Dissolved organic carbon (DOC) transport and export from headwater forests into freshwaters in highly dynamic tropical catchments are still understudied. Here we present a DOC analysis (2017) in a pristine and small (~2.6 km2) tropical catchment of Costa Rica. Storm flows governed a rapid surface and lateral allochthonous DOC transport (62.2% of the annual DOC export). Cross‐correlation analysis of rainfall and stream discharge indicated that DOC transport occurred on average ~1.25 hr after the rainfall maxima, with large contributions of event water, ranging from 42.4±0.3% up to 98.2±0.3% of the total discharge. Carbon export flux (annual mean=6.7±0.1 g C · m‐2 · year‐1) was greater than values reported in subtropical and temperate catchments. Specific ultraviolet absorbance indicated a mixture of hydrophobic humic and hydrophilic nonhumic matter during both baseflow and storm events. Our results highlight the rapid storm‐driven DOC transport and export as well as low biogeochemical attenuation during baseflow episodes in a climate sensitive hot spot. By understanding the key factors controlling the amount of organic carbon transported to streams in dynamic tropical landscapes, better global‐ and catchment‐scale model assessments, conservation practices, and water treatment innovations can be identified.

The Takakura technique converts food waste into compost. This project explored the potential use of composting in offices and workplaces. The method involves using small boxes containing a fermentation substrate where food waste is added. Two Takakura composting boxes (TCBs) were placed in the kitchens of the Chemistry Department and the Environmental Engineering buildings at the Instituto Tecnológico de Costa Rica, Costa Rica. Food waste from both buildings, comprising the food waste of 45 staff members, were composted from June to December 2015. All types of food, except grease, oil, raw meat, and bones, were processed. The mass and volume of food added to the boxes were quantified daily. A chemical analysis of the compost was also performed. A speech was given to educate the staff members about the system. A survey, before and after the speech, was developed to evaluate the knowledge and tolerance towards composting in closed spaces. A total mass of 88.29 kg, equivalent to 232 L of residues, was processed, from which 17.37 kg (37 L) of compost was obtained. This represented a mass and volume reduction of 80% and 84%, respectively. Compost analysis gave a C/N ratio of 14.7/1, indicative of maturity. Most of the staff members (92%) agreed to the separation of waste at the source. However, 37% suggested allocating the box outside the building. The survey, after the speech, showed that educating staff is necessary before installing boxes at a workplace.

Removal new alternative to chemical and mechanical removal for the study of pollen carried on the wild bee scopae. Taxonomic recognition and quantification of the different pollen types collected by bees offer the most direct method to study the diet. To determine the importance of each plant taxon, it is necessary to separate the pollen deposited only in the collecting structures in order to minimize contamination of grains collected passively in other parts of the body. The technique currently applied is based on the mechanical removal of the pollen loads with dissecting needles and repeated washings with ethanol. Metathoracic scopae that underwent this procedure showed traces of pollen in varying amounts when observed under the microscope. As an alternative to this technique chemical removal using HOK is proposed. The leg is removed and treated separatedly to avoid contamination. The deflocculant properties of HOK successfully allowed to separate the pollen adhered to the scopae, which can be then returned to the individual, unaffected by the procedure. Suspend the pollen in a know quantity of mounting fluid permit take the subsamples and determine the total number of pollen grains of each taxon. In this paper, the new technique is presented and its effectiveness is compared to the technique currenty used. Resumen: El reconocimiento taxonómico y la cuantificación de los distintos tipos polínicos colectados por las abejas ofrecen el método más directo para estudiar la dieta. Para determinar la importancia de cada taxón vegetal y minimizar la contaminación, es necesario separar el polen depositado en las estructuras de colecta, de los granos recolectados en forma pasiva en otras partes del cuerpo. La técnica que se aplica hasta el momento se basa en la remoción mecánica de las cargas polínicas con agujas de disección y sucesivos lavados con etanol. Escopas de patas metatoráxicas sometidas a este procedimiento al ser observadas bajo lupa presentaban aún granos de polen en cantidades variables. Como una alternativa a esta técnica proponemos la remoción química, mediante la utilización de HOK. La pata se extrae y es tratada por separado para impedir la contaminación. Las propiedades defloculantes del HOK permiten separar exitosamente el polen adherido a la escopa, la cual puede ser devuelta al ejemplar al no ser afectada por el procedimiento. Suspender todo el contenido de polen en un volumen de medio de montaje conocido y luego tomar una submuestra, permite determinar el número total de granos de polen de cada taxón. En este trabajo se presenta la nueva técnica y se compara su efectividad con la técnica utilizada hasta el momento. Palabras clave: Polen, abejas silvestres, estructuras recolectoras, remoción mecánica, remoción química. ____________ * Esta nueva técnica fue desarrollada y puesta en práctica por las autoras antes del fallecimiento de Marta Caccavari en noviembre de 2009. INTRODUCCIóN El polen representa la principal fuente de pro-teínas para las abejas, con excepción de un grupo pequeño de Meliponini...

