Seeking to establish a theory of experience overcoming the horizon of the Enlightenment, in some of his earlier texts Benjamin reflects on phantasy. These reflections establish a logics or language ...of the world besides the (Neo-Kantian) duality of intuition and reason, or receptivity and spontaneity. This language, instantiated especially by the rainbow, discloses the truth without application of rational categories. The truth, however, does not disclose itself, and cannot be conceived of, simply as a continuum of one medium. Rather, it appears in a discontinuity transcending this medium without disturbing it.
The distribution of species on elevational gradients challenges our understanding of ecological processes, particularly in the context of biotic responses to climate change. We report here the ...distribution of leaf-litter ants on the Barva Transect, a continuous gradient of wet forest on Costa Rica's Atlantic slope. Seven sites were sampled, distributed from 50 to 2000 m. Worker density and microsite occupancy were high and relatively constant from 50 m to 1500 m and then abruptly dropped to near zero at 2000 m. Species density at the 1 m
2
scale was high and constant to 1070 m and then declined at higher elevations. Species richness of assemblages at the 1 km
2
scale was constant or rose slightly from 50 m to 500 m and then steeply declined. Because assemblage richness and species density declined more rapidly than worker density, density compensation with elevation is suggested and supported by a measure of mean population density. Statistically, temperature was the best predictor of both species richness and worker density. Relative humidity, soil nutrients, elevation-specific regional area, and the mid-domain effect were poor predictors of richness. Sites from 50 m to 500 m were similar in species composition. In contrast, assemblages at 1070 m, 1500 m, and 2000 m were highly differentiated. Thus elevational ranges were narrow for species at mid to upper elevations and broad for those at the lowest elevations.
Density compensation at higher elevation suggests that if temperature or productivity are influencing the decline in diversity it must be indirectly through speciation and extinction processes, rather than by greater numbers of individuals. The broad ranges of lowland species may be a response to as yet unmeasured environmental factors (e.g., NPP) or to climate changes associated with the current interglacial period. Interglacial warming may have driven species to higher elevations, but the lack of competitors at the lower range margins may have allowed the lowest-elevation species to move upslope without a concomitant contraction of the lower range boundary. Global warming threatens a loss of narrowly-distributed montane species, but lowland biotic attrition may be ameliorated by range expansion among lowland species.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hydrogeological responses in tropical mountainous springs Salas-Navarro, Jessica; Sánchez-Murillo, Ricardo; Esquivel-Hernández, Germain ...
Isotopes in environmental and health studies,
01/2019, Volume:
55, Issue:
1
Journal Article
Peer reviewed
This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ
18
O and δ
2
H ...in rainfall resulted in a highly significant meteoric water line: δ
2
H = 7.93·δ
18
O + 10.37 (r
2
= 0.97). Rainfall isotopic composition exhibited a strong amount-dependent seasonality. The isotopic variation (δ
18
O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23 ± 0.03 (Sacramento) and 1.42 ± 0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.
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The groundwater of the Barva, Upper Colima, and Lower Colima aquifers, located in the western part of the Central Valley of Costa Rica represents the main source of drinking water in this region. The ...purpose of this study was to design a monitoring network to evaluate groundwater quality in these aquifers within the sub-basins of the Bermúdez, Ciruelas and Río Segundo rivers, and to encourage the participation of stakeholders. Five proposed sites exceeded, in between two and four occasions, the Alert Value of 25 mg/l nitrate as NO3-. These sites, which capture water from the Barva aquifer, were located in areas where urban use and coffee crops predominated. The sites that collected water from this aquifer with the lowest concentrations, below 2 mg/l, were found in the upper sub-basins, where forest and pastures predominate, while those that collected water from the Colima aquifers showed concentrations below 20 mg/l. At least semi-annual monitoring of electrical conductivity, pH, temperature, nitrates and chlorides is recommended. The operation of these networks provides an opportunity for monitoring groundwater quality by stakeholders at basin level as one of the first steps in developing sustainable management of this resource.
