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Woods Hole Oceanographic Institution

Margaret K. Tivey

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Projects
» Microbial colonization as functions of temperature, chemistry, and time in Guaymas Basin

» Inductive Coupled Link for communicating with in situ instruments on the seafloor, developed by Al Bradley, WHOI, Dept of AOPE, with funds from the National Science Foundation.

Click here for a pdf file describing the Inductive Coupled Link

» Geochemical modeling of vent environments (funded by National Science Foundation grant OCE-0002634)

» Permeability and porosity, teaching materials


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Location of experiment.  Arrays were placed at Busted Shroom (see next photo), Toadstool, and Theme Park.


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Microbial colonization as functions of temperature, chemistry, and time in Guaymas Basin

Collaborators:
Joint NSF-MBARI-USGS project to Guaymas Basin vents; PIs M.K. Tivey, D.S. Stakes, A.M. Bradley, J. Seewald, A-L. Reysenbach, A. Page, R. Koski, C.G. Wheat

A joint WHOI-MBARI-Portland State University project is currently underway to investigate the interaction of microorganisms with their geochemical environment in chimney deposits that are actively forming in the Guaymas Basin hydrothermal system. In the spring of 2003, the project included sampling vent fluids, and instrumenting the vents, using newly designed Ti-thermocouple arrays, to trace the evolution of the thermal/chemical/physical environment within newly formed chimney walls over time-scales of minutes to months, and to determine the distribution of microorganisms within this spatial framework. 

In two cruises, one in March 2003, and one in May 2003, we

1. Recovered fluids from 6 different carbonate/sulfide/sulfate structures that vented fluids ranging from 90 to 303ºC

2. Recovered one 4-day old chimney (and two 72-day old chimneys embedded in arrays (final recorded temperatures within the chimneys ranged from 109 to 300C).  These chimneys have been sub-sampled for molecular, chemical, and isotope analyses to identify the presence of organisms in areas of known temperature, and to examine assumptions about how quickly oxygen isotope and sulfur isotope equilibrium are attained in active hydrothermal systems.


3. Collected time-series temperature data of the growth of two chimneys (one over a time period of 4 days, one over a time period of 72 days), and of the temperature fluctuations at a vent where a chimney did not re-grow over the same 72-day time interval.  Diurnal periodicities are observed in the time-series temperature records from a thermocouple that was embedded within a chimney wall, and from thermocouples that were outside the growing chimneys, as well as from thermocouples that were within the hot open channels of one of the chimneys. 

Conclusions:
-Arrays allow "capture" of young chimney material of known temperature and history.

-Recovered material and temperature data can be used to provide an empirical test of sulfate and carbonate oxygen isotope geothermometry within active vent structures.
-Recovered material can be used to examine environments where micro-organisms are present as well as spatial/temporal successions.

-Temperature records document the dynamic environment at vent sites and within structure walls.

-Fluid, temperature, and isotope data provide constraints for transport models that can be used to determine the chemical environment within chimney walls so that microbial populations can be placed in a unified chemical, thermal, temporal context.

 


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