Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14823

Examinar

Mostrando 1 - 13 de 13

Aporte ambiental de la planta de tratamiento de aguas residuales Los Tajos en la remoción de contaminantes fisicoquímicos y microbiológicos
(Universidad Nacional, Costa Rica, 2022-01-31) Mora Aparicio, Carmen; Alfaro-Chinchilla, Carolina; Perez-Molina, Junior Pastor; Vega-Guzmán, Ilena
The objective of the study was to analyze the environmental contribution, in terms of removal of physicochemical and microbiological pollutants, from the Los Tajos Wastewater Treatment Plant (WWTP) to the Torres River. Physicochemical and microbiological data was analyzed including WWTP inflows and outflows (OBD, OCD, TSS, STT, N-NH4 +, P-PO4 3-, Oils, MBAS, and fecal coliforms). The difference in the concentration of pollutants in the Torres River before and after the construction of the WWTP was analyzed using R 3.6.1, associated with seasonality. According to the Dutch Index Methodology, the Torres River was severely polluted before the construction of the WWTP, and the degree of contamination increases following the WWTP discharge, mainly during the rainy season. The WWTP shows significant removal of seven of the eight parameters analyzed, with the most representative removal percentages being: TSS (68.5%), OBD (49.8%), and Oils (54.7%). The quantitative contribution of the WWTP to the Torres River was demonstrated by removing thousands of Mg of pollutants from wastewater during the years of operation (2015-2020), mainly OCD (26,791.8 Mg), STT (24,162.6 Mg), OBD (12,290.0 Mg), and TSS (30,267.7 Mg). Finally, building the WWTP’s next stages, including secondary treatment, is needed to improve the removal of organic matter, surfactants, and nutrients.
Arthropod biodiversity loss and the transformation of a tropical agro-ecosystem
(Chapman & Hall, 1997) Perfecto, Ivette; Vandermeer, John; Hanson, Paul; Cartin, Víctor
The coffee (coffea arabica) agro-ecosystem in the Central Valley of Costa Rica was formerly characterized by a high vegetational diversity. This complex system has been undergoing a major transformation to capital-intensive monocultural plantations where all shade trees are eliminated. In this study we examined the pattern of arthropod biodiversity loss associated with this transformation. Canopy arthropods were sampled in three coffee farms: a traditional plantation with many species of shade trees, a moderately shaded plantation with only Erythrina poeppigeana and coffee, and a coffee monoculture. An insecticidal fogging technique was used to sample both canopy and coffee arthropods. Data are presented on three major taxonomic groups: Coleoptera, non-formicid Hymenoptera, and Formicidae. Data demonstrate that the transformation of the coffee agro-ecosystem results in a significant loss of biological diversity of both canopy arthropods as well as arthropods living in coffee bushes. Percentage of species overlap was very small for all comparisons. Furthermore, species' richness on a per tree basis was found to be within the same order of magnitude as that reported for trees in tropical forests. If results presented here are generalizable, this means that conservation efforts to preserve biological diversity should also include traditional agro-ecosystems as conservation units.
Biogardens as constructed wetlands in tropical climate: A case study in the Central Pacific Coast of Costa Rica
(Elsevier, 2019-03-25) Pérez-Salazar, Roy; Mora Aparicio, Carmen; Alfaro-Chinchilla, Carolina; Sasa Marín, Jihad; Scholz, Carola; Rodríguez-Corrales, José
In Costa Rica, <10% of wastewater is treated before its discharge. This generates a significant impact on the environment, public health, and tourism industry, which is one of the country's main economic activities. Biogardens, subsurface flow artificial wetlands, are alternative systems for the treatment of wastewater. The present study evaluated the removal of organic matter and nutrients in a biogarden located at a hotel in the Central Pacific Coast of Costa Rica between 2012 and 2017. Pretreatment involved septic tanks and grease traps for sewage and gray water, respectively. The biogarden, which is composed of seven wetlands with an average area of 12 m2 and a depth of 0.7 m, contains river cobble as support material, gravel as bed, and Cyperus papyrus and Heliconia sp. plants. Removal of the biochemical oxygen demand (BOD), the chemical oxygen demand (COD), and the total suspended solids (TSS) on average were 80%, 66%, and 72%, respectively, thus producing an effluent in compliance with current national legislation. Furthermore, the biogarden did not emit noxious odors or display an excessive presence of mosquitoes. The results showed consistent and efficient removal of organic matter and nutrients from the wastewater throughout different seasons and pollutant loads, verifying that such systems can be used in decentralized locations (e.g., tourist areas) in tropical climates.
