OCCURRENCE OF HEAVY AND TRANSITION METALS IN POND SEDIMENTS ON BERMUDA

Geochemical analyses were performed on sediment cores obtained from Lover’s Lake, Mill Creek, Spittal Pond, Warwick Pond and Evans Pond on Bermuda by use of ICP-OES to evaluate the anthropogenic impact on these bodies of water. Initially, focus was on the introduction of lead (Pb) to the environment by fuel combustion since the introduction of automobiles after World War II and the switch to unleaded fuels on Bermuda in 1989. However, arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), and zinc (Zn) occurred in concentrations great enough to warrant concern and were also included.

Samples were obtained from the upper portions of the cores. Maximum sample depths ranged from 0.27 m in Evans Pond, Spittal Pond and Lover’s Lake, 0.97 m in Warwick Pond and 1.6 m in Mill Creek. These depths were considered adequate as no permanent occupation occurred on Bermuda prior to colonization of Bermuda in 1609. Radiocarbon dates of 945±55 yBP at 0.38 m in Warwick Pond and 1570±50 yBP at 0.33 m depth in Lover’s Lake supported this premise.

Below 0.8 m in Mill Creek, and 0.6 m in Warwick Pond As, Cd, Cr, Cu, Pb, and Zn occurred in only trace amounts. Above these depths, concentrations for these elements in Mill Creek, Warwick Pond and Spittal Pond show a continuing rise following colonization. In Evans Pond and Lover’s Lake, however, concentrations rise following colonization and then have decreased at varying points. Lead concentrations did not conform to the initial hypothesis in the concentrations did not drop in all the cores. Additionally, Mill Creek represents an exceptional environment in that it is a drainage canal for Pembroke Marsh, which serves as a landfill for the city of Hamilton.

These preliminary data suggest that concentrations of anthropogenically produced metals are posing toxicity threats to organisms on Bermuda and need to be remediated.