Revista Internacional de Contaminación Ambiental
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CONCENTRACIÓN DE CADMIO EN AGUA, SEDIMENTOS, Eichhornia crassipes Y Pomacea canaliculata EN EL RÍO GUAYAS (ECUADOR) Y SUS AFLUENTES
Get PDFIn Ecuador there is evidence of contamination by Cd in the Gulf of Guayaquil, however, little is known about the contamination by this metal in its tributaries. Evaluating the contamination by cadmium in water, sediments, flora as Eichhornia crassipes and fauna as Pomacea canaliculata in the Guayas river and the tributaries, Daule and Babahoyo rivers was the main purpose of this research. Nine stations were sampled, five samples of water, sediment and organisms were taken on each location. Cd concentrations and bioconcentration factors (BCF) were determined. In addition, pH, temperature and salinity parameters were measured. The concentrations of Cd in water were not detectable, while in sediments eight of a total of nine stations exceeded the maximum permissible limits according to the Ecuadorian standard and the Canadian Environmental Quality Guidelines. However, the bioavailable concentrations of the metal in the sediment were lower than the probable effect level (PEL) and the Canadian reference value, minimizing possible damage to the biota. The water hyacinth accumulated higher concentrations of Cd than the gastropod and presented BCF greater than one, indicating that it is a good biomonitor of Cd, unlike the snail. Correlation was also observed between the physical and chemical parameters and the availability of the metal in the sediment and its accumulation in the organisms. It is concluded that there is contamination by Cd in the three rivers and that the E. crassipes can be used as biomonitor of bioavailability of the metal in the ecosystem.En Ecuador existen evidencias de contaminación por cadmio en el Golfo de Guayaquil, sin embargo, poco se conoce sobre la contaminación por este metal en sus ríos afluentes. El propósito de la investigación fue evaluar la contaminación por cadmio en agua, sedimentos, jacinto de agua Eichhornia crassipes y en el caracol Pomacea canaliculata en los ríos Guayas, Daule y Babahoyo. Para ello, se muestrearon nueve estaciones en total, se tomaron cinco muestras de agua, cinco de sedimentos y cinco de organismos por localidad, se determinaron las concentraciones de Cd y los factores de bioconcentración (FBC). Además, se midieron los parámetros pH, temperatura y salinidad. El Cd en agua no fue detectable en los sitios estudiados, mientras que en sedimentos ocho de las nueve estaciones excedieron los límites máximos permisibles según la norma ecuatoriana y la norma canadiense de calidad ambiental. Sin embargo, las concentraciones biodisponibles del metal en el sedimento fueron inferiores al nivel de efecto probable (PEL) y al valor de referencia canadiense, minimizando los posibles daños a la biota. El jacinto de agua acumuló mayores concentraciones de Cd que el gasterópodo y presentó FBC mayores a uno, indicando que es un buen biomonitor de Cd, a diferencia del caracol. También se evidenció correlación entre los parámetros físicos y químicos y la disponibilidad del metal en el sedimento y su acumulación en los organismos. Se concluye que existe contaminación por Cd en los tres ríos y se propone el monitoreo anual de estos, utilizando la especie E. crassipes como biomonitora
ASSESSMENT OF A SIMPLE EXTRACTION METHOD TO DETERMINE THE BIOACCESSIBILITY OF POTENTIALLY TOXIC Tl, As, Pb, Cu, Zn AND Cd IN SOILS CONTAMINATED BY MINING-METALLURGICAL WASTE
Get PDFThe potential to determine the gastric bioaccessibility (BA) of Tl, As, Pb(II), Cu(II), Zn(II) and Cd(II) using a simple extraction method was evaluated in selected samples from soils contaminated by mining and metallurgical wastes. The SBRC (Solubility and Bioavailability Research Consortium) test was used as a gastric BA comparative method versus a simple extraction method using HCl solution at pH 1.5. High correlations (r ≥ 0.98, p ˂ 0.01) were obtained between the two extraction methods for Cd(II), Cu(II), Tl and Zn(II), in all samples investigated. Bioaccessible As, however, only showed a high correlation in the metallurgical area (r = 0.99, p ˂ 0.01), but not in the mining area (r = 0.88, p ˂ 0.01). Conversely, Pb(II) showed a better correlation in samples from the mining area (r = 0.99, p ˂ 0.01) than in those of the metallurgical area (r = 0.92, p ˂ 0.01). Three experimental conditions of the extraction procedures ensured the high correlations observed: (1) Maintaining a strict pH control of 1.5 (± 0.1), (2) a stirring time of 1 h (± 1 min), and (3) filtration of the extraction mixture through a membrane of small pore size (0.05 µm). Bioaccessible Tl was detected in all samples, a fact that has not been reported before in these environments, and