A high amount of nutrients can be found in urban wastewater (UW), which makes it difficult to treat. The purpose of this research was to evaluate the potential of the aquatic macrophytes Eichhornia crassipes, Pistia stratiotes, and Salvinia molesta in the treatment of UW. To evaluate the potential of each macrophyte, phytoremediation bioassays were established; the hydraulic retention time for each bioassay was 15 days. The physicochemical analysis of the water samples considered pH, turbidity, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), total carbon (TC), phosphates (PO43-P), nitrate (NO3-N), and total nitrogen (TN). To evaluate the phytoremediation potential of each plant, the bioconcentration factors (BCFs) and translocation factors (TFs) for NO3-N and PO43-P were evaluated. Likewise, the relative growth rates (RGRs) and total chlorophyll production of the macrophytes were measured. The results showed that the highest efficiency was achieved with the bioassays with E. crassipes, with removal values of 69.7%, 68.8%, 58.7%, 69.4%, 56.3%, and 40.9% for turbidity, COD, TOC, PO43-P, NO3-N, and TN, respectively. The phytoremediation potential results showed that, for BCF, the highest value was 4.88 mg/g of PO43-P with E. crassipes, and for TF, it was 6.17 mg/g of PO43-P with S. molesta. The measurement of RGR and total chlorophyll for E. crassipes showed an increase of 0.00024 gg−1d−1 and an increase of 4.5%, respectively. On the other hand, the other macrophytes suffered decreases in chlorophyll content and RGR. Thus, E. crassipes is defined as the macrophyte with the greatest potential for the UW phytoremediation process.

Rapid urbanization and the increase in world population have led to the generation of substantial volumes of laundry wastewater. In the present research work, the efficiency of Eichhornia crassipes for the treatment of wastewater from domestic laundries was studied. It was created in a system of artificial floating islands and placed in polyethylene cells with a useful volume of 20 L of capacity, a hydraulic retention time of 21 d was established. During the treatment, the parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), and phosphate-phosphorus ions (PO4-P) were determined. All parameters decreased significantly. The pH decreased from 9.33 to 8.29, the EC from 3,999 to 1,745 mS/cm, TDS from 2,000 to 847 mg/L, as well as the COD from 945 to 71 mg/L, and finally the PO43- ions of 202.5 to 5.7 mg/L. According to the results obtained, the system of artificial floating islands with E. crassipes is considered efficient and adequate for the removal of contaminants present in laundry wastewater.

This study aimed to explore the effectiveness potential of Eichhornia crassipes, Pistia stratiotes and Salvinia molesta for the reduction of potentially toxic metals from effluents enriched with Cd, Cr and Pb. Based on a 21-day laboratory-scale experiment, a total of three concentrations at 1, 5 and 10 mg/L were selected to culture each of the macrophytes. In addition, kinetics and prediction models were used to analyze the metal reduction data to understand the behavior and removal rate of each species and with the Taguchi methodology to see what the right conditions for greater efficiency are. The results suggested that the three macrophytes was able to reduce metals Eichhornia crassipes manages to reduce 90.8-99.99% Cd, 90.8-99.9% Cr and 89.6-99.9% Pb, for Pistia stratiotes 74.6-99.9% Cd, 74.6-99.9% Cr and 91.2-99.9% Pb and Salvinia molesta 83.2-99.9% Cd, 62.2-99.9% Cr and 89.2-99% Pb. The first-order model it is adjusted appropriately to the removal of toxic metals for the three plants, having an adjustment of R2 greater than 0.80. Taguchi analysis shows that optimal conditions for metal phytoremediation occur with 1 mg/L of toxic metals and after 21 days.

