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URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/20514

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Agro-Industrial Avocado (Persea americana) Waste Biorefinery
(Multidisciplinary Digital Publishing Institute (MDPI) (Suiza), 2021) Mora-Sandí, Anthony; Ramírez-González, Abigail; Castillo-Henríquez, Luis; Lopretti-Correa, Mary; Jose-Roberto, Vega-Baudrit
Abstract. Significant problems have arisen in the last years, such as climate change, global warming, and hunger. These complications are correlated with the depletion and exploitation of natural resources and environmental contamination. Due to overcrowding, the list of challenges for the next few years is growing. A comprehensive approach was made to the agro-industrial production of Avocado (Persea americana) and the management of all its biomass waste. So, bioprocesses and biorefinery can be used to produce high added-value products. A large number of residues are composed of lignin and cellulose. They have many potentials to be exploited sustainably for chemical and biological conversion; physical, chemical, and natural treatments improve the following operations. There are some applications to many fields such as pharmaceutical, medical, material engineering, and environmental remediation. Possible pathways are mentioned to take advantage of Avocado as biofuels, drugs, bioplastics, and even in the environmental part and emerging technologies such as nanotechnology using bioprocesses and biotech. In conclusion, Avocado and its waste could be transformed into high value-added products in industries above to mitigate global warming and save non-renewable energy.
Tracing groundwater-surface water interactions in a volcanic maar lake using stable isotopes and radon-222
(Authorea (Nueva Jersey), 2024-05-08) Esquivel-Hernández, Germain; Montealegre-Viales, Emanuel; Sánchez-Gutiérrez, Rolando; Villalobos Forbes, Mario; Pérez-Salazar, Roy; Sánchez-Murillo, Ricardo; Mena-Rivera, Leonardo; Birkel, Christian; Ortega, Lucia
Abstract. Groundwater-surface water interactions are important in controlling lake water residence time, biogeochemistry, and water availability for downstream communities in tropical volcanic catchments. To better understand these complex seasonal interactions, a multi-tracer approach including water and inorganic carbon stable isotopes (δ2H, δ18O, δ13CDIC), hydrochemistry, and 222Rn was applied in Lake Hule, northern Costa Rica. Seasonal isotope mass balance calculations using lake, stream, precipitation, and groundwater isotope compositions were supplemented with local hydrometeorological information. Evaporation to inflow ratios (E/I) revealed a small variability between the dry (December-April) and wet seasons (May-November), with relatively low evaporation losses, 2.9±1.0 % and 3.2±1.8 %, respectively. Bayesian end-member analysis indicated that annual inputs from groundwater, precipitation, and runoff represented 61.3±8.1%, 24.4±8.4, and 14.3±5.9% of total inflow, respectively. Temporal variations of δ13CDIC also confirmed the key role carbonate buffering plays in this lake and indicated greater CO2 degassing from groundwater sources in the wet season. This first tracer-aided assessment in a volcanic lake maar of northern Costa Rica provides evidence of previously unknown groundwater-surface water interactions and poses a promising tool for estimating seasonal variability of groundwater discharge into natural lakes across the volcanic front of Central America.
Optimizing cephaeline and emetine production from Ipecac root and antimicrobial activity through maturity harvesting and processing
(2024-09-03) Rodríguez-Víquez, Marco Antonio; Syedd León, Randall Fabio; Rodríguez Rodríguez, Jorengeth Abad; Rodríguez-Rodríguez, Gerardo; Jiménez-Bonilla, Pablo; Álvarez Valverde, Víctor
[Objetive] This study aimed to determine whether there is an optimal harvest time for emetine, cephaeline, and total alkaloids Ipecac (Carapichea ipecacuanha [Brot.] L. Andersson) production. Also, the relationship between antibiotic activity and harvest time was tested. is an herb with medicinal properties cultivated in Northern Costa Rica. The root of this plant is valued according to its alkaloid concentration, which underlies its numerous biological activities. [Methodology] Two Ipecac fields from northern Costa Rican producers were sampled every ~2 months during a year. Samples were dried (through sun and oven), ground, extracted, and analyzed by HPLC and titration to evaluate the alkaloid concentration. Also, antimicrobial activity was determined using the Kirbi-Bauer test. [Results] Our main findings revealed that there is no significant difference between the oven-dried samples and the sun-dried samples. Also, an increase in total alkaloid production is observed in roots until during the first 16 months. Also, there is a variation in alkaloid composition: the cephaeline/emetine ratio increases after 16 months. [Conclusions] The highest alkaloid concentration occurs when plants are harvested between 16 and 19 months old. Additionally, the antibiotic activity is maximum at 16 months, and the cephaeline/emetine ratio is 2 at the same harvest time.