alerts to potential health risks not previously identified.The potential to determine the gastric bioaccessibility (BA) of Tl, As, Pb(II), Cu(II), Zn(II) and Cd(II) using a simple extraction method was evaluated in selected samples from soils contaminated by mining and metallurgical wastes. The SBRC (Solubility and Bioavailability Research Consortium) test was used as a gastric BA comparative method versus a simple extraction method using HCl solution at pH 1.5. High correlations (r ≥ 0.98, p ˂ 0.01) were obtained between the two extraction methods for Cd(II), Cu(II), Tl and Zn(II), in all samples investigated. Bioaccessible As, however, only showed a high correlation in the metallurgical area (r = 0.99, p ˂ 0.01), but not in the mining area (r = 0.88, p ˂ 0.01). Conversely, Pb(II) showed a better correlation in samples from the mining area (r = 0.99, p ˂ 0.01) than in those of the metallurgical area (r = 0.92, p ˂ 0.01). Three experimental conditions of the extraction procedures ensured the high correlations observed: (1) Maintaining a strict pH control of 1.5 (± 0.1), (2) a stirring time of 1 h (± 1 min), and (3) filtration of the extraction mixture through a membrane of small pore size (0.05 µm). Bioaccessible Tl was detected in all samples, a fact that has not been reported before in these environments, and alerts to potential health risks not previously identified
ACETILCOLINESTERASA DE Eisenia foetida COMO INDICADOR DE CONTAMINACIÓN POR PLAGUICIDAS ORGANOFOSFORADOS
Get PDFOrganophosphates are among the most used and the most toxic pesticides that inhibit acetylcholinesterase. The enzyme aceticolinesterase (AChE) is widely used to detect organophosphate pollutants because they are inhibitors of its activity. A source of this enzyme is present in Eisenia foetida, being the AChEs of these earthworms susceptible to this effect. In this work, an enzymatic concentrate of acetylcholinesterase was prepared from E. foetida. The inhibitory effect of commercial organophosphorus pesticides as malathion, diazinon, methamidophos and dimethoate on its enzymatic activity was evaluated, as well as its selectivity when using organochlorine, carbamate and pyrethroid pesticides. Acetylcholinesterase activity was measured using indoxyl acetate as chromogenic substrate. Results showed that all organophosphorus pesticides tested, in concentrations between 1-10 mg/L, were able to decrease acetylcholinesterase activity in percentages of 36 ± 16 % on average. On the other hand, carbamates slightly inhibited the enzymatic activity in a 16 ± 7 %, and organochlorines and pyrethroids showed a little or no significant inhibitory effect of 1 ± 5 % for any tested concentrations. This is because the mode of action of each group of pesticides is different. For this reason, the activity of the enzyme is not significantly affected and it remains catalyzing the decomposition of indoxyl acetate even in the presence of pesticides with chemical groups different to organophosphates, which is indicative of acetylcholinesterase selectivity against this specific type of inhibitors.Entre los plaguicidas inhibidores de la acetilcolinesterasa más usados en la actualidad, y a su vez los más tóxicos, se encuentran los organofosforados. La enzima acetilcolinesterasa (AChE) es ampliamente utilizada para la detección de contaminantes organofosforados, ya que éstos son inhibidores de su actividad. La lombriz de tierra (Eisenia foetida) es una fuente de esta enzima, ya que las AChE presentes en estas lombrices son susceptibles a dicho efecto. En este trabajo se preparó un concentrado enzimático de acetilcolinesterasa de E. foetida, con el cual se evaluó el efecto inhibitorio de plaguicidas organofosforados comerciales como malatión, diazinón, metamidofos y dimetoato, así como su selectividad al utilizar plaguicidas organoclorados, carbamatos y piretroides. La actividad de acetilcolinesterasa se midió usando acetato de indoxilo como sustrato cromogénico. Los resultados mostraron que todos los plaguicidas organofosforados ensayados en concentraciones de 1 a 10 mg/L fueron capaces de disminuir la actividad de acetilcolinesterasa en porcentajes de 36 ± 16 % en promedio, mientras que los carbamatos inhibieron sólo ligeramente la actividad enzimática en un 16 ± 7 %. Los organoclorados y piretroides por su parte presentaron efecto inhibitorio poco o no significativo de 1 ± 5 % para cualquiera de las concentraciones ensayadas debido a que el modo de acción de los grupos de plaguicidas es diferente. Por este motivo, la actividad de la enzima no se ve afectada de manera significativa y continúa catalizando la descomposición del acetato de indoxilo aun en presencia de plaguicidas con grupos químicos diferentes a los organofosforados, lo cual obedece a la selectividad de la acetilcolinesterasa frente a este tipo de inhibidores.
