Georges Bank Monitoring Program: Analysis of Trace Metals in Bottom Sediments during the Third Year of Monitoring

摘要

Of the 12 elements analyzed in bulk sediments collected adjacent to drilling rigs on Georges Bank, only barium was found to increase in concentration during the period when eight exploratory wells were drilled (July 1981 until September 1982). The maximum postdrilling concentration of barium in sediments near a drill site reached 172 ppm. The concentration is not considered hazardous to benthic infauna. No drilling-related changes in the concentrations of the 11 other metals have been observed in bulk sediments at any of the locations sampled in the program. The barite discharged during drilling was found widely distributed around the bank associated with the fine fraction of sediment. For contaminants that are dangerous at any concentration, the same energetic processes of dispersion will endanger a wide area of the bank.