Summary: The municipality of Medellín, Veracruz, México has a type A landfill, whose operation level has recently increased due to landfill closure in the city of Veracruz. The objective of this study is to analyze and evaluate the quality of groundwater surrounding the landfill of the municipality of Medellín., such as hydrogen potential (pH), electrical conductivity (EC), turbidity (T), chemical oxygen demand (COD), total phosphorus (TP), nitrates (NO3 -), total dissolved solids (TDS) and heavy metals Lead (Pb), cadmium (Cd) and copper (Cu) in seven groundwater wells near the landfill during the “north” and dry season. The physicochemical water results from the seven wells analyzed were within the maximum permissible limits of Mexican regulations: turbidity values exceeded international regulations and four wells were found contaminated according to COD levels. The concentrations of Pb and Cd in both seasons were higher than the maximum permissible limits for human consumption in accordance with national and international regulations. Therefore, the results indicated the negative influence of the landfill on groundwater quality.

Resumen: Los rellenos sanitarios se han vuelto una fuente de contaminación de aguas superficiales y subterráneas, debido a la generación de lixiviados que pueden llegar hasta los cuerpos de agua con efectos adversos al ambiente. El municipio de Medellín, Veracruz, México; cuenta con un relleno sanitario tipo A cuyo nivel de operación se ha incrementado recientemente debido a la clausura del relleno sanitario de la ciudad de Veracruz. El objetivo del presente estudio fue analizar la calidad del agua subterránea aledaña al relleno sanitario del municipio de Medellín. Se evaluaron potencial de hidrógeno (pH), conductividad eléctrica (CE), turbidez (T), Demanda Química de Oxigeno (DQO), Fósforo Total (PT), Nitratos, (NO3 -), Sólidos Disueltos Totales (SDT) y metales pesados Plomo (Pb), Cadmio (Cd) y Cobre (Cu) en 7 pozos de agua subterránea próximos al relleno sanitario durante la temporada de “nortes” y estiaje. Los resultados fisicoquímicos del agua de los 7 pozos analizados se encontraron dentro de los límites máximos permisibles de la normatividad mexicana; los valores de turbidez superaron la normatividad internacional y 4 pozos mostraron estar contaminados de acuerdo a los niveles de DQO. Las concentraciones de Pb y Cd en ambas temporadas se encontraron superiores a los límites máximos permisibles para consumo humano de acuerdo con la normatividad nacional e internacional. Los resultados indicaron la influencia negativa del relleno sanitario en la calidad del agua subterránea.

Abstract Introduction: The Mar Muerto lagoon is an ecosystem characterized by high productivity upon which various inhabiting organisms depend. Additionally, it is a system susceptible to environmental impacts. Consequently, indices have been developed to determine the degree of disturbance caused by natural and/or anthropogenic factors. Objective: To assess the degree of disturbance in the Mar Muerto lagoon using a Biotic Integrity Index (BII) based on ichthyofauna. Methods: From December 2019 to March 2021, 12 sampling stations were established in the lagoon. The Biotic Integrity Index was developed by collecting data on hydrological variables (salinity, dissolved oxygen, pH, electrical conductivity, suspended solids, temperature, nitrites, nitrates, phosphates, and transparency) and classifying fish species based on their composition and richness. This was followed by a Water and Habitat Quality Index (WHQI) derived from the characterization and classification of sampling stations based on physicochemical variables. The correlation of the two indices allowed for the evaluation of the effectiveness of the BII. Results: 65 species were reported for the lagoon, with Lile gracilis, Oligoplites altus, Eucinostomus currani, and Gerres simillimus being the most frequently recorded. Only station 10 exhibited poor biotic integrity (BII = 26), while the rest displayed regular biotic integrity (BII = 30 - 44), with station nine presenting the highest calculated value (BII = 42). The assessment of the lagoon’s BII demonstrated an average biotic integrity considered “regular.” Conclusion: Through this study, the functionality of the modified BII for the Mar Muerto lagoon was verified, allowing for the evaluation of the present conservation status and comparison with previous studies.

Resumen Introducción: La laguna Mar Muerto es un ecosistema caracterizado por una gran productividad, de la cual dependen diversos organismos que la habitan; también es un sistema susceptible a impactos ambientales. Por lo anterior, se han desarrollado índices que permiten conocer el grado de alteración por causas naturales y/o antropogénicas. Objetivo: Evaluar el grado de perturbación de la laguna Mar Muerto, mediante un índice de integridad biótica (IBI) basado en la ictiofauna. Métodos: De diciembre 2019 a marzo 2021, se establecieron 12 estaciones de muestreo en la laguna. La elaboración del índice de integridad biótica fue a partir de la recopilación de datos de las variables hidrológicas (salinidad, NO2, NO3, PO4, pH, OD, T, CE, transparencia y SDT) y la clasificación de las especies ícticas según su composición y riqueza; seguido de un índice de calidad de agua y hábitat (ICAH), elaborado a partir de la caracterización y clasificación de las estaciones de muestreo en función de variables fisicoquímicas. La correlación de los dos índices permitió evaluar la efectividad del IBI. Resultados: 65 especies fueron reportadas para la laguna, de las cuales Lile gracilis, Oligoplites altus, Eucinostomus currani y Gerres simillimus se registraron con mayor frecuencia. Sólo la estación 10 presentó una integridad biótica pobre (IBI = 26), el resto presentó un IBI regular (IBI = 30 - 44), siendo la estación nueve la que presentó el valor máximo calculado (IBI = 42). La valoración del IBI de la laguna demostró que ésta presenta una integridad biótica promedio considerada “regular”. Conclusión: A través de este trabajo, se comprobó la funcionalidad del IBI modificado para la laguna Mar Muerto, permitiendo evaluar el grado de conservación presente y compararlo con trabajos previos.