Recent Advances in Carbon Nanotubes for Nervous Tissue Regeneration
(Multidisciplinary Digital Publishing Institute (MDPI) (Suiza), 2019) Redondo, Carlos; Leandro-Mora, Rocío; Blanch-Bermúdez, Daniela; Espinoza Araya, Christopher; Hidalgo-Barrantes, David; Jose-Roberto, Vega-Baudrit
Nanomedicine has allowed for emerging advances in imaging, diagnostics and therapeutics. Regenerative Medicine has taken advantage of a number of nanomaterials for reparation of diseased or damaged tissues in the nervous system involved in memory, cognition and movement. Electrical, thermal, mechanical and biocompatibility aspects of carbon-based nanomaterials (nanotubes, graphene, fullerenes and their derivatives) make them suitable candidates to drive nerve tissue repair and stimulation. This review article focuses on recent advances on the use of carbon nanotube (CNT)-based technologies on nerve tissue engineering; outlining how neurons interact with the nanomaterials interface for promoting neuronal differentiation, growth and network reconstruction for their possible use in therapies of neurodegenerative pathologies and spinal cord injuries.
Green Synthesis of Metal Nanoparticles from Plant Extracts, and Their Possible Application as Antimicrobial Agents in the Agricultural Area
(Multidisciplinary Digital Publishing Institute (MDPI) (Suiza), 2020) Castillo-Henríquez, Luis; Alfaro, Karla; Ugalde Álvarez, Jeisson; Vega-Fernández, Laura; Montes de Oca-Vásquez, Gabriela; Jose-Roberto, Vega-Baudrit
Currently, metal nanoparticles have varied uses for different medical, pharmaceutical, and agricultural applications. Nano-biotechnology combined with green chemistry has great potential for the development of novel and necessary products that benefit human activities, while encourages the reduction of hazardous reagents for nanoparticle production. Green chemistry has an important role due to its contribution to unconventional synthesis methods of gold and silver nanoparticles from plant extracts, which have exhibited antimicrobial potential among other outstanding properties. Biodiversity-rich countries need to collect and convert knowledge from biological resources into processes, compounds, methods, and tools, which need to be achieved along with sustainable use and exploitation of biological diversity. Therefore, this review focuses on the importance of metal nanoparticles, the use of plant extract for their synthesis as well as other available methods, and the relevant antimicrobial activity that can be exploited in a sustainable model of agricultural management through a modern nanotechnological approach.
Analysis of a drinking water disinfection system: an input for improving supply management in a rural aqueduct in Costa Rica
(2024-06-05) Salas-Gónzalez, Edwin; Sánchez-Gutiérrez, Rolando; Fonseca Sanchez, Alicia; Alfaro-Chinchilla, Carolina; Esquivel-Hernández, Germain; Rodríguez Rodríguez, Jorengeth Abad; Rodríguez Corrales, José
Biosensors for the Detection of Bacterial and Viral Clinical Pathogens and COVID-19 Diagnosis
(Multidisciplinary Digital Publishing Institute (MDPI) (Suiza), 2020) Castillo-Henríquez, Luis; Brenes-Acuña, Mariana; Castro-Rojas, Arianna; Cordero-Salmerón, Rolando; Lopretti, Mary; Jose-Roberto, Vega-Baudrit
Biosensors are measurement devices that can sense several biomolecules, and are widely used for the detection of relevant clinical pathogens such as bacteria and viruses, showing outstanding results. Because of the latent existing risk of facing another pandemic like the one we are living due to COVID-19, researchers are constantly looking forward to developing new technologies for diagnosis and treatment of infections caused by different bacteria and viruses. Regarding that, nanotechnology has improved biosensors design and performance through the development of materials and nanoparticles that enhance their affinity, selectivity, and efficacy in detecting these pathogens, such as employing nanoparticles, graphene quantum dots, and electrospun nanofibers. Therefore, this work aims to present a comprehensive review that exposes how biosensors work in terms of bacterial and viral detection, and the nanotechnological features that are contributing to achieving a faster yet still efficient COVID-19 diagnosis at the point-of-care.
