This art icle was downloaded by: [ S. Mahboob] On: 11 Oct ober 2014, At : 21: 51 Publisher: Taylor & Francis I nform a Lt d Regist ered in England and Wales Regist ered Num ber: 1072954 Regist ered office: Mort im er House, 37- 41 Mort im er St reet , London W1T 3JH, UK Toxicological & Environmental Chemistry Publicat ion det ails, including inst ruct ions for aut hors and subscript ion informat ion: ht t p:/ / www.t andfonline.com/ loi/ gt ec20 A study on the accumulation of nine heavy metals in some important fish species from a natural reservoir in Riyadh, Saudi Arabia a a a Shahid Mahboob , H.F. Alkkahem Al-Balwai , F. Al-Misned , K.A. a Al-Ghanim & Z. Ahmad a a Depart ment of Zoology, College of Science, King Saud Universit y, Riyadh, Saudi Arabia Published online: 24 Sep 2014. To cite this article: Shahid Mahboob, H.F. Alkkahem Al-Balwai, F. Al-Misned, K.A. Al-Ghanim & Z. Ahmad (2014): A st udy on t he accumulat ion of nine heavy met als in some import ant fish species from a nat ural reservoir in Riyadh, Saudi Arabia, Toxicological & Environment al Chemist ry, DOI: 10.1080/ 02772248.2014.957485 To link to this article: ht t p:/ / dx.doi.org/ 10.1080/ 02772248.2014.957485 PLEASE SCROLL DOWN FOR ARTI CLE Taylor & Francis m akes every effort t o ensure t he accuracy of all t he inform at ion ( t he “ Cont ent ” ) cont ained in t he publicat ions on our plat form . However, Taylor & Francis, our agent s, and our licensors m ake no represent at ions or warrant ies what soever as t o t he accuracy, com plet eness, or suit abilit y for any purpose of t he Cont ent . Any opinions and views expressed in t his publicat ion are t he opinions and views of t he aut hors, and are not t he views of or endorsed by Taylor & Francis. The accuracy of t he Cont ent should not be relied upon and should be independent ly verified wit h prim ary sources of inform at ion. Taylor and Francis shall not be liable for any losses, act ions, claim s, proceedings, dem ands, cost s, expenses, dam ages, and ot her liabilit ies what soever or howsoever caused arising direct ly or indirect ly in connect ion wit h, in relat ion t o or arising out of t he use of t he Cont ent . This art icle m ay be used for research, t eaching, and privat e st udy purposes. Any subst ant ial or syst em at ic reproduct ion, redist ribut ion, reselling, loan, sub- licensing, syst em at ic supply, or dist ribut ion in any form t o anyone is expressly forbidden. Term s & Downloaded by [S. Mahboob] at 21:51 11 October 2014 Condit ions of access and use can be found at ht t p: / / www.t andfonline.com / page/ t erm sand- condit ions Toxicological & Environmental Chemistry, 2014 http://dx.doi.org/10.1080/02772248.2014.957485 A study on the accumulation of nine heavy metals in some important fish species from a natural reservoir in Riyadh, Saudi Arabia Shahid Mahboob*, H.F. Alkkahem Al-Balwai, F. Al-Misned, K.A. Al-Ghanim and Z. Ahmad Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia Downloaded by [S. Mahboob] at 21:51 11 October 2014 (Received 27 June 2014; accepted 8 August 2014) Concentrations of nine heavy metals (Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe) in the muscles of four fish species (O. niloticus, C. gariepinus, P. latipinna, and A. d. dispar) collected from the Riyadh River were detected using atomic absorption spectrophotometry in two different seasons in 2012. The concentrations of the studied heavy metals except Cd, Pb, Ni, and Cu in Aphanius d. dispar and Poecilia latipinna were found to be below the safe limits suggested by various authorities. This study also showed that Zn was predominant, while Cr was least accumulated metal in the studied fish muscles. Data demonstrated that there was a significant variation in the heavy-metal concentrations in different fish species in the Riyadh River. Significant positive correlations between heavy-metal concentrations in fish muscles were also found both in pre- and post-monsoon seasons. Metal pollution index was calculated to distinguish polluted from unpolluted ecosystems based upon current knowledge of metal bioavailability, bioconcentration, and bioaccumulation patterns. From the human health point of view, this study showed that there was a possible health risk to consumers due to the intake of Aphanius d. dispar and Poecilia latipinna under the current consumption rate in the country. Keywords: concentration; fish; heavy metals; river; pollution; Saudi Arabia Introduction Contamination of freshwaters with a wide range of pollutants is a current matter of concern (Akan et al. 2012). The natural aquatic systems have been extensively contaminated with heavy metals released from domestic, industrial, and other synthetic activities. Heavy-metal contaminations exert devastating effects on the ecological balance of the recipient environment and a diversity of aquatic organisms (Vosyliene and Jankaite 2006). Among animal species, fish are the inhabitants that cannot escape from the detrimental effects of pollutants (Javed and Usmani 2011). The studies carried out on various fish showed that these metals alter the physiological activities and biochemical parameters both in tissues and blood (Basa and Usha 2003). Heavy