Revista Internacional de Contaminación Ambiental
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Ladrillos a base de desechos de mármol, una propuesta sustentable
Get PDFIt is well known that natural resources are deteriorating well beyond their renewal rate. The overexploitation and emission of harmful pollutants are leading to potentially irreversible changes, putting the stability of ecosystems at risk. In this sense, finding a way to reuse industrial waste that does not have a management plan is necessary and is the responsibility of all. This work presents results on the feasibility of using waste marble dust as a base material for the manufacture of non-structural bricks. The bricks were made with mixtures of marble dust, Portland cement, sand, and water; the pastes were molded, pressed and cured with water at room temperature. The compressive strength was evaluated at seven, 14, and 28 days after curing. Water absorption was measured in the cured samples, after being dried at 100 ºC for 24 h. The structure and microstructure of the bricks was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The results obtained for water absorption and compressive strength indicate that the bricks with 28 days of curing could be used as non-structural bricks, since they comply with the reference parameters established in the Mexican standards.Es muy conocido que los recursos naturales se están deteriorando mucho más allá de su tasa de renovación. La sobreexplotación y la emisión de sustancias contaminantes nocivas están llevando a cambios potencialmente irreversibles, poniendo en riesgo la estabilidad de los ecosistemas. En este sentido es necesario —y es tarea de todos— buscar la manera de reutilizar los residuos que se producen como desechos industriales que no cuentan con un plan de manejo. Este trabajo presenta resultados sobre la factibilidad de utilizar polvo de mármol de desecho como material base para la fabricación de ladrillos no estructurales. Los ladrillos fueron fabricados con mezclas de polvo de mármol, cemento Portland, arena y agua; las pastas fueron moldeadas, prensadas y curadas con agua a temperatura ambiente. La resistencia a la compresión fue evaluada siete, 14 y 28 días después del curado. La absorción de agua fue medida en las muestras curadas, después de ser secadas a 100 ºC por 24 h. La estructura y microestructura de los ladrillos fue caracterizada por espectroscopía de infrarrojo por transformada de Fourier, microscopia electrónica de barrido y difracción de rayos X. Los resultados obtenidos en cuanto a la absorción de agua y resistencia a la compresión, indican que los ladrillos con 28 días de curado podrían ser utilizados como ladrillos no estructurales, ya que cumplen con los parámetros de referencia marcados en las normas mexicanas
Assessment of COVID-19 lockdown impact on PM10 and PM2.5 concentrations in the Mexico City Metropolitan Area
Get PDFPM10 and PM2.5 concentrations are regularly monitored because they cause adverse effects on human health. The concentrations of PM10 and PM2.5 vary within a city due to land use, the amount of traffic, and pollution sources. As the COVID-19 pandemic spread around the world, lockdowns were enacted to stop the spread of the virus. These lockdowns meant reduced mobility and the halt of certain economic activities which had an impact on air pollution sources. In this paper, we assess the effect of the lockdown enacted in April-May 2020 in the Mexico City Metropolitan Area on PM10 and PM2.5 concentrations, using statistical analysis tools. MODIS-derived aerosol optical depth is used to assess the change of aerosols spatial distribution during the lockdown. Furthermore, a Mann-Whitney test is applied to PM10 and PM2.5 data from ground-based monitoring stations to evaluate the effects of lockdown. A general reduction of 20 % of PM10 and 10 % in PM2.5 was found. Overall, a 15 % reduction in particulate matter was found in Mexico City due to lockdown.PM10 and PM2.5 concentrations are regularly monitored because they cause adverse effects on human health. The concentrations of PM10 and PM2.5 vary within a city due to land use, the amount of traffic, and pollution sources. As the COVID-19 pandemic spread around the world, lockdowns were enacted to stop the spread of the virus. These lockdowns meant reduced mobility and the halt of certain economic activities which had an impact on air pollution sources. In this paper, we assess the effect of the lockdown enacted in April-May 2020 in the Mexico City Metropolitan Area on PM10 and PM2.5 concentrations, using statistical analysis tools. MODIS-derived aerosol optical depth is used to assess the change of aerosols spatial distribution during the lockdown. Furthermore, a Mann-Whitney test is applied to PM10 and PM2.5 data from ground-based monitoring stations to evaluate the effects of lockdown. A general reduction of 20 % of PM10 and 10 % in PM2.5 was found. Overall, a 15 % reduction in particulate matter was found in Mexico City due to lockdown