Abstract This research allowed us to understand the physical-chemical and microbiological quality of rainwater collected in the downtown area and Medrano neighborhood of the city of Quibdó - Chocó. This population has a high precipitation rate which ranges from 1500mm/year and 8500mm/year, both currently and in the future, although this situation contrasts with the low drinking water coverage, which is only 28.5%. To carry out this study, 5 sampling points were identified, and 4 samples were collected at each point with a periodicity of 1 weekly sampling for 4 weeks, for a total of 20 representative samples. The selected roof tops coverings were made of zinc, asbestos cement, and mantle, and are located in areas of high vehicular and pedestrian activity. The collected samples were analyzed in an accredited laboratory for this purpose. The parameters evaluated for rainwater quality were: apparent color, real color, conductivity, pH, total alkalinity, nitrites, nitrates, total coliforms, and Escherichia Coli. The result of the microbiological analyzes was POSITIVE in 100% of the cases, while 15% of the physical analyses and 34% of the chemical analyses also yielded negative results. Due to the presence mainly of colony-forming units of Escherichia Coli and total coliforms, it was concluded that rainwater in the downtown area and Medrano neighborhood of the city of Quibdó - Chocó, does 5not meet the standards established in the evaluated parameters and required by the regulations, which means that it is not safe for human consumption due to its level of contamination.

Resumen Esta investigación permitió conocer la calidad físico - química y microbiológica del agua lluvia recolectada en la Zona Centro y barrio Medrano de la ciudad de Quibdó - Chocó. Esta población presenta una alta tasa de precipitación la cual oscila entre 1500mm/año y 8500mm/año, tanto en la actualidad como en el futuro, aunque esta situación contraste con la baja cobertura de agua potable que tan solo es del 28,5%. Para realizar dicho estudio se identificaron 5 puntos de muestreo, en cada punto se recolectaron 4 muestras con una periodicidad de 1 muestreo semanal durante 4 semanas, para un total de 20 muestras representativas; las cubiertas seleccionadas fueron de zinc, asbesto cemento y manto; además, están ubicadas en zonas de alta actividad vehicular y peatonal. Las muestras recolectadas fueron analizadas en un laboratorio acreditado para tal fin. Los parámetros evaluados de la calidad del agua lluvia fueron; color aparente, color real, conductividad, pH, alcalinidad total, nitritos, nitratos, Coliformes totales y Escherichia Coli. El resultado de los análisis microbiológicos fue negativo en el 100% de los casos, mientras que el 15% de los análisis físicos y el 34% de los análisis químicos también arrojaron resultados negativos. Debido a la presencia principalmente de unidades formadoras de colonia de Escherichia Coli y Coliformes totales, se concluyó que el agua lluvia en la zona centro y el barrio Medrano de la ciudad de Quibdó - Chocó, no cumple con los estándares establecidos en los parámetros evaluados y requeridos por la norma, lo que significa que no es segura para el consumo humano debido al nivel de contaminación que presenta.

ABSTRACT Introduction: Water supply for industrial use and social consumption decreases due to droughts, overexploitation of groundwater and pollution from agricultural and industrial chemicals. Objective: To evaluate the quality of water for industrial use and social consumption from the supply source belonging to the Central Refinería Ecuador (Sugar Refinery Ecuador). Materials and Methods: The quality of water for industrial use and social consumption was evaluated through the application of testing techniques and methods, in the determination of physical, chemical and microbiological parameters. Results and Discussion: The water quality parameters for industrial use and social consumption evaluated were odor, taste and color of odorless, tasteless and colorless respectively. Total dissolved solids were 553 mg L-1, pH 7,33 pH units, calcium 75 mg L-1, magnesium 45 mg L-1, chloride 45 mg L-1, sulfate of 21 mg L-1, nitrite of 0,03 mg L-1, nitrates of 20,2 mg L-1, total coliforms of 1 222 most probable number per 100 mL and thermotolerant coliforms of 584 most probable number probable per 100 mL. Conclusions: These water quality values are suitable for industrial use, while for social consumption they are not suitable due to microbiological contamination and non-compliance with health protection requirements. Although the physical and chemical values analyzed in water for social consumption are within maximum limits.