Lignocellulosic biomass is a promising alternative and renewable energy source that can be transformed into other value-added products such as activated carbon. The objective was to evaluate the barley husk (Hordeum vulgare L.), the corn cobs (Zea Mays L.) and the agave leaves (Agave salmiana) as potential precursors of activated carbon. These precursors were obtained from Almoloya and Apan in the State of Hidalgo, Mexico. The raw materials were washed with distilled water, dried at 105 ºC for 72 h in an oven, ground in a blade mill to obtain a particle size of 0.3-1.0 mm and finally sieved through mesh sieves of 18 and 45. Humidity was determined according to ASTM D3173 (ASTM, 1996), ash according to ASTM D3174 (ASTM, 2000), volatile matter according to ASTM D3175 (ASTM, 1997), fixed carbon according to ASTM D3172 (ASTM, 1997), total sugars and fats according to TAPPI T204 (TAPPI, 1997), Klason Lignin according to TAPPI T222 (TAPPI, 1998), holocellulose according to the method described by (Wise et al., 1946), and (, ( and ( cellulose according to TAPPI T203 (TAPPI 1999). The results show that contents from 82 to 83% for holocellulose, from 52 to 79% for cellulose, and from 15 to 26% for lignin, were determined. Elemental analysis showed high carbon contents with values of 42-45%. Particle sizes between 390.9 mm and 610.7 mm were found. Thermogravimetric analysis showed similar profiles of thermal decomposition, being cellulose the main stage, with peaks around 300 °C. Regarding the surface morphology, the lignocellulosic residues showed fibrous and porous structure. From these findings, it is established that the precursors analyzed can be considered as potential precursors of activated carbons. The results presented here may facilitate improvements in the pyrolysis and activation areas of this lignocellulosic residues. The conditions for an acceptable yield of biochar were tested, these were: carbonization temperature of 400 °C, carbonization time of 30 min, precursor mass of 2-10 g and N2 flow rate of 150 cc/min. The biocarbons produced under these conditions were physically and chemically characterized. Biochar yields of 19.75% were obtained for corn cob (CCB), 32.88% for barley husk (BHB) and 31.14% for Agave salmiana leaves (ALB). Biocarbons with a predominantly macroporous structure, amorphous structure, numerous oxygen functional groups, anionic surface and moderate ash content were obtained. The results of this investigation show that barley husk, corn cob, and agave leaves are likely precursors for biochar production with good dye adsorption capacities.

Se estudian las formas de hierro extraídas con oxalato ácido de amonio, pirofosfato de sodio, ditionito-citrato-bicarbonato, así como el hierro total en disolución en suelos Alisoles en el municipio de Acaxochitlán, Hidalgo, México. Los suelos estudiados soportan distintos tipos de vegetación forestal: Pinus patula Schlecht and Cham (Pp), Pinus teocote, (Pt) y Quercus spp, (Q). El objetivo del trabajo fue determinar si la vegetación influye significativamente sobre las diferentes fracciones de hierro (Fe) en el suelo. Los contenidos de Fe total son significativamente mayores en suelos bajo vegetación de Pp (14,5% de Fe2O3), el mayor porcentaje de ferrihidrita (38,0% del Fe total en suelo) y de complejos organominerales de Fe y óxidos amorfos de Fe (20,9% y 16,3% respectivamente del Fe total en suelo, se dio en el bosque de Pt. En los suelos bajo bosques de Pp predominaron formas de Fe lábil (56,7% del Fe total en suelo) y formas cristalinas de Fe (goetita/hematita). La vegetación de Q mostró mayor alteración de los suelos y en el caso de Pt y Pp se presentó una mayor evolución en el proceso de organización estructural de los oxihidróxidos de Fe. El tipo de vegetación forestal influye en el grado de evolución del suelo, y en la distribución, contenido y formas de óxidos de Fe. En un orden de mayor a menor el contenido de Fe total en el suelo fue Pinus patula > Quercus spp > Pinus teocote.