Sistema experto difuso para la calificación preliminar de proyectos de captura y almacenamiento de CO2
Get PDFCarbon dioxide capture and storage (CCS), as the process that separates CO2 emitted by industry and energy-related sources, transports it to a storage site and isolates it from the atmosphere over the long term, is an alternative for stabilizing atmospheric concentrations of greenhouse gases. The selection of the capture-storage site is a complex and multiparametric task that requires handling a large number of variables on the natural environment, infrastructure, and repercussions on the environment, among other parameters, and considering that the number of capture and storage sites from which to collect experiences for discarding or ratifying hypotheses, is still minimal. In this research, a diffuse expert system (DES) that assists in qualifying the susceptibility of a geographical context for the development of a CAC project, based on preliminary information on the state of the emission, the availability of infrastructure for transport, the tectonic environment, the specific qualities of the geological formations involved, the geothermal and pressure conditions, as well as the hydrodynamics of the system, is presented. The proposed DES extracts the experiences of experts on the subject who have rated environments and prioritized their effectiveness in CAC and translates them into clear rules that result in a rating for each site.La captura y almacenamiento de dióxido de carbono (CAC), como el proceso que separa el emitido por la industria y fuentes relacionadas con la energía, lo transporta a un lugar de almacenamiento y lo aísla de la atmósfera a largo plazo, es una alternativa para la estabilización de las concentraciones atmosféricas de gases de efecto invernadero. La selección del sitio de captación-almacenamiento es una tarea compleja y multiparamétrica que requiere el manejo de un gran número de variables sobre el medio natural, la infraestructura y las repercusiones en el ambiente, entre otros parámetros, así como tomar en cuenta que el número de sitios de captura y almacenamiento a partir de los cuales es posible compilar experiencias para descartar o ratificar hipótesis, aún es reducido. Al respecto, en esta investigación se presenta un sistema experto difuso (SED) que ayuda a calificar la susceptibilidad de un contexto geográfico para el desarrollo de un proyecto de CAC con base en información preliminar del estado de la emisión, la disponibilidad de infraestructura para el transporte, el ambiente tectónico, las cualidades específicas de las formaciones geológicas involucradas y las condiciones geotérmicas y de presión, así como la hidrodinámica del sistema. El SED propuesto extrae las experiencias de expertos en el tema que han calificado entornos y jerarquizado su efectividad en la CAC y lo traduce en reglas claras que resultan en una calificación para cada sitio
Measures to prevent cross-contamination in the analysis of microplastics: A short literature review
Get PDFMarine environments are the most studied habitats when addressing microplastic pollution. However, there are no standardized methodologies for this analysis, so methodologies are often adapted by researchers. This situation has raised doubts concerning the reliability and reproducibility of results that are related to the null or little use of measures to avoid cross-contamination. The objective of this work was to carry out a short review and analyze the different measures that have been reported in research articles for different marine habitats, published in the ScienceDirect database in 2020, to avoid cross-contamination during fieldwork and laboratory work. From the 115 analyzed articles, eight did not report measures at any stage, 61 took measures during sampling, and 98 did it in the processing stage. Even though most studies take steps to prevent cross-contamination, they do not specify the percentage of contamination avoided. However, from the concentrations of microplastics in the blanks and the total microplastic concentrations in the samples, we estimate that between 4.8 and 69 % of contamination is avoided in sampling and between 0.1 and 48.8 % in the laboratory. This shows the need to establish standards for sampling and sample processing, which must include measures regarding the marine environment studied and the stage addressed, as well as the minimum percentages that should be met for the data to be considered valid and reliable.Marine environments are the most studied habitats when addressing microplastic pollution. However, there are