La presencia de metales pesados, como el plomo (Pb+2), en los cuerpos de agua genera alteraciones sobre la calidad ambiental y la salud pública, debido a su solubilidad y su capacidad de acumulación ...en la cadena trófica, problemática que se puede incrementar por la acumulación de Eichhornia crassipes, una maleza acuática con alta capacidad invasora, cuya presencia en los ecosistemas acuáticos favorece los procesos de eutrofización y crecimiento de microorganismos patógenos, vectores de enfermedades. Como alternativa para la eliminación de metales pesados y el aprovechamiento de tallos TEC y hojas HEC de E. crassipes, se evaluó la capacidad de adsorción y de eficiencia de remoción de Pb+2 en solución acuosa, de dicha biomasa. Inicialmente, se realizaron ensayos batch, para analizar la influencia de la dosis de adsorbente, tiempo de contacto y pH de la solución. Como método de disposición final, se analizó la calcinación, a temperaturas de 700 y 800°C. Los datos experimentales de equilibrio fueron correlacionados, utilizando los modelos de Langmuir y Freundlich. El modelo que mejor se ajustó fue el de Langmuir, con R² = 0,9816 TEC y R² = 0,9854 HEC, lográndose una máxima capacidad de adsorción de 172,41mg/g TEC y 131,58mg/g HEC, con 0,2g de biomasa/200mL, pH 5,5 y 3h de contacto. En todos los ensayos, se lograron remociones de Pb+2 superiores al 97%. Los ensayos de calcinación indican que, a temperaturas ≥800°C, es posible estabilizar la biomasa residual, impidiendo que los cationes metálicos removidos sean liberados de la matriz biológica, por efectos de soluciones lixiviantes de bajo pH.
Optimization of lanthanide‐doped luminescent nanoparticles for use in nanomedicine has encountered some difficulties due to the specific properties of water as a solvent. In this review, the current ...challenges for the adaptation of lanthanide‐doped luminescent nanoparticles to aqueous environments, and promising strategies to optimize their colloidal dispersibility and stability in water and physiological buffers, are summarized. Moreover, the possible luminescence de‐excitation paths caused by water molecule vibrations and how they can be prevented under different measurement conditions are discussed. This review also deals with the latest developments in lanthanide‐doped luminescent nanoparticle design for nanomedicine, to increase the depth at which they can be monitored, which is mainly limited by the absorption bands of water. Furthermore, the anomalous temperature dependence of water and the different effects it has on lanthanide‐doped luminescent nanoparticles in the physiological temperature range are commented on. Finally, a critical opinion on the possible next steps in this field is provided.
This review addresses current challenges for the adaptation of lanthanide‐doped luminescent nanoparticles to aqueous environments. The particular properties of water as a solvent, and their effects on dispersibility, disintegration, luminescence quenching, light absorption and anomalous temperature‐dependences are discussed. Promising strategies for the optimization of lanthanide‐doped nanoparticles are critically reviewed, especially those fostering their use in nanomedicine.
To understand the timing, extent, and magnitude of land use/land cover (LULC) change in buffer areas surrounding Midwestern US waters, we analyzed the full imagery archive (1982-2017) of three ...Landsat footprints covering ~100,000 km
. The study area included urbanizing Chicago, Illinois and St. Louis, Missouri regions and agriculturally dominated landscapes (i.e., Peoria, Illinois). The Continuous Change Detection and Classification algorithm identified 1993-2017 LULC change across three Landsat footprints and in 90 m buffers for ~110,000 surface waters; waters were also size-binned into five groups for buffer LULC change analyses. Importantly, buffer-area LULC change magnitude was frequently much greater than footprint-level change. Surface-water extent in buffers increased by 14-35x the footprint rate and forest decreased by 2-9x. Development in buffering areas increased by 2-4x the footprint-rate in Chicago and Peoria area footprints but was similar to the change rate in the St. Louis area footprint. The LULC buffer-area change varied in waterbody size, with the greatest change typically occurring in the smallest waters (e.g., <0.1 ha). These novel analyses suggest that surface-water buffer LULC change is occurring more rapidly than footprint-level change, likely modifying the hydrology, water quality, and biotic integrity of existing water resources, as well as potentially affecting down-gradient, watershed-scale storages and flows of water, solutes, and particulate matter.
This study contributes to the discussions on the future of the Amazon rainforest under a projected warmer-drier climate from the perspectives of land hydrology. Using IPCC HadGEM2-ES simulations of ...the present and future Amazon climate to drive a land hydrology model that accounts for groundwater constraint on land drainage, we assess potential hydrologic changes in soil water, evapotranspiration (ET), water table depth, and river discharge, assuming unchanged vegetation. We ask: how will ET regimes shift at the end of the 21st century, and will the groundwater help buffer the anticipated water stress in some places-times? We conducted four 10 yr model simulations, at the end of 20th and 21st century, with and without the groundwater. Our model results suggest that, first, over the western and central Amazon, ET will increase due to increased potential evapotranspiration (PET) with warmer temperatures, despite a decrease in soil water; that is, ET will remain PET or atmospheric demand-limited. Second, in the eastern Amazon dry season, ET will decrease in response to decreasing soil water, despite increasing PET demand; that is, ET in these regions-seasons will remain or become more soil water or supply-limited. Third, the area of water-limited regions will likely expand in the eastern Amazonia, with the dry season, as indicated by soil water store, even drier and longer. Fourth, river discharge will be significantly reduced over the entire Amazon but particularly so in the southeastern Amazon. By contrasting model results with and without the groundwater, we found that the slow soil drainage constrained by shallow groundwater can buffer soil water stress, particularly in southeastern Amazon dry season. Our model suggests that, if groundwater buffering effect is accounted for, the future Amazon water stress may be less than that projected by most climate models.
Remote sensing has been an important mean of resource monitor, especially monitoring wetlands where researchers can hardly get to. This paper applied SPOT-5 image to classify the East Dongting Lake ...area into five cover types using the decision tree classification method. The five cover types were water, mudflats, bare ground, low-coverage marsh land and high-coverage marsh land. According to results of band analysis, this paper extracted the water by adding fourth band and first band, resulting that the water body boundaries extracted by band calculated using this method are highly consistent with water body in the image after SPOT-5 panchromatic and Multi-spectral bands fusion. Then a multilayer buffer was created based on waterbody through referring to the elevation value distribution histogram. we defined the levels range and divided the elevation into 6 levels. Finally, relationship between various cover types and elevation and relationship between various cover types and water buffers were analyzed, drawing them with water distance relationship.
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