coupled plasma-optical emission spectrometry, and mercury by cold-vapor atomic absorption spectrometry. The highest concentrations of cadmium (0.235 mg/kg), mercury (0.744 mg/kg) and lead (4.298 mg/kg) exceeded the maximum levels set by European regulations and Codex Alimentarius. Lead concentrations found in fish from three water reservoirs also surpassed the limit of 1 mg/kg established by Mexican regulations. The provisional tolerable weekly intake (PTWI) suggested by the World Health Organization for methyl mercury (1.6 µg/kg bw per week) was exceeded in the spring season (1.94 µg/kg bw per week). This might put consumers at risk of mercury poisoning.

Mining is a major source for metals and metalloids pollution, which could pose a risk for human health. In San Guillermo, Chihuahua, Mexico mining wastes are found adjacent to a residential area. A soil-surface sampling was performed, collecting 88 samples for arsenic determination by atomic absorption. Arsenic concentration data set was interpolated using the ArcGis models: inverse distance weighting (IDW), ordinary kriging (OK), and radial basis function (RBF). For method validation purposes, a set of the data was selected and two tests were performed (P1 and P2). In P1 the models were processed without the validation data; in P2 the validation data were removed one by one, models were processed every time that a data point was removed. An arsenic concentration range of 22.7 to 2190 mg/kg was reported. The 39% of data set was classified as contaminated soil and 61% as industrial land use. In P1 the method of interpolation with the lowest RMSE was RBF (0.80), the highest coefficient of E was RBF (46.25), and the highest Ceff value was with RBF (0.48). In P2 the method with the lowest RMSE was OK (0.76), the highest E value was 50.65 with OK, and the Ceff reported the highest value with OK (0.52). The high arsenic contamination in soil of the site indicates an abundant dispersion of this metalloid. Furthermore, the difference between the models was not very wide. The incorporation of more parameters would be of interest to observe the behavior of interpolation methods.

Lead and chromium contamination represents one of the most serious problems in the aquatic environments. The aim of this work was to develop and validate an accurate, sensitivity, and rapid method for the simultaneous determination of Pb and Cr at trace levels in tissues and fat of marine organisms such as turtle (Chelonia mydas), shark (Rhizoprionodon terraenovae), and dolphin (Tursiops truncatus), utilizing the total reflection X-Ray fluorescence (TXRF) spectroscopy. Working solutions were prepared in 10 mL of a solution 0.005 mol·L⁻¹ EDTA and 1 mol·L⁻¹ HNO₃. In order to correct possible instrument drifts, 20 μg·L⁻¹ of gallium was used as internal standard (IS). The results showed that TXRF method was linear over the concentration ranges of 5.242–100 μg·L⁻¹ for Pb and 2.363–100 μg·L⁻¹ for Cr. Limits of detection (LOD) achieved were 1.573 and 0.709 μg·L⁻¹ for Pb and Cr, respectively, while limits of quantification achieved were 5.242 μg·L⁻¹ for Pb and 2.363 μg·L⁻¹ for Cr. The validated method was accurate and precise enough for determination of these heavy metals in samples of marine organisms as indicated by acceptable values of recovery between 90–101%. In addition, a certified reference material (BCR-279, sea lettuce) and a Centrum tablet were satisfactory analyzed, and the T-test for comparison of means revealed that there were no significant differences at the 95% confidence level between the values obtained with the proposed TXRF method and the certificated values. The repeatability of the method, expressed as relative standard deviation (RSD), was 5.1% and 4%, for Pb and Cr, respectively. In addition, other features of the developed method were a low sample volume of 10 μL, and the sample frequency achieved was 20 h⁻¹.

The objective of this work was to analyze the bisphenols and phthalates (PAEs) migration from meat packages (of sausages, Winnies, and ham found in Mexican markets) to a water simulant. The determination of these compounds was realized by high performance liquid chromatography (HPLC) and diode array detection (DAD) at a wavelength of 254nm. The mobile phase utilized was a mixture of acetonitrile:H₂O (70:30). Elution was performed isocratically at a temperature of 25°C and at a flow rate of 1mL min⁻¹. The LOQs obtained for BPA, DEP, BADGE, DBP, BisDMA, DHP, DOP, and PA in µg mL⁻¹ were 0.53, 2.09, 0.85, 1.45, 5.81, 1.03, 3.12, and 29.6, respectively. Calibration curves exhibited an adequate determination coefficient for all compounds (R² >0.999). Excellent accuracy and precision in measurements ( RSD) were achieved. The recovery study showed good applicability of the method (percentage recovery 80 to 106). The BPA, BADGE, DBP, and DOP concentrations found in samples exceeded the simulant migration limits (SMLs) established by the European Union. The contribution of the current investigation was to provide information related to the presence of bisphenols and PAEs in the package of meat products, highlighting the health risks associated with their exposure.

Water reservoirs in Chihuahua County, Mexico, are affected by some punctual and non-punctual geogenic and anthropogenic pollution sources; fish are located at the top of the food chain and are good indicators for the ecosystems pollution. The study goal was to: (i) determine arsenic concentration in fish collected from the Chuviscar, Chihuahua, San Marcos and El Rejon water reservoirs; (ii) to assess if the fishes are suitable for human consumption and (iii) link the arsenic contents in fish with those in sediment and water reported in studies made the same year for these water reservoirs. Sampling was done in summer, fall and winter. The highest arsenic concentration in the species varied through the sampling periods: Channel catfish (Ictalurus punctatus) with 0.22 ± 0.15 mg/kg dw in winter and Green sunfish (Lepomis cyanellus) with 2.00 ± 0.15 mg/kg dw in summer in El Rejon water reservoir. A positive correlation of arsenic contents was found through all sampling seasons in fish samples and the samples of sediment and water. The contribution of the weekly intake of inorganic arsenic, based on the consumption of 0.245 kg fish muscles/body weight/week was found lower than the acceptable weekly intake of 0.015 mg/kg/body weight for inorganic arsenic suggested by FAO/WHO.

Land use and land cover changes (LULC) are one of the main factors in global environmental change, as well as one of the main causes of soil and biodiversity loss. The main objective of this research was to determine the dynamics of land use changes in the Bustillos basin located in the municipality of Cuauhtémoc, Chihuahua, Mexico. The research consisted of the processing and analysis of satellite images from Landsat Thematic Mapper (TM5) and Landsat Operational Land Imager (OLI8). From the classifications obtained through satellite images, six categories of land use were obtained and later were compared through the use of a cross-tabulation matrix. The results showed that the use of remote sensors applied to the evaluation of the dynamics of land use changes allowed for knowing the changes that occurred in a period of 43 years. To compare the land use of the years 1974 and 2016, maps were obtained with soil covers. This served as the basis for the analysis of the changes that occurred. In this way, it was possible to determine the growth of the urban area (7851.48 hectares) due to the development of economic activity and the increase in population. The category that had a more significant increase was the agricultural areas with a gain in surface of the sub-basin of 28,334.23 hectares. The grassland class lost 21,385.28 hectares; this area was associated with the class of agricultural areas and urban areas. The oak–pine forest had losses of 9150.03 hectares, as well as the pine forest (586.06 hectares). Finally, the class of water bodies lost 228.02 hectares. The results showed that the implementation of dynamic LULC using geographic information systems could be adopted as a planning tool to manage LULC in the Bustillos basin in the future.