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Las emisiones naturales de bromuro de metilo y cloruro de metilo de las marismas saladas costeras
R C Rhew1, B R Miller, R F Weiss
1Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093-0244, USA. rob@gaslab.ucsd.edu
Nature
|February 5, 2000
Resumen
Las marismas saladas costeras son importantes fuentes naturales de bromuro de metilo (CH3Br) y cloruro de metilo (CH3Cl) atmosféricos, cruciales para la salud de la capa de ozono. Estos ecosistemas pueden representar el 10% de las emisiones globales a pesar de su pequeña superficie.
Área de la Ciencia:
- Química de la atmósfera química de la atmósfera.
- Ciencias ambientales Ciencias ambientales.
- Ecología Ecología Ecología.
Sus antecedentes:
- El bromuro de metilo atmosférico (CH3Br) y el cloruro de metilo (CH3Cl) están implicados en el agotamiento del ozono estratosférico.
- Las estimaciones actuales de emisiones de CH3Br y CH3Cl no se concilian con los procesos de pérdida conocidos, lo que indica fuentes naturales potencialmente perdidas.
- Se sospecha que los ecosistemas terrestres juegan un papel más significativo en el presupuesto global de estos compuestos.
Objetivo del estudio:
- Investigar el papel de las marismas saladas costeras como fuente de bromuro de metilo (CH3Br) y cloruro de metilo (CH3Cl) atmosféricos.
- Para cuantificar los flujos de CH3Br y CH3Cl de diferentes zonas de vegetación dentro de las marismas saladas.
- Evaluar la importancia global de las marismas saladas para los presupuestos atmosféricos de CH3Br y CH3Cl.
Principales métodos:
- Se realizaron mediciones de campo de los flujos de CH3Br y CH3Cl en dos ecosistemas de marismas saladas costeras.
- Los flujos se midieron en varias zonas de vegetación para capturar la variabilidad espacial.
- Se monitorearon las variaciones diurnas y estacionales en las emisiones.
Principales resultados:
- Se detectaron flujos significativos de CH3Br y CH3Cl de todas las zonas de vegetación estudiadas en las marismas saladas costeras.
- Los flujos medidos alcanzaron hasta 42 micromol m(-2) d(-1) para CH3Br y 570 micromol m(-2) d(-1) para CH3Cl.
- Se observó una fuerte correlación positiva entre los flujos de CH3Br y CH3Cl, con una relación molar de aproximadamente 1:20.
- Las emisiones exhibieron una considerable variabilidad diurna, estacional y espacial.
Conclusiones:
- Las marismas saladas costeras representan una fuente natural sustancial y previamente subestimada de CH3Br y CH3Cl atmosféricos.
- Estos ecosistemas, a pesar de cubrir una pequeña área global (<0,1%), podrían contribuir aproximadamente un 10% a las emisiones globales de CH3Br y CH3Cl.
- Los hallazgos destacan la importancia de incluir las emisiones de las marismas saladas en los modelos atmosféricos globales para los estudios de agotamiento del ozono.
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