Bioengineered Scaffolds for Thermo-responsive Drug Delivery in Wound Healing
(Multidisciplinary Digital Publishing Institute (MDPI) (Suiza), 2020) Castillo-Henríquez, Luis; Castro-Alpízar, Jose; Lopretti-Correa, Mary; Jose-Roberto, Vega-Baudrit
Innate and adaptive immune responses lead to wound healing by regulating a complex series of events promoting cellular cross-talk. An inflammatory response is presented with its characteristic clinical symptoms: heat, pain, redness, and swelling. Some smart thermo-responsive polymers like chitosan can be used to create biocompatible and biodegradable scaffolds with 3D architectures similar to human structures, allowing their efficient and safe use as tissue engineering and drug delivery systems in chronic wounds. Locally heated tumors above polymer lower critical solution temperature can induce its conversion into a hydrophobic form, enhancing drug release until the thermal stimulus is gone, where a lower release is due to the swelling of the material. This paper integrates the relevant reported contributions of bioengineered scaffolds for thermo-responsive drug delivery in wound healing. Therefore, we present a comprehensive review that aims to demonstrate the capacity of these systems to provide spatially and temporally controlled release strategies for one or more drugs used in wound healing. In this sense, the novel manufacturing techniques of 3D-printing and electrospinning are explored for the tuning of their physicochemical properties to adjust therapies according to the patient’s convenience, as well as reduce drug toxicity and side effects.
Seasonal and Diel Patterns of Total Gaseous Mercury Concentration In Atmospheric Air of the Central Valley of Costa Rica
(2011) Castillo, Aylin; Valdes, Juan; Sibaja, José; Vega, Ilena; Alfaro, Rosa; Morales, José; Esquivel, Germain; Barrantes, Elisa; Black, Paleah; Lean, David
Monitoring mercury in atmospheric air near volcanoes is limited with no previous data for Costa Rica. Seasonal and daily patterns of total gaseous mercury (TGM) were observed at our main sampling location at the Universidad Nacional, Heredia, Costa Rica. The area (lat 10.000230 long -84.109499) is located in the Central Valley of Costa Rica and is 27 km south-east of the Poas volcano (lat 10.199486 long -84.231388). Measurements were made from May 2008 to May 2009 at this location with some additional values obtained at other sites near the Poas volcano including San Luis and Grecia as well as the, Turrialba and Irazu volcanoes. Total gaseous mercury (TGM) was determined in samples collected at a height of 2 m using the Tekran 2537A (Tekran Inc.) gas-phase mercury vapor analyzer. Meteorological data (temperature, relative humidity, wind speed, wind direction, radiation, and precipitation) were obtained from the airport weather station located at Alajuela. Monthly precipitation is typically 85 mm during the dry season (December to April) with winds from the west. The wet season begins in late April and continues to December with monthly rainfall of 328 mm and winds from the north east. The annual mean temperature is 20 degrees C. With the onset of the wet season TGM increased from typical values near 10 to 905 ng m-3. Measurements made within 5 km from the Poas volcano were higher than at Heredia at that time. Diel values measured at the university site increased until midday along with temperature and radiation. Relative humidity showed a reciprocal pattern. We observed that high values of TGM were not related to wind velocity or direction. The strong diel pattern increased with sunrise, peaked at midday and was lowest during the night time. It would seem that elemental mercury from the volcano is oxidized and is deposited to the soils during the dry season when winds are blowing from the volcano. With the onset of heavy rains in April, mercury in the soil is reduced and re-volatilized resulting in the high levels in atmospheric air. Values at other volcano sites were provided. The role of atmospheric pollutants such as hydrogen peroxide and ozone should be included in future studies as they may result in oxidation of reduced mercury. The instability in the air masses may also be a factor and local pollution sources may result in high levels of mercury being circulated to ground level as radiation intensity increases.
