Application of Microbiological Methods to Assess the Potential Impact of Produced Water Discharges

Microbial production and activity in produced water directly recovered from the discharge stream of offshore oil and gas production facilities off the east coast of Canada were examined before and after aeration in a series of concentrations to determine the effect of dilution at sea. Aeration and dilution resulted in reduced toxicity due to volatilization and oxidation of the lighter hydrocarbons including polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, benzene, toluene, ethylbenzene, xylene, and short-chain alkanes (C10–C14). A fraction of the detrimental effects on microbial productivity and activity could also be attributed to the elevated salinity associated with produced water. These results suggest that caution should be used in the manipulation of produced water samples used for toxicity/risk assessment studies.