Analysis of Total Petroleum Hydrocarbons in Water from Ngong and Mathare Rivers, Nairobi County, Kenya

Abstract

Unsustainable industrial development has created negative impacts to global ecosystem quality and biodiversity due to increased load of chemical and biological contaminants released into environment. Ecological sustainability of Nairobi River Basin in Kenya, hangs in the balance between socioeconomic exploitation and environmental management. Nairobi, Ngong and Mathare rivers constitute the three main tributaries of Nairobi River Basin. The basin has witnesssed increased pollution load, destruction of the wetlands and encroachment of the buffer zones due to rapid urbanisation. The objective of this study was to investigate the extent of total petroleum hydrocarbons (TPH) contamination in Mathare and Ngong rivers. We collected water from eight sampling sites constituting the upstream, midstream and downstream of the two rivers. The samples were extracted using HPLC grade dichloromathane and analysed for Total Petroleum Hydrocarbons (TPH) using a Gas Chromatography equipped with Flame Ionisation Detector. TPH in Mathare River ranged from 59.66±8.64 to 463.92±2.63 μg/L, whereas levels in Ngong’ River ranged from 11.85±0.10 to 1,219.95 μg/L. The concentration increased downstream indicating the influence of industrial and urbanistion on the pollution load. The results suggest that industries and municipal activities in the City are contributing to TPH contamination in the Nairobi River Basin tributaries and therefore they are likely to jeopardize ecological quality of the rivers ecosystems if protective measures are not taken.