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The aim of this study was to assess accumulation of heavy metals in tissues of Periwinkle (Tympanotonus fuscatus var radula (L.) obtained from Azuabie creek using Okujagu creek as control location. Fifty samples were collected from each site for three months (October-December 2015). Atomic Absorption Spectrophotometric technique was used in heavy metal analysis. Mean metal concentrations in sediments were as follows Zn: 178.08 mgkg -1 ; Cd: 0.3 mgkg -1 ; Cr: 14.27 mgkg -1 and Pb: 18.75 mgkg -1 . While those in Periwinkle tissue with biosediment accumulation factor (BAF) in parenthesis were thus Zn: 24.42 mgkg -1 (0.137); Cd: 0.02 mgkg -1 (0.067); Cr: 1.57 mgkg -1 (0.11) and Pb 0.01 mgkg -1 0.001). The result of BAF of metals indicated low values which could be related to assimilation and excretion rate of heavy metals in the organisms examined. Variations in the concentration of Zn in the gastropod tissues showed significant difference (p<0.01) between sites, likewise, Cr (p<0.001) and Cd (p<0.05). In conclusion, comparison between the two creeks showed that tissue samples from St1, St2 and St3 (Azuabie creek) had higher concentration of metals in relation to the control station (Okujagu creek) indicating potentials for accumulation, mainly due to differences in anthropogenic activities. Cr, Cd and Pb concentrations in tissue had mean values less than the recommended limits in seafood by FAO/WHO however, regular monitoring is required to observe perturbations.

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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.

Heavy metal bioconcentration in crabs from an estuarine creek in the Niger Delta was examined using atomic absorption spectrophotometry. Health risk via human exposure to metal toxicity was evaluated. Mean metal levels (µg/g) were Cr 2.32 ± 0.71, Ni 2.76 ± 0.48, Cu 12.94 ± 3.53, Pb 5.67 ± 1.03, Ag 1.83 ± 0.71 and Cd 0.73 ± 0.14 with significant difference (p < 0.001) between periods. Ni, Pb and Cd had values above FAO/WHO recommended limits. Estimated daily intake values were below the reference oral doses and the target hazard quotient was <1 for each metal examined while hazard index for all metals was also <1. The target carcinogenic risk value for Ni was 3.4 × 10. Based on the evaluations, the study concluded that consumers of crabs from the study area had minimal/moderate metal toxicity exposures of no significant health concern but recommended continuous monitoring to detect anomalies.