Scientists have found tiny droplets of seawater trapped within salt crystals that can be used to reconstruct the ocean's chemical composition over millions of years. The researchers, from Binghamton University and Princeton University, used specialized equipment to analyze these droplets and found that the concentration of lithium in seawater has decreased by a factor of seven over the past 150 million years.
Lithium is a trace element that is found in seawater in very small amounts. It is thought to be important for the formation of marine organisms and for the regulation of the ocean's acidity. The decline in lithium concentration in seawater is likely due to a combination of factors, including the slowdown of tectonic plate activity and the decrease in seafloor hydrothermal activity.
|Salt formations at the Dead Sea.
Tectonic plate activity is the process by which the Earth's crust is constantly moving and colliding. This activity produces new oceanic crust, which is rich in lithium. The slowdown of tectonic plate activity over the past 150 million years has led to the production of less new oceanic crust, which has resulted in a decrease in the amount of lithium in seawater.
Seafloor hydrothermal activity is the process by which hot water from the Earth's interior is released onto the seafloor. This water is rich in lithium and other trace elements. The decrease in seafloor hydrothermal activity over the past 150 million years has also contributed to the decline in lithium concentration in seawater.
The study, published in the journal Science Advances, provides new insights into the long-term evolution of the ocean. It also has implications for our understanding of climate change, as lithium is a key component of some climate models.
The researchers believe that their findings could be used to develop new methods for monitoring and predicting climate change. They also hope that their work will inspire other scientists to explore the potential of sea salt as a tool for reconstructing Earth's history.
In addition to the decline in lithium concentration, the researchers also found that the magnesium to calcium ratio in seawater has increased over the past 150 million years. This increase is likely due to the same factors that have caused the decline in lithium concentration, namely the slowdown of tectonic plate activity and the decrease in seafloor hydrothermal activity.
The researchers' findings suggest that the ocean's chemical composition has been changing over time in response to changes in the Earth's tectonic and volcanic activity. This information could be used to better understand the Earth's climate history and to predict how the ocean might respond to future climate change.
In other words, these tiny droplets of seawater are like time capsules, preserving the chemical composition of the ocean from millions of years ago. By studying these droplets, scientists can learn more about how the ocean has changed over time and how it might respond to future climate change.
Being a geologist, Sherwood Lollar has licked a lot of rocks throughout her career. This expedition was no different, and she even tasted some of the ancient water off her finger. It’s “very salty and bitter”, she told CNN in an interview. It didn’t exactly age like wine, that’s for sure.