Revista Internacional de Contaminación Ambiental
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Heat transfer analysis of cellular heat exchanger based on a fresh fractal Vicsek model by Galerkin finite element method
Get PDFThe energy density is increasing in modern industry, and the lack of heat transfer efficiency is one of the fatal problems of current equipment, which seriously affects the improvement of production level. The cellular heat exchanger is a kind of heat exchanger used in different fields. It plays an irreplaceable role in energy saving, efficiency improvement and reducing pressure drop. However, when the geometric shape of the fractal heat exchanger is very complex, the heat transfer analysis is impossible or difficult to show. Therefore, the objective of this project is to solve the difficulty of analysis on complex fractal heat exchangers and have a better representation of the physics. A totally fresh tessellation method, which can be used to analyze complex fractal heat exchangers, is introduced in this essay. By the research process, surjective hole-fill maps for Vicsek fractal were established, and Vicsek fractal was represented by continuous tessellations, and the fractal Vicsek model was expressed by continuous subdivision. The transfer theory on fractals and Galerkin finite element method were used to analyze the heat transfer of fractals and tessellations. The results of two analyses, the fractal model and the tesselation model, were almost the same, and confirm the function of the tessellation method in the analysis of complex heat exchangers. Furthermore, it provides a new way to solve the difficult problem of heat transfer analysis of complex geometric heat exchangers.The energy density is increasing in modern industry, and the lack of heat transfer efficiency is one of the fatal problems of current equipment, which seriously affects the improvement of production level. The cellular heat exchanger is a kind of heat exchanger used in different fields. It plays an irreplaceable role in energy saving, efficiency improvement and reducing pressure drop. However, when the geometric shape of the fractal heat exchanger is very complex, the heat transfer analysis is impossible or difficult to show. Therefore, the objective of this project is to solve the difficulty of analysis on complex fractal heat exchangers and have a better representation of the physics. A totally fresh tessellation method, which can be used to analyze complex fractal heat exchangers, is introduced in this essay. By the research process, surjective hole-fill maps for Vicsek fractal were established, and Vicsek fractal was represented by continuous tessellations, and the fractal Vicsek model was expressed by continuous subdivision. The transfer theory on fractals and Galerkin finite element method were used to analyze the heat transfer of fractals and tessellations. The results of two analyses, the fractal model and the tesselation model, were almost the same, and confirm the function of the tessellation method in the analysis of complex heat exchangers. Furthermore, it provides a new way to solve the difficult problem of heat transfer analysis of complex geometric heat exchangers
Water security comprehensive evaluation model based on comprehensive weight and improved matter-element
Get PDFAs a multi-objective decision-making system, water security evaluation is suitable for the evaluation with a matter-element model. However, in the traditional matter-element model, the eigenvalue of matter-element cannot be calculated when it is beyond the range of nodes, and the calculation process is complex and error-prone. In this paper, improved analytic hierarchy process with entropy weight were combined to calculate the water security comprehensive evaluation index weight, avoiding the over-subjective or over-objective weight value. The normalization of matter-element improves the rationality of the matter-element correlation function and expands the application scope of the model, while the standardization of comprehensive proximity improves the accuracy of model results. Guangdong Province was taken as an example to verify the practicability of the model in the evaluation of the water security comprehensive index. The results show that from 2004 to 2019, the overall