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La productividad de los océanos antes de hace aproximadamente 1,9 Gyr estaba limitada por la adsorción de fósforo en
Christian J Bjerrum1, Donald E Canfield
1Danish Center for Earth System Science, Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark. cjb@geo.geol.ku.dk
Nature
|May 10, 2002
Resumen
Tierra temprana de la Tierra temprana.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La paleoceanografía es la paleoceanografía.
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- La producción de oxígeno en la Tierra primitiva dependía de la disponibilidad de nutrientes oceánicos, en particular el fósforo.
- La eliminación del fósforo en los océanos modernos implica la adsorción a los óxidos de hierro.
- Las formaciones de hierro en bandas sugieren una mayor deposición de óxido de hierro en condiciones pasadas de bajo contenido de sulfato.
Objetivo del estudio:
- Para analizar el contenido de fósforo y hierro en formaciones de hierro en bandas.
- Para reconstruir las antiguas concentraciones de ortofosfato en el océano.
- Evaluar el impacto de la disponibilidad de fósforo en la producción de oxígeno de la Tierra primitiva.
Principales métodos:
- Análisis del contenido de fósforo y hierro en muestras geológicas.
- Reconstrucción paleoceanográfica utilizando proxies geoquímicos.
- Modelado del ciclo de nutrientes y su efecto en la fotosíntesis y el enterramiento de carbono.
Principales resultados:
- Las concentraciones de ortofosfatos oceánicos de hace 3,2 a 1,9 mil millones de años eran del 10 al 25 por ciento de los niveles actuales.
- Es probable que durante este período se produjera una mayor eliminación de fósforo a través de la adsorción de óxido de hierro.
- La baja disponibilidad de fósforo limitó significativamente la fotosíntesis temprana y el enterramiento de carbono.
Conclusiones:
- La baja disponibilidad de fósforo limitó la producción de oxígeno en la Tierra primitiva.
- Esta limitación contribuyó a los bajos niveles de oxígeno atmosférico observados en el Arqueo tardío y el Proterozoico temprano.
- La disponibilidad de nutrientes es un factor crítico en la regulación de los niveles de oxígeno planetario en escalas de tiempo geológicas.
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