A Absorption Ðthe process by which chemicals in gaseous,

liquid or solid phases are incorporated into and included within another gas, liquid, or solid chemical. For example, a sponge absorbs water. Acid mine drainage Ðwater draining from areas that have been mined for coal or other mineral ores. The drainage water is acidic, sometimes having a pH less than 2.0, because of its contact with sulfur-bearing material. Acid rain Ð precipitation that has a low pH (here, low pH is defined as anything less than 5.6). The precipitation becomes acidic when moisture in the air reacts with sulfur and nitrogen pollutants in the atmosphere. Acre-foot Ð the volume of water required to cover an area of one acre of land with 12 inches (1 foot) of water depth. One acre-foot equals 325,851 gallons of water. Activated carbon Ð A material produced by heating coa