Study confirms helium levels in the atmosphere are rising

(ORDO NEWS) — Scientists at the Scripps Institution of Oceanography at the University of California, San Diego have used an unprecedented technique to detect rising levels of helium in the atmosphere, solving a question that has plagued atmospheric chemists for decades.

The abundance of the helium-4 isotope ( 4 He) in the atmosphere is rising as 4 He is released from combustion and fossil fuel extraction.

The researchers report that it is growing at a very slow but clearly measurable rate for the first time. By itself, the 4He isotope does not contribute to the greenhouse effect that makes the planet warmer, but its content can serve as an indirect indicator of the use of fossil fuels.

“The main motivation was to resolve a longstanding controversy in the scientific community about the concentration of helium in the atmosphere,” said study lead author Benny Birner, a former graduate student and now researcher at the Scripps Institution of Oceanography at the University of California, San Diego. The 4He

isotope is produced by radioactive decay in the earth’s crust and accumulates in the same places as fossil fuels, in particular natural gas. During the extraction and combustion of fossil fuels, He is accidentally released, providing another tool for assessing the scale of industrial activity.

The breakthrough in the study lies in the technique used by Scripps’ team of oceanographers to measure the amount of helium in the atmosphere.

Birner and Scripps geologists Jeff Severinghouse, Bill Paplavsky, and Ralph Keeling created an accurate method for comparing the He isotope with the levels of the common atmospheric gas, nitrogen.

Since the level of nitrogen in the atmosphere is constant, an increase in the content of He/N 2 indicates the rate of accumulation of 4 He in the atmosphere.

Study co-author and Scripps Oceanographic Department geochemist Ralph Keeling, director of the famous carbon dioxide measurement known as the Keeling curve, called the study “a masterpiece of fundamental geochemistry.”

Although it is relatively easy for scientists to detect helium in air samples, present at the level of five parts per million of air, no one has done work to measure it closely enough to observe an increase in atmospheric levels, he said.

The study also lays the groundwork for scientists to better understand the valuable isotope helium-3 ( 3 He), which is used in nuclear fusion, cryogenics and other fields. Proposals to extract scarce gas from the moon are indicative of the lengths producers will go to extract it.

According to previous work by other researchers, the He isotope exists in the atmosphere in an unchanged ratio with 3 He.

Therefore, the growth of the 4He isotope in the atmosphere measured at Scripps suggests that the He isotope should grow at the same rate as 4He . The Birner group’s study raises several questions about the accuracy of scientists’ previous assumptions about how 3He is formed and how much.

“We don’t know for sure, but I’m wondering if more 3 He is coming out of the Earth than we previously thought, which could possibly be harvested and used as fuel for our fusion reactors in the future,” Birner said.

“This study brings to light the controversy surrounding the rare helium isotope 3 He,” said Keeling. “The implications are far from clear, but they require more work.”


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