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The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilized remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin calx "lime", which was obtained from heating limestone.
The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. [2] The remaining minerals are called " trace elements ". The generally accepted trace elements are iron , chlorine , cobalt , copper , zinc , manganese , molybdenum , iodine , selenium , [ 5 ] and bromine ; [ 6 ] there is some evidence that ...
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium , sulfur , sodium , chlorine , and magnesium .
Chlorine, potassium, magnesium, calcium and phosphorus have important roles due to their ready ionization and utility in regulating membrane activity and osmotic potential. [2] The remaining elements found in living things are primarily metals that play a role in determining protein structure.
The calcium cycle is a transfer of calcium between dissolved and solid phases. There is a continuous supply of calcium ions into waterways from rocks, organisms, and soils. [1] [2] Calcium ions are consumed and removed from aqueous environments as they react to form insoluble structures such as calcium carbonate and calcium silicate, [1] [3] which can deposit to form sediments or the ...
A 2023 report from the Government Accountability Office found that 17 of the agencies reviewed used about 25% or less of their buildings' space. The federal government spends about $2 billion each ...
Mountain building processes result in the return of this geologic carbon to the Earth's surface. There the rocks are weathered and carbon is returned to the atmosphere by degassing and to the ocean by rivers. Other geologic carbon returns to the ocean through the hydrothermal emission of calcium ions. In a given year between 10 and 100 million ...