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Ciclo atmosférico de halógenos durante el día a través de la química de átomos de oxígeno en fase acuosa
Evan Z Dalton1, Erik H Hoffmann2, Thomas Schaefer2
1Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
Journal of the American Chemical Society
|July 18, 2023
Resumen
Se revelan las fuentes diurnas de halógenos atmosféricos. La fotólisis del nitrato en soluciones de cloruro produce cloruro de nitrilo (ClNO2), ofreciendo nuevas perspectivas sobre el ciclo atmosférico de halógenos.
Área de la Ciencia:
- Química de la atmósfera
- Ciclo de halógenos
- La fotoquímica
Sus antecedentes:
- Los átomos de halógeno son oxidantes atmosféricos cruciales.
- Las fuentes diurnas de halógenos atmosféricos, en particular de los aerosoles de sal marina, siguen sin identificarse en gran medida.
- La comprensión actual del ciclo de halógenos durante el día se basa en mecanismos de oxidación específicos.
Objetivo del estudio:
- Para investigar la oxidación fotoquímica de haluros en los aerosoles de sal marina.
- Para identificar las fuentes diurnas desconocidas de halógenos atmosféricos.
- Elucidar las vías de formación del cloruro de nitrilo (ClNO2) en las condiciones atmosféricas pertinentes.
Principales métodos:
- Fotólisis experimental de nitrato en soluciones acuosas de cloruro.
- Análisis químico para identificar los productos de la fotólisis, incluidos Cl2, HOCl y ClNO2.
- Modelado atmosférico para evaluar las implicaciones de las nuevas vías químicas.
Principales resultados:
- La fotólisis de nitrato en soluciones de cloruro genera ClNO2, Cl2 y HOCl.
- O ((3P) de la fotólisis de nitrato oxida el cloruro a Cl2 y HOCl.
- Cl2 y HOCl reaccionan con el nitrito para formar ClNO2, una nueva vía.
- Este mecanismo difiere de la oxidación de cloruro mediada por OH establecida.
Conclusiones:
- La fotólisis del nitrato en los aerosoles de sal marina es una fuente significativa de ClNO2 durante el día.
- Esta vía química recién identificada altera la comprensión del ciclo del halógeno atmosférico.
- Los hallazgos requieren una reevaluación de los modelos atmosféricos actuales relativos a la química de los halógenos.
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