metals potentially accumulated in aquatic environments including water, sediments, and fish, and subsequently transferred to humans through the food chain (Phillips et al. 2014). Generally, heavy metals exert a toxic effect by forming complexes with organic compounds. Composite effluent contaminated with different heavy metals are major environmental pollutants on varied wetland ecosystems (Cheung et al. 2003; Chatterjee, Chattopadhyay, and Mukhopadhyay 2006; Shue et al. 2014). *Corresponding author. Email: mushahid@ksu.edu.sa Ó 2014 Taylor & Francis Downloaded by [S. Mahboob] at 21:51 11 October 2014 2 S. Mahboob et al. Studies from the field and lab experiments showed that accumulation of heavy metals in a tissue is mainly dependent on water concentrations of metals and exposure period; although some other environmental factors such as salinity, pH, hardness, and temperature play significant roles in metal accumulation (Jeffree et al. 2006). The concern is growing more and more serious globally (Nunes, Cavaco, and Carvalho 2014), especially in the developing countries (Chen et al. 2011). Among the bioindicators of the aquatic ecosystem, fish are often deemed as the most suitable objects because they occupy high trophic level and an important food source of human population (Rahman et al. 2012). Metal residues problems in fish tissues are serious as reflected by the high metal concentrations recorded in the water and sediments. The gills are directly in contact with water. Therefore, the concentration of metals in gills reflects their concentration in water where fish reside, whereas the concentrations in liver represent accumulation of metals from water (Pintaeva et al. 2011). Fish are well known for their ability to concentrate heavy metals in their muscles. Keeping this in mind, muscles were selected as a primary site of metal accumulation. Because fish are the important component of human diet, they need to be carefully screened to ensure that unnecessary high level of heavy metals are not being transferred to the human population through consumption of fish. Therefore, this study was aimed to assess contamination status of nine heavy metals in muscles of four common freshwater fish species (O. niloticus, C. gariepinus, P. latipinna, and A. d. dispar) from the Riyadh River, Al-hair, close to Riyadh, Kingdom of Saudi Arabia. Materials and methods Study area “Wadi Hanefah” (Riyadh River) is also known as Riyadh Lake. The river is, in fact, socalled gray water treated by the city’s sewerage system and running for 100 km away into Wadi Hannifah and surrounding areas. It was first developed around 1983 when the first large sewage plant in the Manfouha district of Riyadh started operating and consequently increasing amounts of ground water were pumped from the city center. There is a steep slope down the neighborhood of brick factory and runs almost into the river. Water is quite clean with a swift flow and high volume. The water is used up for irrigation of date palms and vegetables as well as wheat farms in the downstream direction. The population of the Riyadh city is more than four million and all domestic and industrial water discharges into the Wadi Hanefah stream to finally reach the Riyadh River. Sample collection and preservation Four fish species: Oreochromis niloticus (tilapia), Aphanius dispar dispar (Killifish), Poecilia latipinna (Sailfin molly), and Clarias gariepinus (Cat fish) were collected with three replicates from the study area with the help of hand net. Immediately after collection, fish samples were washed thoroughly with freshwater in order to remove mud or other fouling substances and put in a clean polythene bag to transport fish samples to the Fisheries Laboratory Department of Zoology, King Saud University. The muscle tissues were oven dried until constant weights were obtained. Dried samples were powdered in glass mortar, sieved through 1 mm mesh and stored in airtight plastic vials inside desiccators. Toxicological & Environmental Chemistry 3 Digestion The dried fish samples were digested according to the method of Hanson (1973) as described by Rahman et al. (2012). Downloaded by [S. Mahboob] at 21:51 11 October 2014 Analytical methods The solutions were analyzed for Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe by atomic absorption spectrophotometry (PerkinElmer AA800) using air acetylene flame with digital readout system. Analytical conditions for the measurement of the heavy metals in aqueous solution were tabulated. Metal pollution index (MPI) Metal pollution index (MPI) has previously been reported for the study area for the selected metals as described by Teodorovic, Maletin, and Jugovac (2000). Statistical analysis All the samples were collected and analyzed in triplicate, and these tests were statistically similar in paired-samples t-test, at the 95% confidence level. The results were presented as mean. Statistical software, Minitab 16.0 for Windows, was used to test two-way analysis of variance (ANOVA) to determine the effect of seasons and different fish species on the variation of metal concentrations in the four fish species. Other calculations were performed by Microsoft Excel 