Metal levels in sediments and benthos resulting from drilling fluid discharge into the Beaufort Sea

Abstract

From the Abstract: “This study examined the significance of increased metal concenterations in surficial sediment and benthic fauna resulting from drilling fluid disposal in the Beaufort Sea. The study area was Netserk F-40, an artificial island constructed by Esso Resources Limited from local borrow material for use as a drilling platform. Approximately 7,300 barrels of waste drilling mud products were disposed in to the sea during the period of active drilling. The concentrations of mercury, lead, zonc, cadmium, arsenic and chromiumn the waste drilling fluid were 185, 35, 15, 9, 2.4 and 0.7 ties the surficial sediment background values, respectively. This suggested that mercury was the best tracer of the drilling muds in the sediments. Elevated levels of all six metals in the sediments were found at one or more stations in the vicinity of the discharge site, especially within 45 m. Thirty-three infaunal species were identified in the vicinity of the island, benthic density and biomass were depressed in the immediate vicnity of the island. No correlation was found between metal levels in the sediment and levels in infaunal organisms. The only suggestion of possible bioaccumulation was noted for mercury and only at two stations near the discharge site. Detectably adverse effects on the benthos around Netserk F-40 related to the smothering effects of high sediment loads resulting from the dynamic construction and destruction of the island [sic].”