RESUMEN Introducción: El suministro de agua para uso industrial y consumo social disminuye debido a las sequías, la sobreexplotación del agua subterránea y la contaminación procedente de productos químicos agrícolas e industriales. Objetivo: Evaluar la calidad del agua para el uso industrial y consumo social de la fuente de abasto perteneciente al Central Refinería Ecuador. Materiales y Métodos: La calidad del agua para uso industrial y consumo social se evaluó mediante la aplicación de técnicas y métodos de ensayos, en la determinación de los parámetros físicos, químicos y microbiológicos. Resultados y Discusión: Los parámetros de calidad del agua para el uso industrial y el consumo social evaluados fueron el olor, el sabor y el color de inodora, insípida e incolora respectivamente. Los sólidos totales disueltos fueron de 553 mg L-1, el pH de 7,33 unidades de pH, el calcio de 75 mg L-1, el magnesio de 45 mg L-1, el cloruro de 45 mg L-1, el sulfato de 21 mg L-1, el nitrito de 0,03 mg L-1, los nitratos de 20,2 mg L-1, los coliformes totales de 1 222 número más probable por 100 mL y los coliformes termotolerantes de 584 número más probable por 100 mL. Conclusiones: Estos valores de calidad del agua para el uso industrial son aptos, mientras que para el consumo social son no aptos por contaminación microbiológica e incumplimiento de los requisitos de protección sanitarios. Aunque los valores físicos y químicos analizados en el agua para consumo social se encuentran dentro de límites máximos.

Resumo Em 1997 através da Portaria nº 1037/1997 de 1 de outubro foi constituída a Zona Vulnerável n.º 1- Aquífero livre entre Esposende e Vila do Conde, que consta da lista de Zonas Vulneráveis a Nitratos (ZVN) como uma das nove atualmente existentes em Portugal Continental, sendo designada de Zonas Vulnerável Esposende-Vila do Conde. Neste sentido, desde 2007 que a Direção Regional de Agricultura e Pescas do Norte (DRAP Norte) monitoriza esta ZVN com uma metodologia de acompanhamento que implica recolha de dados, análise, extensão rural e formação de técnicos e agricultores como um meio de apoiar a implementação do Programa de Ação para as Zonas Vulneráveis de Portugal Continental (Portaria n.º 259/2012, de 28 de agosto). Com base nessa metodologia, este trabalho teve como objetivo analisar e divulgar os resultados obtidos em 3.764 análises de água realizadas entre 2008-2022 em 12 pontos fixos onde é monitorizada com uma periodicidade quinzenal a quantidade de nitratos (NO3 -) nas águas subterrâneas, tendo como principais fatores diferenciadores os tipos de solos e o sistema de produção agrícola onde estes se encontram. Os resultados obtidos apontam para uma tendência de redução das concentrações médias anuais embora existam oscilações anuais significativas por tipo de solo, por local de amostragem e sistema de produção.

Abstract The Vulnerable Zone nº 1 - Free Aquifer between Esposende and Vila do Conde was created in 1997, through Ordinance nº. 1037/1997 of October 1, and appears on the list of Nitrate Vulnerable Zones to (NVZ) as one of the nine currently existing in Mainland Portugal, designated as Vulnerable Zone of Esposende-Vila do Conde. Since 2007, the Direção Regional de Agricultura e Pescas do Norte (DRAP Norte) has been monitoring this ZVN with a follow-up methodology that involves data collection, analysis, rural extension and training of technicians and farmers as a means of supporting implementation of the Vulnerable Zones Action Program (Ordinance nº 259/2012, of 28 August). Based on this methodology, this work aimed to analyze and disseminate the results obtained in 3,764 water analyzes carried out between 2008-2022 in 12 fixed points where the amount of nitrates (NO3 -) in the underground water is monitored every two weeks, having as main differentiators factors the soils types of and the agricultural production system. The results obtained point to a downward trend in average annual concentrations, with significant annual fluctuations by soil type, sampling location and production system.

Abstract Introduction: The aquaculture industry is constantly growing, registering a global production of almost 88 million tonnes by 2020. This industry brings environmental problems if its effluents are not properly treated. In 2020, the first technology-based company of CONICET was established in Argentine Patagonia whose purpose is the aquaculture production of the green sea urchin, Arbacia dufresnii to develop a range of nutraceutical products. Its cultivation system entails a commitment to sustainability since its creation, and yet it generates effluents with high levels of nitrates and phosphates. Objective: Given this scenario, and valuing bioremediation as a water treatment tool, the use of marine microalgae as phytoremediating agents of aquaculture effluent is proposed in this work. Methods: The microalgae Chaetoceros gracilis, Navicula sp., Tetraselmis suecica, Rhodomona salina, Nanochloropsis galvana and Cylindrotheca closterium were use; which are used as food for sea urchins larvae in the production process. An experiment was designed that compares the microalgal growth and the removal capacity of nutrients in the effluent in contrast to the artificial culture medium currently used in the production cycle. Results: It is possible to remedy the aquaculture industry’s effluent by employing the selected microalgae, with a percentage of removal efficiency of 100 % of the nitrate and an average removal efficiency percentage of 50 % for all the microalgae tested. Likewise, significantly higher microalgal biomass values were obtained when the culture was carried out in the effluent the culture in the artificial environment. Conclusions: The advances in research provided in this work show that it is possible to take advantage of a discard to cultivate microalgae, even improving microalgal productivity for use as food, reducing the costs involved in the microalgal production sector by changing the use of the type of current culture medium (F/2) for that from a current discard. These advances, if scaled and validated, can improve industry sustainability standards within the framework of a circular economy.

