Potential Influences of Common Well Casings on Metal Concentrations in Well Water with Low Dissolved Oxygen.

摘要

Representativeness of analyte concentrations collected from ground water monitoring wells has come into question. The focus of this issue is the selection of well encasement material, stemming from recommendation for only stainless steel and poly(tetrafluoroethylene) (PTFE). Accurate determination of the presence and concentrations of hazardous waste transported with ground water is jeopardized if the materials used in monitoring wells influence the solution chemistry. Recent studies of rigid PVC and PTFE examining the rate at which these two materials sorb organic compounds from aqueous solution, concluded that rigid PVC was superior to PTFE. The other recommended material, stainless steel is composed of iron, chromium and nickel. Metal versus polymeric casings has been questioned. Studies of ground water collected from wells encased with steel indicate that the leaching of metals from these materials is a continuous process. Laboratory experiments have shown stainless steels to have the greatest potential to leach barium, cadmium, lead, and copper or sorb arsenic, chromium and lead in comparison to PVC and PTFE. These studies attributed release or sorption of metal analytes by stainless steel and steel to be associated with corrosion.