Heavy Metal Bioaccumulation as Indicators of Environmental Pollution and Health Risks

Abstract

The rapid increase of Mombasa City population has resulted into a significant rise in demand for decent housing. The inadequacy of planned decent housing has forced low level income households to inhabit slums around Tudor Creek along the Indian Ocean. The expansive unplanned settlement along Mombasa Island lacks basic infrastructural facilities that culminate into raw effluent discharge into the ocean. Environmental pollution present a great risk to human health, especially industrial waste water loaded with heavy metals. An investigation of anthropogenic activities and corresponding environmental pollutants was undertaken in three sites (Mikindani, Moroto and Old Town) within Tudor Creek ecosystem. Floral and faunal populations as well as heavy metal bioaccumulation varied significantly among the three sites. Floral biodiversity was dominated by mangroves that potentially acted as buffers by immobilizing heavy metals and climatic change mitigation through carbon sequestration. The four dominant mangrove species included; Rhizophora mucronata, Sonnerata alba, Ceriops tagal and Avicennia marina, of which R. mucronata was the most diverse with an index of 0.75 and 0.57 at Mikindani and Moroto, respectively. C. tagal inhabited Mikindani site only and expressed diversity index of 0.33. Evaluation of heavy metal bioaccumulation among selected faunal muscles revealed significant concentrations thus acting as indicators of environmental pollution levels and health risks. Heavy metal concentrations detected in water, soil, crustacean, mollusk and fish muscles included Ti, V, Cr and Mn whose ranges were below 0.15 mg/L. However, the concentration of Mn, Fe, Cu, Zn, and Pb in soil and faunal muscles ranged between 0.46 - 914.0 and 1.94 - 1863.0 µg/g, respectively. The generated data suggests that anthropogenic activities and climate change effects exacerbate environmental pollution and health risks.