Available online a t www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2015, 6(6):36-46 ISSN: 0976-8610 CODEN (USA): AASRFC Compositional evaluation and quality status of surface waters of MBAT- ABIATI and Oberekkai Creeks of the great Kwa River, Southeastern Nigeria Bassey Edem Ephraim* and Ifedayo Olumide Ajayi Department of Geology, University of Calabar, Calabar _____________________________________________________________________________________________ ABSTRACT Water samples collected from Mbat-Abbiati and Oberekkai Creeks of the Great Kwa River were subjected to analysis for chemical characteristics, in an effort to determine the suitability of the waters for drinking, irrigation and other purposes. Investigation of the physicochemical properties show that the water displays favorable conditions of temperature, and exhibits low values of total dissolved solids (TDS), electrical conductivity (EC) and salinity, and these boosts the suitability of the surface waters for various purposes. The reduced BOD contents accounts for increased Dissolved Oxygen available for the survival of aquatic organisms in the Creeks. Additionally, the observed slight acidic character of the water appear critical as it is considerably harsh for the sustenance of fauna and flora, and favours dissolution of trace elements which are non-biodegradable and hazardous. Apart from Mg, Fe and Mn, the concentration of most of the studied chemical species in the investigated waters are below the respective permissible limits of the Standard Organization of Nigeria, World Health Organization and Food and Agriculture Organization of Nigeria. Thus, the water is suitable for drinking, irrigation and crop production since both Creeks appear free from any significant pollution or contamination threat regarding - 2 3 - 2+ 2+ + + HCO 3 , SO 4 , PO 4 , Cl , Ca , Mg , Na , K , Cu, Zn and Cr. However, despite the fact that sodium percent (Na %) and alkalinity or sodium hazard (SAR) underlines the suitability of the waters for irrigation purposes, some level of caution must be exercised with respect to Mg, Mn, and Fe contents of the Creek waters before the water can be considered for agricultural purposes. Besides, the accumulation of Mn in the waters is a cause for concern for marine life as it could lead to manganese toxicity in biota. It appears mining/rock quarrying, agricultural and other anthropogenic activities, as well as lithology are responsible for the sourcing of the various major ions, heavy metal, among other chemical character of the surface waters of Mbat-Abbiati and Oberekkai Creek. _____________________________________________________________________________________________ INTRODUCTION The Great Kwa River belongs to the Cross River System, which comprises major tributaries, notably, the Calabar River, Akpayafe River and Mbo River. These tributaries drain through the tropical rain forest belt, consisting of thick rain forest to the North, and freshwater/mangrove swamps to the south. The Great Kwa River originates from the western and northwestern highlands of Oban hills, extends into the Cameroon highlands, and empties into the southeastern corner of the Atlantic Ocean through the Cross River Estuary [1]. Major Creeks are formed as the river and its tributaries drain and sculpture their routes through the freshwater and mangrove terrain of the south. Two of such Creeks includes Mbat-Abbiati and Oberekkai Creeks. These Creeks are located in present-day Akamkpa Local Government Area of Cross River State, Nigeria. Concerns have risen about solute pollution, heavy metal contamination and the potential impact on food systems and human health associated with these Creeks [2]. This is because runoffs containing agrochemicals from agricultural fields in Mbat-Abbiati and Oberekkai Villages and environs enter the river through these Creeks. Also, Mbat-Abbiati and Oberekkai Creeks are well positioned to receive effluents from the quarrying and mining activities located within the neighbourhood. Besides, increased rate of urbanization, industrialization and other forms of modernization have continued to plague the productive capacities of coastal water bodies such as the Great Kwa River. 