Heavy Metal Levels in Nakuru Town and the Surrounding Farmland Soils

Abstract

Heavy metals input in soils has been found to present a serious agro-environmental concerns in areas of intensive industrial and agricultural activities and Nakuru town and its surrounding farmland soil is not an exception. High input of heavy metals beyond the threshold limit values is a potential health hazard to plants, and even to animals and human beings through the food chain. The source of heavy metals in soil is primarily the parent rock material, however significant increases may occur through anthropogenic activities. The main objective of this study was to investigate the presence and levels of total and extractable selected heavy metals such as cadmium, chromium, copper, nickel, lead, and zinc in soils of Nakuru town and the surrounding farmlands busing the flame atomic absorption spectrometric technique. The status of some soil chemical properties such as pH, percentage organic carbon and cation exchange capacity were also investigated using stipulated standard methods. The sampling was done randomly in triplicate from 8 sites within Nakuru town and 8 sites in the surrounding farmlands. The data obtained from the experimental analysis were subjected to both descriptive and inferential statistics. The study revealed the presence of heavy metals in Nakuru town and its surrounding farmland soils but they were in very low levels as compared to world health organization maximum permissible levels. The heavy metal concentrations levels were found to correlate(P≤ 0.05) with the chemical properties either positively or negatively. The levels of heavy metals in Nakuru town soils were observed to be generally higher compared to the levels in the surrounding farmland soils, industrial and domestic emissions being the main contributing factor. The levels of extractable metals in Nakuru town soils had an effect on the levels of extractable metals in the surrounding farmland. It can be concluded from this study that there is no risk of heavy metal toxicity in the study area but accumulation of these heavy metals over time in soil can exceed the stipulated levels hence posing a potential hazard.