Carácteres generales, edad y crecimiento de anadara grandis (Pelecypoda Arcidae)
(Universidad Nacional (Costa Rica), 1986-01-01) Cruz, Rafael A.
Cálculos en el porcentaje de carne por peso análisis de la estructura poblacional de Anadara grandis se realizó entre abril de 1984 y marzo de 1985. El valor promedio del porcentaje de carne fue de 10,93 con un valor máximo de 18, 04 y mínimo de 8,53. El método de frecuencia longitud indicó que hay dos grupos de edad por año con dos picos de desove, uno en enero y otro en abril. La longitud asintótica (L ∞) y el peso asintótico (P ∞) fueron 139,144 mm. y 1.122,024 g., respectivamente. Las ecuaciones generalizadas del crecimiento de Von Bertalanffy fueron, para la longitud: L= 139,144 [1-e -0,122(t-0,698)] Y para el peso: Pt= 1.122,024 [1-e -0,122(t-0,698)] 2,35 Se calculó en 4,40 +/- 0,26mm. y 36,5g. el crecimiento promedio mensual en longitud y peso respectivamente. A. grandis presentó crecimiento alométrico.
Chemical and functional characterization of antimicrobial metabolites isolated from ascidian Rhopalaea Birkelandi
(Universidad Nacional (Costa Rica), 2011-12) Cordero, Maribel; Borbón, Henry; Román, Félix R.; Morrel, Luis; Víquez, Rigoberto; Villegas, Luis R.; Soto, Roy; Vega, Ileana
Marine ecosystems have a very large diversity of resources, most of them still partially unknown, and a few others exploited for development of new industrial and toxicological products. The objective of this investigation was to determine whether the acetone extract of the ascidia R. birkelandi from the Pacific coast of Costa Rica showed qualitative antimicrobial activity against the S. aureus bacteria and the G. candidum fungus, and to verify their main secondary metabolites in the active extract using chromatographic and spectroscopic techniques. Ascidians were collected at Tambor, Guanacaste, Costa Rica, between December 2007 and March 2008. Activity against the Gram positive bacteria and fungi was evaluated using ethanolic (95%) and acetonic extracts. Both extracts showed activity against G. candidum; however, only the acetonic extract showed activity against S. aureus. A coumarin and a hydroxyanthraquinone were isolated from a crude extract of R. birkelandi as metabolites present in the active fraction. Purification and isolation were performed by chromatographic techniques and solid phase extraction. Structural information was obtained by spectroscopic analyses: Ultraviolet (UV-Visible), Fourier Transform Infrared (FT-IR), Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS), Gas Chromatography Mass Spectrometry (GC/MS), Proton Nuclear Magnetic Resonance (1HNMR), and Carbon-13 Magnetic Resonance (13C-NMR). Further studies are recommended for characterization and quantification of the active components of this extract and the possible elucidation of the mechanisms of action.
