Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The bioadsorption of Co(II) and Mn(II) in aqueous solutions was evaluated by Rhodococcus opacus inactivated and treated with NaOH, and the physicochemical characterization of the bioadsorbente. The physicochemical characterization of bacteria was performed by scanning electron microscopy coupled to energy dispersive X-ray analyses (SEM-EDS), Fourier transforms infrared spectroscopy (FTIR,) and Zeta Potential (ZP). Likewise, the operating conditions in the process were determined, evaluating biosorbent concentration, initial metal concentration (Ci), pH, and contact time. The experiments were performed at the laboratory, and the bacteria was previously treated with NaOH (0.1M). The interaction between R. opacus and metal ions was confirmed by the variation of isoelectric point (IEP) and functional groups. Removals and uptake of 87.8 % and 24.9 mg/g for Co(II) and 79.9 % and 6.1 mg/g for Mn(II) were achieved under test-operating conditions. These conditions were pH 7, biomass 4 mg/l, Ci 50 mg/l, and 180 minutes of operation time. While for Mn(II): pH 5, biomass 3 mg/l, Ci 5 mg/,l and 10 minutes operation time. The present study shows that R. opacus can be applied to treat effluents containing low concentrations of Co(II) and Mn(II).

The effect of climate change in this region is considered as one of the driest in the world, according to the evidence found and recorded, may be favorable or unfavorable for water availability. In this work, we seek to evaluate and validate the evidence of climate change such as droughts and floods that are occurring in the southern region of Peru and northern Chile called the headwaters of the Atacama Desert. The analysis of the interrelationships and climate trends was carried out, to demonstrate conditions of climate change about the occurrence of alluviums. In recent years, extraordinary precipitation events have occurred that have generated surface storage, vegetation growth, and alluvial surface flows in areas where they were not normal. The return periods of said extraordinary events were calculated. Likewise, la mancha caliente (“the hot blob”) ―detected by NOAA― brought with it, temperature anomalies between 4 and 6 ° C, and has a high probability of being the agent causing local rainfall in the study area. We consider these events as evidence of climate change; the normal conditions have been altered and the damage is irrefutable, it must be specified, for example, that a large part of the road infrastructure, services, buildings, etc., are not designed to take these conditions into account current climate, therefore, it is necessary to establish the safety regulations and adaptation of buildings to these new conditions that are being presented.

The water security (WS) approach must be practical and measurable to address water-related challenges. Since 2000, the term Water Security has been regularly mentioned worldwide. However, nowadays, there is still not an accepted definition either for a country or for a region. This research conducted a meta-analysis in the context of renewable water and global water stress, evaluating 873 scientific papers and 26 definitions of WS, using bibliometric network analysis, geographic information systems, and data mining to analyze the state of the art of WS. The results indicate that the definitions of WS have an anthropocentric character. The term economic in the context of WS definitions is the most relevant, and the term ecosystems are the least relevant. Less than 30 % of the definitions analyzed are operationalized through some measurement instrument. The most researched topics on WS are evaluation, management, and impact. On the frontier of study are the issues of water footprint, operation of springs, and awareness. In the world, countries such as the United States, China, and the United Kingdom, with little renewable water in their respective continents, are the ones that publish the most and try to define the concept of WS. Therefore, it is concluded that the main problem of WS definitions worldwide is that they cannot be operationalized in some local indexes, hindering their implementation. In addition, the environment has not been relevant in WS research and definitions.

The purpose is to identify the main challenges of municipal wastewater treatment policy in Mexico, through an original descriptive statistical analysis, distinguishing data from the country, as well as by states and municipalities. Five challenges are identified: good intentions; abandonment of treatment plants; operation and preventive maintenance; the vacuum of responsibility, and the priority of treatment in state agendas. The conclusion is that the professionalization of local water and sanitation agencies is key to aspiring to materialize good intentions that will be written in the new General Water Law.

El objetivo de este estudio es entender el papel de los principales impulsores de los cambios históricos de la línea de costa y sus implicaciones en el riesgo de erosión en una franja costera al norte del estado de Sinaloa, ubicada en la costa este del golfo de California. Se analizaron mapas digitales de diferentes años (1981, 1991, 2004 y 2018) utilizando softwares de Sistemas de Información Geográfica (DSAS y CERA) para examinar: a) el desplazamiento y la tasa de cambio en la línea de costa, y b) la vulnerabilidad, las posibles consecuencias y el riesgo de erosión. Los resultados obtenidos indican que entre 1981 y 2018: a) las acciones antrópicas (presas y escolleras) fueron los principales impulsores tanto de los cambios en la línea de costa como del daño ambiental subyacente al riesgo de erosión que se han producido en las últimas décadas; (b) la costa del área de estudio se ha erosionado con un EPR promedio de -3.1 m por año, lo que ha dado lugar a un NSM promedio de -112.9 m, y c) el riesgo de erosión se mantuvo moderado, aunque la vulnerabilidad aumentó de un nivel moderado a un nivel alto y las posibles consecuencias de un nivel muy bajo a uno moderado. Los resultados de este estudio servirán de base para futuros análisis centrados en predecir los cambios en la costa y el riesgo costero.