INHIBICIÓN DE LA BUTIRILCOLINESTERASA EN EL GORRIÓN CASERO EXPUESTO A MALATIÓN
Get PDFThe effect of malathion (organophosphate insecticide) on individuals of the house sparrow (Passer domesticus) caught in an agricultural area of the municipality of Durango, Mexico, was estimated. Butyrylcholinesterase is inhibited by organophosphorus insecticides, therefore, its previous and subsequent activity to the consumption of food treated with malathion was determined in 19 organisms by spectrophotometry. The results show a decrease in BChE activity (11.58 %) after treatment (p = 0.03). The possible relationship between the weight of the birds and BChE activity before and after exposure to the organophosphorus insecticide was explored but no correlation was found between these two variables (Pearson, r = 0.114), so it was decided not to use the variable weight as a covariate in the analyses to compare the enzymatic activity of the birds. The weight of the birds decreased on average 1.54 g after the exposure, possibly due to the stress of capture and the lack of adaptation to captivity. It is possible that the house sparrow and other birds that co-inhabit the agricultural areas where malathion is applied, as well as other organophosphorus insecticides, are prone to develop different levels of intoxication and that in some cases their health condition is compromised.Se estimó el efecto del malatión (insecticida organofosforado) en individuos de gorrión casero (Passer domesticus) capturados en una zona agrícola del municipio de Durango, México. La butirilcolinesterasa se inhibe con los insecticidas organofosforados, por ello mediante espectrofotometría se determinó su actividad previa y posterior al consumo de alimento tratado con malatión en 19 organismos. Los resultados muestran una disminución de la actividad BChE (11.58 %) posterior al tratamiento (p = 0.03). Se exploró la posible relación entre el peso de las aves y la actividad BChE antes y después de la exposición al insecticida organofosforado pero no se encontró correlación entre estas dos variables (Pearson, r = 0.114), por lo que se decidió no utilizar la variable peso como covariable en los análisis para comparar la actividad enzimática de las aves. El peso de las aves disminuyó en promedio 1.54 g posterior a la exposición, posiblemente debido al estrés de captura y la falta de adaptación al cautiverio. Es posible que el gorrión casero y otras aves que cohabitan en las zonas agrícolas donde se aplica malatión, así como otros insecticidas organofosforados, sean propensos a desarrollar diferentes niveles de intoxicación y que en algunos casos se comprometa su estado de salud
ECOTOXICOLOGICAL BIOASSAYS IN QUANTUM DOTS NANOPARTICLES WITH THE MICROALGAE Pseudokirchneriella subcapitata
Get PDFQuantum dots (QDs) nanoparticles are increasingly being used for electronics devices, solar energy generation and medical imaging applications. While the new properties of nanoparticles are more and more studied, little is known about their interactions with aquatic organisms. As a primary producer, phytoplankton serves as an important component of the aquatic ecosystem. According to our bibliographic search, no reports were found on the evaluation of ecotoxicity of QDs in Pseudokirchneriella subcapitata. In this study, QDs were evaluated using ecotoxicological bioassays (cellular toxicity models and potential indicators of the impact in aquatic ecosystems) with the microalgae P. subcapitata. With ecotoxicity concentrations of 0, 1, 2, 3 and 4 nM of QDs with P. subcapitata at 96 h exposure a mean inhibitory concentration of growth (IC50) of the microalgae P. subcapitata IC50 = 1,94 nM of QDs(a) was obtained for orange fluorescence; IC50 = 1.68 nM of QDs(r) for red fluorescence, and IC50 = 2.03 nM of QDs(v) for green fluorescence, observing the following order of sensitivity: QDs (r) ˃ QDs (a) ˃ QDs (v). The toxicity of the QDs are evident by the type of fluorescence detected in the standard solution 4 M of QDs and 10-1M. The images of confocal microscopy of fluorescence showed adhesions of QDs in microalgal cells until low concentrations with high growth rates of P. subcapitata at concentrations of 1 nM compared to concentrations of 10-1 M of QDs nanoparticles with low growth rates.Quantum dots (QDs) nanoparticles are