Determinación de la actividad antibacterial de la esponja Marina Ircinia Campana recolectada en Punta Uva Limón contra Staphylococcusaureus
(Universidad Nacional (Costa Rica), 2012) Rojas Brenes, Rafael; Borbón Alpízar, Henry; Bagnarello Madrigal, Vanessa; Víquez Portuguez, Rigoberto; Soto-Fallas, Roy; Vega Guzman, Ilena; Herrera Núñez, Jacqueline
Las esponjas son organismos multicelulares sim-ples, habitan en ambientes marinos desde los mares polares, hasta las aguas tropicales, donde son más abundantes. Están expuestas a grandes poblaciones de microorganismos, razón que explica el complejo mecanismo de defensa morfológica y celular utilizado por estos organismos para combatir los patógenos. El propósito de este estudio fue evaluar la actividad antibacteriana de la esponja marina Ircinia campanaque habita en el sur de la costa caribeña de Costa rica contra la bacteria Gram positiva Sthapylococcus aureus. Los ejemplares de la especie Ircinia campana fueron recolectados en Punta Uva, en la provincia de Limón durante el mes de julio del 2007. La obtención del componente activo se realizó a través de una extracción con acetona para obtener el extracto crudo; posteriormente, se realizaron separaciones cromatográficas de dicho extracto utilizando fracciones 1:4 hexano:acetato de etilo. Se analizó la actividad antibacterial de las diferentes fracciones incluyendo el extracto crudo. Los resultados obtenidos muestran una zona de inhibición de 14.60 ±0.25 mm del extracto crudo y de 18.70 ±0.25mm para la fracción más activa separada por cromatografía de columna. El metabolito responsable de la actividad antibacterial de la especie analiza-da se logró aislar por Cromatografía Líquida de Alta Resolución (HPLC), además se realizó una caracterización preliminar de su estructura molecularmediante espectroscopia ultravioleta (UV) e infrarroja(IR).
Diagnóstico de las necesidades de capacitación de docentes de biología, química, física y matemática, en áreas disciplinares, pedagógicas, y uso de las tecnologías para la promoción de habilidades de pensamiento científico
(Universidad Nacional, Costa Rica, 2020-08-21) Zuñiga Melendez, Adriana; Duran Apuy, Alejandro; Chavarria Vasquez, Jesennia; Carballo Arce, Ana Francis; Vargas Gonzalez, Xinia; Campos, Nelson; Sevilla Solano, Cecilia; Torres-Salas, Isabel; Gamboa-Araya, Ronny
Este estudio tiene como objetivo conocer las necesidades de capacitación del personal docente de ciencias naturales (biología, química y física) y de ciencias exactas (matemática), de colegios públicos académicos diurnos de la Dirección Regional de Educación de Heredia, para el desarrollo de habilidades científicas. Se trabajó con 72 docentes de matemática y 88 de ciencias naturales. La investigación se realizó desde el paradigma naturalista, con un enfoque cualitativo dominante y con un diseño del tipo de estudio fenomenológico. Se utilizó un instrumento tipo cuestionario, que tenía 12 preguntas dirigidas a indagar las necesidades de capacitación sobre los saberes pedagógicos y el uso de las tecnologías, y se hizo una exploración acerca del grado de interés que tiene el personal docente por recibir capacitación en saberes disciplinares. Las categorías utilizadas para el análisis son las siguientes: aspectos generales del personal docente en ejercicio; intereses de capacitación en el campo disciplinar, pedagógico y uso de las tecnologías; así como retos manifestados. Entre los principales hallazgos se evidenció el interés del cuerpo docente para participar en procesos de actualización en temas como la planificación, mediación y evaluación; además, en el uso de las tecnologías de la información y la comunicación. Además, se determinó que la capacitación en áreas disciplinarias debe estar enfocada al diseño de estrategias de mediación que permitan abarcar los temas de los programas de forma interdisciplinaria y contextualizada, así como en el diseño de procesos evaluativos que permitan evidenciar, en el estudiantado, el grado de apropiación de las habilidades de pensamiento científico y matemático.
