Beryllium-10 (¹⁰Be) is a

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

beryllium Beryllium is a chemical element; it has Symbol (chemistry), symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with ...

. It is formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen. Beryllium-10 has a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 1.39 million years, and decays by

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron ...

to stable boron-10 with a maximum energy of 556.2 keV. It decays through the reaction ¹⁰Be→¹⁰B + e⁻. Light elements in the atmosphere react with high energy galactic cosmic ray particles. The spallation of the reaction products is the source of ¹⁰Be (t, u particles like n or p): :¹⁴N(t,5u)¹⁰Be; Example: ¹⁴N(n,p α)¹⁰Be :¹⁶O(t,7u)¹⁰Be Because beryllium tends to exist in solutions below about pH 5.5 (and rainwater above many industrialized areas can have a pH less than 5), it will dissolve and be transported to the Earth's surface via rainwater. As the

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

quickly becomes more

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

, beryllium drops out of solution. Cosmogenic ¹⁰Be thereby accumulates at the

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

surface, where its relatively long

(1.387 million years) permits a long residence time before decaying to ¹⁰ B. ¹⁰Be and its daughter product have been used to examine

soil erosion Soil erosion is the denudation or wearing away of the Topsoil, upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, Atmosphere of Ea ...

soil formation Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order ( anisotropy) within soils. These alteration ...

from regolith, the development of lateritic soils and the age of

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...

s. It is also formed in nuclear explosions by a reaction of fast neutrons with ¹³C in the carbon dioxide in air, and is one of the historical indicators of past activity at nuclear test sites. ¹⁰Be decay is a significant isotope used as a proxy data measure for

cosmogenic nuclide Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an '' in situ'' Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom ...

s to characterize solar and extra-solar attributes of the past from terrestrial samples. The rate of production of beryllium-10 depends on the activity of the sun. When solar activity is low (low numbers of

sunspot Sunspots are temporary spots on the Sun's surface that are darker than the surrounding area. They are one of the most recognizable Solar phenomena and despite the fact that they are mostly visible in the solar photosphere they usually aff ...

s and low

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

), the barrier against cosmic rays that exists beyond the termination shock is weakened (see Cosmic ray#Cosmic-ray flux). This means more beryllium-10 is produced, and it can be detected millennia later. Beryllium-10 can thus serve as a marker of

Miyake event A Miyake event is an observed sharp enhancement of the production of Cosmogenic nuclide, cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope Carbon-14, in tree rings, as well as Beryl ...

s, such as the 774–775 carbon-14 spike. There can be an effect on climate (see Homeric Minimum).

References

{{Authority control Isotopes of beryllium Radionuclides used in radiometric dating

See also

References