Millions of gallons of hazardous waste resulting from the nation’s nuclear weapons program lie in a remote location in southeastern Washington state called Hanford. Beneath this desert landscape about two million curies of radioactivity and hundreds of thousands of tons of chemicals are captured within the stratified vadose zone below which gives rise to complex subsurface flow paths.
These paths create uncertainties about where the contaminants go and what happens to them. With the mighty Columbia River bordering much of the site, where these nuclear wastes migrate, their composition and how fast they are traveling are of vital importance to both people and the environment.
The November issue of Vadose Zone Journal features a series of papers addressing the mysteries within the vadose zone beneath Hanford. The series outlines scientific work funded by the Department of Energy and carried out by scientists at Pacific Northwest National Laboratory and contributing associates with other national laboratories, universities and contractors.
The detailed series outlines how researchers have investigated Hanford’s vadose zone to better understand the migration of these contaminants, ultimately reducing or stemming their flow toward the Columbia River, thereby protecting the river and the people living downstream. By studying the geologic, biologic, geochemical and hydrologic conditions at the Hanford site, the researchers seek to understand and manipulate the factors that control contaminants’ fate and transport.
To date, studies show that fine-grained sediment layers along with rain, snowfall and other climatic conditions affect contaminant transport. For three decades, scientists have studied what happens when water enters and exits the soil, particularly how it affects the movement of the contaminants under various conditions.
“Understanding how hydrology and chemistry are interacting below the land surface in the vadose zone and the factors that control those interactions are keys to ultimately dealing with the legacy from nuclear waste production at the Hanford site,” said Glendon Gee, Laboratory Fellow at Pacific Northwest National Laboratory. Gee is lead author on the overview paper of the series.
Chemical studies indicate that a number of contaminants, such as cesium, react strongly with Hanford sediments and move only under extreme conditions. Researchers found that another contaminant, uranium, reacts with the sediments in complex ways and its migration varies under different conditions. Other contaminants, such as tritium and nitrate, are relatively mobile. These contaminants have been transported deep into the vadose zone and reached the groundwater. Carbon tetrachloride and other organic compounds have moved in complex ways, as both vapor and liquid, and reached the groundwater.
Additional studies of the fate and transport of contaminants in the vadose zone are ongoing at the Hanford Site. These studies will characterize the extent of contaminant plumes, determine how fast or slow they are migrating and evaluate remediation solutions.
Sara Uttech | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences