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Participant
Interview:
Leigh
Evans
Chemist
Oregon State University/NOAA Vents
Jeff: What are you measuring
with all your fancy equipment?
Leigh: On board ship I'm measuring the amount of dissolved gas in the
vent fluid. On land I'll be measuring helium isotope concentrations. Some
of the samples are sent to labs that measure other gasses in vent fluids
such as methane, hydrogen, carbon dioxide and hydrogen sulfide.
Jeff: Why are you looking
for these particular elements in the vent fluid?
Leigh: Helium is a geochemical indicator of how active a vent is and how
it changes over time. The ratio of He3 to heat varies with time duration
since a seismic event. We can compare He3 in newly formed vents, such
as the 1998 Axial eruption area, with vent fields in that haven't been
perturbed by any type of seismic event. Methane, produced geologically
or biologically, and hydrogen give some insight into other chemical processes
that are occurring in the rocks beneath the sea floor.
Jeff: Isn't helium a good
tracer for studying hydrothermal vent plume movement?
Leigh: Yes. We study plume dynamics with some types of helium isotopes.
Vents inject enriched He3 into the water column, where it finds its buoyant
level, disperses, and is transported with deep ocean currents. In a few
cases we think we know where it's going.
Jeff: What gets you excited
about your research?
Leigh: It pays most of the bills. Also, I'm not building bombs, which
I contributed to during my five years while in the aerospace industry.
Jeff: What kind of societal
benefits result from your research?
Leigh: Plume studies are a check against more sophisticated oceanic circulation
models. A greater understanding of ocean circulation would contribute
to global warming research. It might illuminate questions such as: Where's
all the CO2 going in the ocean?
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