no standardized methodologies for this analysis, so methodologies are often adapted by researchers. This situation has raised doubts concerning the reliability and reproducibility of results that are related to the null or little use of measures to avoid cross-contamination. The objective of this work was to carry out a short review and analyze the different measures that have been reported in research articles for different marine habitats, published in the ScienceDirect database in 2020, to avoid cross-contamination during fieldwork and laboratory work. From the 115 analyzed articles, eight did not report measures at any stage, 61 took measures during sampling, and 98 did it in the processing stage. Even though most studies take steps to prevent cross-contamination, they do not specify the percentage of contamination avoided. However, from the concentrations of microplastics in the blanks and the total microplastic concentrations in the samples, we estimate that between 4.8 and 69 % of contamination is avoided in sampling and between 0.1 and 48.8 % in the laboratory. This shows the need to establish standards for sampling and sample processing, which must include measures regarding the marine environment studied and the stage addressed, as well as the minimum percentages that should be met for the data to be considered valid and reliable
Spatial modeling of physical and chemical parameters for the evaluation of the Río Puerta Grande stream in Mexico City
Get PDFThe Río Puerta Grande stream is in the Tarango micro-basin ravine in Mexico City and is considered environmental value area (EVA) due to its ecological importance. However, despite this, urban sewage is discharged into the stream. A physical, chemical, and biological characterization of its waters was realized in 2020 during the dry season and after the rainy season. As part of the analytical results, in situ and ex-situ parameter spatial distribution maps of seven sampling sites were obtained using ArcGIS software’s inverse distance weighted (IDW) interpolation tool. The variation in concentration for each parameter during the two seasons is shown on the maps, where red indicates the highest concentration and blue is the lowest. At the residual discharge sites, the concentration increased during the dry season; specific parameters in the period after the rainy season decreased due to a dilution effect, whereas others increased, such as fecal coliform, suspended solids, and biochemical oxygen demand (BOD). BOD revealed high concentrations during the dry season when it was influenced by urban discharge but decreased following the rainy season. Despite the low dissolved oxygen value between 4.39 and 3.80 mg/L, the stream does not currently show anoxia. Regarding the overall water quality index (WQI) during both periods, the stream’s water quality at all sites was “Highly contaminated,” according to Montoya et al. According to León-Dinius, the WQI was “Bad” in both seasons and in the period after the rainy season, it was deemed “Bad” and “Very bad”. The contaminants that should be considered as producing the most risk are organic matter (as reflected by BOD) and bacteriological pollutants.The Río Puerta Grande stream is in the Tarango micro-basin ravine in Mexico City and is considered environmental value area (EVA) due to its ecological importance. However, despite this, urban sewage is discharged into the stream. A physical, chemical, and biological characterization of its waters was realized in 2020 during the dry season and after the rainy season. As part of the analytical results, in situ and ex-situ parameter spatial distribution maps of seven sampling sites were obtained using ArcGIS software’s inverse distance weighted (IDW) interpolation tool. The variation in concentration for each parameter during the two seasons is shown on the maps, where red indicates the highest concentration and blue is the lowest. At the residual discharge sites, the concentration increased during the dry season; specific parameters in the period after the rainy season decreased due to a dilution effect, whereas others increased, such as fecal coliform, suspended solids, and biochemical oxygen demand (BOD). BOD revealed high concentrations during the dry season when it was influenced by urban discharge but decreased following the rainy season. Despite the low dissolved oxygen value between 4.39 and 3.80 mg/L, the stream does not currently show anoxia. Regarding the overall water quality index (WQI) during both periods, the stream’s water quality at all sites was “Highly contaminated,” according to Montoya et al. According to León-Dinius, the WQI was “Bad” in both seasons and in the period after the rainy season, it was deemed “Bad” and “Very bad”. The contaminants that should be considered as producing the most risk are organic matter (as reflected by BOD) and bacteriological pollutants