Resumen Introducción: La industria acuícola está en constante crecimiento, registrando una producción mundial de casi 88 millones de toneladas para el año 2020. Esta industria trae consigo problemas ambientales si sus efluentes no son debidamente tratados. En el 2020, se constituyó la primera empresa de base tecnológica del CONICET en la Patagonia Argentina cuyo propósito es la producción acuícola del erizo verde de mar, Arbacia dufresnii con la finalidad de elaborar una gama de productos nutracéuticos. Su sistema de cultivo conlleva un compromiso de sustentabilidad desde su creación, y sin embargo genera efluentes con niveles altos de nitratos y fosfatos. Objetivo: Ante este escenario, y valorizando la biorremediación como herramienta de tratamiento de aguas, se propone en este trabajo la utilización de las microalgas marinas como agentes fitorremediadores del efluente acuícola. Métodos: Se utilizaron las microalgas Chaetoceros gracilis, Navicula sp., Tetraselmis suecica., Rhodomona salina., Nanochloropsis galvana y Cylindrotheca closterium, las cuales son usadas como alimento de las larvas del erizo en el proceso productivo. Se diseñó un experimento que compara el crecimiento microalgal y la capacidad de remoción de los nutrientes en el efluente en contraste con el medio de cultivo artificial actualmente usado en el ciclo productivo. Resultados: Es posible remediar el efluente de la industria acuícola mediante las microalgas seleccionadas, con porcentaje de eficacia de remoción del 100 % del nitrato y un porcentaje de eficacia de remoción promedio de 50 % para todas las microalgas testeadas. Asimismo, se obtuvieron valores de biomasa microalgal significativamente mayores cuando el cultivo fue realizado en el efluente respecto del cultivo en el medio artificial. Conclusiones: Los avances en investigación proporcionados en este trabajo ponen de manifiesto que es posible el aprovechamiento de un descarte para cultivar las microalgas, incluso mejorando la productividad microalgal para su uso como alimento, disminuyendo los costos involucrados en el sector de producción microalgal cambiando el uso del tipo de medio de cultivo actual (F/2) por el proveniente de un descarte. Estos avances si son escalados y validados, pueden mejorar los estándares de sustentabilidad de la industria en el marco de una economía circular.

ABSTRACT Sodic soils pose a challenge for the agricultural production due to their lack of nutrients, poor structure, low organic matter content, and susceptibility to erosion (water and wind). Their recovery is carried out by soil washing and applying calcium salts, which are sometimes unprofitable processes. A low-cost and environmentally friendly alternative to remedy adverse soil conditions is bioremediation using microorganisms or organic amendments. For this reason, this study intended to evaluate the effects of the addition of dry microalgal biomass on sodic soils and suggest its use as an organic amendment. The effect of the microalgal biomass was studied through the mineralization dynamics of carbon and nitrogen sources in short-term experiments. All experiments were performed at laboratory scale. Microalgal biomass was obtained from a consortium grown in dairy wastewater and subsequently dried and pulverized. Four different treatments of dry microalgal biomass were applied to 50 g of sodic soil, and high microbial activity was observed in the soil (obtaining a production of 240 mg C-CO2/kg dry soil), along with the production of nitrates (presenting values 33.8-1.45 mg N-NO3 +/kg dry soil) via the release of ammonia (obtaining 5.46 mg N-NH3 +/kg dry soil), and mineralization of organic N into ammonium (producing 1071.92 mg N-NH4 +/kg dry soil). The microalgal biomass as an organic amendment showed to be prone to mineralization and release of carbon and nitrogen sources, improving the microbial activity in a soil with sodicity problems.obial activity, dairy wastewater.

