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Una fuerte fuente de cloruro de metilo a la atmósfera de las tierras costeras tropicales

Y Yokouchi¹, Y Noijiri, L A Barrie

¹National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan. yokouchi@nies.go.jp

|February 5, 2000

Resumen

El cloruro de metilo (CH3Cl) es un halocarbono atmosférico significativo. Una nueva investigación indica que las tierras costeras cálidas, especialmente las islas tropicales, son una fuente importante, lo que desafía las teorías anteriores de emisión oceánica.

Área de la Ciencia:

Química de la atmósfera química de la atmósfera
Ciencias del medio ambiente Ciencias del medio ambiente.
Investigación de halocarbono Investigación de halocarbono.

Sus antecedentes:

El cloruro de metilo (CH3Cl) es el halocarbono atmosférico más abundante y una fuente natural de cloro estratosférico.
El flujo global estimado de CH3Cl es de 3,5 Tg, con una vida atmosférica de 1,5 años debido a las reacciones de radicales OH.
Anteriormente, la emisión oceánica se consideraba la fuente primaria, con la quema de biomasa como fuente secundaria.

Objetivo del estudio:

Para investigar la fuente de cloruro de metilo atmosférico (CH3Cl) dado los recientes hallazgos de que los flujos oceánicos son insuficientes.
Para identificar fuentes alternativas significativas de emisiones de CH3Cl.

Principales métodos:

Realizó un estudio de monitoreo global de las concentraciones atmosféricas de CH3Cl.
Realizó mediciones puntuales en varios lugares.
Se analizaron las correlaciones entre CH3Cl y compuestos biogénicos de plantas terrestres.
Se examinó la estacionalidad relacionada con OH de las concentraciones de CH3Cl.

Principales resultados:

Mediciones recientes del agua de mar sugieren que los flujos oceánicos representan sólo el 12% del flujo global de CH3Cl.
La evidencia apunta a emisiones significativas de CH3Cl de las tierras costeras cálidas, particularmente las islas tropicales.
Mejoras observadas de CH3Cl atmosférico en los trópicos.
Se encontró una fuerte correlación entre las concentraciones de CH3Cl y los compuestos biogénicos de plantas terrestres.
Se detectó estacionalidad vinculada a OH en latitudes medias y altas.

Conclusiones:

Las tierras costeras cálidas, especialmente las islas tropicales, representan una fuente significativa y previamente subestimada de cloruro de metilo atmosférico.
Una fuerte fuente ecuatorial de CH3Cl puede explicar su distribución uniforme entre los hemisferios.
Es necesario reevaluar las fuentes mundiales de CH3Cl, yendo más allá de los orígenes exclusivamente oceánicos y la quema de biomasa.

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