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Se evaluó el desempeño de los dispositivos pasivos para la determinación de dióxido de nitrógeno en 25 sitios de los cantones de San José y Belén, para lo que, primeramente, se determinó los parámetros de desempeño del método: límite de detección y cuantificación, sesgo y precisión, obteniendo resultados satisfactorios. Al menos cinco sitios en San José y cuatro en Belén presentan valores mayores a 40 µg/m3, que corresponde al criterio recomendado por la Organización Mundial de la Salud para este contaminante. Las concentraciones mayores se presentan en sitios comerciales con alto flujo vehicular donde llegan a alcanzar excedencias de hasta un 45%. Si se compara estos valores con los obtenidos en años anteriores, se registra una tasa de incremento de 11 y 13% en sitios comerciales e industriales, respectivamente. The performance of passive devices were evaluated for the determination of nitrogen dioxide in 25 sites of San Jose and Belen, for which first, the method parameters such as limit of detection and quantification were determined and the bias and precision results were satisfactory. At least five sites in San Jose and four in Belen have values greater than 40 ug / m3, which corresponds to that recommended by the World Health Organization criteria for this contaminant. The highest concentrations are presented for commercial sites with high traffic flow where exceedances can reach up to 45%. If these values are compared with those obtained for previous years a growth rate of 11 and 13% for commercial and industrial sites recorded respectively.

Inorganic ions concentrations were measured on bulk precipitation samples in seven sites in San Jose, Heredia and Belen cities during the rainy season 2012. SO 4 -2 , NO 3 - , Cl - , F - , PO 4 -3 , NH 4 + , K + , Na + , Ca +2 , Mg +2 were analyzed by ion chromatography. The results indicated that Na + and SO 4 2− were the most abundant ions. Pearson's correlation, applied to all data, showed a high correlation between SO 4 2- with NO 3 - , Ca 2+ and NH 4 + , indicating an anthropogenic and neutralization origin respectively. The contribution of NO 3 - to neutralization was relatively small in comparison with SO 4 2− . PCA analysis was used in order to indentify the mainly sources (crustal, neutralization and marine aerosol) and that contribute to the chemical composition of the bulk precipitation samples.

Se realizó la caracterización de las emisiones de amoníaco y sulfuro de hidrógeno generadas en las diferentes modalidades de producción dada en granjas avícolas existentes en Costa Rica. Se encontró que las granjas de producción de huevos poseen las emisiones más importantes debido a que en su mayoría utilizan sistemas de manejo tipo jaula con fosa que genera una alta emisión de amoníaco (16 ppm). Mientras que las granjas de engorde presentaron las emisiones más bajas, como consecuencia de que, casi en su totalidad, usan sistemas de manejo abierto, los cuales son de baja emisión (6 ppm). No se encontraron concentraciones significativas de sulfuro de hidrógeno, excepto cuando se hizo la remoción mecánica del apilamiento de excretas almacenadas por varias semanas, encontrándose picos de emisión de hasta 163 ppm. La dispersión atmosférica de las emisiones de amoníaco fue modelada utilizando el AERMOD (USEPA), para evaluar el impacto en los alrededores. Se encontró cumplimiento con el reglamento de inmisiones a distancias más allá de los perímetros de las granjas; sin embargo, en algunos casos es posible sobrepasar el límite de detección olfatoria que normalmente representa una de las quejas más comunes por este tipo de actividades. A characterization of the ammonia and hydrogen sulfide emissions generated by different production models in poultry farms of Costa Rica was carried out. It was found that egg production farms have the largest emissions since they mostly use management systems based on cages with pits which generates a high emission of ammonia (16 ppm). While the fattening farms had the lower emissions since they mostly use open systems, which are low ammonia emission models (6 ppm). There were no significant concentrations of hydrogen sulfide in the evaluated models, except when a mechanical removal of mounds of chicken manure, with several weeks of storage, took place. A peak of 163 ppm of hydrogen sulfide was observed during the process. The ammonia emissions were modeled for some farms using an atmospheric dispersion model, AERMOD (USEPA), to determine the impact in the surroundings. Using the results of the validated model, it was found that the ammonia concentrations around the farms met the local regulation for air quality. But in some cases is highly probable to exceed the odor threshold for ammonia, which is one of the main complaints of the population living around this kind of agricultural and livestock activities.

