Digging into dirt -- Subsurface science at PNNL
Imagine drinking water that has
dripped through the sponge you’ve just
used to clean the breakfast dishes. This
is happening around the world. Rain
and snow pass through soil polluted
with pesticides, poisonous metals and
radionuclides into the underground
streams that supply rivers, lakes and
“We need to understand this system
better to protect our groundwater and,
by extension, our drinking water,” said
Pacific Northwest National Laboratory’s
Applied Geology and Geochemistry
Group Manager, Wayne Martin.
PNNL builds synergistic teams of
experts, including biologists, statisticians,
hydrologists, geochemists, and computer
scientists. These teams study the
complexities of the whole environment,
not just the soil or groundwater. The
teams provide regulators with answers
to make complex decisions and design
innovative technologies to capture or
Dealing with Arsenic and Lead
at Old Fertilizer Plants
In the mid 1800s, fertilizer
manufacturers began obtaining the
plant nutrient phosphate by processing
apatite ore with sulfuric acid. Pyrite ore,
with traces of arsenic and lead, was a
feedstock used for the onsite production
of sulfuric acid. Waste fluids and solids
from acid and fertilizer production were
disposed of at the sites.
Over a century later, researchers
at PNNL are helping ConocoPhillips
and others deal with the long-term legacy
of contamination and costly cleanup
problems at sites in South Carolina
and Massachusetts. The teams locate
contaminated areas, evaluate the site to
determine the physical and geochemical processes controlling migration of
the dangerous metals, help design
customized remediation methods, and
assist with long-term monitoring.
Stopping Radionuclides at a
Nuclear Weapons Site
Beneath the Hanford Site, a
former plutonium production
complex in southeastern Washington,
lie about two million curies of
radionuclides. One concern is a persistent
plume or smear of uranium that is
moving through the subsurface toward
the Columbia River bordering the Site
on the east.
PNNL researchers have taken a
holistic approach to understanding
where the uranium will move and how
it will react. By looking at the whole
of the environment, not just the soil,
researchers can develop methods that
stop the migration of uranium and
protect the river.
To reliably and cost-effectively
test for uranium in the hyporheic
zone, where the groundwater bubbles
into the river, PNNL researchers are
looking at that ecosystem, including
microbes and fungi that make up
common rock slime, which grows at
the river’s edge. By including ecologists,
biologists and computer scientists, this
team is searching for genes, proteins or
metabolites that indicate the ecosystem
has encountered uranium.
Mapping the Results of
DDT and other pesticides are,
by definition, toxic to insects that can
destroy food crops and carry malaria or
other diseases; however, when companies
dispose of these chemicals improperly,
the consequences can be devastating to humans and the environment.
Just how devastating is what PNNL’s
geostatisticians helped determine.
Geostatistics combines geology
and mathematical statistics and can
be used to understand the spatial
distribution of one or more pollutants
through a complex environment.
When high levels of pesticides were
discovered on southern California’s
coastal shelf, PNNL Staff Scientist
Chris Murray was asked to produce
maps showing the thickness and
contaminant concentrations of the
polluted sediment. The Environmental
Protection Agency used the maps to
evaluate cleanup options.
The future of subsurface science
may be up in the air, literally.
Researchers at PNNL are working to
safely incorporate the greenhouse gas
carbon dioxide into the subsurface.
As part of a large consortium, the
researchers are looking at the feasibility
of pumping the gas deep underground.
There, it would react and become
harmless minerals within the soil.