water security of Guangdong Province showed a trend rising from deteriorated grade to safe grade and the model results were in line with the facts. As a result, the water security comprehensive evaluation model based on comprehensive weight and improved matter-element is simple, practical, and suitable for the multi-level and multi-factor regional water security comprehensive evaluation.As a multi-objective decision-making system, water security evaluation is suitable for the evaluation with a matter-element model. However, in the traditional matter-element model, the eigenvalue of matter-element cannot be calculated when it is beyond the range of nodes, and the calculation process is complex and error-prone. In this paper, improved analytic hierarchy process with entropy weight were combined to calculate the water security comprehensive evaluation index weight, avoiding the over-subjective or over-objective weight value. The normalization of matter-element improves the rationality of the matter-element correlation function and expands the application scope of the model, while the standardization of comprehensive proximity improves the accuracy of model results. Guangdong Province was taken as an example to verify the practicability of the model in the evaluation of the water security comprehensive index. The results show that from 2004 to 2019, the overall water security of Guangdong Province showed a trend rising from deteriorated grade to safe grade and the model results were in line with the facts. As a result, the water security comprehensive evaluation model based on comprehensive weight and improved matter-element is simple, practical, and suitable for the multi-level and multi-factor regional water security comprehensive evaluation
Acute toxicity of the herbicide karmex (diuron) in Macrobrachium acanthurus and M. olfersii prawns
Get PDFFarmers have increased the production of food by using chemical substances such as diuron; however, these components affect the water quality and the species found in these ecosystems. Macrobrachium acanthurus and M. olfersii postlarvae present in the estuary of Río Jamapa, Veracruz were collected to measure the LC50 and LD50 using the herbicide Karmex (diuron: (3-(3,4-dichlorophenyl)-1,1-dimethylurea [DCMU]). The captures of the prawns were made with light traps. Acute toxicity bioassays were carried out at 96 h to determine the mean lethal concentration (LC50). In the experimental design, a geometric series was used considering the control and five concentrations of the herbicide (1.75, 3.5, 6.99, 14, and 28 mg/L). The data analysis was carried out with the Probit method. A maximum LC50 of 10.233 mg/L and LD50 of 8.221 mg/L of Karmex were obtained for M. acanthurus and a maximum LC50 of 9.242 mg/L and LD50 of 7.504 mg/L of Karmex were obtained for M. olfersii. The average lethal concentration was consistent with those of other crustaceans, such as Artemia salina and Daphnia. Based on the response in the bioassays, Macrobrachium acanthurus and M. olfersii postlarvae can be used in toxicology studies.Farmers have increased the production of food by using chemical substances such as diuron; however, these components affect the water quality and the species found in these ecosystems. Macrobrachium acanthurus and M. olfersii postlarvae present in the estuary of Río Jamapa, Veracruz were collected to measure the LC50 and LD50 using the herbicide Karmex (diuron: (3-(3,4-dichlorophenyl)-1,1-dimethylurea [DCMU]). The captures of the prawns were made with light traps. Acute toxicity bioassays were carried out at 96 h to determine the mean lethal concentration (LC50). In the experimental design, a geometric series was used considering the control and five concentrations of the herbicide (1.75, 3.5, 6.99, 14, and 28 mg/L). The data analysis was carried out with the Probit method. A maximum LC50 of 10.233 mg/L and LD50 of 8.221 mg/L of Karmex were obtained for M. acanthurus and a maximum LC50 of 9.242 mg/L and LD50 of 7.504 mg/L of Karmex were obtained for M. olfersii. The average lethal concentration was consistent with those of other crustaceans, such as Artemia salina and Daphnia. Based on the response in the bioassays, Macrobrachium acanthurus and M. olfersii postlarvae can be used in toxicology studies
