Naturally Occurring Radioactive Materials Associated with Offshore Produced Water Discharges in the Gulf Of Mexico

Abstract

During production of oil and gas, fossil water is generally pumped from the reservoir in the formation, and following treatment, this produced water is commonly discharged from platforms located on the outer continental shelf in the Gulf of Mexico. Gulf of Mexico produced waters characteristically have elevated salinities compared to the receiving ambient water and often contain elevated concentrations of inorganic and organic constituents. Among the constituents of some Gulf of Mexico produced waters are naturally occurring radioactive materials (NORM), which is potentially bioaccumulated by marine organisms living around produced water outfalls. Meinhold and Hamilton (1992) identified biological uptake of radium by marine organisms as a potential human health concern because people ingesting radium in food may have increased cancer risk. Concern is therefore growing over the potential bioaccumulation and bioavailability of NORM in indigenous finflsh and shellfish species available for human consumption. Because of this concern, the U.S. Environmental Protection Agency is considering additional regulations based on the potential adverse impacts of platform-associated produced water discharges containing NORM on indigenous fauna inhabiting the Gulf of Mexico outer continental shelf. In response to these potential new regulations, the U.S. Department of Energy has founded a project to assess the environmental and human health risks associated with produced water discharges from offshore and coastal oil and gas operations in the Gulf of Mexico region (Smith, 1995). Relatively little information is available about the fate of radioisotopes in produced water discharges from offshore platforms, and reliable data on bioaccumulation of radium isotopes by marine animals are sparse.