Ournal of Pplied Cience and Nvironmental Anagement

The study investigated the levels of six trace metals V, Cu, Pb, Cd, Fe and Ni in surface sediment of Kalabari creeks. Surface sediments of about 0-2cm depth were collected from June 2009 to April 2010 at two months interval to cover the rainy and dry seasons. Bulk scientific atomic absorption spectrophotometry (AAS) model 200A was used to analyze the samples. The results obtained revealed that the mean levels of the metal occurred in the order Fe > Ni > Cu > Pb >V = Cd, which were 4,767.06 ± 076.5mg/kg, 20.90 ± 10.47mg/kg, 14.67 ± 12.03mg/kg, 1.63 ± 1.16mg/kg respectively. Vanadium and cadmium were below detection limit (BDL) <0.001 in all the samples. The overall mean levels of trace metal in sediment in the rainy season was in the order Fe > Ni > Cu > Pb > Cd = V, while in the dry season, the order was Fe > Cu >Ni > Pb > Cd = V. The results obtained agreed with WHO and FEPA now Federal Ministry of Environment (FMENV) set standard for sediment. © JASEM http://dx.doi.org/10.4314/jasem.v18 i2.6 Introduction: Nigeria is among the nonindustrialized country in the world. Despite this, the country is faced with pollution of its environment; water, air and land. Most of the human activities in Nigeria have resulted to the contamination of the environment. Substances such as crude oil, plastic waste, domestic waste, industrial effluent are major sources of pollutants in the environment (Ellis, 1989, Adewoye et al., 2005, Farombi et al., 2007, Ayandiran et al., 2009). Heavy metals such as lead, cadmium and mercury are not essential for man. Unlike nickel, iron, zinc, copper and vanadium which are essential. However, excess levels in human food can be poisonous. According to Forstner and Prosi (1979) the harmful effects of heavy metals as pollutants result from incomplete biological degradation. Therefore, these metals tend to accumulate in the aquatic environment. Heavy metals are non-biodegradable and once they enter the environment, bioaccumulation occurs in every phases of the environment both sediment and water, by means of metabolic and biosorption process (Hodson, 1988, Carpene et al., 1990, and Wicklund-Glynn, 1991). Stephen (2004) reported the importance of the monitoring of pollution levels of heavy metals in aquatic system, so that approximate measures of the potential hazard can be attained. This measure should give an estimation of the type of effect that could be expected after exposure of heavy metal, in developed country like USA higher levels of metals are often found in the costal sediment. Adriano (2001), reported elevated levels of heavy metals concentrating in USA soil and sediment to be an average of 7.4 ppm. Arsenic concentration was reported in sediment as having average of 33.7ppm (with a range from <0.450 to 455ppm while mercury is 5 to 100 ppb). Copper is a micronutrient for both plants and animals at low concentration; however, it may become toxic to some forms of aquatic life at elevated concentrations. Thus copper concentrations in natural environments and its biological availability, are important. Naturally occurring concentrations, of copper have been reported from 0.03 to 0.23 g/l in surface sea waters and from 0.2 to 3.0 g/l in freshwater system (Bowen, 1985). Copper concentrations in location receiving anthropogenic inputs such as mine tailing discharges can vary anywhere from natural background to 100 g/l (Lopez and Lee, 1977; Hem, 1989) and have in some cases been reported in the 200,000 g/l range in mining area. Mining, leather and leather products, fabricated metal products and electrical equipment are a few of the industries with copper-bearing discharges that contribute to anthropogenic inputs of copper to surface waters (Patterson et al, 1998). Levels of Trace Metals in surface Sediments 190 KPEE .F; EKPETE OA Another metal is nickel, it occurs in the environment only at very low levels. Nickel tetra-carbonyl Ni(CO4) 2+ is particularly known to be poisonous. Human use nickel for different applications; the most common application is the use as an ingredient of steel and metal product, it can be found in common metal