2010. Results and discussion Metals such as iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) are essential metals since they play an important role in biological systems, whereas non-essential metals, such as chromium (Cr), lead (Pb), and cadmium (Cd) are toxic even in trace amounts. The essential metals also produce adverse effects at high concentrations. Thus, only three metals namely Pb, Cd, and mercury (Hg) have been included in the regulations of the European Union for hazardous metals (EC 2001), while the US Food and Drug Administration (USFDA) has included further three elements, namely, Cr, arsenic (As), and nickel (Ni) in the list (Sivaperumal, Sankar, and Nair 2007; USFDA 1993; Ylmaz et al. 2010). Comparison of heavy metals among species of fish The concentration of nine heavy metals including Cr, Cd, Pb, Ni, Cu, Zn, Mn, Fe, and As in muscle tissue of the four fish species studied during the pre-monsoon and postmonsoon seasons are presented in Table 1. Among the analyzed fish samples, Cr was ranged from 0.99 to 2.42, Cd from 1.91 to 2.11, Pb from 2.72 to 4.94, Ni from 3.27 to 7.81, Cu from 19.61 to 41.32, Zn from 197.61 to 440.76, Mn from 21.18 to 39.24, As from 3.77 to 8.42 and Fe from 8.82 to 17.76 mg/kg dry weight basis. Downloaded by [S. Mahboob] at 21:51 11 October 2014 4 S. Mahboob et al. Table 1. Heavy-metal concentration (mg/kg dry weight) for various fish species from a natural reservoir in Riyadh, Saudi Arabia. Metal concentration Fish species O.niloticus Season Pre-monsoon Post-monsoon C. gariepinus Pre-monsoon Post-monsoon P.latipinna Pre-monsoon Post-monsoon A.d. dispar Pre-monsoon Post-monsoon Cr Cd Pb Ni Cu Zn Mn As Fe 1.07 § 0.20 1.49 § 0.34 0.99 § 0. 11 1.28 § 0.25 1.55 § 0.18 1.36 § 0.31 1.32 § 0.34 2.42 § 0.32 1.70 § 0.13 1.76 § 0.27 2.24 § 0.37 2.54 § 0.41 1.91 § 0.34 1.61 § 0.28 3.11 § 0.62 2.31 § 0.47 3.44 § 0.55 3.16 § 0.61 3.10 § 0.67 3.32 § 0.81 2.72 § 0.44 3.68 § 0.60 4.60 § 1.02 4.94 § 0.71 4.24 § 0.87 4.56 § 0.63 3.91 § 0.71 3.27 § 0.44 5.12 § 0.91 7.81 § 0.89 4.77 § 0.55 4.54 § 0.75 25.01 § 1.85 23.62 § 1.90 18.52 § 1.44 19.61 § 1.51 36.26 § 2.33 33.88 § 1.95 39.24 § 2.01 41.32 § 2.21 288.20 § 4.28 307.33 § 5.44 197.61 § 3.11 187.51 § 2.90 326.91 § 6.81 303.06 § 2.28 440.76 § 3.66 422.61 § 2.74 39.24 § 1.77 37.11 § 1.44 27.55 § 1.22 28.52 § 1.51 21.18 § 1.05 18.64 § 1.20 23.11 § 1.18 25.33 § 2.10 3.77 § 0.88 3.05 § 0.50 4.06 § 0.61 4.94 § 0.75 5.32 § 0.81 6.12 § 0.90 8.42 § 1.06 7.47 § 0.95 8.82 § 1.44 7.91 § 1.77 12.77 § 2.04 14.44 § 2.44 8.87 § 1.75 7.54 § 1.15 17.76 § 2.82 14.55 § 1.18 Downloaded by [S. Mahboob] at 21:51 11 October 2014 Toxicological & Environmental Chemistry 5 Chromium (Cr) Chromium does not normally accumulate in fish, and hence low concentrations were reported even from the industrialized part of the world (Rahman et al. 2012). Cr, which is considered as a heavy metal and pollutant, is also a microelement that biologically plays an essential role in glucose metabolism. It is an element extensively used in a wide range of industrial applications. Chromium, As, and Ni are hazardous elements designated by the USFDA (1993), although not covered by EC regulations for fish and other aquatic products. The rate of uptake was higher in young fish, but the body content of Cr declined with age due to rapid elimination. Our results also showed low concentrations range of 0.99 2.42 mg/kg which was several fold lower than that of fish muscle collected from the Red Sea (Ahmad and Naim 2008) and Pearl River (Xie et al. 2010; Amin, Begum, and Mondal 2011) indicating less contamination of fish in this area (Table 2). In this study (Table 1), the highest level of Cr was detected in A d. dispar (2.2 mg/kg as dry weight) during the post-monsoon and lowest in C. gariepinus (0.99 mg/kg as dry weight) during the pre-monsoon (Table 1; Figure 1). The Western Australian Food and Drug regulations noted concentration of 5.5 mg/kg for Cr which was higher than our values (Plaskett and Potter 1979). Cadmium (Cd) Cadmium is deemed as an element capable of producing chronic toxicity even when it is present at concentration of »1 mg/kg. The Australian National Health and Medical Research Council (ANHMRC) standard for Cd in seafood is 2 mg/kg, whereas the Western Australian Authorities proposed concentration of 5.5 mg/kg for Cd (Plaskett and Potter 1979). The Spanish legislation limits the levels for Cd at 1 mg/kg (Demirak et al. 2006). Cd concentration in the fish samples of the Riyadh River was from 1.91 to 3.11 mg/kg and 1.7 to 2.54 mg/kg in pre-monsoon and post-monsoon, respectively (Table 1; Figure 1). The highest amount of Cd was found in A. d. dispar (2.48 mg/kg) and the lowest amount of Cd was present in O. niolticus (1.6 mg/kg). From our experimental study, it was noted that Cd in the selected fish from this river was above the limit except the one proposed by the Western Australian Authorities that discussed the standard values. Lead (Pb) Lead is a non-essential element, a toxic metal that affect humans when ingested or inhaled in high doses, producing deficits or decreases in survival, growth rates, development, and metabolism, in addition to increased mucus formation in fish (Burger and