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Video Experimental Relacionado

Updated: May 31, 2026

Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
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La fraccionamiento de grandes isótopos de azufre no requiere desproporcionamiento.

Min Sub Sim1, Tanja Bosak, Shuhei Ono

  • 1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. mssim@mit.edu

Science (New York, N.Y.)
|July 2, 2011
PubMed
Resumen

Los datos de isótopos de azufre en las rocas no siempre pueden indicar un ciclo complejo de azufre. Las bacterias marinas por sí solas pueden causar importantes agotamientos de azufre-34, desafiando las interpretaciones anteriores de la Tierra.

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Combined Size and Density Fractionation of Soils for Investigations of Organo-Mineral Interactions

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Área de la Ciencia:

  • La geoquímica es la geoquímica.
  • Microbiología Microbiología.
  • Historia de la Tierra Historia de la Tierra

Sus antecedentes:

  • Los isótopos de azufre en los sulfuros y sulfatos sedimentarios son clave para comprender el ciclo del azufre en la Tierra.
  • Los grandes agotamientos de azufre-34 ((34) S) en los sulfuros en relación con los sulfatos (más de 47 ‰) suelen sugerir una desproporción de azufre junto con la reducción de sulfatos.

Objetivo del estudio:

  • Para investigar si las bacterias reductoras de sulfato por sí solas pueden producir grandes fraccionamientos de isótopos de azufre.
  • Reevaluar la interpretación de los registros de isótopos sedimentarios de azufre, particularmente en lo que respecta a los entornos de la Tierra temprana.

Principales métodos:

  • Cultivo de una bacteria marina reductora de sulfatos bajo condiciones controladas de laboratorio.
  • Medición de las composiciones isotópicas de azufre ((34) S) tanto en sulfato como en sulfuro producido por las bacterias.

Principales resultados:

  • Un cultivo puro de bacterias reductoras de sulfatos marinos logró depleciones significativas de azufre-34 de hasta 66‰.
  • Esta fraccionamiento se produjo únicamente a través de la reducción de sulfato, sin oxidación extracelular de azufre o desproporcionamiento.

Conclusiones:

  • Las grandes fraccionamientos de isótopos de azufre en rocas sedimentarias antiguas no indican exclusivamente una desproporción de azufre o un ciclo complejo de azufre.
  • Los hallazgos desafían el uso de tales fraccionamientos como proxies inequívocos para los eventos de oxigenación del Proterozoico o metabolismos específicos.