OBERLE, WILLIAM, LEE WARFIELD, and JEFF MANSHIP, Ecology & Environment, Inc., Albuquerque, NM

ABSTRACT: Mercury Contamination in the Oil and Gas Industry

Mercury contamination of surficial soils and building structures is a concern to the oil, natural gas, and utility industries. Spillage from mercury-filled manometers that measure pipeline pressures is a major source of mercury contamination. Because of its chemical characteristics, the mobility of mercury within the soil posed significant health and environmental impacts. Inorganic mercury strongly adsorbs onto fine soil particles and organic matter, readily volatilizes into the atmospheres, and is leachable into aqueous systems. Under acidic conditions or with microbial action, elemental mercury and mercury oxides may transform into the water-soluble organic form, methyl mercury. Soil pH and Cl concentration are key elements to speciation and chemical transformation. Adsorption is p dependent and proportional to the cation exchange capacity. Adsorption appears to be the dominant process in mercury soil retention. Methyl mercury readily bioconcentrates in fish and shellfish, posing a threat to the food chain and human health. Mercury vapors emanating from contaminated soils or building materials also can pose worker health problems. Chemical reactions of elemental, inorganic and organic mercury with different soil types limits the remedial alternatives currently available. Three general types of response actions exist for the remediation of mercury-containing sites: (1) source removal and ex-situ treatment, (2) application of in-situ corrective measures and, (3) no action. Treatment alternatives include retorting/roasting, acid leaching, extraction with complexing a ents, soil washing/ion exchange, gravitational separation, electroreclamation, and immobilization/stabilization. Of these, only retorting/roasting and acid leaching are considered the best demonstrated available technology.