Perilous Times
Deep Plumes Of Oil Cause Dead Zones In The Gulf
by Staff Writers
Washington DC (SPX) Aug 26, 2010
A new simulation of oil and methane leaked into the Gulf of Mexico
suggests that deep hypoxic zones or "dead zones" could form near the
source of the pollution.
The research investigates five scenarios of oil and methane plumes at
different depths and incorporates an estimated rate of flow from the
Deepwater Horizon spill, which released oil and methane gas into the
Gulf from April to mid July of this year.
A scientific paper on the research has been accepted for publication by
Geophysical Research Letters, a journal of the American Geophysical
Union,
Scientists at the National Oceanic and Atmospheric Administration
(NOAA) and Princeton University conducted the research. Based on their
simulations, they conclude that the ocean hypoxia or toxic
concentrations of dissolved oil arising from the Deepwater Horizon
blowout are likely to be "locally significant but regionally confined
to the northern Gulf of Mexico."
A hypoxic or "dead" zone is a region of ocean where oxygen levels have
dropped too low to support most forms of life, typically because
microbes consuming a glut of nutrients in the water use up the local
oxygen as they consume the material.
"According to our simulations, these hypoxic areas will be peaking in
October," says study coauthor Robert Hallberg of the NOAA Geophysical
Fluid Dynamics Laboratory in Princeton, N.J.. "Oxygen drawdown will go
away slowly, as the tainted water is mixed with Gulf waters that
weren't affected. We're estimating a couple of years" before the dead
zone has dissipated, he adds.
Although the Princeton-NOAA study was carried out when the flow rate
from the Deepwater Horizon spill was still underestimated, the
simulated leak lasted longer than did the actual spill.
Consequently, says Alistair Adcroft of Princeton University and the
NOAA Geophysical Fluid Dynamics Laboratory, another study coauthor,
"the overall impact on oxygen turns out to be about the same" as would
be expected from the Deepwater Horizon spill.