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Fotoproducción de radicales hidroxilo en el mar y su impacto potencial en los procesos marinos
Science (New York, N.Y.)
|November 2, 1990
Resumen
La luz solar genera radicales hidroxilo (.OH) en el agua de mar, principalmente de la materia orgánica disuelta. Estos radicales degradan la materia orgánica disuelta en aguas profundas de manera más eficiente que las aguas superficiales, lo que afecta las mediciones de carbono.
Área de la Ciencia:
- Química del medio ambiente Química del medio ambiente
- Oceanografía La oceanografía es la oceanografía.
- La fotoquímica es la fotoquímica.
Sus antecedentes:
- Los radicales hidroxilo (.OH) son oxidantes clave en los entornos acuáticos.
- Comprender la producción y la reactividad de OH es crucial para los ciclos biogeoquímicos marinos.
Objetivo del estudio:
- Para cuantificar las tasas de producción fotoquímica y las concentraciones de estado estacionario de .OH en el agua de mar iluminada por el sol.
- Para identificar las fuentes primarias de .OH en diferentes regiones oceánicas.
- Para evaluar la eficiencia de degradación de la materia orgánica disuelta (DOM) por .OH en el mar profundo.
Principales métodos:
- Mediciones in situ de las tasas de producción y concentraciones de .OH en aguas costeras y aguas superficiales oceánicas abiertas.
- Análisis del espectro solar, en particular las longitudes de onda ultravioleta B (UVB) (280-320 nm).
- Experimentos comparativos de degradación de DOM desde diferentes profundidades oceánicas utilizando .OH.
Principales resultados:
- Las tasas de producción de .OH fotoquímicas variaron de 10 a 110 nanomolares por hora.
- Las concentraciones de .OH en estado de equilibrio oscilaron entre 1,1 x 10(-18) y 12 x 10(-18) molares.
- La materia orgánica disuelta (DOM) es la principal fuente de .OH en la mayoría de los océanos de superficie, con una fotólisis significativa de nitrito y nitrato en las zonas ascendentes.
- El DOM de aguas profundas se degrada de 6 a 15 veces más fácilmente por .OH que el DOM de superficie.
Conclusiones:
- La luz solar, especialmente la radiación UVB, impulsa la producción de .OH en el agua de mar.
- .OH juega un papel importante en la degradación del DOM marino, con mayor eficiencia en aguas más profundas.
- Las diferentes tasas de degradación de DOM por .OH pueden explicar las discrepancias en las mediciones de carbono orgánico disuelto.
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