SMCL is secondary maximum contaminant level. Concentrations of arsenic and selenium in streambed sediment are variable in the study area. The source of iron in the shallow alluvial aquifers may be the minerals in the alluvial materials derived from the igneous and metamorphic bedrock or possibly from supplemental iron that is in some fertilizers. SMCL is secondary maximum contaminant level. Radon, which can cause lung cancer, is a radioactive, odorless, and chemically inert gas that occurs naturally in the air, soil, and ground water.
Radon is a decay product of radium, which in turn is a decay product of uranium.
Rocks break down mechanically and chemically to form sediments that contain various amounts of uranium, depending on the source rocks. Radon in ground water affects radon concentrations in indoor air in homes because it escapes to the indoor air as people use water. Open water-distribution systems allow ground water to aerate and radon to escape. Research suggests that ingestion of water with high radon concentrations also may pose risks, although these risks are believed to be much lower than those from inhalation of radon. Elevated radon concentrations do not appear to be related to a particular geologic formation or land use.