RESUMEN Los suelos sódicos representan un reto para la industria agrícola debido a su falta de nutrientes, mala estructura, poca materia orgánica y susceptibilidad a sufrir erosión hídrica y eólica. Su recuperación se realiza mediante lavados y aplicación de sales de calcio, los cuales a veces resultan ser procesos poco rentables. Una alternativa de tratamiento de bajo costo y amigable con el ambiente es la aplicación de microorganismos y enmiendas orgánicas con la finalidad de mejorar las condiciones adversas del suelo. Por tal motivo, este estudio se propuso evaluar los efectos de la adición de biomasa microalgal seca en suelos sódicos y sugerir su uso como enmienda orgánica. Se estudió el efecto de la biomasa microalgal mediante dinámicas de mineralización de fuentes de carbono y nitrógeno en experimentos a corto plazo. Todos los experimentos se realizaron a escala de laboratorio. Microalgal biomass was obtained from a consortium grown in dairy wastewater and subsequently dried and pulverized. En frascos de vidrio con 50 g de suelo sódico, se aplicaron cuatro concentraciones distintas de biomasa microalgal seca, observándose en el suelo una actividad microbiana alta (producción de 240 mg C-CO2/kg suelo seco), mineralización de nitratos (de 33.8 a 1.45 mg N-NO3 − /kg suelo seco) vía liberación de amoniaco (5.46 mg N-NH3 +/kg suelo seco) y mineralización del nitrógeno orgánico a amonio (1071.92 mg N-NH4 +/kg suelo seco). La biomasa microalgal resultó ser una enmienda orgánica susceptible a la mineralización y con liberación de fuentes de carbono y nitrógeno, mejorando la actividad microbiana en el suelo con problemas de sodicidad.

Abstract It is increasingly important to find solutions for the problem of the aluminium anodising industry which generates a large amount of acid and alkaline wastewater, composed of high amounts of phosphates, sulphates, nitrates and aluminium. The sulphate removal trough ettringite precipitation is a simple process and involves a low-cost operating. The ettringite can be also formed during the cement hydration in soil-cement mixtures which causes several damages such as expansion. However, the effect of ettringite on the compressive strength, tensile strength and microstructure have few studies. This paper presents a novel experimental study on the influence of the industrial effluent treatment ettringite in resistance and microstructure of soil-cement mixtures. Experimental tests were performed using natural soil, soil mixed with 5% and 6% of cement and soil mixed with 5% and 6% of cement and ettringite for each material. The resistance of the materials was evaluated by unconfined compressive strength and indirect tensile strength, after 3, 7 and 14 days of cure. Additionally, several characterization tests and microstructure analysis were performed. Regarding the experimental results, the compressive strength and tensile strength decreases about 75% and 85%, respectively, when ettringite was added in soil-cement mixtures. The microstructure of natural soil, soil-cement and soil-cement-ettringite mixtures shows that the addition of cement and ettringite, simultaneously, increases the ettringite crystal formation mainly because the cement functions as a source of sulfate ions contributing with the formation of more crystals. Experimental results indicate that the incorporation of ettringite in soil-cement mixtures is not suitable for geotechnical applications.

Abstract The Private Reserve of Natural Patrimony (RPPN) of the Santuário of Caraça is found in a mountain region within the Quadrilátero Ferrífero geological province in the State of Minas Gerais. In this region, intense metamorphic processes shaped their siliciclastic rocks, enabling the formation of fractures and diaclasis, the favourite routes of weathering during the development of karst landscapes. The natural cavities thus formed, mainly in the RPPN sector called “Pico do Inficionado”, provide shelter for countless swifts of the species Streptoprocne zonaris and S. biscutata, responsible for the accumulation of guano on the floor. However, guano is a substance rich in nutrients, mainly phosphates and nitrates, and this is the main nutrient supply in permanently dry caves. This work studied the physical (density) and chemical (organic carbon, nitrogen, potassium, phosphorus, sodium, calcium, magnesium, aluminium and pH) characteristics of 21 guanos layers, correlating their contents with the depth of seven deposits and separating the results into factors. Considering that, knowing that the guano deposits contain crucial elements such as Ca, Mg, and especially P and N, which act as an energy source for many chemotrophic organisms, the subdivision of the studied elements allowed us to defer three factors: the first one features the concentrations of Al, P, K, Na and CO, the second one was determined for N, pH and density. Finally, the third factor was based on Ca and Mg. The quartzitic material influences the chemical and physical composition of the deepest guano. As the rock changes, elements like Al and K are released and enrich the deeper layers, as well as increasing density due to the presence of sand in the material.

