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RE: Vida en Marte: nuevos experimentos.



At 09:02 PM 11/24/96 +0100, you wrote:
>> De: Javier <ssta en lix.intercom.es>
>> GONZALO: TE AGRADECERE QUE ME
>
>	Uy, perdon, ... no es exactamente asi, dije una cosa que no era. El
>oxigeno no proviene del que esta contenido en la materia organica, es otra
>cosa. (El origen de la confusion es muy tonto: al leer eso de 'surges' lo
>traduje por bombeo; esto es debido a que suelo ver la palabra asociada a un
>tipo de inestabilidad que se da en los compresores, pero que en espanyol se
>llama bombeo, aunque lo normal es que se use la palabra inglesa. (He mirado
>el diccionario y ya he visto que una cosa no es traducion literal de la
>otra)). Y claro, al entender eso del bombeo de oxigeno a la atmosfera, y
>mas adelante lo del almacenamiento de carbono organico... Pido disculpas
>por la metedura de pata. Si no me equivoco, lo que DesMarais dice que
>ocurre es que, al estar la materia organica enterrada, el equilibrio que el
>dice respiracion-fotosintesis se rompio, porque la materia organica es
>consumida por las bacterias en la respiracion para producir CO2, de manera
>que la 'cantidad' de respiracion no fue capaz de consumir todo el oxigeno
>para mantener la concentracion inicial, y esta aumento. Pongo la nota de
>prensa, y asi nos ahorramos complicaciones de errores de interpretacion. De
>todas maneras, advierto que yo no tengo nada que ver con DesMarais, y no
>pienso defender ni rebatir su hipotesis, porque no es mi campo y entiendo
>mas bien poco tirando a nada de estas cosas, asi que me fio del, digamos,
>'debate cientifico habitual'. Solo lo cuento porque me parece interesante:
>
>RELEASE:  96-219
>
>RESEARCH SUGGESTS MOST OF EARTH'S OXYGEN 
>SUPPLY WAS PRODUCED BY GEOLOGIC EVENTS
>
>       Refined calculations and new evidence support a 
>revolutionary suggestion that global-scale geologic events 
>produced the bulk of Earth's oxygen supply, a NASA scientist 
>reported today. 
>
>       Scientists have long believed that oxygen collected in 
>Earth's early atmosphere as a by-product of plant life from a 
>process called photosynthesis, in which plants take carbon 
>dioxide and water to produce organic matter and oxygen.  Dr. 
>David DesMarais, of NASA's Ames Research Center, Mountain 
>View, CA, first suggested in 1992 a relationship between 
>oxygen and the collision of continents, the resultant 
>colossal mountain ranges and increased erosion burying huge 
>amounts of organic matter in ocean beds.
>
>       "Although photosynthesis did provide an oxygen source 
>strong enough to sustain the amount of existing oxygen, the 
>creation and assembly of large modern-sized continents was 
>responsible for early dramatic increases in oxygen," 
>DesMarais said.
>
> (...)
>       DesMarais' research correlates oxygen "surges" in the 
>atmosphere 2.2 to 2.0 billion years ago with changes in the 
>amount of carbon stored in Earth's crust at that time.  
>During that time, several of Earth's "micro" continents 
>crashed together forming new, stable modern-sized continents.  
>As the continental fragments collided, towering mountain 
>ranges formed.  Their steep slopes produced rapid erosion and 
>sedimentation, key to DesMarais' theory.
>
>       Organic matter is normally consumed by bacteria and 
>animals, a process that utilizes oxygen (respiration), 
>producing energy and carbon dioxide and water as by-products.  
>According to DesMarais, when huge amounts of organic matter 
>were buried during cataclysmic collisions, oxygen was freed 
>to accumulate in Earth's early atmosphere. 
>
>       "The cycle of photosynthesis (which produces oxygen) 
>and respiration (where oxygen is consumed) is an almost 
>break-even process," DesMarais said.  Only when large amounts 
>of organic material are buried in ocean sediments during 
>tectonic upheavals can the amount of oxygen in the atmosphere 
>increase substantially, he added.
>
>       An independent recent study concludes that 
>approximately three large continental masses were assembled 
>between 2.5 and 1.9 billion years ago by the collision of 
>smaller land masses.  Two of these were assembled between 2.2 
>and 1.9 billion years ago.  These collisions formed 
>Himalayan-class mountains with high rates of sedimentation in 
>the ocean, burying organic matter.
>(...)
>
>	
>	Saludos
>	Gonzalo J. Perez
>	gonj en ctv.es
>

Gonzalo,
 no me extranna que te confundieras. El articulo no esta bien escrito, e
invita a la confusion. El oxigeno se libera "por falta de consumo", al
reducirse el numero de organismos que lo fijan, y se rompio el "regimen
permanente" de que habla el autor,  pero no por otra razon. Pero hay que
leerlo dos y hasta tres veces para darse cuenta.


Saludos

Javier

ssta en lix.intercom.es