Gochfeld 2005). Among the individual fish species, A. d. dispar (4.94 mg/kg) contained the highest Pb concentration during the post-monsoon, whereas P. latipinna (2.72 mg/kg) contained the lowest during the pre-monsoon (Figure 1). The maximum permitted concentration of Pb proposed by the ANHMRC is 2 mg/kg on a wet weight basis (Bebbington et al. 1977; Plaskett and Potter 1979). According to the UK Food Regulations, Pb concentration in fish should not exceed 2 mg/kg as a fresh weight basis (Cronin et al. 1998). There is also legislation in other countries regulating the maximum concentration of metals. Spanish legislation also limits the levels of Pb at 2 mg/kg (Demirak et al. 2006). The present observation showed that the level of Pb in all the four fish species (O. niloticus, C. gariepinus, P. latipinna, and A.d dispar) was above the proposed acceptable limit for human consumption. Downloaded by [S. Mahboob] at 21:51 11 October 2014 6 Table 2. Comparison of heavy-metal accumulation in fish muscle with reported values from various parts of the world. Okumenshi River, Nigeria Gulf of Cambay, India Southern California Kicherra River, Russia Red Seaa (Jordan) Aegean and Mediterranean Seab (Turkey) Pearl Rivera (China) Parangipettaia (India) Hooghly Rivera (India) Riversa (Bangladesh) Gumti Rivera (Bangladesh) Bangshi Rivera (Bangladesh) Riyadh River (KSA) Cr Cd Pb Ni Cu Zn Mn As Fe Reference 0.06 0.62 0.01 0.17 NA NA 1.97 NA NA 0.77 ND NA 0.23 0.6 1.0 0.01 0.10 1.09 1.66 1.33 0.007 0.3 ND NA NA 2.37 12.3 20.8 NA 38.24 27.8 54.8 2.88 5.85 NA NA 0.11 0.37 NA 2.10 10.08 NA NA NA NA Raphael, Augustina, and Frank (2011) Reddy et al. (2007) Bruce et al. (1975) Pintaeva et al. (2011) 1.0 10.3 0.5 2 1.5 8.3 1.0 5.0 0.5 2 1.9 35.0 1.0 3.3 NA NA 0.07 1.48 0.01 0.39 0.21 1.28 .03 1.72 0.51 7.05 3.51 53.5 0.18 2.78 NA NA ND-5.36 0.415 1.562 ND-33.2 0.004 0.11 0.05 1.94 0.062 1.56 NA 3.69 1.17 6.72 NA 2.62 2.02 0.103 0.807 NA NA 0.17 1.46 NA NA NA ND-3.89 0.62 1.20 12.4 19.96 2.2 3.69 16.22 47.97 12.13- 44.74 NA NA NA NA NA 0.04 0.13 NA 0.29 10.05 0.5 4.05 1.2 6.1 1.8 8.4 1.48 23.3 1.48 21.3 33.01 286.45 3.14 186.9 4.76 71.61 4.1 51.67 NA NA NA NA 0.47 2.07 0.09 0.87 1.76 10.27 0.69 4.36 8.33 43.18 42.83 418.05 9.43 51.17 1.97 6.24 NA Sharif et al. (1993) Amin, Begum, and Mondal (2011) Rahman et al. (2012) 0.87 2.42 1.76-.3.11 2.72 4.94 3.27 7.81 19.61 41.32 197.61 440.76 21.18 39.24 3.77 8.42 8.82 17.76 Present research Note: ND: not detected; NA: not analyzed. a Values present in the ranges or mean expressed as mg/kg dry weight. b Values present the ranges or mean expressed as mg/kg wet weight. Ahmad and Naim (2008) Turkmen et al. (2009) Xie et al. (2010) Lakshmanan et al. (2009) De et al. (2010) S. Mahboob et al. Sample area Toxicological & Environmental Chemistry 7 mg/kg dry weight 6 Pb 5 4 3 2 1 0 Cd O. niloƟcus Cr C. gariepinus P. laƟpinna A .d. dispar Nickel (Ni) Nickel normally occurs at low levels in the environment and produces a variety of pulmonary adverse health effects, such as inflammation, fibrosis, emphysema, and tumors (Forti et al. 2011). In this study, the highest amount of Ni was found in P. latipinna (7.81 mg/kg) and the lowest amount in C. gariepinus (3.27 mg/kg). The range of Ni concentration in the four species of fish was 3.27 7.81 mg/kg and 2.84 6.11 mg/kg in the pre-monsoon and the post-monsoon, respectively (Figure 2). These values are similar to that reported by Sharif et al. (1993). Ni concentrations in the river water fish except P. latipinna were below the established safe level of 5.5 mg/kg by the Western Australian Food and Drug Regulations (Plaskett and Potter 1979). Copper (Cu) Copper is an essential part of several enzymes and necessary for the synthesis of hemoglobin (Sivaperumal, Sankar, and Nair 2007). Most of the aquatic organisms have 20 mg/kg dry weight Downloaded by [S. Mahboob] at 21:51 11 October 2014 Figure 1. Concentration of Cr, Cd, and Pb in white muscle of fishes from a natural reservoir in Riyadh in two different seasons. Fe 15 10 5 0 As Ni O. niloƟcus C. gariepinus P. laƟpinna A .d. dispar Figure 2. Concentration of Ni, AS, and Fe in white muscle of fishes from a natural reservoir in Riyadh in two different seasons. 8 S. Mahboob et al. Zinc (Zn) Zinc is a heavy metal, has a tendency to get bioaccumulated in the fatty tissues of aquatic organisms, including fish, and is known to affect reproductive physiology in fishes. Zinc, an essential micronutrient for both animals and humans, is a cofactor in nearly 300 enzymes in all marine organisms. Zinc toxicity is rare, yet it can be toxic above the limit of 50 mg/kg wet weight in muscle. It appears to have a protective effect against the toxicities of both Cd and Pb. Gorell et al. (1997) reported that chronic exposure to Cu and Zn is associated with Parkinson’s disease and these elements might act alone or together over time to initiate the disease (Prasad 1983). Fish are known to have a high threshold level of Zn. The concentration of Zn in the muscles of the sampled fish species in this study ranged from 197.61 to 440.76 mg/kg and 187.51 to 422.61mg/kg as a dry weight basis in the pre-monsoon and the post-monsoon, respectively (Figure 3). The highest