Nitrogen and Phosphorous Retention in Tropical Eutrophic Reservoirs with Water Level Fluctuations: A Case Study Using Mass Balances on a Long-Term Series

Nitrogen and phosphorous loading drives eutrophication of aquatic systems. Lakes and reservoirs are often effective N and P sinks, but the variability of their biogeochemical dynamics is still poorly documented, particularly in tropical systems. To contribute to the extending of information on tropical reservoirs and to increase the insight on the factors affecting N and P cycling in aquatic ecosystems, we here report on a long-term N and P mass balance (2003–2018) in Valle de Bravo, Mexico, which showed that this tropical eutrophic reservoir lake acts as a net sink of N (−41.7 g N m y) and P (−2.7 g P m y), mainly occurring through net sedimentation, equivalent to 181% and 68% of their respective loading (23.0 g N m y and 4.2 g P m y). The N mass balance also showed that the Valle de Bravo reservoir has a high net N atmospheric influx (31.6 g N m y), which was 1.3 times the external load and likely dominated by N fixation. P flux was driven mainly by external load, while in the case of N, net fixation also contributed. During a period of high water level fluctuations, the net N atmospheric flux decreased by 50% compared to high level years. Our results outlining water regulation can be used as a useful management tool of water bodies, by decreasing anoxic conditions and net atmospheric fluxes, either through decreasing nitrogen fixation and/or promoting denitrification and other microbial processes that alleviate the N load. These findings also sustain the usefulness of long-term mass balances to assess biogeochemical dynamics and its variability.This research was funded by UNAM, PAPIIT-IN207702 and CONACYT-SEMARNAT, C01-1125 projects to M.M-

Vertical Boundary Mixing Events during Stratification Govern Heat and Nutrient Dynamics in a Windy Tropical Reservoir Lake with Important Water-Level Fluctuations: A Long-Term (2001–2021) Study

hysical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) reservoir lake, where strong diurnal winds drive internal waves, boundary mixing, and hypolimnetic warming during stratification periods. We monitored VB during 21 years (2001–2021) when important water-level fluctuations occurred, affecting mixing and nutrient flux. Stability also varied as a function of water level. Hypolimnetic warming (0.009–0.028 °C day−1) occurred in all the stratifications monitored. We analyzed temperature distributions and modeled the hypolimnion heat budget to assess vertical mixing between layers (0.639–3.515 × 10−6 m3 day−1), vertical diffusivity coefficient KZ (2.5 × 10−6–13.6 × 10−6 m2 s−1), and vertical nutrient transport to the epilimnion. Nutrient flux from the metalimnion to the epilimnion ranged 0.42–5.99 mg P m−2day−1 for soluble reactive phosphorus (SRP) and 5.8–101.7 mg N m−2day−1 for dissolved inorganic nitrogen (DIN). Vertical mixing and the associated nutrient fluxes increase evidently as the water level decreases 8 m below capacity, and they can increase up to fivefold if the water level drops over 12 m. The observed changes related to water level affect nutrient recycling, ecosystemic metabolic balance, and planktonic composition of VB.This research was funded by UNAM (PAPIIT-IN207702 and PAPIIT-IN111321) and by CONACYT-SEMARNAT (C01-1125) projects to M.M.-I.Peer reviewe

Cuentos del Olivar

En este apasionante viaje tenemos las puertas abiertas para todo aquel que se quiera sumar, ya sea trabajando en pos de la difusión de la cultura ligada al olivo o disfrutando de lecturas como las que se recogen en este libro, que seguro les depara un sabroso disfrute y les descubre una cultura del olivar que tiene a sus espaldas varios milenios de historia. Les deseo que paladeen cada uno de estos relatos, que conforman un excelente aperitivo literario.Área de Historia del Art

Investigadoras en la UNAM : trabajo académico, productividad y calidad de vida

La implementación de los sistemas de estímulos económicos por rendimiento académico introdujo modificaciones sustantivas en las formas de trabajo y en la cultura laboral en la Universidad. En este libro las autoras analizan cómo se articulan las lógicas de la productividad, que provienen de dichos sistemas, con la condición de género, para crear diferencias sutiles que profundizan, aún más, las desigualdades ya existentes entre investigadores e investigadoras de la UNAM

Vertical boundary mixing events during stratification govern heat and nutrient dynamics in a windy tropical reservoir lake with important water-level fluctuations: A long-term (2001–2021) study

Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) reservoir lake, where strong diurnal winds drive internal waves, boundary mixing, and hypolimnetic warming during stratification periods. We monitored VB during 21 years (2001–2021) when important water-level fluctuations occurred, affecting mixing and nutrient flux. Stability also varied as a function of water level. Hypolimnetic warming (0.009–0.028◦ C day−1) occurred in all the stratifications monitored. We analyzed temperature distributions and modeled the hypolimnion heat budget to assess vertical mixing between layers (0.639–3.515 × 10−6 m3 day−1), vertical diffusivity coefficient KZ (2.5 × 10−6 –13.6 × 10−6 m2 s−1), and vertical nutrient transport to the epilimnion. Nutrient flux from the metalimnion to the epilimnion ranged 0.42–5.99 mg P m−2 day−1 for soluble reactive phosphorus (SRP) and 5.8–101.7 mg N m−2 day−1 for dissolved inorganic nitrogen (DIN). Vertical mixing and the associated nutrient fluxes increase evidently as the water level decreases 8 m below capacity, and they can increase up to fivefold if the water level drops over 12 m. The observed changes related to water level affect nutrient recycling, ecosystemic metabolic balance, and planktonic composition of VB

II. Conflictos entre felinos y humanos en América Latina.

Este libro contó con el liderazgo del Instituto Humboldt y de las Fundaciones Herencia Ambiental Caribe y Panthera. En 32 capítulos se recoge el esfuerzo de 77 instituciones y 110 autores que representan 18 países y abordan el conflicto entre humanos y felinos en América Latina. Es la compilación más completa que se ha elaborado acerca del tema en Latinoamérica, involucrando el análisis, la planificación, el manejo y la resolución de los conflictos entre humanos y felinos.BogotáCiencias de la Biodiversida