Chemical and isotopic composition and potential for contamination of water in the upper Floridan Aquifer, west-central Florida, 1986-89

Major ions, unstable field constitutents, and the environmental isotopes tritium, deuterium, and oxygen-18 were measured in water from 112 wells that are open to the uppermost producing zones of the upper Floridan Aquifer. Tritium analyses indicate that the unconfined aquifer in northern areas contains relatively young water that has entered the aquifer since 1953, whereas the confined aquifer in southern areas contains older water. The potential for contamination of the upper Floridan Aquifer generally is greatest in those areas where the aquifer is unconfined and recharge has been shown to be high.