El agua de los acuíferos Barva, Colima Superior y Colima Inferior, ubicados en el sector oeste del Valle Central de Costa Rica, representa la principal fuente de abastecimiento de agua potable en esta región. El propósito de este estudio fue diseñar una red de monitoreo o vigilancia para la calidad del agua de estos acuíferos en las subcuencas de los ríos Bermúdez, Ciruelas y río Segundo, así como fomentar la participación de actores sociales para el funcionamiento de cada red de vigilancia. De los sitios propuestos, cinco sobrepasaron, de dos a cuatro ocasiones, el Valor Alerta de 25 mg/l de nitratos como NO3-. Estos sitios, los cuales captaron agua del acuífero Barva, se encontraban en zonas donde predominaba el uso urbano y cultivos de café. Los lugares que captaron agua de este acuífero con las menores concentraciones, por debajo de los 2 mg/l, se encontraban en las zonas altas de las subcuencas, en donde predomina el bosque y los pastos, mientras que los que captaron agua de los Colima mostraron concentraciones por debajo de los 20 mg/l. Se recomienda la vigilancia semestral de al menos conductividad eléctrica, pH, temperatura, nitratos y cloruros. El funcionamiento de estas redes ofrece una oportunidad para la vigilancia de la calidad del agua subterránea por parte de actores clave en el nivel de cuenca, como uno de los primeros pasos en el desarrollo de un manejo sostenible de este recurso.
A água dos aquíferos Barva, Colima Superior e Colima Inferior, localizados no setor oeste do Vale Central da Costa Rica, representa a principal fonte de abastecimento de água potável nessa região. O propósito deste estudo foi desenhar uma rede de monitoramento ou vigilância para a qualidade da água desses aquíferos nas sub-bacias dos rios Bermudez, Ciruelas e rio Segundo, assim como fomentar a participação de atores sociais para o funcionamento de cada rede de vigilância. Dos lugares propostos, cinco ultrapassaram, em duas a quatro ocasiões, o valor alerta de 25 mg/l de nitratos como NO3. Estes lugares, que captaram água do aquífero Barva, encontravam-se em zonas onde predominava o uso urbano e os cultivos de café. Os lugares que captaram água deste aquífero com as menores concentrações, ou seja, abaixo dos 2 mg/l, encontravam-se nas zonas altas das sub-bacias, onde predomina a floresta e os pastos, enquanto os que captaram água dos Colima mostraram concentrações abaixo dos 20 mg/l. Recomenda-se a vigilância semestral pelo menos de condutividade eléctrica, pH, temperatura, nitratos e cloretos. O funcionamento destas redes oferece uma oportunidade para a vigilância da qualidade da água subterrânea por parte de atores chave em nível de bacia, como um dos primeiros passos no desenvolvimento de um manejo sustentável deste recurso.
Nitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa ...Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.
Plain Language Summary
This study analyzed different nitrate sources in a complex tropical groundwater system and how they were affected by changes in land use over the last decades. In general, high‐elevation areas near protected forests are represented by lower nitrate levels, while mid‐ and low‐elevations areas exhibited greater nitrate and chloride concentrations. Our results suggest that groundwater nitrate reflects a legacy mixture of sewage (domestic septic tanks), soil nitrogen (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. The identified nitrate groundwater legacy in the Central Valley of Costa Rica, evidenced by unprecedented decadal nitrate isotope data, could serve as a valid example of the potential impact of abrupt urbanization growth across the wet tropics.