Alternative use of the hydrogel 3005K4® copolymer with ligninolytic enzymes for treating contaminated soil
Get PDFIn this study, we found that a copolymer of acrylamide and potassium acrylate (Hydrogel 3005K4®) in two particle sizes (1-2 mm and 2-4 mm) could absorb conditioned Galhaup media recovered from Trametes versicolor growth containing ligninolytic enzymes. It was found that the most efficient absorption capacity of the copolymer in the presence of the conditioned medium was using a 0.2:10 weight/volume (w/v) copolymer-conditioned medium ratio for both particle sizes. This ratio is a quarter of its absorption capacity in distilled water. A different desorption behavior of the medium was also observed, depending on whether the copolymer was exposed to the soil, water, or air. The ligninolytic enzyme media absorbed by the Hydrogel 3005K4® showed slower desorption of conditioned medium in soil for 10 days and faster desorption in air and water between 24 and 72 h. The enzymes were capable to preserve the activity after absorption. The versatility of this vector holding the enzymes may be attractive for reduce the presence of organic compounds (pesticides, polycyclic aromatic hydrocarbons, synthetic and natural dyes) on soil as part of a bioremediation technique, with a possibility of being reused.In this study, we found that a copolymer of acrylamide and potassium acrylate (Hydrogel 3005K4®) in two particle sizes (1-2 mm and 2-4 mm) could absorb conditioned Galhaup media recovered from Trametes versicolor growth containing ligninolytic enzymes. It was found that the most efficient absorption capacity of the copolymer in the presence of the conditioned medium was using a 0.2:10 weight/volume (w/v) copolymer-conditioned medium ratio for both particle sizes. This ratio is a quarter of its absorption capacity in distilled water. A different desorption behavior of the medium was also observed, depending on whether the copolymer was exposed to the soil, water, or air. The ligninolytic enzyme media absorbed by the Hydrogel 3005K4® showed slower desorption of conditioned medium in soil for 10 days and faster desorption in air and water between 24 and 72 h. The enzymes were capable to preserve the activity after absorption. The versatility of this vector holding the enzymes may be attractive for reduce the presence of organic compounds (pesticides, polycyclic aromatic hydrocarbons, synthetic and natural dyes) on soil as part of a bioremediation technique, with a possibility of being reused
Improved Prediction Method for Gas Hydrate Saturation in Sea Areas
Get PDFNinety-eight % of the world’s natural gas hydrate (commonly known as hydrate) are distributed in the stability zone of the sea areas. There are also rich hydrates in the stability zone of the Shenhu Sea Area in China. Drilling in the Shenhu Sea Area of China reveals that a lot of hydrate exist in suspension mode. Now the Wood method is for predicting hydrate in suspension mode, but the practical application in the Shenhu Sea Area shows that this method leads to large errors in predicting hydrate saturation. In order to address the problem of low accuracy of the Wood method in predicting hydrate saturation in suspension mode, this paper has first pointed out that the low accuracy of the Wood method is primarily caused by the systematic analytic error of stratigraphic parameters, which is derived from insufficient understanding of sediment composition and porosity in sea area by existing analytic technology. The paper puts forward the Wood-SE method alternatively. The practical application in the Shenhu Sea Area shows that the absolute error of this method mainly falls within the range of -10%, 10%. Most of the absolute error of the Wood method is above 20%. The error of main hydrate occurrence section could even reach 60%.Ninety-eight % of the world’s natural gas hydrate (commonly known as hydrate) are distributed in the stability zone of the sea areas. There are also rich hydrates in the stability zone of the Shenhu Sea Area in China. Drilling in the Shenhu Sea Area of China reveals that a lot of hydrate exist in suspension mode. Now the Wood method is for predicting hydrate in suspension mode, but the practical application in the Shenhu Sea Area shows that this method leads to large errors in predicting hydrate saturation. In order to address the problem of low accuracy of the Wood method in predicting hydrate saturation in suspension mode, this paper has first pointed out that the low accuracy of the Wood method is primarily caused by the systematic analytic error of stratigraphic parameters, which is derived from insufficient understanding of sediment composition and porosity in sea area by existing analytic technology. The paper puts forward the Wood-SE method alternatively. The practical application in the Shenhu Sea Area shows that the absolute error of this method mainly falls within the range of -10%, 10%. Most of the absolute error of the Wood method is above 20%. The error of main hydrate occurrence section could even reach 60%