Safety Equipment For Storage And Handling Of Chemicals In University Laboratories
(2018) Mora, Jose; Sibaja, José; Piedra-Marin, Gilberto; Molina, Oscar
Persons who work in scientific laboratories must deal with different types of hazards. The main objective of laboratory safety operations is the prevention of accidents and emergencies. However, the potential for accidents is real, and when they take place, good safety equipment and adequate emergency protocols can help to minimize injuries or damages. The main purpose of this research was to determine the quantity of laboratories that had in their facilities any safety materials and equipment, in order to evaluate the necessity to install new equipment according to; 1) the descriptions of operations and tasks related to the handling, storage, and disposal of hazardous materials in the laboratories, and, 2) a list of potentially hazardous substances, including toxic chemical, biological, and physical agents that might cause harm to a facility´s employees. In order to get such information, a diagnosis of health and safety equipment and material availability, and their management in academic instructional and research laboratories was carried out in 91 laboratories. According with the results obtained, the hazardous products stored in biological and clinical laboratories are mainly infectious products. In chemical laboratories, flammable substances are the most common hazard chemicals stored, and physical laboratories mainly stored corrosive chemical products. In general, the majority of flammable, toxic, corrosive and explosive products are localized in chemical laboratories. Most of the laboratories inspected did not have adequate storage facilities for flammable, toxic, explosive and corrosive products. Some had ―solvent rooms‖ with quite inadequate facilities, and in the absence of adequate solvent cabinets, fume hoods or open shelving were used for storage. The inspection and training processes, as well as the purchase and installation procedures used, made the laboratories safer through the use of best practices and protective equipment. However, the restricted space in laboratories also makes it difficult to install some safety equipment. The need for, and possibility of installation of, other systems such as fire alarms, smoke detectors, and emergency exits must be evaluated. Careful handling and use of chemicals, together with the availability of adequate and proper safety equipment, and the application of good practices in housekeeping and personal hygiene, will greatly reduce the probability and severity of injuries.
Riesgo químico por exposición laboral a SO2 y H2S en el Parque Nacional Volcán Poás
(Universidad Nacional (Costa Rica), 2023-08-01) Morales Alpízar, David; Sibaja, José; mora barrantes, jose carlos; Martínez Cruz, María; Borbon Alpizar, Henry; Retana Díaz, Alexa; Alfaro Solís, Rosa
[Objetivo] Verificar el cumplimiento de los niveles de exposición a SO2 y H2S, de los guardaparques del parque, tomando como referencia la norma internacional OSHA. [Metodología] Se estudió la concentración del SO2 desde setiembre 2018 hasta diciembre 2019 y para el H2S de febrero 2019 hasta diciembre 2019, haciendo uso de equipos de detección portátiles MultiRae. Los puntos de muestreo se colocaron en la casa de guardaparques, la caseta de entrada, el centro de visitantes y el mirador. El nivel de riesgo químico se determinó considerando: la salud de los trabajadores, el tiempo de exposición, el equipo de seguridad, las capacitaciones y los valores de TWA y STEL obtenidos. [Resultados] El valor más alto de la concentración de SO2, 16,0 ppm, se registró en el centro de visitantes, y el de H2S, 45 ppm, se presentó en la casa de guardaparques. La concentración promedio de los gases estuvo cercana al límite de detección para ambos gases, sugiriendo que, los gases en general no se dirigen hacia las zonas de visitación. Ningún puesto de medición superó los 2 ppm para el SO2 en 8 horas (TWA). Sin embargo, en el centro de visitantes y en el mirador para visitantes, se superó los 5 ppm de SO2 en 15 minutos (STEL), con concentraciones de 10,1 ppm y 7,4 ppm, respectivamente. [Conclusiones] Se obtuvieron niveles bajos de riesgo químico, para ambos gases, en los puntos muestreados, a excepción del punto del centro de visitantes, donde el nivel de riesgo fue medio.