36 Pelagia Research Library Bassey Edem Ephraim and Ifedayo Olumide Ajayi Adv. Appl. Sci. Res., 2015, 6(6):36-46 _____________________________________________________________________________ In view of the fact that much of the populace in the catchment area of the river depends on surface waters to meet their water needs, it becomes necessary to determine the suitability of the water of the Great Kwa River and its tributaries for drinking, irrigation and other purposes. Accordingly, the waters of Mbat-Abbiati and Oberekkai Creeks are studied to determine its suitability for drinking, irrigation and for other usage. The standards for the assessments of the drinking water qualities of the waters are derived from the Nigerian Standard for Drinking Water Quality [3], the World Health Organization guideline for drinking water [4] and the Food and Agriculture Organization (FAO) water quality guidelines for agriculture, surface irrigation and drainage [5]. GEOLOGICAL BACKGROUND The study area is an integral part of the Calabar Flank, which is unique in many respects. Geologically, the Calabar Flank is that part of the Southern Nigerian Sedimentary basin that is bounded by the Oban Massif to the North, Abakaliki-Benue trough to the Northwest, Niger Delta to the South, and Cameroon Volcanic ridge to the Northeast [6, 7] (Fig. 1). In terms of lithology, the Calabar Flank is underlain by Cretaceous Sedimentary rock deposits comprising sandstones, limestones, marlstones and shales (Fig. 2). The Mfamosing Limestone Formation, which constitute the main carbonate – bearing deposit occurring within the area, is about 50m thick at outcrop (type section) and 450m thick in the subsurface on the Ituk high [8]. This limestone-bearing Formation is overlain by a thick sequence of black to grey shale unit, called Ekenkpon Formation [9]. This shale Formation is also characterized by minor intercalation of marls, calcareous mudstone and oyster beds. The Ekenkpon shales are overlain by a thick marl unit, the New Netim Marl [9]. This unit is nodular and shaly at the base and is interbedded with thin layer of shales in up-section. The New Netim Marl is unconformably overlain by carbonaceous dark grey shales, the Nkporo Formation [10]. The Nkporo shales cap the Cretaceous sequence in the Calabar flank as its sequence is overlain by pebbly sandstone unit of the Tertiary Benin Formation. MATERIALS AND METHODS Study Area The hydrographic areas of the two Creeks are located within the plains of Mbat-Abbiati and Oberekkai in present- day Akamkpa Local Government Area of Cross River State, Nigeria and are delimited by Latitude 5°05’N and 5°06’N and latitudes 8°27’E and 8°29’E, situated within present-day Akamkpa Local Government Area of Cross River State, southeastern Nigeria (Fig. 2). As riverine areas, the study locations are linked to each other and other surrounding communities by water bodies. Thus, boats and canoes are the main mode of transportation in the whole area. However, villages and farm settlements within the area are interconnected by bush paths, thereby making the areas also accessible on foot. The choice of Mbat-Abbiati and Oberekkai Creeks for the present study was informed primarily by the fact that these Creeks represent, to a large extent, the major water bodies that are useful for drinking and irrigation purposes in the region, as well as serve as important habitats for aquatic organisms. Moreover, the Creeks are located in downstream region to receive effluent from the mining and rock quarrying activities in the area. Sampling and Analysis The surface water occurring at various locations within the study Creeks were sampled for the purpose of this study. Water samples were collected from the two Creeks, and stored in well-labeled ½-litre water bottles which were previously thoroughly washed and rinsed with distilled water. Six sampling points within each Creeks were strategically selected to account for the Creek area, totaling twelve sampling points for both Creeks. All the sampling points were randomly selected within the main body of each Creek, to provide adequate coverage of the entire Creek surface. At each sampling point, water samples were taken below the surface and labelled according to each sample location. The water samples for cation (Ca 2+ , Mg 2+ , Na +, and K +) and heavy metals determinations were preserved 2- - - - immediately with an on-site acidification with HNO 3, while water samples for anion (SO 4 , Cl , HCO 3 , NO 3 , F) determinations were not acidified. Physico-chemical parameters such as temperature, pH and electrical conductivity (EC) were measured directly in the field. Temperature was determined with the aid of a Mercury – in – Glass Thermometer, while pH was measured with a digital pH meter. The accuracy of the pH measurement was given as ±0.05 pH unit. Turbidity was measured with a Spectrophotometer (Dr 3000). Conductivity was measured with a conductivity meter, which gives conductivity ( σ) values in µS cm -1. Salinity was determined with the use of salinity meter (HANNA MODEL). Total Dissolved Solids was determined mathematically by multiplying the value of conductivity by 0.6. 37 Pelagia Research Library Bassey Edem Ephraim and Ifedayo Olumide Ajayi Adv. Appl. Sci. Res., 2015, 6(6):36-46 _____________________________________________________________________________