amount of Zn was recorded in A. d. dispar (410.71 mg/kg as dry weight) and lowest in C. griepinus (197.61 mg/kg) among the four species of fish in this study. The amount of Zn determined in all the fish samples was below the standard of 1000 mg/kg set by 500 mg/kg dry weight Downloaded by [S. Mahboob] at 21:51 11 October 2014 evolved mechanisms to regulate concentrations of this metal in their tissues in the presence of varying concentrations in the ambient water, sediments, and food. The richest sources of Cu are shellfish, especially oysters and crustaceans (Underwood 1977). However, high intake of Cu produces adverse health problems (Gorell et al. 1997). The concentration of Cu ranged from 19.61 to 41.32 mg/kg, with the highest concentration recorded in A. d. dispar (41.32 mg/kg as dry weight) during the post-monsoon and lowest was in C. gariepinus (19.61 mg/kg) during the pre-monsoon (Table 1, Figure 3). The permissible limit of Cu proposed by ANHMRC and Food and Agriculture Organization (FAO), was 30 mg/kg fresh weight (Bebbington et al. 1977; Dural, Goksu, and Ozak 2007). According to UK Food Standards Committee Report, Cu concentration in food should not exceed the value of 20 mg/kg as wet weight (Cronin et al. 1998). The concentration of Cu in all the studied fish species was higher than the safe limits suggested by various international agencies. Similar findings were also reported by Rahman et al. (2012). Zn 400 300 O. niloƟcus 200 100 0 Cu Mn C. gariepinus P. laƟpinna A .d. dispar Figure 3. Concentration of Cu, Mn, and Zn in white muscles of fishes from a natural reservoir in Riyadh in two different seasons. Downloaded by [S. Mahboob] at 21:51 11 October 2014 Table 3. Two-way analysis of variance (ANOVA) for the effect of inter-season and inter-species on the variation of concentration of various metals in fish muscle. Cr Effects df F Cd p df F Pb p df F Ni p df F Cu p df F Zn p df F Mn p df F As p df F Fe p df F p a p: Level of significance. a Season: pre-monsoon. b Fish species: O. niloticus; P. latipinna; C. gariepinus; A. A. dispar. Toxicological & Environmental Chemistry Season 1 3.54 0.16 1 0.79 0.44 1 0.75 0.46 1 0.09 0.79 1 0.59 0.50 1 0.02 0.89 1 0.64 0.48 1 0.01 0.09 1 0.33 0.6 Fish 3 16.12 0.02 3 8.83 0.05 3 14.83 0.03 3 8.14 0.05 3 11.71 0.001 3 150.55 0.001 3 21.16 0.01 3 25.96 0.01 3 20.40 0.01 Species b Error 3 3 3 3 3 3 3 3 3 Total 7 7 7 7 7 7 7 7 7 9 10 S. Mahboob et al. Downloaded by [S. Mahboob] at 21:51 11 October 2014 ANHMRC (Bebbington et al. 1977) and World Health Organization (WHO; Cliton, Ujagwung, and Michael 2008). Manganese (Mn) Manganese is an essential element for both animals and plants, and its deficiencies result in severe skeletal and reproductive abnormalities in mammals (Sivaperumal, Sankar, and Nair 2007). Although Mn is an element of low toxicity, it has considerable biological significance. No maximum limit is specified for Mn in fish samples. Levels for Mn accumulation during this study are shown in Table 1. The concentration of Mn ranged from 21.18 to 39.24 mg/kg and 18.64 to 37.11 mg/kg in the pre-monsoon and the post-monsoon, respectively. O. niloticus showed the highest Mn concentration of 39.24 mg/kg and P. latipinna showed the minimum of 21.18 mg/kg (Figure 3). Normally, water contains low level (0.05 mg/kg) of Mn (Bowen 1966), but in this study, all fish accumulated higher concentration of Mn due to the tendency of various species of fish to concentrate certain elements in their tissue more than the surrounding medium. These findings are in agreement with the amount found in fish species by Amin, Begum, and Mondal (2011). Arsenic (As) Arsenic is widespread in the environment due to both anthropogenic and natural processes. It is a ubiquitous, but potentially a toxic, trace element. The USFDA (1993) indicated that fish and other seafood account for 90% of the total As exposure. Figure 3 shows As concentration ranged from 3.77 to 8.42 mg/kg (pre-monsoon) and 3.05 to 7.47 mg/kg (post-monsoon). According to the Australian New Zealand Food Standards Code (ANZFA 2011), the maximum permitted concentration for As was 2 mg/kg wet weight. None of the fish samples exceeded the ANZFA recommended value of 9.6 mg/kg dry weight (assuming 79% moisture content). The Environmental Protection Agency (EPA) set As tissue residues of 1.3 mg/kg fresh weight freshwater fish as the criterion for human health protection (Burger and Gochfeld 2005). Sharif et al. (1993) reported As concentration of 2.84 3.94 mg/kg dry weight in tropical marine fish of Bangladesh. Iron (Fe) In the four fish species in this study, Fe accumulation in muscles was found from 8.82 to 17.76 mg/kg (pre-monsoon) and 7.91 to 14.55 mg/kg (post-monsoon). A. d. dispar showed the highest Fe concentration of 17.76 mg/kg and O. niloticus showed the minimum of 7.91 mg/kg (Figure 2). According to WHO (1996), the maximum permitted daily intake concentration of Fe is 0.5 mg/kg body weight. None of the fish samples exceeded the ANZFA recommended value of 151 mg/kg dry weight. Carvalho, Santiago, and Nunes (2005) obtained Fe values of the order of 9 (7 11) mg metal/g dry weight in muscle and 8 (6 10) mg metal/g dry weight in muscle of Solea vulgaris