Browsing by Autor "L. Alanoca"

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Association of a Specific Algal Group with Methylmercury Accumulation in Periphyton of a Tropical High-Altitude Andean Lake
(Springer Science+Business Media, 2016) William G. Lanza; Darío Achá; David Point; Jérémy Masbou; L. Alanoca; David Amouroux; Xavier Lazzaro
Diurnal variability and biogeochemical reactivity of mercury species in an extreme high-altitude lake ecosystem of the Bolivian Altiplano
(Springer Science+Business Media, 2015) L. Alanoca; David Amouroux; Mathilde Monperrus; E. Tessier; Marisol Goñi‐Urriza; Rémy Guyoneaud; Darío Achá; Claire Gassie; Stéphane Audry; M.E. García
Sources of mercury in surface waters of the upper Madeira erosive basins, Bolivia
(Springer Science+Business Media, 2003) Laurence Maurice; L. Alanoca; Pascal Fraizy; Philippe Vauchel
The human activities impact on the mercury (Hg) distribution in the Amazon waters is still discussed but very few information regarding the Hg sources from the highly turbid Andean headwaters have been published. The annual load of suspended sediments eroded from the Bolivian Andes, averages 300x10 6 tons in the Beni river, of which till 97% is exported during the rainy season. At the edge of the Bolivian Andean piedmont, the total Hg concentration vary from 8 ng/l during the dry season, to 1600 ng/l during the high water period. During this stage, it appears that the maximum concentrations of Hg associated with the fine particles and the highest Hg specific fluxes are observed in the rivers exploited for their alluvial gold during the last century. The black-shales series associated to the gold deposits are characterised by high natural Hg contents, which can be released in the hydrographic system by both chemical and physical weathering. But if we compare two clear water rivers characterised by the same suspended sediment concentrations, the maximum specific Hg flux varies between 126 kg/km 2 .j in the pristine river, to 590 kg/km 2 .j in the river characterised by recent human activities.
Sulfate-Reducing Bacteria in Floating Macrophyte Rhizospheres from an Amazonian Floodplain Lake in Bolivia and Their Association with Hg Methylation
(American Society for Microbiology, 2005) Darío Achá; Volga Iñiguez; Marc Roulet; Jean Remy Davée Guimarães; Ruddy Luna; L. Alanoca; Samanta Sánchez
Five subgroups of sulfate-reducing bacteria (SRB) were detected by PCR in three macrophyte rhizospheres (Polygonum densiflorum, Hymenachne donacifolia, and Ludwigia helminthorriza) and three subgroups in Eichhornia crassipes from La Granja, a floodplain lake from the upper Madeira basin. The SRB community varied according to the macrophyte species but with different degrees of association with their roots. The rhizosphere of the C4 plant Polygonum densiflorum had higher frequencies of SRB subgroups as well as higher mercury methylation potentials (27.5 to 36.1%) and carbon (16.06 +/- 5.40%), nitrogen (2.03 +/- 0.64%), Hg (94.50 +/- 6.86 ng Hg g(-1)), and methylmercury (8.25 +/- 1.45 ng Hg g(-1)) contents than the rhizosphere of the C3 plant Eichhornia crassipes. Mercury methylation in Polygonum densiflorum and Eichhornia crassipes was reduced when SRB metabolism was inhibited by sodium molybdate.
Synergistic effects of mining and urban effluents on the level and distribution of methylmercury in a shallow aquatic ecosystem of the Bolivian Altiplano
(Royal Society of Chemistry, 2016) L. Alanoca; Stéphane Guédron; David Amouroux; Stéphane Audry; Mathilde Monperrus; Emmanuel Tessier; Sylvaine Goix; Darío Achá; Patrick Seyler; David Point
Lake Uru Uru (3686 m a.s.l.) located in the Bolivian Altiplano region receives both mining effluents and urban wastewater discharges originating from the surrounding local cities which are under rapid development. We followed the spatiotemporal distribution of different mercury (Hg) compounds and other metal(oid)s (e.g., Fe, Mn, Sb, Ti and W) in both water and sediments during the wet and dry seasons along a north-south transect of this shallow lake system. Along the transect, the highest Hg and metal(oid) concentrations in both water and sediments were found downstream of the confluences with mining effluents. Although a dilution effect was found for major elements during the wet season, mean Hg and metal(oid) concentrations did not significantly differ from the dry season due to the increase in acid mine drainage (AMD) inputs into the lake from upstream mining areas. In particular, high filtered (<0.45 μm) mono-methylmercury (MMHg) concentrations (0.69 ± 0.47 ng L-1) were measured in surface water representing 49 ± 11% of the total filtered Hg concentrations (THgF) for both seasons. Enhanced MMHg lability in relation with the water alkalinity, coupled with abundant organic ligands and colloids (especially for downstream mining effluents), are likely factors favoring Hg methylation and MMHg preservation while inhibiting MMHg photodegradation. Lake sediments were identified as the major source of MMHg for the shallow water column. During the dry season, diffusive fluxes were estimated to be 227 ng m-2 d-1 for MMHg. This contribution was found to be negligible during the wet season due to a probable shift of the redox front downwards in the sediments. During the wet season, the results obtained suggest that various sources such as mining effluents and benthic or macrophytic biofilms significantly contribute to MMHg inputs in the water column. This work demonstrates the seasonally dependent synergistic effect of AMD and urban effluents on the shallow, productive and evaporative high altitude lake ecosystems which promotes the formation of natural organometallic toxins such as MMHg in the water column.
Trauma de la muñeca y la mano en el sistema público de salud del departamento de Cochabamba, Bolivia
(2025) L. Alanoca; Henry Adam Pardo Claure; Daniel Illanes Velarde
Introducción: Las lesiones traumáticas de muñeca y mano constituyen una causa frecuente de consulta en servicios de emergencia y representan una carga relevante en países de ingresos medios como Bolivia. Su caracterización epidemiológica es fundamental para orientar intervenciones preventivas y la planificación sanitaria. Metodología: Este estudio descriptivo retrospectivo se basó en registros del SNIS correspondientes al año 2024. Incluyó todos los casos codificados con CIE-10 S60–S69 atendidos en servicios de emergencia del sistema público del departamento de Cochabamba. Se estimaron frecuencias absolutas y proporciones, y se aplicó la prueba de chi-cuadrado para evaluar asociaciones entre sexo y tipo de lesión. Resultados: Se registraron 2.894 casos de trauma de muñeca y mano; el 64,9 % correspondió al sexo masculino. Las categorías más frecuentes fueron heridas abiertas (69,8 %) y fracturas (11,6 %). El grupo etario de 15–39 años concentró el 47,2 % de los casos. Se identificó asociación significativa entre el tipo de lesión y el sexo (χ² = 23,12; p = 0,0016). Discusión: Los hallazgos son consistentes con la literatura internacional que reporta mayor incidencia de lesiones severas en varones jóvenes expuestos a actividades laborales de riesgo. La elevada proporción de heridas abiertas y fracturas subraya la necesidad de fortalecer la prevención laboral, mejorar los registros del SNIS y ampliar la capacidad de servicios especializados en trauma y rehabilitación. Este estudio constituye el primer análisis departamental basado en datos oficiales del SNIS en Cochabamba.