products such as jewelry. An uptake of large quantities of nickel can cause allergic reactions such as skin rashes mainly from jewelry, asthma and chronic bronchitis, birth defects, respiratory failure, etc. The analysis of trace metal in sediment permits pollution detection that could escape water analysis and provides information about the critical sites of the system under consideration (Horsfall and Spiff, 2005). Based on the importance of sediment in aquatic environment, this study was conducted in Kalabari creeks in the lower reaches of New Calabar River in the Niger Delta. The area was chosen for the study because it received domestic, industrial, agricultural, and natural runoff from a heavy populated and fast growing industrial city – Port Harcourt. Most of the companies or industries located in Port Harcourt are oil and gas companies. The aim of the study is to ascertain levels of these metals – nickel, vanadium, copper, iron, lead, and cadmium in sediment, whether its present level agrees with the levels recommended by WHO and FEPA now FMENV (Federal Ministry of Environment). METERIALS AND METHODS Study area: Kalabari creek is located in the lower reaches of New Calabar River. This area consist of some settlements/communities whose main activities is fishing and cultivation of crops which are their source of livelihood. There were five sampling points; Ogbakiri, Tombia, Okporota, Buguma and Sama all along the creeks in the New Calabar River. These creeks are less than two kilometers from Port Harcourt main town, where many industries and companies are cited. The industrial, domestic and water runoff from these creeks empty into the Atlantic Ocean. The area normally witness low and high tides, during high tide, seawater are carried to these area and debris are deposited on the sediment surface. During rainy season, large volumes of water are carried from the hinter land to these creeks. Fig. 1: Map showing lower reaches of New Calabar River and sampling sites. Sampling and Analysis: The sediment samples were collected from five sampling stations from June 2009 to April 2010 to cover two seasons, dry and wet/rainy. The rainy season covers from June to October 2009 and dry season covers from December 2009 to April 2010. The samples were collected at Levels of Trace Metals in surface Sediments 191 KPEE .F; EKPETE OA two months interval. 2cm 3 of top sediment were collected from each site and rap in polythene bags and stored in a cooler packed with ice blocks. About 5g of the sediment samples were removed and dried at 105 0 C and were homogenized in a mortar. Two grams of the powdered sediment samples were further dried to constant weight and 1.0g were accurately weighed into 50ml volumetric flasks with Sartorous analytical balance model 2842. To each of the volumetric flask, 3ml of concentrated nitric acid (HNO3), 1ml perchloric acid (HClO4) 60% and 1ml sulphuric acid H2SO4 in the ratio of 3:1:were added and heated on a hot plate to near dryness. The content of each flask was diluted with 5ml of de-ionized water and were heated for 30 minutes. Then 10ml of de-ionized water was added and filtered with Whatman No. 1 filter paper and preserved pending analysis. Samples were analyzed using Buck Scientific atomic absorption spectrophotometer model 200A equipped with air-acetylene flame. RESULTS AND DISCUSSION Table 1: Seasonal trace metal levels in surface sediments of Kalabari Creeks in mg/kg Site V Ni Cu Fe Pb Cd Rainy Dry Rainy Dry Rainy Dry Rainy Dry Rainy Dry Rainy Dry 1 BDL BDL 42 ± 12.7 25.6 ± 5.15 19.3 ± 1.7 21.6 ± 5.2 559.7 ± 120.9 25983 ± 3742.2 3.06 ± 0.54 0.98 ± 0.26 BDL BDL 2 BDL BDL 32.5 ± 14.89 23.7 ± 6.25 6.48 ± 0.92 48.3 ± 10.53 515.9 ± 275.2 933.5 ± 258.0 1.9 ± 0.14 1.22 ± 0.62 BDL BDL 3 BDL BDL 7.42 ± 5.9 15.2 ± 4.3 1.43 ± 0.59 17.9 ± 16.70 8795 ± 13803 .2 18586 ± 2932.3 0.77 ± 0.13 2.49 ± 0.73 BDL BDL 4 BDL BDL 12.1 ± 4.9 35.62 ± 9.11 0.603 ± 0.37 15.4 ± 1.77 22662 ± 2849. 1 14546 ± 15468.2 0.29 ± 0.10 5.13 ± 1.7 BDL BDL 5 BDL BDL 9.82 ± 5.3 8.33 ± 11.10 0.46 ± 0.73 15.3 ± 10.4 253.1 ± 22.5 2222 ± 515 0.16 ± 0.19 0.37 ± 0.05 BDL BDL Overall Mean Std dev. BDL Nil BDL Nil 20.77