and Lophius piscatorius, respectively. This discrepancy might be because Fe content depends on species, individuals, and sampling period. The differences occur between species that inhabit both kinds of bottom and other species. Because similar Fe concentrations were measured in species with more affinity for rocky bottoms and species with more affinity for sandy/ muddy bottoms, data indicate that the greatest difference occurs between pelagic and benthic species with increased value in benthic species. Downloaded by [S. Mahboob] at 21:51 11 October 2014 Toxicological & Environmental Chemistry 11 The concentrations of the heavy metals detected in fish in this study were compared with other reported values (Table 2) as an effort to determine the degree of contamination in the study area. Reported results in the literatures showed that metal contents in fish muscles varied widely depending on where and which species were caught (Table 2). The metal content in various fish species from Parangipettai (Lakshmanan et al. 2009), Aegean and Mediterranean Sea (Turkmen et al. 2009), Gulf of Cambay (Reddy et al. 2007), and Okumeshi River (Raphael, Augustina, and Frank 2011) were lower than the findings of this study. Sharif et al. (1993) measured concentrations of metals in the freshwater fish from different rivers in Bangladesh and were not in agreement with the present results except Pb and Ni. The effect of two different seasons on four different fish species captured from the Riyadh River, Saudi Arabia is presented in Table 3. The metal concentration in the edible fish fillet of each fish species for two seasons was used for two-way ANOVA (Table 3). The data obtained from ANOVA clearly demonstrated that there was a significant variation (CI D 95%) of heavy-metal concentrations in different fish species in this water body. However, seasonal variation exerted no significant impact in four species of fish collected from the Riyadh River. Correlation of heavy metals Studies from the field and lab showed that accumulation of heavy metals in a tissue is mainly dependent upon water concentrations of metals and exposure period, although some other environmental factors such as salinity, pH, hardness, and temperature play significant roles in metal accumulation (Canlı and Atlı 2003; Barlas, Akbulut, and Aydo gan 2005).Table 4 showed the correlations between each analyzed trace metal, listing the Pearson product moment correlation coefficients. The concentrations of the investigated metals in fish were significantly correlated with each other during both seasons. Significant correlations were found between Cr and Pb (r D 0.877), Cr and Cu (r D 0.844), Cr and Zn (r D 0.861), Cr and As (r D 0.782), Cd and Pb (r D 0.642), Cd and Fe (r D 0.924), Pb Cu (r D 0.729), Pb As (r D 0.782), Ni and Cd (r D 0.642), Cu Zn (r D 0.924), Cu Mn (r D 0.687), Cu As (r D 0.862), Zn As (r D 0.651), and Mn As (r D 0.831) at p < 0.01 level during the pre-monsoon (Table 4). During the post-monsoon, Cd Cu (r D 0.698), Cd Zn (r D 0.865), Cd Mn (r D 0.939), Pb Ni (r D 0.897), and Zn Fe (r D 0.786), Ni Pb, Mn Pb, Mn Cd, and Mn Zn were significantly correlated (Table 4). These correlations indicate that the distributions of these pairs of metals were regulated by common local inputs and similar dispersion processes in the study area, except for As and Fe in pre-monsoon and Cr, Mn, As, and Fe in post-monsoon. These results corroborate with the findings of Rahman et al. (2012). Metal pollution index Metal pollution index is a mathematical model which might resolve some of the highlighted problems (Teodorovic, Maletin, and Jugovac 2000). MPI is utilized to explain the results from the metal concentrations (Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe) as one value if possible, yet overcoming the difficulties with both application and understanding of demanding statistical analysis. According to Jorgensen and Pedersen (1994), this implies that the nine metal concentrations need to be normalized to make it possible to sum up and average the different metal concentrations into one value. The mean values 12 S. Mahboob et al. Table 4. Correlation between heavy metals in the fish samples during the two seasons (pre- and post-monsoon). Downloaded by [S. Mahboob] at 21:51 11 October 2014 Cr Cd Pb Ni Cu Zn Pre-monsoon Cr 1 0.347 0.877 0.241 Cd 0.344 1 0.601 ¡0.672   Pb 0.861 0.597 1 0.110 Ni 0.277 ¡0.642 0.092 1 Cu 0.884 0.197 0.702 0.557 0.776 0.598 Zn 0.821 0.121 Mn ¡0.444 ¡0.102 ¡0.311 0.595   As 0.768 0.402 0.690 0.460 Fe 0.490 0.924 0.664 ¡0.438 0.844 0.861 0.127 0.041 0.748 0.788 0.551 0.542 1 0.924  0.933 1 0.644 ¡0.398 0.862 0.661 0.254 0.142 Post-monsoon Cr Cd Pb Ni Cu Zn Mn As Fe 0.288 0.698 0.055 0.164 1 0.011 0.090 0.170 0.408  1 0.359 0.044 0.628 0.252 0.573 0.272 0.061 0.208 0.363 1 0.144 0.106 0.643 0.906 0.932 0.364 0.204 0.036 0.141 1 0.851 0.049 0.041 0.475 0.033 0.126 0.566 0.118 0.897 1 0.137 0.121 0.172 0.346 0.190 0.501 0.865 0.046 0.148 0.006 1 0.381 0.075 0.804 Mn As Fe ¡0.452 0.744 0.552 ¡0.088 0.362 0.911  ¡0.304 0.782 0.646  0.579 0.401 ¡0.511 0.628 0.862 0.321 ¡0.376 0.651 0.151 1 ¡0.831 0.598  ¡0.806 1 0.522 0.601 0.480 1 0.235 0.939 0.475 0.178 0.096 