Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol. 3, No.12, 2013 163 Spatial Variation in Physico-Chemical Parameters of Eastern Obolo Estuary, Niger Delta, Nigeria James P. Udoh 1 * John E. Ukpatu 1 and Aniekan J. Otoh 2 1. Department of Department of Fisheries and Aquatic Environmental Management, University of Uyo, Uyo- 52001, Nigeria. 2. Department of Animal Science, Akwa Ibom State University, Obio Akpa Campus, Oruk Anam, Akwa Ibom State, Nigeria. * E-mail of the corresponding author: jjamesphilip@gmail.com Abstract Aspects of the physicochemical parameters of Eastern Obolo estuary, Eastern Obolo, were investigated for three months at five locations: Okorombokho, Iko, Amadaka, Emereoke and Obianga. Mean concentrations of some of the measured parameters at the five sampling locations showed significant statistical differences: Nickel (F = 18.48, df 2,8; P<0.001), Potassium (F = 4.47, df 2,8; P<0.05), Total dissolved solids (F = 32.26, df 4,8; P<0.001), pH (F = 21.55, df 4,9; P<0.001), Salinity (F = 73.15; df 4,8; P<0.001), Dissolved Oxygen (F = 5.06, df 2,8; P<0.05), Temperature (F = 10.96, df 2.8; P<0.01), and Conductivity (F = 71.94, df 4,8; P<0.01). Mean differences of other parameters were not statistically significant. The variability of the concentrations of the parameters during the period of study was lowest for dissolved oxygen (2.2%) and highest for hardness (68.4%). The availability of nickel in these waters indicated crude oil pollution. The mean values of nickel, potassium, total dissolved solids, sodium, copper, zinc, total hydrocarbons and biochemical oxygen demand from all stations exceeded the recommended limits for aquatic life or potable water. Hence, the Eastern Obolo estuary may not be an efficient source of drinking water for the community but it definitely helps flush out anthropogenic pollutants into the sea. Keywords: estuarine flushing, nickel, potassium, total dissolved solids, sodium, copper, zinc, total hydrocarbons 1. Introduction: The quality of aquatic bionetworks is vital for the productivity, survival and support of aquatic organisms found in them. It is an index of health and well being of the ecosystem and has direct impact on human health. Physicochemical parameters of water provide nutritional balance and ultimately govern the biotic relationships of organisms in an aquatic ecosystem; including ability to withstand pollution load. Industrialization, urbanization and modern agriculture practices directly impact the water resources quantitatively and qualitatively. Many industries are sited near these bodies of water presumably to facilitate easy discharge of effluents and other pollutants into them. A typical example, is the siting of several flow stations on the territorial waters of the Eastern Obolo with its attendant and often incessant oil spillages, gas flares which eventually leads to acid rains (Udoessien 2003) experienced in the area. Most of the studies conducted on the monitoring and assessment of river and estuarine water quality in the South-south Nigeria are within the lower and upper Cross River estuary (Lowenberg & Kunzel 1992; Ekwu & Sikoki 2006), Calabar River (Asuquo 1999), and a few in the Bonny estuary (Dubbin-Green 1990), New Calabar River (Ekeh & Sikoki 2003) and Nkoro River (Abowei 2010) in the Niger Delta region. Other studies conducted include those of Lagos Lagoon (Ayoola & Kuton 2009) and Tarkwa Bay (Edokpayi et al. 2010), in western Nigeria. Eastern Obolo estuary is a unique aquatic environment in the tropical belt with marked maritime influence due to riverine inflow, vertical mixing, coastal nutrient enrichment, oil pollution and other anthropogenic sources. It is also one of the ecologically and economically rich marine ecosystems in the Niger Delta region of Nigeria providing breeding grounds for a variety of fish and shrimp species. Numerous activities such as oil exploitation and exploration, laundry, fuel wood exploitation and capture fisheries take place along the estuary/watershed. Small concentrations of anions and cations of heavy metals are continuously present in the drinking water, which could consequently pose health risk to the communities. This study seeks to provide basic information and to enrich the scientific knowledge of the coastal ecosystem of Nigeria with particular reference Eastern Obolo estuary and other similar water bodies where little or no information is available for its effective management and sustainability; and to prevent further degradation of the area. 2. Materials and Methods This study was carried out in a stretch of the Eastern Obolo estuary, located (4 o 33’N - 4 o 50’ N; 7 o 45’E - 7 o 55’E) about 650m above sea level in the tropical mangrove forest belt east of the Niger Delta between the lower Imo