Summary: The continuous use of excessive nitrogenous fertilizers generates environmental risks by increasing nitrate accumulation, volatilization and leaching in soil, which causes losses and low efficiencies in the use of nitrogen (N). The objective of the present study is to evaluate the application of nitrogenous nanocomposites (NCN) as a slow-release fertilizer (SRF) in soil and its effect on growth of the lettuce crop. The NCN was prepared by sorption of a cationic surfactant on a bentonite clay. The study was performed in soil columns; the evaluated treatments were ratios of NCN and conventional fertilizer (FC) 25/0, 50/0, 75/0 and 100/0, 0/100, 25/75, 50/50 and 75/25. The variables evaluated were: fresh weight, dry biomass, leaf area, electrical conductivity, NO3- concentration in leachate and leaf, soil plant analysis development (SPAD) and normalized difference vegetation index (NDVI) units, as well as NCN release in deionized water. The results obtained indicate that the NCN treatments equaled the control after 40 days except for the 25/0 treatment that reduced the fresh weight variables by 20% and leaf area by 18% with respect to the 0/100 control. The SPAD and NVDI values did not have significant differences between treatments. The NCN/FC 0/100, 50/50 and 75/25 ratios increased nitrate concentration in leaves by 19%. The 100/0 treatment increased total dry biomass with 48%, 87% root volume and 73% root dry biomass. The results of the release in deionized water confirmed that NCN gradually releases nitrates and in higher amounts than those calculated. Finally, to conclude the nanocomposite material has the potential to be used as a slow-release fertilizer when growth increases. Therefore, nanocomposites could be an alternative to reduce the use of conventional fertilizers and nitrogen losses in soil.

Resumen: El uso continuo de fertilizantes nitrogenados en exceso genera riesgos ambientales al aumentar en el suelo la acumulación, volatilización y lixiviación de nitratos, que provocan pérdidas y baja eficiencia en la utilización de N. En este estudio, el objetivo fue evaluar la aplicación de nanocompuestos nitrogenados (NCN) como fertilizante de liberación lenta en el suelo y su efecto en el crecimiento del cultivo de lechuga. El NCN se preparó por la sorción de un surfactante catiónico en una arcilla de bentonita. El estudio se realizó en columnas de suelo, los tratamientos evaluados fueron relaciones de NCN y fertilizante convencional (FC) 25/0, 50/0, 75/0 y 100/0, 0/100, 25/75, 50/50 y 75/25. Las variables evaluadas fueron: peso fresco, biomasa seca, área foliar, conductividad eléctrica, concentración de NO3 - en lixiviado y hoja, unidades SPAD y NDVI, además de la liberación del NCN en agua desionizada. Los resultados obtenidos indican que después de 40 días los tratamientos con NCN igualaron al control excepto el tratamiento 25/0 que redujo las variables peso fresco 20% y el área foliar 18% con respecto al control 0/100. Los valores de SPAD y NVDI no tuvieron diferencias significativas entre tratamientos. Las relaciones NCN/FC 0/100, 50/50 y 75/25 aumentaron 19% la concentración de nitratos en hojas. El tratamiento 100/0 aumentó biomasa seca total con 48%, 87% el volumen radical y 73% la biomasa seca de raíz. Los resultados de la liberación en agua desionizada confirmaron que el NCN libera gradualmente nitratos y en mayor cantidad que lo calculado. Finalmente, se concluye que el material nanocompuesto tiene el potencial de usarse como fertilizante de lenta liberación al aumentar crecimiento, por lo que podría ser una alternativa para reducir el uso de fertilizantes convencionales y disminuir las pérdidas de nitrógeno en suelo.

Abstract s The profound deficiencies that the country faces in water management policies are reflected in the physicochemical, microbiological and biological contamination of national rivers. The objective of this study was to propose a community water monitoring strategy to improve the management of the Jorco River located in the canton of Acosta. The quality of the water in the upper, middle and lower part of the micro-basin was monitored during the rainy season, using two physicochemical quality indices (ICA): the Dutch and the Calvo-TEC; as well as a biological one: the BMWP-CR. The quality indicators of turbidity, alkalinity, ammonia, ammoniacal nitrogen, nitrates, and fecal coliforms exceeded the permissibility limits in some samples; however, dissolved oxygen showed that there are good levels of oxygen for river recovery. Biochemical oxygen demand was low, indicating low organic load, and macroinvertebrates showed a degraded aquatic ecosystem. The Dutch ICA overestimated the quality of the water with respect to the ICA Calvo-TEC. The latter showed more realistic results because it uses more quality indicators, since it is based on environmental conditions and Costa Rican regulations. The ICA BMWP-CR revealed extreme contamination during the month of greatest rainfall. It was concluded that there is a problem of contamination in the river water whose main causes may be due to the lack of forest cover in the riparian zones, the expansion of coffee cultivation, the discharge of domestic wastewater and livestock activities. Therefore, an action plan was proposed to the municipal council and validated with them, to improve water quality with the participation of different actors in the area.