The aim of the study was to characterize taxonomic, physical, and morphologically distinct species agaváceas tequila, mezcal and pulque grown in different regions of Mexico. Four species were evaluated Agave lechuguilla Torr., Agave salmiana B. Otto ex Salm-Dick, both from the state of Hidalgo; Agave angustifolia Haw. From the state of Oaxaca and Agave tequilana Weber, Var. Azul, Jalisco. The work was divided into two phases: botanical phase and physical study. In the botanical phase classification and taxonomic characterization of phenological, ecological and ethnobotanical database was revised. In the physical phase size and leaf characteristics of the plant is characterized. We analyzed moisture, fiber granulometry and scanning electron microscopy to assess fiber morphologies. From the results of physical characterization and fiber lengths found, we concluded that there is high potential to produce cellulose pulp. The species A. angustifolia and A. tequilana were presented minor percentage of sizes <0.5 mm that could affect an alkaline pulping process. For the species A. tequilana 98.5% fibers <1 mm being the majority corresponding to the fraction 0.5-1.0 mm (84.3%) which corresponds to a size suitable for cellulosic pulp paper making was obtained. The species A. angustifolia showed 85.06% fibers <1 mm fraction between 0.5-1.0 mm majority (65.2%).

Weathering is one of the most important phenomena that affect the balance dynamics of the Earth's crust. The chemical composition of soil samples and hardened horizons from seven profiles (P1 to P7) of the State of Mexico was compared to detect the degree of alteration by means of weathering indices. In hardened horizons, the dominant elements are SiO2, Al2O3, Na2O, K2O and TiO2, corresponding to 86.8 % of the total oxides. The weathering indices based on the mobility and immobilization of alkaline and alkaline earth elements reveal that the B horizons and the hardened horizons of profiles P4, P5, P6 and P7 are generally more altered than the surface horizons, therefore they have a greater pedogenic development. Profiles P1, P2 and P3 show incipient weathering. The geochemical indices and chemical relationships used in this study to evaluate weathering and associated basic alteration processes showed consistent results. These coincide in indicating incipient to moderate weathering acting in the seven profiles, with variable intensity in all the hardened horizons. The intensity variation defines a sequence of chemical weathering for the hardened horizons: P6> P4> P5> P7> P2> P3> P1, where P6 has the highest degree of weathering in the indices: CIA, CPA, CIA-K, CIW, PIA,IPark, V.

Constructed wetlands, including floating islands, are a suitable technology for wastewater treatment. They are low cost and respectful with the environment, which is why they are significantly beneficial for agricultural irrigation systems. One of the limiting factors in structuring efficient constructed wetlands is the choice of plant species that can tolerate and eliminate contaminants. Macrophytes have an important role, since they allow their filtration, retention and absorption, among other processes. The objective of the work has been to show the diversity of emergent and aquatic species used for the treatment, highlighting species such as Typha latifolia, Typha doingness and Eichhornia crassipes, as species of constant use. In efficiency, they manage to eliminate nutrients and organic matter in excess, as well as toxic elements such as zinc, cadmium, lead, chromium, mercury, among others, in values between 15-95%. Some studies also address emerging pollutants, showing that wetlands successfully mitigate the presence of contamination by these micro-pollutants, eliminating paracetamol, ibuprofen, caffeine and antibiotics, among others, in values of 75-99%. Constructed wetlands are a frequent management practice for the mitigation of pollutants, the management of the biomass generated is an issue little explored and rarely considered. It is important to highlight several works where biomass is used to feed animals, such as fertilizers, to generate building blocks and production of bioenergy through biogas.

Los sistemas de humedales artificiales se consideran una tecnología adecuada para el tratamiento de aguas contaminadas y, en comparación con los sistemas convencionales, son de bajo costo y respetuosos con el medio ambiente. Las macrofitas tienen un papel importante en la reducción de contaminantes, ya que permiten su absorción, entre otros procesos. En el presente estudios se muestra el uso de Lemna minor, Pistia stratiotes, Eichhornia crassipes las cuales son macrofitas flotantes, con el objetivo de disminuir la contaminación presente en un agua residual sintética. Para evaluar la eficiencia de remoción se generó un agua sintética con una DQO inicial del 1,229 mg de DQO/L y se plantearon 5 experimentos 3 de ellos con cada macrofita de manera individual y 2 con la combinación de estas. Después de 21 días de evaluación la mayor remoción obtenida es de 96 % en los experimentos donde se encuentran en combinación las macrofitas flotantes, los experimentos individuales Eichhornia crassipes alcanza remociones de 92 %, Pistia stratiotes 90 % y Lemna minor 77 %. El uso de macrofitas flotantes en humedales artificiales es eficiente para el tratamiento de aguas residuales sintéticas.

