Two creeks (Azuabie and Obufe) in the upper Bonny Estuary, Nigeria were studied to determine how industrial and other anthropogenic activities have influenced their relative sediment qualities. Total organic carbon, total hydrocarbons, zinc, lead, cadmium and iron were significantly higher in the Azuabie creek, while phosphate, nitrate, copper and chromium did not show significant differences between the two creeks. Principal component analysis (PCA) ordinations discriminated all locations in the Obufe creek into a cluster along with the less-contaminated sites in the Azuabie creek. The other two sites in the Azuabie creek clustered separately, showing that they were contamination hot-spots.
The effects of copper, cadmium and lead on the bioaccumulation of zinc were studied in populations of the gastropod mollusc Littorina saxatilis from sites in the Isle of Man subjected to varying degrees of mine-related metal contamination. Exposures to 2 mg/L Zn alone and in combinations with 0.01 mg/L, 0.1 mg/L and 1 mg/L of the respective metals were conducted at ∼10 • C in semi-static assays. Copper had a significant antagonistic effect on Zn accumulation at 1 mg/L Cu, but was not antagonistic at 0.01 and 0.1 mg/L Cu. Prior exposure to metals in the field did not appear to affect the interactive effect of copper as all populations showed similar patterns. Combinations of Zn with Cd or Pb at the above concentrations did not show any significant effects on Zn accumulation. On the other hand, Zn had an antagonistic effect on Cd and Pb accumulation but showed inconsistent effects on Cu accumulation. Interactions of Cu and Zn in particular may have repercussions for interpretation of biomonitoring data in L. saxatilis.
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