La composición isotópica del agua (hidrógeno y oxígeno) es una herramienta muy útil para estimar balances hídricos, recarga de agua subterránea y evaporación. Los isótopos estables del agua en conjunto con herramientas hidrogeológicas y de datación, se han utilizado para aumentar nuestro conocimiento de la distribución y la cantidad de agua subterránea renovable y no renovable. La composición isotópica de la precipitación y el agua subterránea están disponibles en algunas partes de México, aunque hay poca información de la Península de Yucatán, un área que depende casi por completo del agua subterránea; para la cual, la estimación actual de disponibilidad de agua subterránea es incierta. En esta nota, recopilamos los datos publicados y no publicados de δ2H y δ18O en el agua meteórica (la precipitación), así como aguas subterráneas y del suelo, para obtener una línea de agua meteórica regional (LAMR) a escala peninsular, expresada por la ecuación δ2H = 8.18 δ18O + 10.29. Los datos que se tienen actualmente sugieren que la precipitación pluvial se origina en sistemas de convección, eventos de baja presión, de humedad de eventos frontales y humedad condensada. Las líneas de evaporación del agua subterránea sugieren mezcla de agua con diferente composición isotópica, pero también proporcionan información sobre rápida recarga del agua meteórica, probablemente debido a eventos de lluvia de gran intensidad. Presentamos un paisaje isotópico de aguas subterráneas de la Península de Yucatán y finalmente abordamos el potencial uso de datos isotópicos para el manejo de las aguas subterráneas.

Using biomass as an adsorbent constitutes a potential alternative for removing heavy metals in industrial wastewater, representing a high environmental risk. In this work, the adsorption of Pb+2 and Cd+2 was performed using the cocoa shell as an adsorbent in columns, and the dynamic simulation of the process using the Aspen Adsorption® V10 software, to validate the simulation results and those obtained experimentally. The simulator and experimental rupture curves converge in almost the entire trajectory, with slight variations in the final stretch of the curve, with the rupture times coinciding for both metals, giving correlation coefficients (R2) of 0.984 and 0.998 for Pb+2 and Cd+2, respectively, as well as error values (SSE) less than 5%. The effect produced by the variation of the bed height and the flow rate in the rupture curves was analyzed; as the bed height increases and the flow rate decreases, the rupture time increases, favoring the adsorption of both metals. The results of this research show the importance of the use of Aspen Adsorption® software in the biosorption process due to the similarity with experimental results, providing its use saving time and resources.

This article presents a model to simulate and predict the maximum weekly water demand of a DMA belonging to the distribution network of Guanajuato city. The model is made up of two sub-models, one deterministic and one stochastic, which can be calibrated with historical demand data. The Fourier series describes the deterministic sub-model, while the stochastic sub-model involves the quantile function of the log-logistic distribution. Data from a holistic telemetry system were used to calibrate and validate the model to test the model's goodness in describing the demand behavior. Such a system consists of a network of stations for the measurement and recording of data and a system for storing and processing the information.

The opportune calculations of the daily reference evapotranspiration (ETo) quantify and schedule the use of the water availability and consequently determine a daily consumption, mostly in the conditions where the lack of climatic information interrupts the performance of diverse models to estimate the daily reference evapotranspiration in a certain region. Therefore, the objective of this work is to evaluate the behavior of the equations of Hargreaves-Samani, Priestley and Taylor, García and López, and Linacre in the calculation of daily reference evapotranspiration (ETo) for the equation of FAO Penman-Monteith (PM) using daily information from five stations near the rice production area of Valle del Cauca, Colombia. The daily evapotranspiration of 28 consecutive years was estimated, the results were confirmed by the statistical indicators: Determination Coefficient (R2); the square root of the mean square of the error (RMSE); Nash-Sutcliffe Efficiency (NSE), and box diagrams. The Priestley-Taylor (PT) and Linacre (LN) models have shown the closest results to the standard model. Bengala and Ciat Quilichao stations are shown as the areas with the best behavior of all the models with the coefficient of determination index (R2); all the stations presented acceptable results with the square root of the mean square of the error (RMSE) for the different comparisons made but not with the Nash-Sutcliffe Efficiency (Nash-Sutcliffe Efficiency). However, there is limited evidence of the daily use of the Garcia and Lopez model, being this method and that of the Hargreaves-Samani the least ideal for the Independence station.

It was studied the removal capacity of Chromium (VI) in an aqueous solution by the modified biomass of rice grain, using the diphenylcarbazide colorimetric method, to evaluate the metal concentration. The biosorption at different pHs (1, 2, 3, and 4) was evaluated at different times. Too, the effect of temperature in the range of 28 to 60 °C and removal at different initial concentrations of Cr (VI) from 200 to 1 000 mg/L, were studied. The most removal of metal, was eight days, with 100 and 79 %, for both biomasses, modified and not modified, respectively, at 28 °C, pH 1.0, and 1 g of biomass. Concerning the incubation temperature, the highest removal was at 60 °C, with 100 % of removal after five days. Additionally, the biomass concentration does influence the metal removal, and efficiently remove the metal from contaminated earth and wastewater (71 and 73 %, respectively), after 10 days of incubation with 10 g of biomass.