increasingly being used for electronics devices, solar energy generation and medical imaging applications. While the new properties of nanoparticles are more and more studied, little is known about their interactions with aquatic organisms. As a primary producer, phytoplankton serves as an important component of the aquatic ecosystem. According to our bibliographic search, no reports were found on the evaluation of ecotoxicity of QDs in Pseudokirchneriella subcapitata. In this study, QDs were evaluated using ecotoxicological bioassays (cellular toxicity models and potential indicators of the impact in aquatic ecosystems) with the microalgae P. subcapitata. With ecotoxicity concentrations of 0, 1, 2, 3 and 4 nM of QDs with P. subcapitata at 96 h exposure a mean inhibitory concentration of growth (IC50) of the microalgae P. subcapitata IC50 = 1,94 nM of QDs(a) was obtained for orange fluorescence; IC50 = 1.68 nM of QDs(r) for red fluorescence, and IC50 = 2.03 nM of QDs(v) for green fluorescence, observing the following order of sensitivity: QDs (r) ˃ QDs (a) ˃ QDs (v). The toxicity of the QDs are evident by the type of fluorescence detected in the standard solution 4 M of QDs and 10-1M. The images of confocal microscopy of fluorescence showed adhesions of QDs in microalgal cells until low concentrations with high growth rates of P. subcapitata at concentrations of 1 nM compared to concentrations of 10-1 M of QDs nanoparticles with low growth rates
HORMIGÓN SUSTENTABLE BASADO EN FIBRAS DE NEUMÁTICOS FUERA DE USO
Get PDFWaste tires are considered to be massive trash and are usually abandoned in legal or illegal landfills. Their abandonment is associated with environmental impacts on land use and visual pollution, among others. Conversely, its recycling allows to valorize these residues by generating by-products such as rubber granules, steel fibers and textile fibers for new industrial applications. Several studies report the use of rubber and steel fibers of waste tires in concrete. The objective of this research was to compare the mechanical strength of concrete without the addition of tires residues (control group) at the ages of 7, 17 and 28 days, to concrete added with commercial steel fiber, and rubber and steel fibers from waste tires. The doses used were 50 kg/m3 in concrete with commercial steel fiber, 10.5 and 7 kg/m3 in concrete with recycled rubber granules, and 50 and 35 kg/m3 in concrete with recycled steel fibers. The results indicated that concretes with the addition of rubber and steel fibers showed in all cases a slight decrease in the compressive strength compared to the witness at the age of 28 days. Conversely, concrete with the addition of steel and rubber fibers presented better flexural strength than the witness concrete, except in the case of concrete with 50 kg/m3 of recycled steel fiber.Los neumáticos fuera de uso se consideran residuos masivos y normalmente son abandonados en vertederos legales o ilegales. Su abandono se asocia con impactos medioambientales en el uso del suelo y la contaminación visual, entre otros. Por el contrario, su reciclado permite valorizar estos residuos al generar subproductos tales como gránulos de caucho, fibras de acero y fibras textiles para nuevas aplicaciones industriales. Diversos estudios reportan la utilización de fibras de caucho y de acero de neumáticos fuera de uso en hormigones. El objetivo de esta investigación fue evaluar y comparar la resistencia mecánica de un hormigón sin adición (testigo) a las edades de 7, 17 y 28 días, con hormigones con adición de fibra de acero comercial, fibras de caucho y fibras de acero de neumáticos fuera de uso. Las dosis utilizadas fueron 50 kg/m3 en hormigones con fibra de acero comercial, 10.5 y 7 kg/m3 en hormigones con fibras de caucho reciclado, y 50 y 35 kg/m3 en hormigones con fibras de acero reciclado. Los resultados indicaron que los hormigones con adiciones de fibras de caucho y fibras de acero presentaron en todos los casos una leve disminución de la resistencia a la compresión respecto del testigo a la edad de 28 días. Por el contrario, los hormigones con adiciones de fibras de acero y fibras de caucho presentaron mejor resistencia a la flexo-tracción que el hormigón testigo, excepto el hormigón con dosis de 50 kg/m3 de fibra de acero reciclado
