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Ciclo rápido del nitrógeno reactivo en la capa límite marina
Chunxiang Ye1, Xianliang Zhou1,2, Dennis Pu2
1Wadsworth Center, New York State Department of Health, Albany, New York, USA.
Nature
|April 12, 2016
Resumen
La fotólisis de partículas de nitrato recicla rápidamente el ácido nítrico en óxidos de nitrógeno en la atmósfera marina. Este proceso, particularmente significativo sobre los océanos, actúa como una fuente clave de oxidantes atmosféricos y aerosoles.
Área de la Ciencia:
- Química de la atmósfera
- Ciencias del medio ambiente
- Geoquímica
Sus antecedentes:
- Los óxidos de nitrógeno (NOx) son cruciales para los oxidantes y aerosoles atmosféricos.
- El ácido nítrico (HNO3) se consideró un sumidero permanente de NOx, pero las observaciones muestran discrepancias con los modelos.
- Se propone un proceso de "renoxificación" para explicar el reciclaje de NOx, pero los mecanismos no están claros.
Objetivo del estudio:
- Investigar los mecanismos de reciclado del ácido nítrico en óxidos de nitrógeno en la troposfera.
- Cuantificar la contribución de la fotólisis del nitrato de partículas a la regeneración de los NOx.
- Evaluar la importancia global de este proceso de reciclado en las regiones oceánicas.
Principales métodos:
- Mediciones aéreas sobre el Océano Atlántico Norte para recopilar datos atmosféricos.
- Experimentos de laboratorio para estudiar las velocidades de fotólisis de las partículas de nitrato.
- Cálculos del modelo de caja utilizando el mecanismo químico maestro para simular procesos químicos.
Principales resultados:
- Pruebas de reciclaje rápido del ácido nítrico a ácido nitroso (HONO) y óxidos de nitrógeno (NOx) mediante fotólisis de partículas de nitrato en la capa límite marina.
- La velocidad de fotólisis del nitrato de partículas es significativamente mayor (más de dos órdenes de magnitud) que la del ácido nítrico gaseoso.
- Los cálculos del modelo indican que la fotólisis de partículas de nitrato mantiene los niveles de HONO y NOx observados al mediodía en entornos marinos.
Conclusiones:
- La fotólisis del nitrato de partículas es una fuente significativa de óxidos de nitrógeno troposféricos, especialmente sobre los océanos.
- Este mecanismo de reciclaje puede mejorar la formación de oxidantes atmosféricos y aerosoles secundarios a nivel mundial.
- Los hallazgos desafían la visión tradicional del ácido nítrico como un sumidero permanente de NOx.
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