干旱区生态环境知识资源中心

The Atacama Desert is one of the driest and oldest deserts of the world that extends along the Pacific coast of South America. We have collected surface soil samples from the driest parts of the Atacama Desert (24degreesS) to the less and zones (28degrees) along a transect at about 70degreesW. The samples were subjected to flash pyrolysis at 750degreesC in an inert atmosphere. The resultant gas fragments were separated by gas chromatography and identified by mass spectrometry. The samples from the most arid zones are basically free of organic matter. No organics are detected using scan mode (60-200 m/e) mass spectrometry. Benzene is just barely detectable using selective-ion-monitoring mass spectrometry. We think that the concentration of organics in desert soils can be used as a proxy for habitability. A lack of organics may indicate an oxidizing environment possibly caused by UV radiation similar to conditions expected on Mars.