Resources and Environment 2013, 3(3): 59-64 DOI: 10.5923/j.re.20130303.03
Levels of Bioaccumulation of Some Heavy Metals in Fish (Tilapia zilli) and Their Concentration in Water and Sediment of Owubu Creek, Niger Delta, Nigeria Upadhi Friday* , Wokoma O. A. F, Edoghotu Jonah Azibodi Department of Biology, Faculty of Pure and Applied Sciences, Ignatius Ajuru University of Education, Rumuolumin, P.M .B 5047, Port Harcourt, Rivers State, Nigeria
Abstract Bioaccumu lation of some heavy metals were determined in water, sediment and fish samples fro m owubu
creek using atomic absorption spectrometer. The result indicated that the order of b ioaccumulat ion of heavy metals in water were 2.85, 0.35, 0.03 and 0.02 for Cu>Pb>Fe>Mg, with Cu having the highest bioaccumulation. In sediment the order of bioaccumulat ion was Fe>Cu>Pb >Cd with their values of 674, 8.31, 6.22 and 0.01 respectively, with Fe having the h ighest value. The order of bioaccumu lation of metals in fish tissue and digestive systems were Fe>Cu>Pb and Fe>Cu>Pb with their values of 72.17, 4.29, 0.01 and 46.12, 2,55, 0.13 respectively, there was high bioaccu mulation of heavy metal in tissue system than in digestive system. The bioaccu mulation factor in fish tissue were 26.81, 0.10, and 0.01 for Cu, Fe, and Pb, while the bioaccumulat ion factor in the d igestive system were 15.93, 0.06 and 0.02 for Cu, Fe and Pb. The b ioaccumulat ion factor in tissue was higher than in d igestive system, th is suggest that the fish samp les could be used to monitor Cu, Fe, Pb pollution levels in owubu creek.
Keywords Bioaccumulat ion, Heavy Metals, Fish, Bioconcentration, Sediment, Water
1. Introduction The accumulat ion of some heavy metals in freshwater ecosystem has been a major concern. Heavy metals generally enter the aquatic environment through natural (atmospheric deposition, erosion of geological matrix) or anthropogenic activities (caused by industrial effluents, domestic sewage, mining and agricultural waste[1]. Fish being one of the main aquatic organisms in the food chain often accumulate large amounts of certain metal above the levels in aquatic environment[2]. Heavy metals are commonly found in natural waters and some are essentials to living organisms, yet they may become highly toxic when present in high concentration[3]. The natural aquatic systems may equally be contaminated with heavy metals released fro m domestic, industrial and other man- made sources[4,5]. As these metals equally gain access into the ecosystem through anthropogenic source yet distributed in the water body, suspended solids and sediments during the course of their mob ility [6]. The rate o f b ioaccu mu lat ion of heavy metals in aquatic organisms depend on the organisms ability * Corresponding author:
[email protected] (Upadhi Friday) Published online at http://journal.sapub.org/re Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved
to digest the metals and concentration of the metals in water[7], the concentration of the heavy metals in the surrounding sediment, as well as feeding habit of the organism. Aquatic animals (including fish) bioaccu mulate trace metals in considerable amounts exposed. Fishes have been recognized as good accumulator of organic and inorganic pollutants[8]. Since heavy metals cannot be degraded, they are deposited, in water, assimilate therefo re are available for fish to incorporate[9]. Fish, part icularly of the Tilapia family is the most abundant, cheep and accessible source of protein in the study area, as such its contamination can easily affect hu mans which is the ultimate consumers. The study is therefore designed to determine the levels of bio accumulat ion of heavy metals (Cu, Fe, Pb, Hg, and Cd in tissue and digestive system of Tillapia Zilli and its concentration in water and sediment of Owubu Creek in Niger Delta, Nigeria so as to protect human life.