Validación de un método de cromatografía líquida (HPLC-UV/Vis) para la cuantificación de aldehídos agua de lluvia y aire
(2023-07-13) Araya Araya, María Melissa; Sibaja Brenes, José Pablo; Soto-Fallas, Roy; mora barrantes, jose carlos; Alfaro Solís, Rosa; Borbón Alpízar, Henry; Valdés González, Juan
Los aldehídos son compuestos presentes en la atmósfera que se forman por la degradación fotoquímica de otros compuestos orgánicos en la tropósfera, pueden ser emitidos por fuentes naturales o antropogénicas. En el presente trabajo se implementó un método analítico para la cuantificación de muestras de aldehídos en matrices como aire y agua de lluvia. El muestreo y el análisis de los aldehídos utilizó la metodología TO-11 de la Agencia de Protección Ambiental de los Estados Unidos (EPA). El muestreo se realizó mediante el uso de cartuchos de adsorción recubiertos con una disolución de 2,4-DNFH, formando una hidrazona con los aldehídos presentes en el agua de lluvia y en el aire. Estos fueron analizados mediante un cromatógrafo de líquido acoplado a un detector UV-Visible (HPLC-UV/Vis). Para la validación de la técnica de análisis y la calidad analítica de los resultados se determinaron: linealidad, sensibilidad, límites de cuantificación, límites de detección, repetibilidad, reproducibilidad y el porcentaje de recuperación. En el caso de la repetibilidad, se utilizó la comparación del coeficiente de variación de Horwitz con los porcentajes de desviación estándar relativo (% DER) de las muestras. Los límites de detección obtenidos oscilan entre 0,18 μg/m3 para el acetaldehído y 3,20 μg/m3 en el caso de la acroleína, mientras que los límites de cuantificación están entre 0,62 μg/m3 para el acetaldehído y 4,70 μg/m3 para el heptanal, datos que garantizan la calidad analítica del método. En general, el método de análisis para los aldehídos mostró buena correlación lineal, con valores de R2 igual o mayores a 0,9991 para cada curva de calibración, y valores de porcentajes de desvío relativo menores al 2,25 %, indicando una buena precisión en el análisis.
Utilización de índices de contaminación por hidrocarburos en pianguas (Anadara Tuberculosa) obtenidas en el Golfo de Nicoya, Costa Rica para la categorización del grado de contaminación.
(Universidad Nacional (Costa Rica), 2019-06-07) Morera González, Marilú; Saravia Arguedas, Ana Yury; García Céspedes, Jairo; Mena-Rivera, Leonardo
Antropogénicas que lo hacen vulnerable a la contaminación por sustancias como los hidrocarburos del petróleo, los cuales pueden asociarse con otras partículas y quedar disponibles para la biota y bioacumularse en el tejido lipídico de los organismos. La aplicación de índices de contaminación permite realizar una valoración de la presencia de estos compuestos. Debido a la alta captura y comercialización se utilizó la piangua, cuyas muestras se obtuvieron de junio del 2013 a diciembre del 2014, se digirieron en Soxhlet, se purificaron en columna de alúmina activada para separar los hidrocarburos alifáticos de los aromáticos y se analizaron por cromatografía de gases acoplado al detector de masas (GC-MS) y por espectrofluorofotometría, respectivamente. A los resultados obtenidos se les aplicó los índices propuestos por Ramírez et al. petrogénicos en la isla de Chira tanto en época seca como en época lluviosa en contraste con las demás zonas muestreadas, Mata Limón, Chacarita, Paquera y Punta Morales que solo presentan altas concentraciones en una de las dos épocas y en menor grado que Chira.
