SPATIO-TEMPORAL DISTRIBUTION OF HEAVY METALS IN OBIOKPOK NSIT RIVER, AKWA IBOM STATE, NIGERIA: INFLUENCE OF DREDGING ACTIVITIES AND ECOLOGICAL IMPLICATIONS

Abstract

The study investigated the spatial and temporal distribution of iron (Fe), copper (Cu), and zinc (Zn) in Obiokpok Nsit River, Akwa Ibom State, Nigeria, with emphasis on the influence of dredging activities and the associated ecological implications. Water samples were collected monthly from three sampling stations representing varying levels of anthropogenic disturbance between September 2023 and January 2024. Heavy metal concentrations were determined using standard analytical procedures recommended by the American Public Health Association (APHA), while contamination status was evaluated using World Health Organization (WHO) standards. The results revealed elevated concentrations of the investigated heavy metals across all sampling stations throughout the study period. Mean iron concentrations ranged from 1.10 – 4.11 mg/, copper ranged from 0.87 – 3.42 mg/L, while zinc ranged from 3.71 – 6.32 mg/L Spatial variations were significant (P<0.05) for all the heavy metals measured, whereas, temporal analysis demonstrated moderate monthly fluctuations. The study demonstrates that dredging related disturbances contribute to heavy metal mobilization and persistence within Obiokpok Nsit River. Continuous environmental monitoring, stricter regulation of dredging activities, and implementation of sustainable management strategies are therefore necessary to reduce further contamination and protect the ecological integrity of the river system.