Resumen Las profundas deficiencias que enfrenta el país en políticas de gestión hídrica se reflejan en la contaminación fisicoquímica, microbiológica y biológica de los ríos nacionales. El objetivo de este estudio fue proponer una estrategia de monitoreo hídrico comunitario para mejorar la gestión del río Jorco ubicado en el cantón de Acosta. Se monitoreó la calidad del agua en la parte alta, media y baja de la microcuenca durante la época lluviosa, utilizando dos índices de calidad (ICA) fisicoquímicos: el Holandés y el Calvo-TEC; así como uno biológico: el BMWP-CR. Los indicadores de calidad de turbiedad, alcalinidad, amoniaco, nitrógeno amoniacal, nitratos, y coliformes fecales superaron los límites de permisibilidad en algunos muestreos; sin embargo, el oxígeno disuelto mostró que existen buenos niveles de oxígeno para la recuperación del río. La demanda bioquímica de oxígeno fue baja, indicando una carga orgánica baja y los macroinvertebrados mostraron un ecosistema acuático degradado. El ICA Holandés sobrevaloró la calidad del agua con respecto al ICA Calvo-TEC. Este último mostró resultados más realistas debido a que utiliza más indicadores de calidad, ya que este parte de las condiciones ambientales y la normativa costarricense. Por su parte, el ICA BMWP-CR reveló una contaminación extrema durante el mes de mayor lluvia. Se concluyó que existe un problema de contaminación en el agua del río cuyas causas principales pueden ser por la falta de cobertura boscosa en las zonas riparias, la expansión del cultivo de café, el vertido de aguas residuales domésticas y las actividades ganaderas. Por lo tanto, se propuso al consejo municipal un plan de acción y validado con ellos, con el fin de mejorar la calidad del agua con participación de diferentes actores de la zona.

Abstract Introduction: Until today, the fishing effort by foreign fleets in the Costa Rican Pacific has not been analyzed. Objective: To determine the spatial distribution of the fishing effort of those fleets, variables that shape that distribution, and if they interact with management figures and highly fragile ecosystems. Methods: Using fishing effort data from 2012 to 2020, obtained from Global Fishing Watch, an Index of Fishing Effort (IEP) was calculated to apply geospatial and multivariate statistics, as well as multiple regression models. A grid with 55 905 cells of 0.10 degrees was used to apply Hot Spot Analysis, and another grid with 24 176 cell-year-month analysis units of 0.25 degrees was used to apply a Linear Regression Model. Results: The data reveals the fishing activity of international fleets associated with four types of fishing gear, and a wide coverage of a high IEP by two fleets throughout the nine years analyzed. The IEP is primarily associated with location and varies by month and year. There is also relative evidence that its influenced by the concentration of oxygen and nitrates. Conclusions: International fleets come into direct conflict with officially defined zones for national fleets and disrespect protected oceanic areas and a declared non-fishing zone to protect marine resources in the Costa Rican Pacific. Their activities in the Dome may affect a national yellowfin tuna fishery.

Resumen El área protegida denominada Parque Nacional Río Dulce se encuentra ubicada en el nororiente del caribe de Guatemala. Es administrada por el Consejo Nacional de Áreas Protegidas (CONAP) y regido por un plan maestro. Sin embargo, afronta cada día retos, tales como a) el incremento de desarrollo inmobiliario debido a su belleza escénica, b) el incremento poblacional de las comunidades reconocidas dentro de las diversas zonas del parque y c) vertidos no regularizados de aguas residuales tipos ordinarias y especiales. Ante esta incipiente situación, se hace necesaria la evaluación de la calidad del agua de Río Dulce a través de métodos reconocidos internacionalmente; tal el caso del Índice de Calidad del Agua ICA-NSF, con la finalidad de interpretar los resultados de una manera holística y poder discutirlos en ámbitos académicos, no solo a nivel local, sino internacional. Para ello se georreferenciaron doce estaciones de muestreo en las desembocaduras de los principales tributarios a lo largo del Parque Nacional Río Dulce. Posterior a las colectas de muestras de agua y análisis en laboratorio de los parámetros: coliformes fecales, potencial de hidrógeno, demanda bioquímica de oxígeno, nitratos, fósforo total, temperatura, turbidez, sólidos totales disueltos y oxígeno disuelto, se estimó el ICA-NSF mediante la calculadora en línea del Centro de Investigación del Agua de los Estados Unidos de América. De manera general, considerando la calidad del agua de los afluentes, el ICA-NSF varió entre 71 y 90, lo que se cualifica como una calidad buena. Los parámetros críticos en la disminución del ICA-NSF en las diversas estaciones evaluadas fueron la presencia de coliformes fecales y los sólidos totales disueltos, lo que permite generar lineamientos para el manejo sustentable del Parque Nacional Río Dulce. Se concluye que el agua del Río Dulce no es apta para el consumo humano de forma directa, necesitando de un proceso de potabilización.

Abstract The protected area called Río Dulce National Park is located in the northeastern Caribbean region of Guatemala. It is administered by the National Council of Protected Areas (CONAP) and governed by a master plan. However, it faces challenges every day, such as a) the increase in real estate development due to its scenic beauty, b) the population increase of the recognized communities within the various areas of the park, c) non-regularized discharges of ordinary and special wastewater. Given this incipient situation, it is necessary to evaluate the quality of the water in Río Dulce through internationally recognized methods; such is the case of the ICA-NSF Water Quality Index, with the aim of interpreting the results in a holistic manner and being able to discuss them in academic settings, not only locally, but also internationally. For this, twelve sampling stations were georeferenced at the source of the main tributaries along the Río Dulce National Park. After the collection of water samples and laboratory analysis of the parameters: fecal coliforms, hydrogen potential, biochemical oxygen demand, nitrates, total phosphorus, temperature, turbidity, total dissolved solids and dissolved oxygen, the ICA-NSF was estimated using the online calculator from the Water Research Center of the United States of America. In general, considering the quality of the water of the tributaries, the ICA-NSF varied between 71 and 90, which qualifies as good quality. The critical parameters in the decrease of the ICA-NSF in the various stations evaluated were the presence of fecal coliforms and total dissolved solids, which allows the generation of guidelines for the sustainable management of the Río Dulce National Park. It is concluded that the water of the Río Dulce is not suitable for human consumption directly, requiring a purification process.

