Term (also microelement) for chemical elements that only occur in low concentrations (traces). Extremely low concentrations are also referred to as ultra-trace elements. In geochemistry, material components and accompanying elements of rocks and minerals in concentrations below 0.1% or 1000 ppm (millionths) are referred to as trace elements. In analytical chemistry, the threshold value is 100 ppm or 100 µg/g (= 100 mg/kg) or 0.01 %. In biology, essential trace elements are chemical elements that are essential for organisms and occur in the organism in proportions of less than 50 mg/kg.
Trace elements: Picture 1 = boron, picture 2 = iron, picture 3 = copper, image 4 = manganese, 5 = molybdenum
![]()
If I were to rate websites, you would deserve the highest rating. It is rare to come across websites that provide such a large amount of data and are still so intuitive to use. Respect for the lovingly researched and informatively prepared encyclopedia. Keep it up!
Lothar Lindner
Innsbruck