Abstract. Castor bean (Ricinus communis) can be a high-demand crop for the production of biodiesel, an alternative biofuel similar to conventional diesel. The objective of the work has been to optimize the method of obtaining biodiesel from a “green technology” process, directly splitting the seeds of three macerated castor varieties, without prior extraction of the oil with n-hexane as is traditional. Also using low-cost heterogeneous basic catalysts, friendly to the environment. It has been shown that it is feasible to obtain biodiesel as an eco-fuel from castor beans directly, without prior oil extraction with the consequent saving of n-hexane solvent and the non-use of sodium hydroxide. It is feasible to substitute methanol for ethanol (less toxic and cheaper), and as a novel aspect, the use of BaCO3 as a heterogeneous catalyst, not reported in any reference of those consulted. Yield percentages ranging between 31% and 45% were obtained, comparable to those obtained from previous oil extractions. It was concluded that of the three varieties of castor bean evaluated, the variety HG-A-1 (collected in Atotonilco el Grande, Municipality of the State of Hidalgo) classified as IBEA type, is the one that presents the best results. Keywords: Barium carbonate, Castor oil, Eco-fuel, Ethanol, Seed.

Socio-environmental conflicts are situations that exemplify human rights transgressions caused by extractive activities. These are present in developing countries where extractivism, imperialism, and colonialism paradigms prevail. In the context of Mexico, criminalization, violence, and the absence of rule of law promote these conflicts, frequently aggravated by involvement with private interests. In the last 20 years, the relationship between human rights in the mining sector and its impact on the environment has been a critical research subject. This paper aims to carry out a systematic review to analyze human rights transgressions related to the mining industry’s impact in Mexico, and identify factors causing socio-environmental conflicts. The current study shows a systematic analysis based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. This method contributed to the collection of references that describe conflicts due to human rights transgressions and environmental damage in mining areas in Mexico. Human rights transgressions caused by mining in a Mexican context demonstrate the inability of the state to stop the increase in socio-environmental conflicts and its lack of concern towards preventing damage to the environment.

ABSTRACT Soil respiration in forest ecosystems is considered to be the second most important carbon flux between the biosphere and the atmosphere. In tropical forests, the factor that most influences soil respiration is the temporal variation in temperature, and in water content or precipitation; the soil temperature is relatively constant. The behavior of the RS was established, and this ecological process was estimated and modeled for a tropical mountain forest in the State of Hidalgo, Mexico. It has contributed to strengthening the theoretical framework for the restoration and ecological conservation of this forest, considered a National Park, this has been the main objective of this work. Its relationship with the climatic parameters and factors that regulate CO2-soil-atmosphere fluxes in an annual cycle was analyzed. The daytime respiratory rate was slightly higher (average of 3.54 tmCO2/ha) than the nocturnal one (average of 3.35 tmCO2/ha), depending on the ambient temperature and the climatic conditions. The humic acid found in the soils was classified for the mountainous wooded area of the Chico National Park. Andosols are humic soils and humic acids were classified predominantly as type A. According to the results obtained, with only one year of evaluation, it should be noted that it is necessary to carry out a greater number of evaluations, at least during a period of 5 to 10 years and for different seasonal periods, in order to strengthen the responses found for this ecosystem.

En el presente artículo de investigación, se genera una propuesta para la creación de una plataforma digital híbrida (tMOOC), que integre de manera exitosa xMOOCs y cMOOCs, para constituir de manera satisfactoria a los cuatro pilares de la educación, propuestos en el informe Delors. El trabajo está orientado a la enseñanza de una técnica histológica que permite transparentar tejidos blandos (diafanizar) y teñir de manera específica tejidos duros (hueso y cartílago), con la finalidad de enseñar osteología comparada de manera masiva y gratuita.