0.372 1 0.016 0.562 0.044 0.362 0.070 0.367 0.190 0.121 0.028 1 0.183 0.168 0.265 0.140 0.191 0.422 0.786 0.566 0.211 1 p  0.05. of fish muscle burden (Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe) from the study area (Riyadh River) were selected. Such normalization is used to account for the biological variation in a non-polluted area. Since no significant difference was observed between metal concentration except Cd, Pb, Ni, and Cu in A. d. dispar and O. niloticus in the study area, the sample was pooled so reference values represent the mean of 49 specimens (Table 5). Furthermore, data were logarithmically transformed to achieve normal distribution of the element values and, what is more important, to diminish the more than 1000-fold difference between least and most abundant elements. Without such transformation, the least abundant elements would be without influence on the results (Julshamn and Grahl-Nielsen 1996). MPI was calculated as MPI ¼ log n¼5 X ½X Š; i¼1 ref i where ref i represents a normalizer, or a reference value for each of the nine chosen metals (Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe) in fish muscle, while X represents the mean value (n  10, SD up to 20%) of the metal concentration in the same tissues of the study area in all four fish species. If calculated as proposed, MPI distinguishes “polluted” from “non-polluted” reference site: if this combined index is above 1, the concentrations of Toxicological & Environmental Chemistry 13 Table 5. Comparison of the estimated daily intake of heavy metals from fish species studied with the recommended daily dietary intake. Metal X-Mean concentration (mg/kg dry weight) mean (n D 7) § SD Downloaded by [S. Mahboob] at 21:51 11 October 2014 Cr Cd Pb Ni Cu Zn Mn As Fe 1.40 § 0.35 2.05 § 0.43 3.65 § 0.51 4.50 § 0.77 30.59 § 4.64 301.42 § 6.92 27.28 § 5.31 5.40 § 1.10 11.22 § 2.77 Reference value (ref.) X/ref. 0.98 0.56 0.27 0.88 3.12 18.24 2.88 0.44 1.65 P 1.42 3.68 13.51 5.11 9.80 16.52 9.47 12.27 6.8 73.48 1.87 MPI D log P Note: Reference values mean (n D 49) concentration in pooled sample from Riyadh River. trace metals would be considered elevated and ecosystem could be regarded as “polluted”. Table 5 presents the muscle concentrations of Cr, Cd, Pb, Ni, Cu, Zn, Mn, As, and Fe from the Riyadh River and the controlled site. The concentration of Cd, Pb, Ni, and Cu in fish muscles were higher in the river, the metal load was used in MPI calculation. In addition, the values of X/ref. ratio are presented and MPI is calculated. According to its value (1.87) in the study area, it may be regarded as “polluted” when Cd, Pb, Ni, and Cu are concerned. As indicated in Table 5, the main component of the index is the Cu concentration, followed by Ni, Pb, and Cd. The rest of the concentrations (essential and in the same time the most abundant metals) tend to contribute to a smaller extent. Our results suggest where the muscle metal burden-based classification failed, while MPI succeeded: the most toxic and hazardous elements (Pb and Cd) contribute the most to this combined index. Conclusions In general, the findings of this study suggest that the heavy-metal concentrations detected in fish muscles sampled from the Riyadh River, with the exception of Cd, Pb, Ni, and Cu content were within the standard limits proposed by various agencies (ANHMRC, ANZFA, Western Australian Food and Drug Regulations etc.). It was found that A. d. dispar and O. niloticus comparatively have a higher accumulation of the tested heavy metals. It was noted that the concentrations of Zn were found considerably higher among nine heavy metals in the studied fish species. Therefore, evidence indicates that these metals except Cd, Pb, Ni, and Cu should not pose any health threat to consumers resulting from the consumption of these fish species. Acknowledgments The authors would like to express their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through the Research Group Project No. RG-1435-012. 14 S. Mahboob et al. Downloaded by [S. Mahboob] at 21:51 11 October 2014 References Ahmad, H.A.H., and S.I. Naim. 2008. “Heavy Metals in Eleven Common Species of Fish from the Gulf of Aqaba, Red Sea.” Jordan Journal of Biological Sciences 1: 13 18. Akan, J.C., M. Salwa, B.S. Yikala, and Z.M. Chellube. 2012. “Study on the Distribution of Heavy Metals in Different Tissues of Fishes from River Benue in Vinikilang, Adamawa State, Nigeria.” British Journal of Applied Science & Technology 2: 311 333. Amin, M.N., A. Begum, and M.G.K. Mondal. 2011. “Trace Element Concentrations Present in Five Species of Freshwater Fish of Bangladesh.” Bangladesh Journal of Scientific and Industrial Research 46: 27 32. ANZFA. 2011. Australian and New Zealand Food Standards Code, Standard 1.4.1 - Contaminants and Natural Toxicants (F2011C00542). Accessed October 12, 2012. http://www.comlaw.gov. au/Details/F2011C00542. Barlas, N., N. Akbulut, and M. Aydogan. 