2. Materials and Methods 2.1. Sampling Site Owubu creek system is a fresh water body, located in a swamp in Ukpeliede Co mmunity in Ahoada West Local Govern ment Area o f Rivers State, Niger, Delta Nigeria. The creek lies between the latitude 60 30I to 50 70I E and
Upadhi Friday et al.: Levels of Bioaccumulation of Some Heavy M etals in Fish (Tilapia zilli) and Their Concentration in Water and Sediment of Owubu Creek, Niger Delta, Nigeria
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longitude 50 to 52I N, the creek is lin ked to Orashie River. Owubu creek received effluents such as agricultural run-off, fro m farm lands, adjourning and oil spill fro m Nigeria Agip Oil Co mpany oil wells and flow stations located within the bank of the creek. Owubu Creek is very important to the local dwellers because of its economic value, as it is used for recreational act ivities and fishing which is the major occupation of the native. 2.2. Sample Collection A total of 12 samp les were co llected in three stations monthly fro m the creek system during the sampling period (between March and July 2012). The samples collected are surface water, sediment and fish. Water samp les were treated with nitric acid while fish samples were preserved in cold box before transferring to the laboratory for further analysis. 2.3. Procedure Water samples were digested according to the methods described in[10], wh ile sediments were d igested after drying according to[11] method. Different fish organs were digested after drying according to prescribed methods in[12]. The levels of Cb, Fe, Hg, Pb and Cu in fish were determined by Shimad zu atomic absorption spectrophotometer using different cathode lamps with air acetylene flame method. Before acid d igestion, fish samp les were dissected and different organs(tissue and digestive systems) separately and frozen according[13]. The cathode lamps had wave length ranged fro m 190 to 900[13]. 2.4. Bio-Accumul ati on Factor (BAF) Bio-Accumu lation Factor (BAF) is exp ressed as the ratio of the contaminant in an organism to the concentration in the
amb ient environ ment at a steady state, where the organism can take in the contaminant through ingestion with its food as well as through content[14, 15].
3. Results The data were analy zed separately for each station using descriptive statistics (mean, range and standard deviation). 3.1. Water Samples The mean concentration of heavy metal in water samples were 2.85± 0.40, 0.35±0.14, 0.03±0.21 and 0.02±0.02 ppb respectively (Table 1and Figure 1). Average mean concentration of Cu was the h ighest and that of Mg was the lowest in water. Cd was not detected in water sample. The order of heavy metal accu mu lation in water sample was Cu>Pb>Fe>Mg>Cd. Table 1. Mean heavy metals (ppb) in water of Owubu creek compared to international permissible limits Parameter Mean St.Dv
Cadmium 0.00 0.01
Iron 0.03 0.21
Mercury 0.02 0.02
Lead 0.35 0.14
Copper 2.85 0.40
WHO(1985)
0.005
1.00
0.05
0.05
1.5
3.2. Sedi ment Samples Mean concentrations in sediment samp le were 674±12.31, 8.31±0.31, 6.22±0.16, and 0.01±0.01 ppb respectively (Table 2 and Figure 2). Fe has the highest Value in sediment, while Cd have the lowest value in the sediment sample, Mg was not detected in sediment. The order of heavy metal concentrations in sediment was Fe>Cu>Pb >Cd.
