With the aim of evaluating temporal changes in sedimentation and organic carbon (C org ) supplied over the last~100 years, a sediment core was collected at Soledad Lagoon, a costal ecosystem surrounded by mangroves, located in the Cispatá Estuary (Caribbean coast of Colombia). The core sediments were characterized by low concentrations of calcium carbonate (0.2-2.9%), organic matter (3-8%), total nitrogen (0.11-0.38%), and total phosphorus (0.19-0.65 mg g −1 ). Fe and Al concentrations ranged from 4% to 5%, and Mn from 356 to 1,047 μg g −1 .The 210 Pb-derived sediment and mass accumulation rates were 1.54±0.18 mm year −1 and 0.08±0.01 gcm −2 year −1 , respectively. The sediment core did not provide evidence of human impact, such as enhancement of primary production or nutrient enrichment, which may result from recent land uses changes or climate change. The C org fluxes estimated for Soledad Lagoon core lay in the higher side of carbon fluxes to coastal ecosystems (314-409 gm −2 year −1 ) and the relatively high C org preservation observed (~45%) indicate that these lagoon sediments has been a net and efficient sink of C org during the last century, which corroborate the importance of mangrove areas as important sites for carbon burial and therefore, long-term sequestration of C org .
This project assessed the technical feasibility of organic matter (COD) removal in livestock effluents, by electrocoagulation. An experimental design was used to block two factors at three levels, to evaluate the effect of the variables distance between electrodes and pH, using aluminum sacrificial electrodes. Maximum removal (90.16%) was obtained at 7 units pH, and 2.0 cm distance between electrodes. This study demonstrated the technical feasibility of electrocoagulation (EC) for the removal of organic matter as COD, present in wastewater from the livestock industry.
Objetivo. Se evaluó la distribución de mercurio total (HgT) en sedimentos superficiales, peces, cabello, plantas de arroz y macrofitas, como también el índice de geoacumulación por HgT en sedimentos y el potencial de riesgo por consumo de pescado en diferentes municipios afectados por actividades de minería aurífera que se han desarrollado alrededor en la región de la Mojana, Colombia. Materiales y métodos. La concentración de HgT se determinó mediante descomposición térmica, utilizando un analizador directo de mercurio DMA-80. Resultados. En promedio, las concentraciones de HgT en peces fueron 0.223 ± 0.027 μg/g. Del total de las muestras, 11.6% de peces sobrepasaron el límite permisible establecido por la Organización Mundial de la Salud (0.5 μg/g), siendo 4.2% para especies no carnívoras y 7.4% para especies carnívoras. De las especies ícticas, 76.9% presentan valores de índice de riesgo (HI) superiores a 1. El Índice de Geoacumulación (Igeo) en sedimentos, presenta grado de contaminación de no-contaminado a contaminación moderada para las diferentes estaciones de muestreo. La concentración de HgT en cabello osciló entre 0.17 – 8.8 µg/g. 47% de la población supera el límite permisible establecido como referencia por USEPA: 1 µg g-1. Las concentraciones de HgT en macrofitas (Eichhornia crassipes) y plantas de cultivos de arroz fueron superiores en estaciones de muestreo que reciben corrientes de agua que transportan cargas contaminantes desde áreas de explotación mineras, tendencia similar presentada para sedimentos y peces. Conclusiones. Las actividades mineras han generado un proceso de contaminación gradual por Hg en la cadena alimenticia y actualmente los niveles en peces, arroz y cabello representan una seria preocupación para la salud humana.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.