Condiciones de trabajo y prácticas con plaguicidas en trabajadores de control de vectores en México
Get PDFIn Mexico, organophosphorus, carbamates and pyrethroid pesticides are used as part of the program for the control of diseases transmitted by the Aedes aegypti mosquito. Therefore, sprayer operators represent one of the populations with a higher risk of occupational exposure to these compounds. This study aimed to analyze the working conditions that increase the opportunity for pesticide exposure in workers employed in the program to control the adult A. aegypti mosquito in the state of Morelos, and how these conditions shape the work habits and their safety practices. We performed a qualitative study on the Health Services of Morelos workers involved in the vector-borne diseases control program. Data was obtained through focus groups and ethnographic records during April and May 2014. According to the gathered information from participants, the work environment and precarious working conditions modulate risk behaviors in pesticide handling by representing concrete barriers that hinder the adoption of safety measures. Hence, it is imperative to create working conditions aimed at reducing the incidence of pesticide exposure in health workers who perform chemical control of vector-borne diseases.En México se utilizan plaguicidas organofosforados, carbamatos y piretroides en el programa de manejo de enfermedades trasmitidas por Aedes aegypti, por lo que los trabajadores que laboran en dichos programas como fumigadores constituyen una de las poblaciones con mayor riesgo de exposición ocupacional a estos compuestos. El objetivo de este estudio fue analizar las condiciones de trabajo que incrementan la oportunidad de exposición a plaguicidas en el personal responsable del control del mosquito adulto A. aegypti en Morelos y cómo aquéllas moldean las prácticas de estos trabajadores. Se llevó a cabo un estudio cualitativo en 68 trabajadores de los Servicios de Salud de Morelos adscritos al programa de control de vectores. La información sobre condiciones de trabajo, percepción y prácticas de riesgo se obtuvo mediante grupos focales y registro etnográfico durante abril y mayo del 2014. De acuerdo con la información obtenida, el contexto de trabajo y las condiciones laborales precarias modulan las conductas de riesgo en el manejo de plaguicidas al representar barreras concretas que dificultan la adopción de medidas de seguridad. Los resultados de este estudio muestran la importancia de generar condiciones laborales destinadas a reducir la oportunidad de exposición a plaguicidas en el personal de salud que realiza tareas de control químico de enfermedades transmitidas por vector
Estudio de biomarcadores del petróleo a partir de la meteorización de un crudo en agua de mar
Get PDFWhen an oil spill occurs in aquatic systems, different weathering processes take place on this resource that modify its composition. As a result, it is difficult to assign responsibility for pollution caused by this resource. However, in crude oil there are molecules known as biomarkers with the potential to resist weathering processes depending on the exposure time, alteration kinetics and alteration phenomena that this resource undergoes when exposed to the environment. In the present work, the stability of biomarkers was analyzed for a crude oil spilled in seawater under laboratory conditions for a period of one year, with the objective of testing their usefulness in litigation related to oil spills and/or oil theft. To this end, biomarker profiles were analyzed by gas chromatography coupled to mass spectrometry from the crude fractions. Specific parameters such as Pr/n-C17 (pristane/heptadecane), 4-MeDBT/1-MeDBT (methyldibenzothiofene) y stigmastane C29αS/hopane C30 known as diagnostic ratios changed around values less than 5 % with respect to their relative standard deviation over the course of one year. Notably, the Pr/Ph ratios, (n-C13 + n-C14)/(n-C25 + n-C26) and (N0 + N1)/N2 (N = naphthalenes) were the only ones with percentages above 5 % and these results were associated with an evaporation process on the crude oil. On the other hand, the analysis of the chromatograms obtained indicated that biodegradation was also involved in the weathering of hydrocarbons. However, most of the biomarkers remained unaltered under the test conditions throughout the study time, which demonstrates their potential to solve the problems mentioned above.Cuando se