Mobility and hydrodynamics of Selected heavy metals and coliforms on a cross-section of Nairobi river

Abstract

The current study was aimed at investigating the mobility and hydrodynamics of selected heavy metals and coliforms on a section of Nairobi River, from Waiyaki way-Riverside junction to Kamukunji grounds. It also explored the interaction of one of the heavy metals, Pb2 +, with Escherichia coli. The mobility of the heavy metals and coliforms in water was determined by collecting samples of water at point I (reference point) then sampling again the same water 100m downstream at each of the three sampling points (Waiyaki way-Riverside junction, Ngara area and Kamukunji grounds) during wet and dry seasons. Metal content in samples was determined using Atomic Absorption Spectrophotometer. The hydrodynamics of the river were determined by determining the surface speed of the river at different sampling points using floats and a tracer (milk). Other parameters that described the quality of the river water, namely, pH, DO, TDS, TSS, conductivity and turbidity were also measured. The E.coli count was determined by the multiple tube fermentation technique. The mobility of the heavy metals from the soil to the river was determined by collecting soil samples from 4m, 2m and 1m away from the river, determining the metal content and then comparing the value obtained to metal content in sediments on river bank and river bed. The coordinates for each sampling point were obtained using a GPS...............