The findings of a recently published study on ancient groundwaters could have important implications for carbon sequestration and deep underground storage of waste from nuclear power as well as oil and gas production.
University of Saskatchewan researcher and professor of civil, geological, and environment engineering, Dr. Grant Ferguson says, “Groundwater at depths of several hundred meters or more can be hundred of millions of years old and are often thought of stagnant and isolated from the atmosphere and the water cycle.” This is why subsurface areas are targeted as potential sites for subsurface disposal.”
The study is among the first to employ a relatively new krypton-81 technique to date deep groundwater. With the longer decay period of radioactive krypton 81, it can be used to calculate the age of the water up to 1.2 million-years-old.
Research for the study was conducted in the Paradox Basin which is part of the southwestern regions of Utah and Colorado. The findings were surprising to the research team involved because they found young groundwater at a depth where conventionally much older aquifers are located.
Dr. Jennifer McIntosh, co-Author and adjunct professor at the U of S says, “We expected to find that groundwater would get progressively older as you go deeper. Instead, we found million-year-old groundwater, which is relatively young, about three kilometers beneath the surface in sediments that are hundreds of millions of years old.”
This study will prove useful in the future because the same techniques can be applied to characterize sites elsewhere to learn how they are connected to the atmosphere and the surface.
Dr. Ferguson says, “From a Saskatchewan perspective, we are thinking about the different ways we use subsurface, weather that’s in storing fluids from oil and gas, or carbon sequestration, we will have these legacies going forward.”
The team plans to extend this work to other regions including the Canadian Prairies. According to Ferguson, the geological events, such as the rise of the Rocky Mountains 80 million to 50 million years ago and the glaciation that covered much of North America starting about 2.8 million years ago would have created massive hydrological changes.
