Metal pollution in sediments and bivalves in Marovo Lagoon, Solomon Islands

Heavy metal concentrations were determined in sediment and bivalve samples from Marovo Lagoon in the Solomon Islands. In the sediments, heavy metal levels ranged from 10 ± 3–47 ± 2 μg/g Cd, 25 ± 4–351 ± 5 μg/g Cr, 145 ± 3–418 ± 7 μg/g Cu and 20 ± 3–371 ± 5 μg/g Pb. When compared to the baseline values measured in a 1991 study of the same lagoon, a simple relative ratio in the range of 2–43 was noted for all metals in sediments as compared to baseline and confirms significant anthropogenic influence. The heavy metal contamination of bivalves showed level ranges of 2.00 ± 0.01–10 ± 1 μg/g Cd, 9 ± 3–42 ± 2 μg/g Cr, 47 ± 3–76 ± 3 μg/g Cu and 24 ± 11–86 ± 14 μg/g Pb. The higher levels of metals in the Marovo Lagoon sediments when compared to other Pacific studies are attributed to intense logging activities around the bay and other potential anthropogenic sources such as mining and discharge of waste into the lagoon.