produce un derrame de crudo sobre sistemas acuáticos tienen lugar diferentes procesos de meteorización sobre este recurso que modifican su composición. Como resultado de estas transformaciones se dificulta la asignación de responsabilidades respecto a las contaminaciones producidas con los hidrocarburos. Sin embargo, en el crudo existen unas moléculas conocidas como biomarcadores con el potencial de resistir los procesos de meteorización según el tiempo de exposición, la cinética de alteración y los fenómenos de transformación por los que atraviesa este recurso cuando es expuesto al ambiente. En el presente trabajo se analizó la estabilidad de los biomarcadores para un crudo vertido en agua de mar en condiciones de laboratorio por el período de un año, con el objetivo de probar su utilidad en litigios vinculados a derrames y hurtos de hidrocarburos. Para tal fin, se analizaron los perfiles de biomarcadores por cromatografía de gases acoplada a espectrometría de masas a partir de las fracciones del crudo. Además, se calcularon parámetros específicos tales como P/n-C17 (pristano/heptadecano), 4-MeDBT/1-MeDBT (metildibenzotiofenos) y estigmastano C29αS/hopano C30 conocidos como relaciones de diagnóstico que se modificaron en torno a valores menores del 5 % respecto de su desviación estándar relativa en el transcurso de un año. Cabe destacar que las relaciones P/F, (n-C13 + n-C14)/(n-C25 + n-C26) y (N0 + N1)/N2 (N = naftalenos) fueron las únicas con porcentajes por encima del 5 % y estos resultados se asociaron a un proceso de evaporación sobre el crudo. Por otro lado, el análisis de los cromatogramas obtenidos indicó que la biodegradación también estuvo implicada en la meteorización de los hidrocarburos. Sin embargo, la mayoría de los biomarcadores permanecieron inalterados bajo las condiciones de ensayo a lo largo del tiempo de estudio lo que demuestra su potencialidad para resolver los problemas antes mencionados
Uso de la harina del pez diablo (Pterygoplichthys spp.) en la fertilización orgánica del tomate (Solanum lycopersicum L.)
Get PDFThe devilfish (Pterygoplichthys spp.) has been reported as an invasive species in several ecosystems of the state of Chiapas, Mexico. The objective of this study was to evaluate the effect of the application times of devil fish flour (DFF) as a source of organic fertilization on Solanum lycopersicum L. var. Río Grande under greenhouse conditions. Soil without flour (SDFF), soil and flour 15 days before transplanting (DFF15), and ground with flour at the transplanting time (DFF0), respectively, constituted the experiment. It was identified that DFF had high protein, ash, phosphorus, and potassium contents (46.22, 31.13, 3.43, and 2.3 %, respectively). Plant height showed a 13 % increase at 126 days after transplanting with DFF15, and a 52 % increase in stem thickness compared to SDFF. Foliage dry weight increased 5.8-fold in DFF0 and 1.8-fold for root length in DFF15. Also, DFF15 increased the chlorophyll content in tomato leaves by up to 39.8 %. DFF15 fruits were the only ones that achieved physiological and commercial maturity, meeting consumption criteria for polar and equatorial diameter, and lycopene content (5.7 and 5.2 cm, and 0.017 mg/g fruit fresh weight, respectively). The results obtained from the devilfish meal show its suitability for use as an organic fertilizer in agricultural production.Se ha reportado al pez diablo (Pterygoplichthys spp.) como especie invasora en diversos ecosistemas del estado de Chiapas, México. El objetivo de este estudio fue evaluar el efecto de los tiempos de aplicación de la harina del pez diablo (HPD) como fuente de fertilización orgánica en el cultivo de Solanum lycopersicum L. var. Río Grande en condiciones de invernadero. En el experimento se utilizó suelo sin harina (SHPD), suelo y harina 15 días antes del trasplante (HPD15) y suelo con harina al momento del trasplante (HPD0). Se identificó que la HPD presentó un elevado contenido en proteínas, cenizas, fósforo y potasio (46.22, 31.13, 3.43 y 2.3 %, respectivamente). La altura de la planta mostró un aumento del 13 % a los 126 días después del trasplante con HPD15, así como un aumento del 52 % en el grosor del tallo en comparación con SHPD. El peso seco del follaje aumentó 5.8 veces en HPD0 y 1.8 veces para la longitud de la raíz en HPD15. Además, HPD15 pudo aumentar el contenido de clorofila en las hojas de tomate hasta en un 39.8 %. Los frutos de HPD15 fueron los únicos que lograron madurez fisiológica y comercial, cumpliendo con los criterios de consumo en el diámetro polar y ecuatorial, y contenido de licopeno (5.7 y 5.2 cm, y 0.017 mg/g de peso fresco de fruto, respectivamente). Los resultados obtenidos a partir de la harina de pez diablo, muestran que se puede utilizar como abono orgánico en la producción agrícola