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Ultrastructura en soluciones salinas congeladas / grabadas: sobre la limpieza interna del hielo
Fredric M Menger1, Ashley L Galloway, Mary E Chlebowski
1Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA. menger@emory.edu
Journal of the American Chemical Society
|May 13, 2004
Resumen
El drenaje de salmuera de hielo marino fue modelado utilizando cryo-etch de alta resolución microscopía electrónica secundaria. La solución salina congelada formó cercas heladas, lo que indica una rápida expulsión de sal durante la congelación.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La geofísica es la geofísica.
- Química Física es la química física.
Sus antecedentes:
- La formación de hielo marino implica la congelación del agua de mar, que atrapa la salmuera concentrada dentro de su matriz de hielo.
- A medida que el hielo marino crece y se calienta, la salmuera puede drenar hacia abajo a través de canales, influyendo en las propiedades del hielo y la salinidad del océano.
Objetivo del estudio:
- Investigar el mecanismo de drenaje de la salmuera en soluciones salinas congeladas.
- Para visualizar los cambios microestructurales durante la congelación y descongelación de las soluciones salinas.
Principales métodos:
- Las soluciones salinas (2-3,5%) fueron congeladas o congeladas a alta presión.
- Se utilizó la microscopía electrónica de barrido de alta resolución (cryo-HRSEM) para examinar la estructura del hielo.
- La sublimación de alto vacío (grabado) eliminó el hielo puro, revelando las restantes estructuras ricas en sal.
Principales resultados:
- Cryo-HRSEM reveló "cercas" de hielo granulares que rodean áreas de hielo amorfo anterior.
- Estas cercas, de aproximadamente 1-2 μm de altura, sobrevivieron al grabado, lo que sugiere que están compuestas de salmuera congelada.
- La formación de estas vallas implica una rápida expulsión de sal (dentro de 5-6 ms) durante la congelación.
Conclusiones:
- El estudio proporciona evidencia de una rápida expulsión de sal durante la formación del hielo marino, visualizada a través de la formación de vallas ricas en salmuera.
- Estos hallazgos apoyan los modelos de formación de canales de salmuera y migración de sales dentro de soluciones salinas congeladas.
- El mecanismo observado pone de relieve la velocidad a la que el hielo marino puede segregar la sal.
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