|MadSci Network: Environment/Ecology|
Of the examples you gave, only asbestos fibers would be expected to be measured in microns. Microns are units for particles that can be seen with a light microscope. A micron is a thousandth of a millimeter, which is in turn a thousandth of a meter (about a yard if you live in that backward country, the United States of America). Lead and chlorine are atomic sized contaminants, far smaller even than viruses, which are in turn far smaller than bacteria. Bacteria are typically measured in microns. Here are sizes that different types of microscopes can "see". Snipped from another posting on the MadScie archives: "Light Microscopes up to about 200 nm (= .2 microns)(about the size of bacteria) TEMs to about 0.1 nm (about the diameter of an atom!) and STMs can resolve features as small as 1/100 of an atomic diameter!!!" TEM=transmission electron microscope STM=scanning tunnelling microscope Snipped from another posting: "Coxsackie B virus, which you mentioned, has a diameter of approximately 30 nanometers, or 0.03 microns. " Another snppet: "Atomic radii, in angstoms, from Nebergall, Holtzclaw, and Robinson, "General Chemistry", 6th ed, DC Heath, Lexington, MA, 1980: Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine 1.52 1.11 0.88 0.77 0.70 0.66 0.64 " (Angstroms are one ten-thousanth of a micron.) Lead and chlorine in solution are probably a bit bigger than the atoms listed above but not by much. Hope this helps David Winsemius, MD
Try the links in the MadSci Library for more information on Environment/Ecology.