Key Points
Four decades of land use change have increased groundwater nitrate concentrations in central Costa Rica
Deeper aquifer units were characterized by low nitrate concentrations, whereas greater values were reported in the shallow unconfined unit
Nitrogen and oxygen stable isotopes revealed unknown recharge mechanisms and nitrogen pollution sources in a tropical volcanic aquifer
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High groundwater demand in the Great Metropolitan Area (GMA) of Costa Rica, combined with the presence of many septic systems, imposes the necessity to define adequate dimensions for setback ...distances or protection zones around wellheads to prevent contamination of aquifers by pathogenic organisms. Numerical 3-D simulations of transport of viruses under natural hydrogeological conditions of the northwest section of GMA were performed, considering both porous and fractured porous media with variable saturation. Based on the sensitivity analysis, principal transport parameters for the conditions in the study area are injection concentration, hydraulic conductivity, inactivation rate and attachment rate. Furthermore, a comparative analysis of the arrival of viruses to the water table and the modeling domain’s boundary was carried out using two approaches: maximum permissible concentration criteria and travel time criteria (TT) of 100 days frequently applied in Costa Rica for fractured rocks aquifers. The analysis indicates that under conditions of low mobility and high removal rates (typical for soils of volcanic origin), the TT approach overestimates the dimension of the protection zone. On the other hand, when conditions of high mobility and low removal rate are considered, the TT approach usually underestimates that dimension. It is recommended to perform more field and laboratory studies to obtain better representative parameters for soils of volcanic origin.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
El cambio climático es producido por los gases de efecto invernadero generados principalmente por la actividad humana que alterael equilibrio en la atmósfera. La comunidad internacional en general y ...las instituciones nacionales en particular se han preocupadopor la medición y mitigación del impacto antropógeno en la naturaleza. La metodología utilizada para la medición de la huella decarbono generada por la actividad antropogénica de la Municipalidad de Barva se basa en la propuesta por la IntergovernmentalPanel on Climate Change (IPCC, 2007), con las adaptaciones para adecuarla a la realidad de Costa Rica. Esta metodología permitecuantificar las toneladas de dióxido de carbono generadas por las personas, las instituciones y las empresas en un lugar y en un tiempodeterminado. La medición de la huella de carbono aplicada en el 2010 a las actividades realizadas por la Municipalidad de Barvapermite cuantificar el impacto que tiene en el medio ambiente y proponer acciones para su mitigación. Los terrenos reforestados yconservados que posee el Gobierno Local tenían la capacidad de compensar la totalidad de sus emisiones (482 Ton CO2) y aumentarlaen un 82% adicional para el 2010. Los retos son mantener y mejorar los procesos que permitan hacer más eficiente el consumo depapel, plástico, combustible y electricidad.
La leyenda de la laguna del volcán Barva Kattia Chinchilla Sánchez
Revista de filología y lingüística de la Universidad de Costa Rica,
08/2015, Volume:
19, Issue:
2
Journal Article
Peer reviewed
Open access
Este artículo es un análisis simbólico de dos elementos míticos muy frecuentes: el árbol y la serpiente, en la leyenda de la laguna del volcán Barva. This article is a symbolic analysis of two ...mythical elements very frequent: the tree and the snake, in the legend of the Barva Volcano lagoon.
La mayor parte del agua para consumo humano y para el desarrollo de las actividades económicas en el Valle Central de Costa Rica proviene de los acuíferos ubicados en dicha región. Sin embargo, ...muchas de estas actividades se llevan a cabo sobre la zona de recarga del acuífero libre Barva, representando una amenaza a la calidad de sus aguas. El objetivo de este estudio fue elaborar un mapa de carga contaminante para los cantones de Santa Bárbara, Barva y San Rafael, Heredia, Costa Rica, como un primer paso en la generación de un mapa de riesgo para el acuífero Barva. Para esto, se seleccionaron, ubicaron y clasificaron las actividades, según el método POSH (Pollutant Origin Surcharge Hydraulically). Luego, el territorio se subdividió en celdas de 250 x 250 m y a cada una se le asignó el valor máximo de potencial de carga contaminante, según el valor asignado a las fuentes en esa celda. De las 2103 celdas, un 45% se encontró bajo al menos una actividad con potencial de carga contaminante elevado, un 32% con al menos una actividad con potencial moderado, un 14% con al menos una actividad con potencial reducido y un 9% con potencial nulo. Además, los subacuíferos Bambinos y Los Ángeles fueron identificados como los sectores más críticos. La información generada contribuirá al diseño e implementación de medidas de control más estrictas, encaminadas a minimizar la probabilidad de contaminación.
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