EFECTO GENOTÓXICO DE DOS TINTAS EMPLEADAS EN EL ARTE DEL TATUAJE
Get PDFThe present study provides answers about the genotoxic effect of two inks used in the art of tattooing. Currently, there is no information on the genotoxic effects that some of the chemical compounds in this inks can produce on human health. The objective of this study was to know the genotoxic effects of black and white ink, mostly used in tattoo art. In this investigation, the micronucleus test was applied in peripheral blood cells of CD-1 mice and the structural chromosomal aberration test in human lymphocyte cultures. The results obtained indicated that the average values of both the dividing cells (% IM), the frequency of micronuclei (% MCN) in the peripheral blood cells of the mice and the average number of structural chromosomal aberrations in human lymphocyte cells showed significant differences, therefore they were subjected to Dunnett’s multiple comparison test analysis (p < 0.05). It was concluded that the chemical components of the white and black inks have cytotoxic effects in peripheral blood cells of the CD-1 mouse and human lymphocyte cells, while the chemical compounds of the two inks produce genotoxic effects in peripheral blood cells of CD-1 mice and only the white ink had genotoxic effects on human lymphocyte cells at a 10 mg/ml concentration.El presente estudio aporta respuestas sobre el efecto genotóxico de dos tintas usadas en el arte del tatuaje. En la actualidad no hay información sobre los efectos genotóxicos que puedan producir algunos de los compuestos químicos de las tintas sobre la salud humana. El objetivo de este estudio fue conocer los efectos genotóxicos de la tinta negra y blanca, empleadas mayormente en el arte del tatuaje. En esta investigación se aplicaron la prueba de micronúcleos en células de sangre periférica de ratones CD-1 y la prueba de aberraciones cromosómicas estructurales en cultivos de linfocitos humanos. Los resultados obtenidos mostraron diferencias significativas en los valores promedio de las células en división (% IM), la frecuencia de micronúcleos (% MCN) en las células de sangre periférica de los ratones y el número promedio de aberraciones cromosómicas estructurales de las células de linfocitos humanos, por lo que fueron sometidos al análisis de la prueba de comparación múltiple de Dunnett (p < 0.05). Se concluyó que los componentes químicos de las tintas blanca y negra tienen efectos citotóxicos en las células de sangre periférica de ratón CD-1 y en las células de linfocitos humanos. En cuanto a los efectos genotóxicos de dichos compuestos, ambas tintas los producen en células de sangre periférica de ratón CD-1 y sólo la tinta blanca tuvo efectos genotóxicos en las células de linfocitos humanos en la concentración de 10 mg/mL
SISTEMA ACOPLADO REACTOR ANAEROBIO CON DEFLECTORES-HUMEDAL ARTIFICIAL COMO ALTERNATIVA PARA REÚSO DE AGUA RESIDUAL EN RIEGO DE ÁREAS VERDES
Get PDFA coupled anaerobic baffled reactor-constructed wetland system was used for the treatment of wastewater from a research center, whose composition is different from domestic wastewater due to its origin. The anaerobic baffled reactor was used at full scale (20 m3) while the constructed wetland with sugar cane and heliconia plants was used at pilot scale (1.36 m3). System efficiency was measured in terms of organic matter removal as chemical oxygen demand (COD) and biochemical oxygen demand (BOD5), total suspended solids (TSS) and total and fecal coliforms. The lowest organic matter concentration of 22 mg/L was found at day 140 in the system effluent; it was slightly higher than the Mexican regulation for gardening irrigation, although it complies with the European regulation for water B class that can be used for irrigation of alimentary crops which are not in contact with the water, irrigation for crops for processed foods or irrigation for cattle food. The removal of TSS and coliforms with the system was higher than 90%, thus it compares well with similar systems and effluent concentrations and complies with European and Mexican regulation for gardening irrigation. Concentrations of organic matter such as COD and BOD5 in the effluent of the wetland were 22 mg/L (slightly higher than Mexican regulation but compliant with the European regulation for water class B) at 140 days of