EVALUACIÓN DEL PROCESO DE COMPOSTAJE DE RESIDUOS AVÍCOLAS EMPLEANDO DIFERENTES MEZCLAS DE SUSTRATOS
Get PDFAgricultural residues, particularly those from poultry activity, may have a negative impact, contributing to soil, water and air pollution. The composting process is an alternative to this. The objective of this work is to reuse these residues and evaluate the composting process at the laboratory level in four treatments: poultry manure + straw (P + S), poultry manure + straw + ash (P + S + A), poultry manure + straw + eggs (P + S + E), and poultry manure + straw + eggs + ash (P + S + E + A),all of them in the adequate proportions so that the carbon:nitrogen ratio is suitable for composting (C/N < 20). Additionally, for comparative studies, a semi-industrial pile level of 20 m3 under environmental conditions and a bioassay of the final compost were carried out to measure its phytotoxicity. In order to evaluate the composting process, the physical and chemical parameters (pH, electrical conductivity [EC], organic matter [OM], nitrogen [N] and C/N ratio) were analyzed, with their respective analysis of variance of multiple range, to determine the effect of the treatments; to compare the means, the least significant difference test was used at a level of significance of p ≤ 0.05. The results obtained from the different mixes of substrates during the time the compost was done, showed a good agronomic quality, not presenting concentrations of phytotoxic compounds that affect crops; therefore, it can be used as organic fertilizer and cultivation substrate.Los residuos agropecuarios, en particular los procedentes de la actividad avícola, pueden contribuir a la contaminación del suelo, agua y aire, y generar un impacto negativo, siendo el proceso de compostaje una alternativa. Este trabajo ha tenido como objetivo reutilizar estos residuos y evaluar el proceso de compostaje a nivel de laboratorio en cuatro tratamientos: gallinaza + paja (G + P), gallinaza + paja + cenizas (G + P + C), gallinaza + paja + huevos (G + P + H), y gallinaza + paja + huevos + cenizas (G + P + H + C), todos ellos con la cantidades adecuadas para que la relación C/N < 20 sea idónea para el compostaje. Adicionalmente, para estudios comparativos se realizó una pila a escala semiindustrial de 20 m3 en condiciones ambientales y un bioensayo del compost final para medir su fitoxicidad. Con el fin de evaluar el proceso de compostaje, en los tratamientos y en la pila se realizaron análisis físicos y químicos de los siguientes parámetros: pH, conductividad eléctrica (CE), materia orgánica (MO), nitrógeno (N) y relación carbono:nitrógeno (C/N), con sus respectivos análisis de varianza de múltiple rango. Para determinar el efecto de los tratamientos y comparar las medias se utilizó la prueba de la mínima diferencia significativa a un nivel de significación de p ≤ 0.05. Los resultados obtenidos a partir de las diferentes mezclas de sustratos en el tiempo en que se realizó el compostaje, reflejan una buena calidad agronómica, ya que éste no presentó concentraciones de compuestos fitotóxicos que afecten los cultivos y por lo tanto puede utilizarse como abono orgánico y sustrato de cultivos
PRINCIPALES PROCESOS QUE IMPACTAN LA CALIDAD DEL AGUA PARA EL RIEGO EN POZOS COSTEROS DEL CENTRO SUR CUBANO
Get PDFWater quality is a variable to be controlled in irrigated agriculture. The objective of the present investigation was to identify the main processes that impact water quality for irrigation in wells located in the southeast of the coast of Cienfuegos Bay. A database from Hydraulic Resources enterprise was used, which included the concentrations of the major components and the electrical conductivity of the water of seven wells during the 1983-2013 period. To facilitate the data processing, a similarity analysis was performed that found three groups of wells with different physical and chemical characteristics. The identification of influential processes in each group was achieved through ionic relations and principal component analysis. In the characterization of water for irrigation, the following indicators were used: potential salinity (SP), permeability index (IP), sodium adsorption ratio, possible sodium percentage, residual sodium carbonate, electrical conductivity, total hardness (TH), Kelly relation