Investigating the impacts of biochar on water fluxes in 2 tropical agriculture using stable isotopes
(European Geosciences Union, 2020) C. Fischer, Benjamin M.; Morillas, Laura; Rojas-Conejo, Johanna; Sanchez-Murillo, Ricardo; Suárez Serrano, Andrea; Frentress, Jay; Cheng, Chih-Hsin; García, Mónica; Manzoni, Stefano; Johnson, Mark; Lyon, Steve W
Amending soils with biochar, a pyrolyzed organic material, is an emerging practice to potentially increase plant available water. However, it is not clear (1) to what extent biochar amendments increase soil water storage relative to non-amended soils and (2) whether plants grown in biochar amended soils access different pools of water compared to those grown in non-amended soils. To investigate these questions, we set up an upland rice field experiment in a tropical seasonally dry region in Costa Rica, with plots treated with two different biochar amendments and control plots, from where we collected hydrometric and isotopic data (δ18O and δ2H from rain, soil, groundwater and rice plants). Our results show that the soil water retention curves for biochar treated soils shifted, indicating that rice plants had 2 % to 7 % more water available throughout the growing season relative to the control plots. In addition, we observed a within treatment variability in the soil water retention curves which was in the same order of magnitude as one would expect from responses due to differences in biochar application rates or due to differences in biochar typologies. The stable water isotope composition of plant water showed that the rice plants across all plots preferentially utilized the more variable soil water from the top 20 cm of the soil instead of using the deeper and less variable sources of water. Our results indicated that rice plants in biochar amended soils could access larger stores of water more consistently and thus could withstand dry spells of seven extra days relative to rice grown in non-treated soils. Though supplemental irrigation was required to facilitate plant growth during extended dry periods. Therefore, biochar amendments can complement, but not necessarily replace, other water management strategies.
Chirripo Hydrological Research Site: advancing stable isotope hydrology in the Central American Paramo
(AUTHOREA, 2021) Esquivel-Hernández, Germain; Sanchez-Murillo, Ricardo; Vargas Salazar, Enzo
Tropical mountainous ecosystems are recognized as providers of valuable ecological and hydrological services (Viviroli et al, 2007). In Central America, the P aramo, a high-elevation tropical grassland ecosystem, extends over ~ 200 km2 in Costa Rica and Panama, with ~50% of this area located within the Chirripo National Park between 3,100 and 3,820 m asl (-83.49deg, 9.46deg). Vegetation mostly consists of 0.5 to 2.5 m tall bamboo dominated (Chusquea subtessellata ) grasslands, covering up to 60% of the total Paramo area in Costa Rica (Fig.1a). The climate is controlled by the northeast trade winds, the latitudinal migration of the Intertropical Convergence Zone (ITCZ), cold continental outbreaks (i.e., northerly winds), and the seasonal influence of Caribbean cyclones. These circulation patterns produce two rainfall maxima on the Paci fic slope, one in June and one in September, which are interrupted by a relative minimum between July-August, known as the Mid-Summer Drought, due to intensi cation of trade winds over the Caribbean Sea (Magana et al., 1999; Waylen, 1996). The wettest season extends from May to November (contributing up to 89% of the annual precipitation), whereas the driest season is from December to April (Fig. 2a; Esquivel-Hernandez et al., 2018). The surface water system of Chirripo is characterized by a lake district which comprises approximately 30 lakes of glacial origin and streams owing down the Caribbean and Pacifi c slopes (Fig1b).
Stable isotopic characterization of nitrate wet deposition in the tropical urban atmosphere of Costa Rica
(Research Square, 2021) Villalobos Forbes, Mario; Esquivel-Hernández, Germain; Sanchez-Murillo, Ricardo; Sánchez-Gutiérrez, Rolando; Matiatos, Ioannis
Increasing energy consumption and food production worldwide results in anthropogenic emissions of reactive nitrogen into the atmosphere. To date, however, little information is available on tropical urban environments where inorganic nitrogen is vastly transported and deposited through precipitation on terrestrial and aquatic ecosystems. To fill this gap, we present compositions of water stable isotopes in precipitation and atmospheric nitrate (δ 18 O-H2O, δ 2 H-H2O, δ 15 N-NO3-, and δ 18 O-NO3-) collected daily between August 2018 and November 2019 in a tropical urban atmosphere of central Costa Rica. Rainfall generation processes (convective and stratiform) were identified using stable isotopes in precipitation combined with air mass back trajectory analysis. A Bayesian isotope mixing model forced with δ 15 N-NO3-values corrected for potential 15 N fractionation effects reveal the predominant contribution of biomass burning and lightning to nitrate wet deposition. δ 18 O-28 NO3-values in Caribbean convective rainfall reflect the oxidation chemistry of NOx sources whereas δ 15 N-NO3-values in Pacific stratiform rainfall indicate the transport of nitrogen sources contributing to nitrate in atmospheric deposition. These findings provide necessary baseline information about the combination of water and nitrogen stable isotopes with atmospheric chemistry and hydrometeorological techniques to better understand wet deposition processes and to characterize the origin of inorganic nitrogen loadings in tropical regions.
