Beryllium-10

Beryllium-10 (10Be) is a <a href="/facts/Radioactivity/Ya6FVjt4">radioactive</a> <a href="/facts/Isotopes_of_beryllium/bNvHB5xg">isotope</a> of <a href="/facts/Beryllium/dv295voP">beryllium</a>. It is formed in the Earth's atmosphere mainly by <a href="/facts/Cosmic_ray_spallation/gSlq9VEP">cosmic ray spallation</a> of nitrogen and oxygen. Beryllium-10 has a <a href="/facts/Half-life/kGVH8BAB">half-life</a> of 1.39 × 106 years, and decays by <a href="/facts/Beta_decay/vxTBlckp">beta decay</a> to stable <a href="/facts/Isotopes_of_boron/1n6X5bwg">boron-10</a> 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 <a href="/facts/Galactic_cosmic_ray/uxCVdTKd">galactic cosmic ray</a> particles. The <a href="/facts/Spallation/k7AsUBbk">spallation</a> 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 <a href="/facts/Solution_(chemistry)/MGchhMQV">solutions</a> below about <a href="/facts/PH/RnSv8D7y">pH</a> 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 <a href="/facts/Precipitation_(chemistry)/s3BgsLLY">precipitation</a> quickly becomes more <a href="/facts/Alkaline/s6NqPGSP">alkaline</a>, beryllium drops out of solution. Cosmogenic 10Be thereby accumulates at the <a href="/facts/Soil/5Ddpr3QM">soil</a> surface, where its relatively long <a href="/facts/Half-life/kGVH8BAB">half-life</a> (1.387 million years) permits a long residence time before decaying to 10<a href="/facts/Boron/Pmwgd7Mf">B</a>.
10Be and its daughter product have been used to examine <a href="/facts/Soil_erosion/pbwuyY5H">soil erosion</a>, <a href="/facts/Soil_formation/sJty93z9">soil formation</a> from <a href="/facts/Regolith/EdXuHK56">regolith</a>, the development of <a href="/facts/Laterite/3FYFwspo">lateritic soils</a> and the age of <a href="/facts/Ice_core/QnzraAoN">ice cores</a>. It is also formed in nuclear explosions by a reaction of <a href="/facts/Fast_neutron/UMKR4XgJ">fast neutrons</a> with <a href="/facts/Carbon-13/Iho4LUtW">13C</a> 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 <a href="/facts/Proxy_data/kuCVBpBL">proxy data</a> measure for <a href="/facts/Cosmogenic_nuclide/TlJwc4wV">cosmogenic nuclides</a> 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 <a href="/facts/Sunspot/7E8cWSGl">sunspots</a> and low <a href="/facts/Solar_wind/BvuB3dT8">solar wind</a>), the barrier against cosmic rays that exists beyond the <a href="/facts/Termination_shock/Yc9ToWbA">termination shock</a> is weakened (see <a href="/facts/Cosmic_ray/uxCVdTKd">Cosmic ray#Cosmic-ray flux</a>). This means more beryllium-10 is produced, and it can be detected millennia later. Beryllium-10 can thus serve as a marker of <a href="/facts/Miyake_event/bNIGokkD">Miyake events</a>, such as the <a href="/facts/774%25E2%2580%2593775_carbon-14_spike/atFfzBA2">774–775 carbon-14 spike</a>. There can be an effect on climate (see <a href="/facts/Homeric_Minimum/WPldz13x">Homeric Minimum</a>).

Beryllium-10 open-in-new

Beryllium-10