Environmental Safety and Management of Heavy Metals along Machakos Road, Nairobi County, Kenya

Environmental pollution falls within the sustainable development goals agenda, climate action, and the purview of the laws of Kenya. Environmental protection is paramount in the sustainable use of natural resources for the sake of future generations. Heavy metals occurring naturally or anthropogenically severely affect humans and the environment when they exceed their concentration standards. This research aimed to assess the heavy metal elements present and examine physio-chemical properties of the soil. The study utilized experimental encompassing a assessment of selected heavy metals in the study area. Soil and ground water samples were collected to determine the heavy metal concentrations using the X-ray fluorescence (XRF) analytical method. The data was collected from seven sample sites with 56 samples collected. Soil and water quality parameters exhibited notable spatial variation, with the Industrial Area showing the highest electrical conductivity at 987.45 µS/cm (soil) and 1428.44 µS/cm (water). The Construction site recorded the most acidic soil at pH 4.48, while Residential and Off-Road Runoff areas showed the highest soil moisture at 12.61% and 31.95%, respectively. Elevated levels of heavy metals such as Fe (up to 3.75 ± 0.54 mg/L), Zn (5.32 ± 0.45 mg/L), and Pb (0.20 ± 0.02 mg/L) were recorded, exceeding WHO permissible limits in industrial, dumpsite, and runoff sites. Soil pH ranged from 4.48 (construction) to 7.3 (control), with high electrical conductivity observed in the industrial area (987.45 µS/cm), indicating enhanced metal solubility and mobility. Concentrations of Mn, Fe, Zn, Se, and Cd were found to be significantly above WHO permissible limits at P ≤ 0.05. The research is a positive contribution to science since it aids in quantitatively identifying toxic substances and heavy metal pollution within the area of interest.