General Water Terms Aquifer: a water saturated zone of sand gravel or rock Aquitard: an impermeable or confining layer of clay or rock Artesian well: a well drilled down into a deep aquifer that is under pressure, bringing the level of the well water higher than the surrounding water table, perhaps even causing it to "pump" itself Confined aquifer: an aquifer sandwiched between aquitards Leaching: downward transport through the ground of dissolved or suspended minerals, fertilizers and other substances by water Overdraft: removing water from an aquifer faster than it can be recharged Porosity: water holding capacity in the spaces in a substance or substrate (such as sand, gravel, or clay) Permeability: the ease of water movement through a substrate (this depends on the pore sizes and shapres of openings) Recharge: the natural or human induced percolation of water into an aquifer for replenishment Unconfined aquifer: an aquifer that has no upper confining layer Water table: the upper surface of the zone of saturation in the ground Watershed: region where water that runs off ridges, mountains, or highlands flows to a common outlet or drainage Zone of saturation: area where all available spaces within rocks and the soil are filled with water Hydrological (Water) Cycle Terms Evaporation- water changing from liquid to vapor and going up into the atmosphere Transpiration- water evaporating from plants Condensation- water vapor molecules coming together to form a liquid Precipitation- rain, snow, etc. Runoff- water flowing down a hill, mountain, or field into a lake, stream, or other body of water Infiltration- the absorption of water into the ground Percolation- water working its way deeper into the ground to an aquifer Age-Dating Terms Isotopes: Two or more atoms having the same number of protons (the same element), but having different numbers of neutrons and hence a different mass. Naturally occurring chemical elements are usually mixtures of isotopes. Radioactive isotopes: Atoms that disintegrate by the emission of particles or electromagnetic radiation (photons). In the process, the nucleus of the atom is transformed with a change in the number of neutrons and protons. Beta decay: A specific type of radioactive decay where and electron is ejected and a neutron is transformed into a proton. Tritium: An isotope of hydrogen with one proton and two neutrons. Tritium is radioactive with a half-life of 12.4 years. Tritium decays by beta decay and becomes a stable atom of helium, specifically, 3He that has 2 protons and one neutron. Most helium in nature is 4He (2 protons and two neutrons). Half-life: The time it takes for one half of the atoms present in a sample to decay to something else. After one half-life, one half of the atoms of the original type are left. Mass spectrometer: This is an instrument that can separate and measure individual isotopes. The mass spectrometer discussed in this talk consists of an ion source, a magnet and an ion detector. The ions are formed and accelerated in the ion source. The magnet bends the path of the ion beam depending on the mass of the ion. The detector measures when ions of a particular mass arrive. Examples of Common Infectious Agents Found in Water (Just when you thought it was safe to go back in the water!) Protozoa Giardia Cryptosporidium Helminths Ascaris (roundworm) Trichuris (whipworm) Taenia (tapeworm) Bacteria Shigella Salmonella Cholera E. coli Legionella Campylobacter Viruses Enteroviruses Polioviruses Coxsackie Norwalk Hepatitis A Rotaviruses