Previous Article |
Table of Contents
| Next Article
PHYSICS
Tubular precipitation and redox gradients on a bubbling template
,
, 
*Department of Soil, Water, and Environmental Science,
Department of Physics, and
Program in Applied Mathematics, University of Arizona, Tucson, AZ 85721
Communicated by Herman Z. Cummins, City College of the City University of New York, New York, NY, June 25, 2004 (received for review May 6, 2004)
Tubular structures created by precipitation abound in nature, from chimneys at hydrothermal vents to soda straws in caves. Their formation is controlled by chemical gradients within which precipitation occurs, defining a surface that templates the growing structure. We report a self-organized periodic templating mechanism producing tubular structures electrochemically in iron-ammonium-sulfate solutions; iron oxides precipitate on the surface of bubbles that linger at the tube rim and then detach, leaving behind a ring of material. The acidbase and redox gradients spontaneously generated by diffusion of ammonia from the bubble into solution organize radial compositional layering within the tube wall, a mechanism studied on a larger scale by complex Liesegang patterns of iron oxides formed as ammonia diffuses through a gel containing FeSO4. When magnetite forms within the wall, a tube may grow curved in an external magnetic field. Connections with free-boundary problems in speleothem formation are emphasized.
To whom correspondence should be addressed at: Department of Physics, University of Arizona, 1118 East 4th Street, Tucson, AZ 85721. E-mail: gold{at}physics.arizona.edu.
© 2004 by The National Academy of Sciences of the USA
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg What's this?
This article has been cited by other articles in HighWire Press-hosted journals:
![]() |
P. Baaske, F. M. Weinert, S. Duhr, K. H. Lemke, M. J. Russell, and D. Braun From the Cover: Extreme accumulation of nucleotides in simulated hydrothermal pore systems PNAS, May 29, 2007; 104(22): 9346 - 9351. [Abstract] [Full Text] [PDF] |
||||