No abstract

in Wiley Online Library (wileyonlinelibrary.com).The dictyodendrins A-E were the first marine natural products that show inhibition of telomerase. A versatile and convergent route was described for the synthesis of derivatives of these pyrrolo[2,3-c]carbazole alkaloids as potential inhibitors of telomerase, by cyclotrimerization [2 + 2 + 2] of ruthenium-catalyzed diynamides diarylacetylenes.

Tropical peatlands are distributed mainly in coastal lowlands; however high elevation regions exhibit a large prevalence of small and fragmented peatlands that are mostly understudied. Artificial drainage of peatlands to expand the area of cattle farming, horticulture, and urbanization is increasing carbon losses to the atmosphere and streams worldwide. Here, we present an exploratory characterization of dissolved carbon optical properties in ombrotrophic peat bogs of the Talamanca range of Costa Rica, across an altitudinal gradient (2,400–3,100 m a.s.l.) during the rainy season. Dissolved organic matter (DOM) sources and decomposition processes were evaluated in the light of dissolved organic and inorganic carbon (DOC and DIC), optical properties, and major water chemistry. DOC concentrations ranged from 0.2 up to 47.0 mg/L. DIC concentrations were below 2 mg/L and δ13CDIC values indicated a mixture between soil organic matter, CO2 in soil water, and to a lesser degree DIC derived from bacterial CO2. Absolute fluorescence intensity of humic-like peaks was 6–7 times greater than fresh-like peaks across all sites. Fluorescence peak ratios coupled with the biological and humification indexes point to a greater relative contribution of recalcitrant soil-derived DOM. Excitation/Emission matrices denoted a high prevalence of humic and fulvic acids in the peat bogs, with moderate intensities in soluble microbial by-products-like and aromatic protein regions at three sites. Our data provides a baseline to underpin tropical carbon dynamics across high elevation peatlands.

El objetivo fue identificar y analizar los aspectos más relevantes del contexto socioambiental de un cantón urbano, que inciden en la contaminación del recurso hídrico. Se realizó una investigación descriptiva con un enfoque mixto, en la cual, recopilando información primaria y secundaria, se lograron obtener datos relacionados con la percepción socioambiental en el cantón, los patrones de cambio en el uso de suelo, la identificación de fuentes potenciales de contaminación al recurso hídrico por vertidos y el estado actual de la gestión para las aguas residuales generadas en el cantón. Esto fue obtenido a través de un sondeo preliminar de percepción, verificación de información en campo, uso de imágenes satelitales, bases de datos de autoridades reguladoras, entre otras herramientas, con miras a, posteriormente, ser sistematizado y procesado para los análisis respectivos. Se observó que, en la población consultada, lo percibido en relación con el recurso hídrico es satisfactorio en términos de abastecimiento, no obstante, se evidenció desinterés con el manejo de las aguas residuales de los hogares. Para el uso del suelo, se notó un aumento en el área de uso urbano y una disminución en la zona boscosa, cambios que han incrementado en los últimos años. Además, fue posible identificar más de 230 fuentes potenciales de contaminación del recurso hídrico expresadas como vertidos directos o indirectos de aguas residuales. En cuanto a los vertidos regulados, los reportes operacionales evidenciaron un alto cumplimiento respecto a la normativa nacional, sin embargo, la carga orgánica neta vertida es alta. Las actividades comerciales y el crecimiento urbano del cantón inciden de manera negativa para acelerar los procesos de contaminación del recurso hídrico de la zona de estudio, por lo que se encuentran bajo una presión constante que debe manejarse a través de procesos participativos con enfoque de gestión integrada.

Introduction: The implementation of wastewater treatment systems such as constructed wetlands has a growing interest in the last decade due to its low cost and high effectiveness in treating industrial and residential wastewater. Objective: To evaluate the spatial variation of physicochemical parameters in a constructed wetland system of sub-superficial flow of Pennisetum alopecuroides (Pennisetum) and a Control (unplanted). The purpose is to provide an analysis of spatial dynamic of physicochemical parameters using R programming language. Methods: Each of the cells (Pennisetum and Control) had 12 piezometers, organized in three columns and four rows with a separation distance of 3,25m and 4,35m, respectively. The turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammoniacal nitrogen (N-NH4), organic nitrogen (N-org.) and phosphorous (P-PO4-3) were measured in water under in-flow and out-flow of both conditions Control and Pennisetum (n= 8). Additionally, the oxidation-reduction potential (ORP), dissolved oxygen (DO), conductivity, pH and water temperature, were measured (n= 167) in the piezometers. Results: No statistically significant differences between cells for TKN, N-NH4, conductivity, turbidity, BOD, and COD were found; but both Control and Pennisetum cells showed a significant reduction in these parameters (P<0,05). Overall, TKN and N-NH4 removal were from 65,8 to 84,1% and 67,5 to 90,8%, respectively; and decrease in turbidity, conductivity, BOD, and COD, were between 95,1-95,4%; 15-22,4%; 65,2-77,9% and 57,4-60,3% respectively. Both cells showed ORP increasing gradient along the water-flow direction, contrary to conductivity (p<0,05). However, OD, pH and temperature were inconsistent in the direction of the water flow in both cells. Conclusions: Pennisetum demonstrated pollutant removal efficiency, but presented results similar to the control cells, therefore, remains unclear if it is a superior option or not. Spatial variation analysis did not reflect any obstruction of flow along the CWs; but some preferential flow paths can be distinguished. An open-source repository of R was provided.