The spatial distribution of physical, chemical and biological soil, affecting crop yields, however, the spatial dependence of soil biological parameters has been little explored. A study was conducted to establish the influence on soil fertility showed spatial variations of physical, chemical and biological properties of two agricultural soils in Hidalgo State (Mexico), belonging to the order Cambisol with low clay content activity. Soils A, (with a phase-clay-sandy, shallow horizon imperfect drainage), the municipality of Apan and soil B (with a light phase and thick, with stones), the municipality of Emiliano Zapata, were sampled in a network of 10x10m at 10, 20 and 40 cm deep. Were determined by physical, chemical and biological both soils. Geostatistical analyzes were performed using SPSS version 17.0. Texture, soil moisture and organic compounds changes affect the spatial distribution of the physical, chemical and biological properties of soils tested. The spatial variability of organic carbon, total nitrogen and C/N increased significantly with depth in the two soils, while the bulk density showed little spatial variation.

Chromium (Cr) is an element present in nature in mineral form. It has a dual effect, both as an essential micronutrient and a carcinogenic agent depending on its chemical form and concentration. It is present in various environmental matrices such as water, soil, and air, coming from natural and anthropogenic sources, and causes harmful effects on biota, ecosystems, and even human beings. This study's objective was to evaluate chromium toxicity and teratogenicity in zebrafish embryos of Danio rerio exposed to chromium through the D. rerio teratology assay (DarTA) test by evaluating spine malformations. To this end, the chromium toxicity curve was calculated from zebrafish embryos exposed to potassium dichromate (K2Cr2O7), and the probit test was used to establish the mean lethal concentration (LC50) and three subtoxic concentrations LC25, LC12.5, and LC6.25 to evaluate the teratogenicity. The results showed that potassium dichromate was statistically positive for the teratogenic effect at the three highest concentrations evaluated. Potassium dichromate exposure causes abnormal embryonic development and teratogenic effects, including severe heart defects in zebrafish embryos. Therefore, we conclude that potassium dichromate is toxic to the zebrafish developmental stages. The finding that potassium dichromate is teratogenic in zebrafish embryos suggests that this metal should be tested and evaluate potential risk in mammalian systems.

Se presenta un método de análisis rápido para la evaluación de potencial de riesgo genotóxico asociado a metales pesados presentes en agua potable. Este método se basa en el análisis de las principales características fisicoquímicas, cinética ambiental, biodisponibilidad, efectos biológicos reportados y/o potenciales que puedan incrementar la probabilidad de manifestar un efecto adverso. Se planteó un caso de estudio en Zimapán Hidalgo, debido a que existen evidencias de la presencia de metales pesados de interés toxicológico en el agua potable. Los resultados de la aplicación de la metodología ERPRG muestran que el cromo, cadmio, arsénico y plomo se encuentran en la categoría de potencial de riesgo alto; mientras que el mercurio en la categoría de riesgo intermedio. ERPRG, es una herramienta que permite identificar situaciones de potencial de riesgo biológico y ambiental, basada en el análisis sistemático de reportes bibliográficos y estudios previos que permiten determinar cualitativamente el impacto de variables ambientales, biológicas y situacionales de manera clara, rápida y resumida.

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Background. Understanding the toxicity mechanism of arsenic has been hampered by biological, chemical factors, including the dose response ratio, the specificity and sensitivity of species used in bioassays from toxicological studies to understand their toxicodynamics. Goals. The purpose of this study was to evaluate the embryotoxic, teratogenic and genotoxic effect caused by exposure to arsenic, through the frequency analysis of malformations and micronuclei in peripheral blood erythrocytes in zebrafish. Methods. The toxicity curve of arsenic in zebrafish embryos was calculated from exposure to concentrations between 0.0031 and 0.05 mg L-1 of sodium arsenite (NaAsO2) for 72 hours to determine the mean lethal concentration (LC50) for the embryotoxicity and teratogenesis test. For the genotoxicity test, the calculation of the toxicity curve with adult zebrafish that were exposed to concentrations between 0.035 and 0.044 mg L-1 for 48 hours was previously performed in order to establish LC50. Results. The effect of sodium arsenite was shown to be statistically positive for embryotoxicity and teratogenesis tests at the evaluated concentrations. Exposure to sodium arsenite resulted in abnormal embryonic development at each of the test concentrations, in addition to malformations. And a statistically significant increase in the frequency of micronucleated erythrocytes of 0.035, showing genotoxic damage of arsenic. Conclusions. This study showed that the induction of nuclear abnormalities in erythrocytes, as well as abnormalities in embryonic development, are extremely sensitive indicators in the study of toxicological effects, and suggest that the risk potential of this metalloid should be tested in future research.