operation. Concentrations of TSS (10 mg/L) and total coliforms (93 MPN/100 mL), positively compared with other systems and complied with the European and Mexican regulations. Using the coupled anaerobic baffled reactor-constructed wetland system it was possible to remove TSS and coliforms in compliance with European and Mexican regulations for gardening irrigation; however, organic matter removal as BOD5 must be improved.Se utilizó un sistema acoplado reactor anaerobio con deflectores-humedal artificial para el tratamiento de agua residual proveniente de un centro de investigación, que por su origen tiene características diferentes al agua residual doméstica. El reactor anaerobio se utilizó a escala completa (20 m3) y el humedal artificial con plantas de caña de azúcar y heliconias a escala piloto (1.36 m3). La eficiencia se determinó en términos de la remoción de materia orgánica medida como demanda química de oxígeno (DQO) y demanda bioquímica de oxígeno (DBO5), sólidos suspendidos (SST) y organismos coliformes totales y fecales. A los 140 días de operación se logró la menor concentración de materia orgánica medida como DBO5 en el efluente del sistema, que fue de 22 mg/L. Ésta fue ligeramente superior a la norma mexicana para riego de áreas verdes con contacto directo, aunque cumple con la norma europea Clase B, es decir, para riego de cultivos alimentarios que no entren en contacto con el agua, para riego de alimentos que serán procesados o para riego de alimentos para ganado. La remoción de SST y organismos coliformes totales alcanzada con el sistema fue superiores al 90%, por lo cual se compara favorablemente con sistemas similares. Las concentraciones de salida lograron cumplir normas nacionales y la norma europea. Con el sistema acoplado reactor anaerobio con deflectores-humedal artificial fue posible remover SST y organismos coliformes fecales cumpliendo con las normas europea y mexicana vigentes para el riego en áreas verdes; sin embargo, requiere mejoras en cuanto a la salida de materia orgánica medida como DBO5
RESIDUOS DE PLAGUICIDAS EN BRÓCOLI (Brassica oleracea var. Itálica) PARA EL MERCADO NACIONAL E INTERNACIONAL
Get PDFThe objective of this research was to analyze the agronomic characteristics and the presence of pesticides residues in broccoli heads ready for commercialization, in two production systems, one for the national market and other for export. Seventy-eight samples from a package of Irapuato, Guanajuato, Mexico and the supply center of Huixcolotla Puebla, Mexico were analyzed. For the agronomic evaluation, the following variables were considered: yield, weight, diameter, and color of the head. Pesticide residues were analyzed with the AOAC method 2007.01, modified by using ultra high efficiency liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) as a separation and quantification technique. The mean values of head diameter and weight were 15.13 cm and 464.95 g for Guanajuato and 13.67 cm and 539.47 g for Puebla, respectively. These values comply with the standards for the national market. The results from the analysis of pesticides residues indicate that 42 of the 78 samples were free of pesticides, 14 samples had non-quantifiable concentrations (traces) and 22 samples contained at least one residue. The pesticide residues found were: boscalid (0.0061 mg/kg), dimethoate (0.0068 mg/kg), imidacloprid (0.0087 mg/kg), methamidophos (0.0266 mg/kg), ometoate (0.0111 mg/kg), penconazole (0.0039 mg/kg), propamocarb (0.0061 mg/kg), and thiametoxan (0.0045 mg/kg). In none of the cases the found concentrations exceed the maximum residues limits established by the National Service for Agro-Alimentary Public Health, Safety and Quality, and the Environmental Protection Agency.La investigación tuvo como objetivo analizar las características agronómicas y la presencia de residuos de plaguicidas en cabezuela de brócoli (Brassica oleracea var. Itálica) listas para su comercialización en dos sistemas de producción, uno para el mercado nacional y otro para exportación. Se analizaron 78 muestras provenientes de un empaque de Irapuato, Guanajuato, México, y de la Central de Abasto de Huixcolotla, Puebla, México. Para la evaluación agronómica se consideraron las siguientes variables: rendimiento peso, diámetro y color de la cabezuela. El análisis de residuos