Ecosystemic Assessment of Surface Water Quality in the Virilla River: Towards Sanitation Processes in Costa Rica
(Universidad Nacional (Costa Rica), 2018) Mena-Rivera, Leonardo; Vásquez-Bolaños, Oscar; Gómez-Castro, Cinthya; Fonseca-Sánchez, Alicia; Rodríguez-Rodríguez, Abad; Sánchez-Gutiérrez, Rolando
Water quality information is essential supporting decision making in water management processes. The lack of information restricts, at some point, the implementation of adequate sanitation, which is still scarce in developing countries. In this study, an ecosystemic water quality assessment was conducted in the Virilla river in Costa Rica, in a section of particular interest for future sanitation development. It included the monitoring of physical, chemical, microbiological and benthic macroinvertebrate parameters from 2014 to 2016. Mutivariate statistics and water quality indexes were used for data interpretation. Results indicated that water quality decreased downstream towards more urbanised areas. Particularly, extreme values of phosphorous, nitrogen and E. coli were found. Sample sites were grouped in two clusters, which were consistent with land use. Benthic macroinverterbrates diversity was predominantly represented by Baetidae, Chironomidae, Leptohyphidae, Hydropsychidae, Simuliidae and Physidae. They were mostly influenced by water temperature, nitrite, ammonium, soluble reactive phosphorous, total solids, alkalinity, nitrate and total suspended solids. Three water quality indexes consistently showed the poor condition of the water body. The overall results indicate that the main sources of pollution in the river are likely to be wastewater discharges. Thus, special efforts should be undertaken regarding its regulation in the country.
Evaluación Físico-Química de los Sedimentos en el Estero Tamarindo y sus tribuatrios, Guanacaste, Costa Rica
(Universidad Nacional (Costa Rica), 2012) Bravo Chaves, Francela María; Piedra-Marin, Gilberto; Piedra Castro, Lilliana
Se evaluaron los sedimentos del estero Tamarindo y de los ríos que confluyen en él con el propósito de determinar el efecto de las actividades antropogénicas de las comunidades aledañas. Los parámetros escogidos para la evaluación fueron tex-tura, fósforo total, porcentaje de materia orgánica y concentración de metales pesados (Pb, Cu, Ni y Cr). El estudio abarcó cuatro actividades de mues-treo entre octubre 2007 y abril 2008 incluyendo cuatro épocas climáticas: época lluviosa, transición lluviosa-seca, época seca y transición seca-lluviosa. Se definieron cinco puntos de muestreo dentro del estuario y tres adicionales en los ríos Matapalo, Lomas y Lajas. Para evaluar la calidad de los sedimentos se utilizó la norma establecida por el Ministerio del Ambiente de ontario, Canadá. Se determinó que las actividades antropogénicas de las comunidades aledañas al estero ejercen un impacto negativo sobre la calidad de los sedimentos; el efecto de contaminación generado por tales actividades se clasificó como efecto menor.
Exploration of photoprotective and antibiotic activity of wild Polypodiaceae ferns from Costa Rica
(Springer (Alemania), 2024) Salazar‑Chacón, Yaclyn; Gutiérrez‑Bolaños, María José; Padilla - Cordero, Jimena; Vidaurre‑Rodriguez, Camilo; Carvajal-Miranda, Yendry; Rojas Alvarado, Alexander; Rodríguez‑Rodríguez, Jorengeth Abad; Rodríguez‑Rodríguez, Gerardo; Álvarez Valverde, Víctor; Jiménez‑Bonilla, Pablo
Skin disorders affect millions of people all over the world. There are limited options to treat dermal illnesses such as vitiligo, psoriasis, and atopic dermatitis (eczema). Central American ferns are a potential source of bioactive metabolites against those diseases. Currently, Polypodium leucotomos Poir. is the only one being commercially utilized for this purpose. In this work, we evaluated the concentration of the skin bioactive compounds: quinic and chlorogenic acid, in the extract of 20 wild ferns from Costa Rica. We also evaluated the antimicrobial capabilities of the crude extracts of wild ferns and the sun protection factor (SPF) of the extracts. We found 19 out of 20 have either an important concentration of the compounds mentioned above or antimicrobial properties. Also, most samples result in higher SPF than P. aureum’s rhizome. We also have studied the fern acclimatization, at different shading conditions, finding a significant influence of the culturing conditions on metabolite production. After acclimatization. So far, we demonstrate that various ferns included in this study are a potential source of treatments for skin conditions.