Tracer-aided modelling reveals quick runo generation and groundwater losses producing young stream ow ages in a tropical rainforest catchment
(2021-05-29) Mayer-Anhalt, Leia; Birkel, Christian; Sanchez-Murillo, Ricardo; Shulz, Stephan
There is still limited understanding of how waters mix, where waters come from and for how long they reside in tropical catchments. In this study, we used a tracer-aided model (TAM) and a gamma convolution integral model (GM) to assess runogeneration, mixing processes, water ages and transit times (TT) in the pristine humid tropical rainforest Quebrada Grandecatchment in central Costa Rica. Models are based on a four-year data record (2016 to 2019) of continuous hydrometric and stable isotope observations. Both models agreed on a young water component of fewer than 95 days in age for 75% of the study period. The streamow water ages ranged from around two months for wetter years (2017) and up to 9.5 months for drier (2019) years with a better agreement between the GM estimated TTs and TAM water ages for younger waters. Such short TTs and water ages result from high annual rainfall volumes even during drier years with 4,300 mm of annual precipitation (2019)indicating consistent quick near-surface runo generation with limited mixing of waters and a supra-regional groundwater ow of likely unmeasured older waters. The TAM in addition to the GM allowed simulating streamow (KGE > 0.78), suggesting an average groundwater contribution of less than 40% to streamow. The model parameter uncertainty was constrained in calibration using stable water isotopes (d2H), justifying the higher TAM model parameterization. We conclude that the multi-model analysis provided consistent water age estimates of a young water dominated catchment. This study represents an outlier compared to the globally predominant old water paradox, exhibiting a tropical rainforest catchment with higher new waterfractions than older water.
Deciphering complex groundwater age distributions and recharge processes in a tropical and fractured volcanic aquifer system
(Authorea (Nueva Jersey), 2021) Sanchez-Murillo, Ricardo; Montero Rodríguez, Irene; Corrales Salazar, José; Esquivel-Hernández, Germain; Castro-Chacón, Laura; Rojas-Jiménez, Luis; Vargas-Víquez, José; ; ; Boll, Jan
Abstract. Groundwater recharge in highly-fractured volcanic aquifers remains poorly understood in the humid tropics, whereby rapid demographic growth and unregulated land use change are resulting in extensive surface water pollution and a large dependency on groundwater extraction. Here we present a multi-tracer approach including δ18O-δ2H, 3H/3He, and noble gases within the most prominent multi-aquifer system of central Costa Rica, with the objective to assess dominant groundwater recharge characteristics and age distributions. We sampled wells and large springs across an elevation gradient from 868 to 2,421 m asl. Our results suggest relatively young apparent ages ranging from 0.0±3.2 up to 76.6±9.9 years. Helium isotopes R/RA (0.99 to 5.4) indicate a dominant signal from the upper mantle across the aquifer. Potential recharge elevations ranged from ~1,400 to 2,650 m asl, with recharge temperatures varying from ~11°C to 19°C with a mean value of 14.5±1.9°C. Recharge estimates ranged from 129±78 to 1,605±196 mm/yr with a mean value of 642±117 mm/yr, representing 20.1±4.0% of the total mean annual rainfall as effective recharge. The shallow unconfined aquifer is characterised by young and rapidly infiltrating waters, whereas the deeper aquifer units have relatively older waters. These results are intended to guide the delineation and mapping of critical recharge areas in mountain headwaters to enhance water security and sustainability in the most important headwater dependent systems of Costa Rica.

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