The inhibitory effects of Corexit 9500A, Alaska North Slope Crude oil (ANSC), and mixtures of the two on the ammonia-oxidizing bacteria, Nitrosomonas europaea, and the ammonia-oxidizing archaea, Nitrosopumilus maritimus, were investigated. Corexit 9500A was found to be minimally toxic to both microorganisms with concentrations of 2000 and 3000 ppm yielding...