This might seem strange, but the biggest aquifer on the planet is actually underneath the floor of the world's oceans, with a liquid volume that amounts to 2 percent of the amount of water in the oceans themselves.
Scientists also say that the oceanic crustal aquifer, as it's called, is also one of the world's biggest ecosystems. It's believed to harbor a vast reservoir of microbial life that may exert a powerful, though not yet well-understood, effect upon the oceans above it.
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Researchers have had a difficult time probing the oceanic crustal aquifer, as it's called, since getting to the bottom of it requires drilling through layers of sediment until they hit rock. But now, a newly-published article in the journal Scientific Reports details the microbial life found in samples obtained by drilling up to 820 feet into the ocean floor, about 2.7 miles under the surface of the water in a portion of the Atlantic known as the North Pond.
"In many cases, we found the same general group (of bacteria) in the crustal aquifer and in bottom seawater, but different species within that group," Marine Biological Laboratory associate scientist Julie Huber said in a press release. That means distinct differences in potential microbial activity between the two sites, such as more carbon fixation in the aquifer."
Some of this life that's deep in the oceanic crustal aquifer may be isolated, due to reduced permeability as the cracks become filled with clay and minerals.
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It's the first study to describe the sub-seafloor microbial community in a "cold" crustal aquifer site that scientists had to drill deeply to reach. Previous studies focused on the hot, volcanic fluids at mid-ocean ridges and the sub-seafloor microbes that survive there.
The oceanic crust continually interacts with the ocean above it. Seawater runs through its rocky crevices, creating a dynamic aquifer through which the entire volume of the ocean circulates every 200,000 years.
The samples were obtained in 2011 by the Integrated Ocean Drilling Program.