Abstract CuCrO2 was synthesized by solution combustion synthesis (SCS) and applied as a heterogeneous catalyst to produce soybean biodiesel. The combustion reaction was carried out using urea as a fuel, and copper (II) and chromium (III) nitrates as precursors. After the powders’ obtention, these were calcined and functionalized in an acidic medium. The powders were characterized by thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR) techniques. The TG curve revealed that the formation of the CuCrO2 in the combustion reaction remained stable up to 1000 °C. The XRD results confirmed the formation of the CuCrO2 compound. The SEM images showed that the crystallinity of the samples increased after the calcination process. The IR spectra showed the presence of delafossite characteristic bands. After the transesterification reaction, biodiesel was obtained with a yield of around 80%. Thus, catalysts based on delafossite synthesized through the combustion method and functionalized showed to be promising for the transesterification reaction of vegetable oils.

ABSTRACT The ecological condition is a parameter that allows us to diagnose the structure and functionality of rivers. The Margaritas River basin, located in the municipality of Pijijiapan, Chiapas, Mexico, is an important source of water recharge and supply. In order to evaluate the ecological condition present at three altitudinal gradients of the Margaritas River, a visual evaluation of the physical habitat was performed following Barbour’s protocol and some physical-chemical parameters were determined (depth, dissolved oxygen, electrical conductivity, temperature, salinity and hydrogen potential). Ammonium, nitrite, nitrate and phosphate ions were also measured at the three study sites. Three replicates were carried out and an analysis of variance and comparison of means by Tukey-kramer (p ≥ 0.05) was applied. The results showed a suboptimal (Margaritas 1 and 2 sites) and marginal (Río Ramón site) habitat condition. Physicochemical parameters presented significant differences for site-specific electrical conductivity (F2,6 = 68.77 p ≤ 0.0001), electrical conductivity at 25 ºC (F2,6 = 59.67 p = 0.0001) and water temperature (F2,6 = 160.66, p ≤ 0.0001), where the highest values correspond to site Margaritas 2. The amount of nitrates (6.83 ± 0.55 mg/L) and nitrites (3.67 ± 1.15 mg/L) at site Margaritas 2 were the highest values obtained. Finally, phosphate ions presented their highest values at the Río Ramón site (0.12 ± 0.05 mg/L). The results obtained provide a current perspective on the state and condition of the Margaritas River, and it is necessary to implement appropriate management strategies for each study area.

RESUMEN La condición ecológica es un parámetro que permite diagnosticar la estructura y funcionalidad de los ríos. La cuenca del Río Margaritas, localizada en el municipio de Pijijiapan, Chiapas, México es una fuente importante de recarga y provisión hídrica. Con el objetivo de evaluar la condición ecológica presente en un gradiente altitudinal del Río Margaritas, se realizó la evaluación visual del hábitat físico a través del protocolo de Barbour y se determinaron los parámetros fisicoquímicos (profundidad, oxígeno disuelto, conductividad eléctrica, temperatura, salinidad y potencial de Hidrógeno). También se cuantificaron los iones de amonio, nitritos, nitratos y fosfatos en tres sitios de estudio. Se realizaron tres repeticiones y se aplicó un análisis de varianza y comparación de medias por Tukey-kramer (p ≥ 0.05). Los resultados mostraron una condición de hábitat sub óptima (sitios Margaritas 1 y 2) y marginal (sitio Río Ramón). Los parámetros fisicoquímicos presentaron diferencias significativas para la conductividad eléctrica específica en el sitio (F2,6 = 68.77 p ≤ 0.0001), conductividad eléctrica a 25 ºC (F2,6 = 59.67 p = 0.0001) y temperatura del agua (F2,6 = 160.66, p ≤ 0.0001), donde los valores más altos fueron los del sitio Margaritas 2. La concentración de nitratos (6.83 ± 0.55 mg/L) y nitritos (3.67 ± 1.15 mg/L) obtenidos en el sitio Margaritas 2 fueron los valores más altos. Finalmente, los iones de fosfato presentaron los valores más altos en el sitio Río Ramón (0.12 ± 0.05 mg/L). Los resultados obtenidos brindan una perspectiva actual sobre el estado y condición del Río Margaritas, siendo necesario implementar estrategias de gestión propicias para cada zona de estudio.