de plaguicidas se realizó mediante el método 2007.01 de la AOAC modificado, usando cromatografía líquida de ultra alta eficiencia acoplada a espectrometría de masas en tándem (UHPLC-MS/MS) como técnica de separación y cuantificación. Los valores medios de diámetro y peso de cabezuela fueron de 15.13 cm y 464.95 g para Guanajuato y de 13.67 cm y 539.47 g para Puebla, respectivamente. El diámetro y peso de la cabezuela cumplen con los estándares para el mercado nacional. Los resultados de los análisis de residuos de plaguicidas indican que, de las 78 muestras, 42 resultaron libres de plaguicidas, 14 con concentraciones no cuantificables (trazas) y 22 con al menos un residuo. Los plaguicidas encontrados fueron boscalid (0.0061 mg/kg), dimetoato (0.0068 mg/kg), imidacloprid (0.0087 mg/kg), metamidofos (0.0266 mg/kg), ometoato (0.0111 mg/kg), penconazole (0.0039 mg/kg), propamocarb (0.0061 mg/kg) y thiametoxan (0.0045 mg/kg). Las concentraciones encontradas no rebasan los límites máximos de residuos establecidos por el Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria y la Environmental Protection Agency
DEGRADACIÓN AMBIENTAL ANTRÓPICA DE LAS BARRANCAS EL CONDE Y MALINALLI DE LA CIUDAD DE PUEBLA, MÉXICO
Get PDFA percentage of the waste generated in Puebla city is disposed of without control in the city´s ravine system. Due to this, and to the presence of irregular human settlements, the ravines suffer degradation processes that put their continuity at risk, endangering the ecosystem services they provide to the city. That situation is shown in the condition of the El Conde and Malinalli ravines, which exemplify what happens in the urban system of ravines. The evaluation was done through the Margalef and Pielou indexes and a set of nine indicators that measure various components of the ravines. The results indicate that both ravines are diverse regarding the species category, from a medium to a high level. El Conde ravine presents a poor ecosystem status, which is the second lowest level on a five-level quality scale and is related to the impact generated by anthropic action, while Malinalli ravine exhibits an excellent quality level. The diversity of species, as an indicator of high ecological quality and criteria for the preservation of ecosystems, supports the proposal to recover and preserve both ravines, an urgent action in the case of El Conde due to the anthropic impact it is undergoing.Un porcentaje de los desechos generados en la ciudad de Puebla se elimina sin control en el sistema de barrancas de la urbe. Por esta causa y debido a la presencia de asentamientos humanos irregulares, dichas barrancas sufren procesos de degradación que ponen en riesgo su continuidad y con ello los servicios ecosistémicos que proporcionan a la ciudad. Tal situación se exhibe en el estado en que se encuentran las barrancas El Conde y Malinalli, el cual ejemplifica lo que ocurre en el sistema urbano de barrancas. La evaluación se hizo a través de los índices de Margalef y de Pielou, así como de un conjunto de nueve indicadores que miden diversos componentes de las barrancas. Los resultados indican que el grado de diversidad de especies en ambas barrancas es medio a alto. La barranca El Conde presenta un estado ecosistémico pobre, que es el segundo nivel más bajo en una escala de cinco niveles de calidad y tiene que ver con el impacto generado por la acción antrópica, mientras que la barranca Malinalli exhibe un nivel de calidad excelente. La diversidad de especies, en tanto indicador de alta calidad ecológica y criterio para la preservación de los ecosistemas, sustenta la propuesta de recuperar y conservar ambas barrancas, acción urgente para el caso de la barranca El Conde por el impacto antrópico que exhibe
ACTUALIZACIÓN DEL INVENTARIO NACIONAL DE EMISIONES DE 2013 PARA LA MODELACIÓN DE LA CALIDAD DEL AIRE EN EL CENTRO DE MÉXICO