Chlorination is one of the most important stages in the treatment of drinking water due to its effectiveness in the inactivation of pathogenic organisms. However, the reaction between chlorine and natural organic matter (NOM) generates harmful disinfection by-products (DBPs), such as trihalomethanes (THMs). In this research, drinking water quality data was collected from the distribution networks of 19 rural and semi urban systems that use water sources as: springs, surfaces, and a mixture of both, in three provinces of the Paci c slope of Costa Rica during April 2018 to September 2019. Twelve models were developed from four data sets: all water sources, spring, surface, and mixture of spring and surface waters. Linear, logarithmic, and exponential multivariate regression models were developed for each data set to predict the concentration of total trihalomethanes (TTHMs) in the distribution networks. Concentrations of TTHMs were found between < 0.20 to 91.31 µg/L, with chloroform being the dominant species accounting for 62% of TTHMs on average. Turbidity, free residual chlorine, total organic carbon (TOC), dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV 254 ) showed a signi cant correlation with TTHMs. In all the data sets the linear models presented the best goodness-of-t and were moderately robust. Four models, the best of each data set, were validated with data from the same systems, and, according to the criteria of R 2 , SE, MSE and MAE, spring water and mixed spring/surface water models showed a satisfactory level of explanation of the variability of the data. Moreover, the models seem to better predict TTHMs concentrations below 30 µg/L. These models were satisfactory and could be useful for decision-making in drinking water supply systems and be considered in possible modi cations in current legislation. prediction in Costa Rica, and to the best of the authors knowledge in the Central American and Caribbean region. Furthermore, this study was focused in rural and semi urban areas, where no studies was found in the literature.In Costa Rica, 93% of the population received drinking water in 2019 (PEN and CONARE 2020). Moreover, in the same year, 19.4% of homes in rural and semi-urban areas were supplied with water by local Associations Administrators of Aqueduct and Sewerage Systems, (ASADAs in Spanish) (Sánchez-Hernández 2019). In addition, in 2016, 14.3% of the population was supplied by 24 municipalities and the rest by duly organized public companies (AyA 2016). The main water sources used are groundwater, springs, surface water and the mixture of the two latter ones, moreover, in all cases chlorine disinfection is the method used (Arellano-Hartig et al. 2020). In general, due to economic and analytical capacity limitations, monitoring of THMs is scarce, mainly at the ASADAs and municipal level. Thus, the objective of this study was to develop a series of prediction models of TTHMs in the distribution systems of rural and semi-urban areas supplied by springs, surface water and t...

Se realizó un análisis de la generación de los residuos producidos en el Campus Central del Instituto Tecnológico de Costa Rica, tanto para los materiales recuperados por el Centro de Acopio Institucional (MADI), así como para los residuos enviados al relleno sanitario. Las cantidades de los residuos valorizables fueron proporcionados por el MADI. Se emplearon referencias bibliográficas para contar con las cantidades de los residuos orgánicos provenientes de la Soda Comedor. Las cantidades de residuos enviados al relleno sanitario se obtuvieron mediante un estudio de composición durante el primer semestre del 2013 y 2014, basándose en la metodología recomendada por el Ministerio de Salud de Costa Rica, MINSA. Los tipos de residuos se simplificaron en tres categorías: valorizable, compostable y no recuperable. Se escogió el 50% de los centros de transferencia de materiales, que son enviados al relleno. El estudio de composición se basó en muestras que variaron entre el 23,3 y el 73,4% de la masa total de residuos de los centros de transferencia. Se encontró que del total de residuos enviados al relleno un (60 ± 1) % no eran valorizables, mientras que un (29 ± 2) % y un (12 ± 1) % pudieron ser recuperados por MADI o compostables, respectivamente. Para el 2015, el MADI recuperó el 63% de los residuos con potencial valorizable y la Soda Comedor un 66% de los residuos de alimentos. Sin embargo, se debe trabajar en una estrategia que pueda mejorar el desempeño de la gestión de residuos sólidos institucionales.