Hydrogeochemical baseline in a human altered landscape of the Central Pacific coast of Costa Rica
(Springer Nature, 2020) Sánchez-Gutiérrez, Rolando; Mena-Rivera, Leonardo; Sanchez-Murillo, Ricardo; Fonseca , Alicia ; Madrigal-Solís, Helga
Abstract Groundwater pollution in tropical and human-altered coastal landscapes is receiving novel attention due to decreasing in annual recharge as a consequence of recurrent droughts and overexploitation, whereby saline intrusion, point and diffuse source contamination, and water conflicts are common denominators. This study presents a detailed groundwater evaluation in a coastal aquifer within the central Pacific coast of Costa Rica. Three sampling campaigns including major ions, heavy metals, and fecal coliform analyses were conducted between July 2013 and March 2014 across 17 wells within the alluvial and fissured units of the Jaco´ aquifer. The groundwater system is classified as mixed HCO3 -–Ca2?–Mg2? type. Coliforms presence was found in two wells,nearby Mona Creek headwaters and near the coastal line. Heavy metal concentrations were below quantification limits in most of the wells; however, chromium concentrations up to 6.56 lg/L were quantified within the coastal line and central portion of the alluvial aquifer in 20 out of the 48 samples. The spatial distribution of major ions (K?, Na?, Ca2?, Mg2?, Cl-,SO42-, and HCO3 -) exhibited an increasing trend towards the central portion of the alluvial aquifer, which may be potentially associated with the large unregulated urban expansion, invoking a need of a continuous water quality monitoring program in this touristic hot spot. This study provides useful information for other similar coastal aquifers in Central America, whereby increasing population growth and unregulated touristic, industrial, and agricultural activities are posing a truly challenge to ensure water security and sustainability parallel to the economic development in a changing climate.
Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica
(Taylor & Francis, 2016) Sánchez-Murillo, Ricardo; Esquivel-Hernández, Germain; Sáenz-Rosales, Oscar; Piedra-Marin, Gilberto; Fonseca-Sánchez, Alicia; Madrigal-Solís, Helga; Ulloa-Chaverri, Franz; Rojas-Jiménez, Luis D.; Vargas-Víquez, José A.
The linkage between precipitation and recharge is still poorlyunderstood in the Central America region. This study focuses onstable isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica. During the dry season, rainfall samples corresponded to enriched events with high deuterium excess. By mid-May, the Intertropical Convergence Zone poses over Costa Rica resulting in a depletion of 18O/16O and 2 H/H ratios. A parsimonious four variable regression model (r2= 0.52) was able to predict daily δ18Oin precipitation. Air mass back trajectories indicated a combination of Caribbean Sea and Pacific Ocean sources, which is clearly depicted in groundwater isoscape. Aquifers relying on Pacific-originated recharge exhibited a more depleted pattern, whereas recharge areas relying on Caribbean parental moisture showed an enrichment trend. These results can be used to enhance modelling efforts in Central America where scarcity of long-term data limits water resources management plans.
Producción de pescado seco-salado utilizando secadores solares
(Universidad Nacional (Costa Rica), 1986-01-01) Herrera Ramírez, Carlos; Elizondo Almeida, Luis J.
La técnica de seco-salado de pescado es un método de preservación efectivo, rápido y barato que se ha utilizado durante cientos de años controlando la temperatura y la concentración de sal en proteínas como el pescado por medio de un Secador solar.

Examinar

Examinando Artículos científicos por browse.metadata.procedence "Escuela de Ciencias Biológicas"