Land-Based Activities as Pollution Sources on Fresh Water Resources: A Case Study of Selected Heavy Metal Contamination in River Mukurumudzi, Kwale County

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Kenya Aquatica Journal
Pollution of water-body ecosystems by heavy metals through uncontrolled anthropogenic activitieslead to serious ecological problems in many parts of the world. These metals continue to accumulateto high toxic levels as they are discharged into water-bodies from agricultural activities, industrialand domestic wastes, and mining operations. This study focused on assessing the concentration ofselected heavy metals (Fe, Pb, Cu, Cd and As) in the waters and sediments of River Mukurumudzi inKwale County, Kenya. Four sampling points along the course of the river were purposely chosen owingto their proximity to identified land based pollution sources, these were titanium mining sites, largescale sugarcane plantations, human settlements and a control site. Samples were collected in threedifferent seasons (long rain, short rain, and dry season). The heavy metals were analyzed using AtomicAbsorption Spectrophotometer (AAS). The results showed that the level of Fe and Cu in water was thehighest during the rainy season while all the other metals were found to be below detectable limits.In sediments, Fe (0.64 mg/L, 1.97 mg/L, 0.33 mg/L and 0.21 mg/L), Cu (0.1 mg/L, 0.14 mg/L, 0.14 mg/Land 0.1 mg/L), and Pb (0.14 mg/L, 0.21 mg/L, 0.12 mg/L and 0.33 mg/L) were detected at Shimba Hills,Nguluku, Bomani and Gazi consecutively. The concentrations of metals in water were found to bewithin the NEMA and WHO safe limits. Though River Mukurumudzi is not contaminated with the selectedheavy metals it is established that the anthropogenic activities along the river are contributing someof the heavy metals. As such, this study recommends that conservation measures be put in place toavoid contamination of the river.