3 2.5 2 1.5 1 0.5 0 CU
Pb
Fe
Figure 1. Mean heavy metal concentration in water of owubu creek
Mg
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700 600 500 400 300 200 100 0 Fe
Cu
Pb
Cd
Figure 2. Mean heavy metal concentration in sediment of owubu creek Table 2. Mean heavy metals (ppb) concentrations in sediment of Owubu creek Parameter Mean St. Dv
Cadmium 0.01 0.01
Iron 674 12.31
Mercury 0.00 0.00
Lead 6.22 0.16
Copper 8.31 0.31
3.3. Fish Samples
80 70 60 50 Tissue system
40 30 20 10 0 Fe
Cu
Pb
Figure 3. Mean heavy metal concentration in fish of owubu creek
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Upadhi Friday et al.: Levels of Bioaccumulation of Some Heavy M etals in Fish (Tilapia zilli) and Their Concentration in Water and Sediment of Owubu Creek, Niger Delta, Nigeria Table 3. Mean heavy metals (ppb) concentrations in different tissues of Tilapia zilli Parameter Tissues System Mean
Cadmium
Iron
Mercury
Lead
Copper
0.00
72.17
0.00
0.12
4.29
St. Dv
0.00
10.69
0.00
0.13
1.22
Mean
0.00
46.12
0.00
0.13
2.55
St.Dv
0.00
4.42
0.00
0.11
1.38
Digestive System
Table 4. Bioaccumulation Factor of heavy metals in fish of owubu creek Heavy metals Cadmium Iron Mercury Lead Copper
Sediment 0.01 674 ND 6.22 0.16
Tissue System ND 72.17 ND 0.12 4.29
BAF 0.10 0.01 26.81
The mean concentration of heavy metals in tissue and digestive systems of fish are represented in Table 3 and Figure 3. The mean concentration of Fe in tissue and digestive systems were 72.17±10.69 and 46.12±4.42 ppb respectively. The result however revealed that tissue system accumulated the highest concentration while the d igestive system accumulated the lowest concentration. Mean concentrations of Cu in both systems were 4.29±1.22 and 2.55±1.38 ppb, this shows that Cu concentration was highest in tissue than in the digestive system. Mean concentration of Pb was 0.12±0.13 and 0.13±0.11 ppb respectively, this result indicate that Pb accu mulated highest in the digestive system and lowest in the tissue system. Cd and Mg were not detected in tissue and digestive systems. The data revealed that tissue accumulated the highest concentration of heavy metals in this study than the digestive system. The order of heavy metal concentrations in tissue was Fe> Cu>Pb, while the order o f heavy metal concentration in digestive system was Fe>Cu >Pb. 3.4. Accumulation Factor (B AF) The bioaccumulation factor in tissue and digestive systems of the fish samp le is shown in Tab le 4. The result showed that Cu, Fe and Pb have bioaccumu lation factor of 26.81, 0.10 and 0.01 ppb respectively in t issue, where as the bioaccumulat ion factor in Cu, Fe and Pb for the digestive system were 15.93, 0.06 and 0.02 ppb respectively. This result however indicates that bioaccumulation factor was highest in the tissue system than in the digestive system.
4. Discussion Occurrence of metal contaminants especially the heavy metals in excess of natural loads has become a prob lem of increasing concern. The situation has arisen as a result of the rapid population growth, increase urbanization and expansion of industrial activit ies, explorat ion and exploitation o f natural resources, extension of irrigation and
Sediment 0.01 674 ND 6.22 0.16
Digestive System ND 46.12 ND 0.13 2.55
BAF 0.06 0.02 15.93
other agricultural practices as well as lack of environ mental regulations[3, 13]. The levels of heavy metals recorded in water in this study were generally low when compared with the limit of ch ronic values suggested[16]. The accumu lation of heavy metals in water recorded in this study is lower than values previously obtained[13]. Lo w concentration in water corroborated with this report[17]. Low concentration of pollutants in study was due to adsorption of pollutant compounds by particulate matter, and sediment particles fro m the water colu mn. Thus, the creek sediment contains very significant amounts of heavy metals when compared with their concentration in water. Sediments therefore act as the most important reservoir or sink for metals and other pollutants in the aquatic environment[18]. The concentration of Fe and Pb obtained in this study is however higher when co mpared with concentrations in non oil exploration locations of Sombrero River (I9). Concentrations of Cu, Mg and Cd are lo wer than values obtained in Wadi Hanifah, Saudi Arabia[13]. Heavy metal contamination in sediment can affect water quality and bioaccumulat ion of metals in aquatic organisms. This may resulte in potential long term implication on human health and ecosystems[20]. The results of the present study showed that tissue accumulate highest concentrations of Fe and Cu than Pb. The values of Fe and Cu obtained fro m tissues in this study are higher above the values obtained in freshwater fro m Ko llidam River, Tan ilnadu, India[2]. Concentrations of heavy metals in digestive system is lower than values obtained in tissue, however the concentrations of Cu and Pb is higher in digestive system than in t issue. Difference in bioaccumulat ion level in different organs can primarily be attributed to differences in physiological ro le in organ, other factors such as regulatory ability, behavior and feeding habit may equally play significant role in bioaccumu lation differences in the organs[9, 14]. The chemical nature of metal ionic strength and PH tends to be a master variable in accumulat ion process. Low accu mulat ion and concentration in the digestive system recorded in this study does not conform to the findings of[7].
