Physicochemical Characteristics and Heavy Metal Levels in Water Samples from Five River Systems in Delta State, Nigeria

Abstract

Physicochemical characteristics and heavy metal levels in water samples from five river systems in central part of Delta State, Nigeria were investigated to access the quality status of the rivers. All the watersheds selected for study were well distributed and possessed similar geology, climate, soil, and vegetation characteristics. Studies on the water samples collected from the rivers showed that the physicochemical characteristics of the river varied significantly. The mean concentration of total solids within the rivers were 35.46mg/l, 31.57mg/l, 18.82mg/l and 45.53mg/l for Ase, Agbarho, Ethiope, Ekakpamre and Afiesere rivers respectively. Similarly, the mean concentration of heavy metal in the river system gave the following ranges zinc 0.93-2.96mg/l, copper 0.01-0.03mg/l, lead 0.003-0.08mg/l, cadmium 0.00-0.004mg/l, chromium 0.001-0.03mg/l, nickel 0.01-0.004mg/l, manganese 0.008-0.04mg/l, iron 0.03-0.08mg/l. A comparison of the heavy metal concentration in the respective samples and recommended international standard such as WHO 1993 showed that the rivers were not significantly contaminated and are therefore suitable for domestic and industrial purpose. From the findings, there is need to protect the quality of the water systems for recreational, industrial and domestic uses. It is hoped that the result of this study would help the Delta State government and other interest groups to maintain existing projects, plan and also to execute properly future development programs in the study area. @ JASEM Chemical enrichment in river system are derived through a combined effect of both industrial and municipal effluents and runoffs from surrounding area or through solution effects from adjacent soil. The presence of nutrients in rivers may be attributed to the process of organic mineralization of nitrates and phosphates derived principally from surface runoffs from the immediate vicinity (forests, farms and settlement) and perhaps by insitu minerialization (Ikomi 1997; Kaizer and Adaipkoh 2007; Kaizer and Osakwe 2007). Soil erosion is closely linked with high surface runoffs and rapid siltation of surface water system resulting in subsequent decline in its portability. Eroded materials may exist in river systems as dissolved solids or suspended solids but within a particular regime of flow, river systems bear with them sediments, which constitute the by-products of processes operating within the environment through which they flow. These are derived though leaching of soil profiles, surface runoffs, direct dumping of wastes (municipal and industry), soil erosion; atmospheric fallouts e.t.c. Heavy metals are toxic and can accumulate in a system without being noticed (Ihenyen 2002). This makes them a source of concern. Sources of heavy metals includes industrial activates (mining, oil exploration activities, manufacturing and agricultural practices), domestics and commercial practices that generates wastes, and natural factors. Metal content in rivers may vary between the water column and bed sediments. However, variation in concentration of parameters depends on concentration from processes operating within the catchments. For the purpose of this study, bed sediments were not considered as part of the sediment load in this study because of the complexity in assessing the actual amount of bed sediments carried along with the water column during each flow regime. This work is therefore aimed at studying the physicochemical characteristics and heavy metal content of the various river systems with a view of accessing the effects of land use on the quality of rivers. It is hoped that the research findings would help in proper assessment of the contaminant status of the various watersheds, aimed towards improving surface water quality within the inland oil producing area of Delta State. Description of Study Area: The studied watersheds are located in Delta State, Nigeria (longitudes 3 0 E-9 0 E and latitudes 4 0 30 1 N-5 0 21 1 N) and lies within the southern oil rich Niger Delta region. Five watersheds were selected for study. They include the Ethiope, Agbarho, Ekakpamre, Afiesere and Ase rivers. The watersheds were well distributed and posses similar geology, climates, soil, vegetation and drainage characteristics (Atakpo et al., 2000; Ikomi and Ojieh 1997; Ikomi and Emuh 2000). MATERIALS AND METHOD 93 waters samples were collected systematically from five watersheds within the period of 12months in three sets from January to December. The water samples were collected at an average distance of about 1km apart from each watershed. Duplicate samples were collected at each point in chemically clean 1liter containers each and labeled A and B with