and adsorption ratio of magnesium. The water of the three groups was calcium carbonate, with a higher proportion of these ions in the first group. The main processes identified were: rock washing, cation exchange, chloride and sodium contribution and salinization of the waters. The water met the requirements for irrigation; however, in the wells of the second and third group, there was an increase in the TH indicator, with a decrease in the PI related to anthropogenic activities developed in the basins.La calidad del agua constituye una variable a controlar en la agricultura de regadío. El objetivo de la investigación fue identificar los principales procesos que impactaron la calidad del agua para el riego en pozos ubicados en sureste del litoral de la bahía Cienfuegos. Los datos proceden de la empresa Recursos Hidráulicos e incluye las concentraciones de los componentes mayoritarios y la conductividad eléctrica (CE) del agua de siete pozos, durante la etapa 1983-2015. Para facilitar el tratamiento se aplicó un análisis de similitud y se obtuvieron tres grupos de pozos con diferentes características físicas y químicas. La identificación de los procesos influyentes en cada grupo se logró mediante las relaciones iónicas y el análisis de componentes principales. En la caracterización del agua para el riego se usaron los indicadores: salinidad potencial (SP), índice de permeabilidad (IP), relación de adsorción del sodio (RAS), porciento de sodio posible (PSP), carbonato de sodio residual (CSR), CE, dureza total (DT), relación de Kelly (RK) y relación de adsorción del magnesio (RAM). El agua de los tres grupos fue bicarbonatada cálcica, con mayor proporción de estos iones en el primer grupo. Los principales procesos identificados fueron: lavado de la roca, intercambio catiónico, aporte de cloruro y sodio y la salinización de las aguas. El agua cumplió los requisitos establecidos para el riego. Sin embargo, en los pozos del segundo y tercer grupo se observó un incremento en la DT y una disminución del IP vinculado a actividades antrópicas desarrolladas en las cuencas
THE FINITE ELEMENT ANALYSIS OF EN ZI TAN AQUEDUCT IN OPERATION PERIOD
Get PDFAs the water resources distribution in China is extremely uneven, inter-basin water transfer project has become an important part of China’s water conservancy construction. As part of the the major hydraulic structure in water delivery network across rivers and transportation routes, the design and analysis on aqueduct is important. En Zi Tan Aqueduct is located in Shimen County of Hunan in China. Main content of this paper is about the finite element analysis of the aqueduct on operation period. En Zi Tan Aqueduct is designed flow is of 5.0m3/s, longitudinal slope of 1/650, a total length of 1001m. The aqueduct is simple supported beam type, main body is reinforced concrete structure, the cross section is U-shaped and groove in each section length 13m. Top of the tank unilateral laying the bridge deck and railings in order to facilitate pedestrians. The study is using general finite element software to analize, stress and deformation changes on aqueduct body in the operation process; the water load and the earthquake influence on stress and deformation of aqueduct.As the water resources distribution in China is extremely uneven, inter-basin water transfer project has become an important part of China’s water conservancy construction. As part of the the major hydraulic structure in water delivery network across rivers and transportation routes, the design and analysis on aqueduct is important. En Zi Tan Aqueduct is located in Shimen County of Hunan in China. Main content of this paper is about the finite element analysis of the aqueduct on operation period. En Zi Tan Aqueduct is designed flow is of 5.0m3/s, longitudinal slope of 1/650, a total length of 1001m. The aqueduct is simple supported beam type, main body is reinforced concrete structure, the cross section is U-shaped and groove in each section length 13m. Top of the tank unilateral laying the bridge deck and railings in order to facilitate pedestrians. The study is using general finite element software to analize, stress and deformation changes on aqueduct body in the operation process; the water load and the earthquake influence on stress and deformation of aqueduct