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Central Nigeria. Pak. J. Anal. Environ. Chem. 2011 Vol. 12, No. 1&2, 25-31.
Bioaccumulat ion factor in tissue were 26.81, 0.10 and 0.01 for Cu, Fe and Pb respectively. Bioaccu mulat ion factor of Fe in T. zilli of this study is relat ively h igher to that of T. fuscastu and C. gasa of So mbreiro River[21]. Bioaccumulat ion factor in digestive system were 15.93, 0.06 and 0.02 for Cu, Fe and Pb respectively and is lower than BAF obtained in digestive system of fish obtained in River Benue[7]. Th is observation also reveals the status of heavy metal bioaccu mulat ion of heavy metals in t issue and digestive systems of fish of Owubu creek. The h igh level of bioaccumulat ion factor of Cu and Fe shows that they are good bio- indicator to monitor heavy metal pollution in the creek. However, it is quite ev ident in this study that there is heavy metal b ioaccumulated in water, sediment and fish of Owubu creek.
[11] L. Kouadia, J.H.Trefry, Saline trace metal contamination in the Ivory Coast West Africa. Air, Water Soil Pollut. 32: 145-154. 1987.
5. Conclusions
[12] AOAC, Official M ethods of Analysis of AOAC international. 16th ed., Vol. (Cunnif, P.Ed.), AOAC Int. Arlington, Virginia, USA. 1995.
The result of this study give valuable informat ion on the bioaccumulat ion of heavy metals in the various matrixes considered in this study, bioaccumulation of heavy metal was highest in sediment samples when co mpared with water samples. The studies also revealed that fish tissue have the tendency of accu mulating iron, copper and min imu m of lead. While digestive system has tendency to accumulate maximu m of lead and a minimu m accu mu lation of iron and copper. Copper, iron and lead has bioaccumulation factors in tissue and digestive systems. This is an indication that fish in owubu creek has the ability to accumu late the metals of this study. However the concentration of heavy metal in water samples recorded in this study is below maximu m levels of reco mmended by regulatory agencies(WHO) .
[8]
R.P, King and G. E and Jonathan, Aquatic Environmental Perturbations and monitoring, African experience, USA. 2003.
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P. M , Linnik and I .B, Zubenko, Role of bottom sediments in the secondary pollution of aquatic environments by heavy metals compounds. Lakes and Reservoirs Res. M anage. 5(1): 11-21. 2000
[10] APHA, Standard M ethods for the Examination of Water and Waste Water. American Public Health Association, 18th ed., Academic Press. Washinton D.C.1992. pp. 214-218.
[13] A.S. Abdel-Baki, M . A, Dkhil, and S. Al-Quraishy, Bioaccumulation of some heavy metals in tilapia fish relevant to their concentration in water and sediment of Wadi Hanifer, Saudi Arabia. African Journaln of Biotechnology. 2011, Vol. 10(13). pp.2541-2547. [14] (USEPA), U.S. Environmental Protection A gency, M ethods for M easuring the Toxicity and Bioaccumulation of sediment Associated Contaminants with Freshwater Invertebrates. 2nd Edn., EPA boo/R-9910064, Office of Research and Development Washington, DC. 2000b. [15] F.Upadhi and O. A. F. Wokoma, Examination of Some Pesticides Residues in Surface Water, Sediment and Fish Tissue of Elechi Creek, Niger Delta, Nigeria. Research Journal of Environmental and Earth Sciencse 4(11): 939-944.2012. [16] WHO, Guidelines for Drinking Water Quality(Recommenda tions). WHO. Geneva.1985.
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