WA6 Alaska North-Slope Environmental Monitoring
Room 18A/B, Level 4
8:00 AM - 12:00 PM, Wednesday, 12 November 2003
Chair: Boehm, Paul ,
(376) Trace metals in sediments near oil development sites in the coastal Beaufort Sea.
Trocine, R1, Trefry, J1, Rember, R1, 1 Florida Institute of Technology, Melbourne, FL, USA
ABSTRACT- Increased offshore development in the Alaskan Arctic has stimulated interest in assessing potential perturbations in the natural system before the onset of any adverse environmental effects. Concentrations of trace metals in sediments provide one sensitive indicator of anthropogenic inputs from offshore activity. Sediments in coastal waters of the western Beaufort Sea are naturally patchy with respect to sediment granulometry, organic carbon content and concentrations of trace metals. Results for surface sediments and age-dated cores show that nearly all samples contain natural levels of Ag, Ba, Be, Co, Cr, Cu, Hg, Ni, Pb, Sb, Tl, V and Zn, with metal/Al ratios that have been constant for many decades. Metal concentrations for incoming river suspended particles compare well with sediment metal values and, along with vertical distributions in sediments, show no discernible diagenetic impacts that distort the sedimentary record for metals, except for Mn and As. Concentrations of Ba, Hg, Ag, Sb and Zn are slightly elevated in a total of eight instances or in only 0.7% of the 1222 data points for metals in surface sediments. These results and the approach used to identify metal contamination provide a framework for continued efforts to assess any cumulative impacts of offshore development in the coastal Beaufort Sea. However, the sediments in this region are dynamic and care must be taken to collect samples that are representative of the most recent inputs.
Key words: trace metals, sediment, Beaufort Sea, Alaska