Haze aerosols in the atmosphere of early Earth: manna from heaven.
An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Such a haze layer may also have existed on the early Earth, providing an ultraviolet shield for greenhouse gases needed to warm the planet enough for life to arise and evolve. Despite the implications of such a haze layer, little is known about the organic material produced under early Earth conditions when both CO(2) and CH(4) may have been abundant in the atmosphere. For the first time, we experimentally demonstrate that organic haze can be generated in different CH(4)/CO(2) ratios. Here, we show that haze aerosols are able to form at CH(4) mixing ratios of 1,000 ppmv, a level likely to be present on early Earth. In addition, we find that organic hazes will form at C/O ratios as low as 0.6, which is lower than the predicted value of unity. We also show that as the C/O ratio decreases, the organic particles produced are more oxidized and contain biologically labile compounds. After life arose, the haze may thus have provided food for biota.
Trainer
Melissa G
MG
Department of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, Colorado 80309-0216, USA.
Pavlov
Alexander A
AA
Curtis
Daniel B
DB
McKay
Christopher P
CP
Worsnop
Douglas R
DR
Delia
Alice E
AE
Toohey
Darin W
DW
Toon
Owen B
OB
Tolbert
Margaret A
MA
D000336:Aerosols; D001272:Atmosphere / Q000737:chemistry*; D002245:Carbon Dioxide; D018534:Earth, Planet; D018559:Exobiology; D013058:Mass Spectrometry; D008697:Methane; D019021:Natural History; D009584:Nitrogen; D018539:Saturn
D000336:Aerosols; D002245:Carbon Dioxide; D009584:Nitrogen; D008697:Methane