Get PDFAir pollutant emissions inventories are an essential input parameter for air quality modeling. During its elaboration process, there are uncertainties that cause errors in numerical simulations. The need to continually improve data accuracy or adjust it to the actual conditions being described is indisputable. In this work, the spatial,temporal, and chemical speciation distribution model (DiETE) was applied to the 2013 Mexico National Emissions Inventory in order to obtain a spatially and temporarily disaggregated database, ready for numerical modeling with the Weather Research and Forecasting Model with Chemistry (WRF-Chem) in Central Mexico. Also, the model performance was evaluated for ozone in an environmental contingency episode that took place between May 15 and 21, 2017, based on the comparison with stations observations from Mexico City’s Red Automática de Monitoreo Atmosférico (automatic air quality monitoring network). Statistical metrics showed lower correlation for all variables analyzed and it was decided to update the inventory through a nonparametric methodology based on scale factors. This led us to obtain statistical parameters with larger correlations and model values closer to the observations, which accurately describe the spatial and temporal behavior of the variables. The adjustments made to the inventory were validated through its application to another case of environmental contingency from March 14-17, 2016, with considerable improvements in the performance of the model.Los inventarios de emisiones de contaminantes atmosféricos constituyen un parámetro de entrada imprescindible para los modelos de calidad del aire. Durante su proceso de elaboración, existen incertidumbres que conducen a errores en las simulaciones numéricas, siendo indiscutible la necesidad de mejorar continuamente la precisión de sus datos o ajustarlos a las condiciones reales que intenta describir. En este trabajo se aplicó el modelo de distribución espacial, temporal y de especiación química (DiETE) al Inventario Nacional de Emisiones de México de 2013 para obtener una base de datos desagregada espacial y temporalmente, lista para la modelación numérica con el modelo Weather Research and Forecasting with Chemistry (WRF-Chem) en el Centro de México. Se evaluó el desempeño del modelo en un episodio de contingencia ambiental por ozono ocurrido del 15 al 21 de mayo de 2017, a partir de la comparación con observaciones de estaciones de la Red Automática de Monitoreo Atmosférico de la Ciudad de México. Las métricas estadísticas mostraron baja correlación entre el modelo y las mediciones para todas las variables analizadas y se decidió actualizar el inventario a partir de una metodología no paramétrica de factores de escalamiento. Esto permitió obtener una mejor correlación con valores del modelo más próximos a las observaciones y que describen acertadamente el comportamiento espacial y temp,oral de las variables. Los ajustes realizados al inventario se validaron mediante su aplicación a otro caso de contingencia ambiental del 14 al 17 de marzo de 2016, apreciándose mejoras considerables en el desempeño del modelo
ACTINOBACTERIAS DEGRADADORAS DE POLIPROPILENO
Get PDFThe accumulation of synthetic polymers is a great environmental contamination issue, since there are no efficient methods to dispose them safely; however, there is evidence about the degradation of plastics by actinobacteria. In this work we tested the degradation capacity of tree biopolymers and a synthetic polymer by actinobacteria isolated from the soil of a landfill in Bariloche. On the one hand, we studied the degradation of natural polymers (starch, hemicellulose, cellulose) in a solid medium, and on the other hand, we studied the degradation of polypropylene sheets inoculated with the isolates and cultured in liquid medium for six weeks at 37 ºC. We then measured weight loss in the sheets and studied colonization of the polypropylene surface using light and electron microscopy. The data were analyzed with a two-way ANOVA and Tukey’s test. Of the 35 total isolates, 88 % corresponded to the Streptomyces genus and 3 % to the rest of genera (Actinomadura, Pseudonocardia, Saccharomonospora and Thermoactinomyces). Of the isolates, 63 % were able to degrade starch, 86 % hemicellulose, 34 % microcrystalline cellulose (exoglucanases), and 88% carboxymethyl cellulose (endoglucanases). Colonization of the polypropylene surface was observed in all treatments. Two of the strains studied, Streptomyces sp. MP32 and Actinomadura sp. MP5 reduced the weight of the polypropylene sheets (p ≤ 0.05). These preliminary results show the ability of actinobacteria to colonize the polypropylene surface, with potential use in soils or environments contaminated