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Capacidad de oxidación atmosférica sostenida por un bosque tropical
J Lelieveld1, T M Butler, J N Crowley
1Max Planck Institute for Chemistry, 27 Becherweg, 55128 Mainz, Germany. lelieveld@mpch-mainz.mpg.de
Nature
|April 11, 2008
Resumen
Los bosques tropicales liberan compuestos orgánicos volátiles (COV) que sorprendentemente mantienen altos niveles atmosféricos de radicales hidroxilo (OH). Esto sugiere un mecanismo natural para la autolimpieza atmosférica, incluso en entornos prístinos.
Área de la Ciencia:
- Química de la atmósfera La química de la atmósfera
- Biogeoquímica La biogeoquímica es la bioquímica.
- Ciencias ambientales Ciencias ambientales.
Sus antecedentes:
- La vegetación terrestre, en particular las selvas tropicales, emite sustancialmente compuestos orgánicos volátiles (COV) a la atmósfera.
- La oxidación atmosférica, impulsada principalmente por los radicales hidroxilo (OH), elimina estos COV.
- Anteriormente, se pensaba que los COV biogénicos agotaban el OH en el aire no contaminado, reduciendo la capacidad de oxidación atmosférica.
Objetivo del estudio:
- Para investigar las concentraciones atmosféricas de gases traza sobre la selva amazónica.
- Para comprender las concentraciones inesperadamente altas de radicales hidroxilo (OH) observadas.
- Explorar el papel de la oxidación biogénica de COV en el mantenimiento de la capacidad de oxidación atmosférica en entornos con bajo contenido de óxido de nitrógeno (NOx).
Principales métodos:
- Mediciones basadas en aeronaves de gases traza atmosféricos sobre el bosque amazónico.
- Modelado de la química de la atmósfera.
- Experimentos de laboratorio que investigan los mecanismos de oxidación del isopreno.
Principales resultados:
- Se observaron concentraciones inesperadamente altas de radicales hidroxilo (OH) en la atmósfera amazónica prístina.
- Propuso que la oxidación de los COV naturales, especialmente el isopreno, recicla eficientemente el OH en condiciones de bajos niveles de NOx.
- Los cálculos del modelo y los resultados de laboratorio sugieren una eficiencia de reciclaje de OH del 40-80% en la oxidación del isopreno, lo que explica los altos niveles de OH observados.
Conclusiones:
- La biosfera juega un papel crucial en el mantenimiento del equilibrio de oxidación atmosférica a través de un reciclaje eficiente de OH.
- La oxidación biogénica de COV es un factor importante en la regulación de la química atmosférica, incluso en regiones remotas y no contaminadas.
- Se necesitan más estudios de laboratorio para dilucidar completamente los mecanismos químicos detrás del reciclaje de OH en la oxidación del isopreno.
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