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Cinética de la reacción OH con metil cloroformo y sus implicaciones atmosféricas
Science (New York, N.Y.)
|July 10, 1992
Resumen
Nuevas mediciones muestran que las tasas de reacción de los radicales hidroxilo con metilcloroformo son más bajas de lo que se pensaba. Este hallazgo tiene un impacto en la química atmosférica, afectando los cálculos de las concentraciones de hidroxilo troposférico y la vida atmosférica de varios compuestos.
Área de la Ciencia:
- Química de la atmósfera química de la atmósfera
- La cinética química es la cinética química.
- Ciencias del medio ambiente Ciencias del medio ambiente.
Sus antecedentes:
- El metil cloroformo (CH3) es un importante gas traza en la atmósfera.
- Los radicales hidroxilo (OH) son oxidantes clave en la troposfera, influyendo en la vida útil de muchos contaminantes.
- Existen mediciones anteriores de los coeficientes de velocidad de reacción de los radicales OH con metilcloroformo.
Objetivo del estudio:
- Para medir con precisión los coeficientes de velocidad para la reacción de los radicales hidroxilo con metilcloroformo.
- Proporcionar datos cinéticos actualizados para el modelado atmosférico.
- Reevaluar la vida útil atmosférica y el impacto del metilcloroformo y sus compuestos relacionados.
Principales métodos:
- Utilizó la técnica de fluorescencia inducida por láser de fotólisis pulsada (PP-LIF).
- Se llevaron a cabo mediciones cinéticas en un rango de temperatura de 243 379 Kelvin.
- Comparó los resultados experimentales con los coeficientes de tasa informados previamente.
Principales resultados:
- Los coeficientes de velocidad medidos en 298 K y 277 K fueron aproximadamente un 20% y un 15% más bajos, respectivamente, que los valores reportados anteriormente.
- Los datos cinéticos actualizados sugieren un aumento de aproximadamente un 15% en las concentraciones derivadas de OH troposféricas basadas en el presupuesto de metilcloroformo.
- Los tiempos de vida atmosféricos previstos para las especies reactivas al OH en la troposfera se reducen en aproximadamente un 15%.
Conclusiones:
- El estudio proporciona coeficientes de velocidad más precisos para la reacción OH + CH ((3) CCl ((3).
- Los datos cinéticos revisados requieren ajustes en los modelos atmosféricos relacionados con las concentraciones de OH y la vida útil de las especies.
- Estos hallazgos tienen implicaciones para el cálculo de los potenciales de calentamiento global y de agotamiento de la capa de ozono.
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