by synthetic polymers.La acumulación de polímeros sintéticos es un gran problema de contaminación ambiental, ya que no existen métodos eficientes para su eliminación segura; sin embargo, hay evidencias sobre su degradación por actinobacterias. En este trabajo se evaluó la capacidad de degradación de actinobacterias aisladas de suelo del vertedero de Bariloche, sobre tres biopolímeros y un polímero sintético. Por un lado, se estudió la degradación de polímeros naturales (almidón, hemicelulosa, celulosa) en medio sólido, y por otro el otro se evaluó la degradación de láminas de polipropileno inoculadas con los aislamientos y cultivadas en medio líquido durante seis semanas a 37 ºC. Luego se midió la pérdida de peso en las láminas y se estudió la colonización de la superficie del polipropileno mediante microscopia óptica y electrónica. Los datos fueron analizados con un ANOVA de dos vías y la prueba de Tukey. De los 35 aislamientos totales, el 88 % correspondió al género Streptomyces y el 3 % a los demás géneros (Actinomadura, Pseudonocardia, Saccharomonospora y Thermoactinomyces). El 63 % de los aislamientos tuvo la capacidad de degradar almidón, el 86 % hemicelulosa, el 34 % celulosa microcristalina (exoglucanasas) y el 88 % carboximetilcelulosa (endoglucanasas). Se observó colonización de la superficie de polipropileno en todos los tratamientos. Dos de las cepas estudiadas (Streptomyces sp. MP32 y Actinomadura sp. MP5) redujeron el peso de las láminas de polipropileno (p ≤ 0.05). Estos resultados preliminares muestran la capacidad de las actinobacterias para colonizar la superficie del polipropileno, con potencial uso en suelos o ambientes contaminados por plásticos
TROPHIC STATUS OF A TROPICAL COASTAL LAGOON IN MARGARITA ISLAND, VENEZUELA
Get PDFPunta de Piedras Lagoon is a coastal lagoon located south of Margarita Island, in the Venezuelan Caribbean Sea. This lagoon has ecological and economic importance for the inhabitants of nearby communities. Currently, the urban and industrial development in its surroundings represents a potential source of pollutants, providing concentrations of nutrients that could affect the ecological balance of the area. The trophic status of Punta de Piedras Lagoon was evaluated using various trophic indices. The concentrations of chlorophyll-a and nutrients (ammonium, nitrites, nitrates, and orthophosphates) were estimated in 10 stations with a monthly frequency from February 2005 to January 2006. These data were used to estimate the trophic condition based on the Karydis and TRIX trophic indices, and by comparison with Organization for Economic Co-operation and Development reference values. It was found that Punta de Piedras lagoon presented mesotrophic conditions in most of the water body having considerable differences between indices. The values of the closest station to Paseo Esther Gil corresponded to eutrophic waters. However, the circulation and residence time of water allow an exchange with the adjacent sea, which prevents the eutrophication process in the lagoon.Punta de Piedras Lagoon is a coastal lagoon located south of Margarita Island, in the Venezuelan Caribbean Sea. This lagoon has ecological and economic importance for the inhabitants of nearby communities. Currently, the urban and industrial development in its surroundings represents a potential source of pollutants, providing concentrations of nutrients that could affect the ecological balance of the area. The trophic status of Punta de Piedras Lagoon was evaluated using various trophic indices. The concentrations of chlorophyll-a and nutrients (ammonium, nitrites, nitrates, and orthophosphates) were estimated in 10 stations with a monthly frequency from February 2005 to January 2006. These data were used to estimate the trophic condition based on the Karydis and TRIX trophic indices, and by comparison with Organization for Economic Co-operation and Development reference values. It was found that Punta de Piedras lagoon presented mesotrophic conditions in most of the water body having considerable differences between indices. The values of the closest station to Paseo Esther Gil corresponded to eutrophic waters. However, the circulation and residence time of water allow an exchange with the adjacent sea, which prevents the eutrophication process in the lagoon