La respiración del suelo (RS) en ecosistemas boscosos se considera como el segundo flujo de carbono más importante entre la biosfera y la atmósfera; cerca de la mitad de la RS se deriva de la actividad metabólica, soporte y crecimiento radicular y asociación con micorrizas. En bosques tropicales, el factor que mayor influencia tiene sobre la variación temporal de la RS, no es tanto la temperatura, sino el contenido de agua o la precipitación debido a que la temperatura del suelo es relativamente constante. El objetivo del trabajo ha sido establecer el comportamiento de la RS y tratar de estimar y modelar el proceso ecológico de la RS en la fase priseral arbustiva de un bosque de montaña en el Estado de Hidalgo, con el fin de fortalecer el marco teórico de la ecología de la restauración y de la biología de la conservación, así como analizar su relación con los parámetros meteorológicos para entender cuáles son los factores que regulan los flujos del CO2 suelo-atmósfera en un ciclo anual. Por los resultados alcanzados, debe señalarse que será necesario realizar un número mayor de evaluaciones en un tiempo de 3 a 5 años y en épocas y períodos estacionales con vistas a reforzar estos resultados. Se pudo concluir tres aspectos importantes, en primer lugar, que la RS es parte del reservorio de carbono en ecosistemas forestales; la RS del suelo es una variable dependiente del tiempo y de la altitud, a mayores tiempos mayores valores de RS y a mayores altitudes también. Se encontró que la tasa de respiración diurna (TRSD) es ligeramente mayor que la nocturna (TRSN), al parecer dependiente de la temperatura ambiente. Se logró clasificar los AH de suelos de la zona boscosa de montaña del Parque Nacional del Chico. Ya se reportaba que eran suelos andisoles húmicos, pero en este trabajo se clasifican como AH de tipo A predominante.

The objective of this work was to evaluate the capacity as nano-adsorbent of NFe, synthesized by green synthesis, supported on silica (SGNFe) and without supporting, for the elimination of dye (methylene blue) in water and the toxic herbicide Paraquat, in contaminated water. The NFe by green synthesis from eucalyptus extract, did not result in an absolute reducing effect as expected, which would allow obtaining the NFe only in zero valence. Only a partial reduction of Fe2+ was obtained, which was denoted by the presence of Fe0 in the XRD and a partial oxidation of Fe2+ to Fe3+ observed by the presence of the magnetite phase. If the presence of almost spherical NFe was corroborated by the analysis and distribution of particle size and corroborated by scanning electron microscopy (SEM). The NFe obtained and the doped silica gel (SGNFe), as well as the silica (SG) used as a precursor, showed negative charges in semi-colloidal suspensions, checked by zeta potential (pZ) and electrophoretic mobility. The SG, NFe and SGNFe in this study report cationic dye adsorption efficiencies AM between 98-99% as well as adsorption capacities (qt) between 24.5-24.8 mg/g. However, the percentages of efficiency in the adsorption of the cationic herbicide Paraquat in water, oscillated with efficiencies between 81-98% and presented a very low adsorption capacity (qt) very low, between 0.53-0.89 mg/g. It is important to continue this line of research, seeking to improve and/or optimize the synthesis conditions to increase the values of qt Keywords: Nanoparticles, adsorption capacity, paraquat, eucalyptus, efficiency.