Se midieron los flujos de las emisiones de metano (CH4) generados a través de la interfaz aire-agua en tres embalses hidroeléctricos en Costa Rica (Brasil, Nuestro Amo y Lago Cote) durante tres años (2009-2011), utilizando la técnica de la cámara estática flotante. Las muestras fueron tomadas durante una semana, tanto de día como de noche, a través de cuatro campañas cada año. Para la determinación de los flujos de metano, la superficie del agua de cada embalse se dividió en cuadrículas de 4 x 4 igualmente espaciadas. Durante este período, los flujos de emisión de CH4 mostraron valores promedio que oscilaron así: entre 759 y 4.282 en el embalse Brasil, entre 77 y 733 en el embalse Nuestro Amo y entre 10,9 y 44,2 mg CH4 m-2d-1 en Lago Cote. Los flujos de CH4 mostraron fuertes variaciones tanto estacionales como diurnas. Las tasas de emisión de CH4 resultaron ser mayores durante la época seca, y las relaciones entre flujos nocturnos de metano con respecto a los diurnos aumentó de 0,35 a 0,72 en Brasil y de 0,43 a 0,64 en Nuestro Amo, en esa temporada. Los flujos de emisión de CH4 correlacionaron positivamente con la temperatura del suelo, el nivel freático y las concentraciones de clorofila a en el agua. The emission fluxes of methane (CH4) across air–water interface were measured in three hydroelectric dams in Costa Rica (Brasil, Nuestro Amo and Cote Lake) during three years cycle (2009-2011), using the floating static chamber technique. Samples were taken during one week, both day and night time, through four campaigns per year. For the methane flux determination the water surface was divided in a 4x4 grid equally spaced. During this period, CH4 fluxes showed average values that ranged from 759 – 4282 (Brasil), 77 – 733 (Nuestro Amo) and 10,9 – 44,2 mg CH4 m-2 d-1 (Cote Lake), respectively. The fluxes of CH4 showed both strong seasonal and diurnal variations. CH4 emission rate was highest in dry season and there was a significant difference for CH4 emissions between day and night, the ratios between nighttime to daytime methane flux increased from 0,35 to 0,72, 0,43 to 0,64 for Brasil and Nuestro Amo, respectively in this season. CH4 emission was correlated positively with soil temperature, water table and chlorophyll a water concentrations.

In this work, we considered data of 25 water quality variables collected between January 2006 to December 2010 at 64 monitoring sites along the Virilla River Subbasin in Costa Rica. Factor analysis identified two potential pollution sources that explained 80.9% of the total variance in LP, two potential pollution sources that explained 77.1% of the total variance in MP, and two potential pollution sources that explained 67.8% of the total variance in HP. Most water quality variables were influenced primarily by pollution due to industrial wastewater, agricultural activities and urban runoff.

Laboratorio de Análisis Ambiental Concentrations of inorganic ions (Cl -, H +, SO 4 2-, NO 3 -, NH 4 +, Na +, K +, Ca 2+, Mg 2+) and metals (V, Ni, Cu, Pb, Cr Mn, Al, Fe) in bulk precipitation and PM 10 samples collected in the metropolitan area of Costa Rica were analyzed. Good correlations between acidity in bulk precipitation with the concentrations of aerosols in the air were observed. The scavenging of the pollutants from the air directly affects the pH and composition of the bulk precipitation. The major ions in bulk precipitation in the metropolitan area of Costa Rica were SO 4 2-, NH 4 +, Ca 2 +, Na + ion percentages with 41.4, 12.0, 10.9 and 9.1 respectively. Al, Fe and Mn were the most abundant trace metals. The alkaline cations, NH 4 + and Ca 2+, acted as acid neutralizers and buffered the acidity of bulk precipitation. Meteorological conditions presented during the events determine the composition of bulk precipitation samples. Concentraciones de iones inorgánicos (Cl -, H +, SO 4 2-, NO 3 -, NH 4 +, Na +, K +, Ca 2+, Mg 2+) y metales (V, Ni, Cu, Pb, Cr Se analizaron muestras de Mn, Al, Fe) en precipitación masiva y PM 10 recolectadas en el área metropolitana de Costa Rica. Se observaron buenas correlaciones entre la acidez en la precipitación masiva con las concentraciones de aerosoles en el aire. La eliminación de los contaminantes del aire afecta directamente el pH y la composición de la precipitación en masa. Los principales iones en la precipitación a granel en el área metropolitana de Costa Rica fueron los porcentajes de iones SO 4 2-, NH 4 +, Ca 2 +, Na + con 41,4, 12,0, 10,9 y 9,1 respectivamente. Al, Fe y Mn fueron los metales traza más abundantes. Los cationes alcalinos, NH 4 + y Ca 2+, actuaron como neutralizadores de ácidos y amortiguaron la acidez de la precipitación en masa. Las condiciones meteorológicas presentadas durante los eventos determinan la composición de las muestras de precipitación a granel Concentrações de íons inorgânicos (Cl -, H +, SO 4 2-, NO 3 -, NH 4 +, Na +, K +, Ca 2+, Mg 2+) e metais (V, Ni, Cu, Pb, Cr Mn, Al, Fe) na precipitação em massa e amostras de PM 10 coletadas na área metropolitana da Costa Rica foram analisadas. Boas correlações entre a acidez na precipitação em massa com as concentrações de aerossóis no ar foram observadas. A eliminação dos poluentes do ar afeta diretamente o pH e a composição da precipitação em massa. Os principais íons na precipitação em massa na área metropolitana da Costa Rica foram as porcentagens de íons SO 4 2-, NH 4 +, Ca 2 +, Na + com 41,4, 12,0, 10,9 e 9,1, respectivamente. Al, Fe e Mn foram os metais traço mais abundantes. Os cátions alcalinos, NH 4 + e Ca 2+, atuaram como neutralizadores de ácido e tamponaram a acidez da precipitação em massa. As condições meteorológicas apresentadas durante os eventos determinam a composição das amostras de precipitação em massa. Universidad Nacional, Costa Rica Universidad de Costa Rica Universidad Nacional Autónoma de México Escuela de Ciencias Ambientales