2005. “Assessment of Heavy Metal Residues in the Sediment and Water Samples of Uluabat Lake, Turkey.” Bulletin of Environmental Contamination and Toxicology 74: 286 293. Basa, S.P, and R.A. Usha. 2003. “Cadmium Induced Antioxidant Defense Mechanism in Freshwater Teleost Oreochromis mossambicus (Tilapia).” Ecotoxicology Environment Safety 2: 218 221. Bebbington, G.N., N.J. Mackay, R. Chvojka, R.J. Williams, A. Dunn, and E.H. Auty. 1977. “Heavy Metals, Selenium and Arsenic in Nine Species of Australian Commercial Fish.” Australian Journal of Marine and Freshwater Research 28: 277 286. Bowen, H.J.M. 1966. Trace Elements in Biochemistry. New York, NY: Academic Press. Bruce, A.F., C.F. Rimmon, L.W. Richard, D.W. Robert, and F.G. William. 1975. “Levels of Toxic Metals in Marine Organisms Collected from Southern California Coastal Waters.” Environmental Health Perspective 12: 71 76. Burger, J., and M. Gochfeld. 2005. “Heavy Metals in Commercial Fish in New Jersey.” Environmental Research 99: 403 412. Canlı, M, and G. Atlı. 2003. “The Relationships Between Heavy Metal (Cd, Cr, Cu, Fe, Pb, Zn) Levels and the Size of Six Mediterranean Fish Species.” Environmental Pollution 121: 129 136. Carvalho, M.L., S. Santiago, and M.L. Nunes. 2005. “Assessment of the Essential Element and Heavy Metal Content of Edible Fish Muscle.” Analytical and Bioanalytical Chemistry 382: 426 432. Chatterjee, S., B. Chattopadhyay, and S.K. Mukhopadhyay. 2006. “Trace Metal Distribution in Tissues of Cichlids (Orechromis niloticus and O. mossambicus) Collected from Wastewater Fed Fishponds in East Calcutta Wetlands a Ramsar Site.” Acta Ichthyologica et Piscatoria 36: 119 125. Chen, C., Y. Qian, Q. Chen, and C. Li. 2011. “Assessment of Daily Intake of Toxic Elements Due to Consumption of Vegetable, Fruits, Meat, and Seafood by Inhabitants of Xiamen.” Chinese Journal of Food Science 76: 181 188. Cheung, K.C., B.H.T. Poon, C.Y. Lan, and M.H. Wong. 2003. “Assessment of Metal and Nutrient Concentration in River Water and Sediment Collected from the Cities in the Pearl River Delta, South China.” Chemosphere 52: 1431 1440. Cliton, H.I., G.U. Ujagwung, and H. Michael. 2008. “Trace Metals in the Tissues and Shells of Tympanotonus fuscatus var. Radula from the Mangrove Swamps of the Bukuma Oil Field, Niger Delta.” European Journal of Scientific Research 24: 468 476. Cronin, M., I.M. Davies, A. Newton, J.M. Pirie, G. Topping, and S. Swan. 1998. “Trace Metal Concentrations in Deep Sea Fish from the North Atlantic.” Marine Environmental Research 45: 225 238. De, T.K., M. De, S. Das, R. Ray, and P.B. Ghosh. 2010. “Level of Heavy Metals in Some Edible Marine Fishes of Mangrove Dominated Tropical Estuarine Areas of Hooghly River, North East Coast of Bay of Bengal, India.” Bulletin of Environmental Contamination and Toxicology 85: 385 390. Demirak, A., F. Yilmaz, A. L. Tuna, and N. Ozdemir. 2006. “Heavy Metals in Water, Sediment and Tissues of Leciscus cephalus from a Stream in Southwestern Turkey.” Chemosphere 63: 1451 1458. Dural, M., M.Z.L. Goksu, and A.A. Ozak. 2007. “Investigation of Heavy Metal Levels in Economically Important Fish Species Captured from the Tuzla Lagoon.” Food Chemistry 102: 415 421. Downloaded by [S. Mahboob] at 21:51 11 October 2014 Toxicological & Environmental Chemistry 15 EU Commission Regulation as regards heavy metals. Directive 2001/22/EC, No. 466/2001. EEC as amended by regulation 221/2002/EC. Forti, E., S. Salovaara, Y. Cetin, A. Bulgheroni, R.W. Pfaller, and P. Prieto. 2011. “In Vitro Evaluation of the Toxicity Induced by Nickel Soluble and Particulate forms in Human Airway Epithelial Cells.” Toxicology in Vitro 25: 454 461. Gorell, J.M., C.C. Johnson, B.A. Rybicki, E.L. Peterson, G.X. Kortsha, and G.G. Brown. 1997. “Occupational Exposures to Metals as Risk Factors for Parkinson’s Disease.” Neurology 48: 650 658. Hanson, N.W. 1973. Official Standardized and Recommended Methods of Analysis. 2nd ed., 270 274 London: The Society for Analytical Chemistry. Javed, S., and N. Usmani. 2011. “Accumulation of Heavy Metal in Fishes: Human Health Concern.” International Journal of Environmental Sciences 2: 659 670. Jeffree, R.A., M. Warnau, F. Oberhansli, and J.L.Teyssie. 2006. “Bioaccumulation of Heavy Metals and Radionuclides from Seawater by Encased Embryos of the Spotted Dogfish Scyliorhinus canicula.” Marine Pollution Bulletin 52: 1278 1286. Jorgensen, L.A., and B. Pedersen. 1994. “Trace Metals in Fish Used for Time Trend Analysis and as Environmental Indicators.” Marine Pollution Bulletin 28: 235 243. Julshamn, K., and O. Grahl-Nielsen. 1996. “Distribution of Trace Elements from Industrial Discharges in the Hardangerfjord, Norway: A Multivariate Data Analysis of Saithe, Flounder and Blue Mussel as Sentinel Organisms.” Marine Pollution Bulletin 32: 564 571. Lakshmanan, R., K. Kesavan, P. Vijayanand, V. Rajaram, and S. Rajagopal. 2009. “Heavy Metals Accumulation in Five Commercially Important Fishes of Parangipettai, Southeast Coast of India.” Advanced Journal of Food Science and Technology 1: 63 65. Nunes, E., A. Cavaco, and C. Carvalho. 2014. “Children’s Health Risk and Benefits of Fish Consumption: Risk Indices Based on a Diet Diary Follow-up of Two Weeks.” Journal of Toxicology and Environmental Health A 77: 103 114. Phillips, N.R., M. Stewart, G. Olsen, and C.W. Hickey. 2014. “Human Health Risks of Geothermally Derived Metals and Other Contaminants in Wild Caught Fish.” Journal of Toxicology and Environmental Health A 77:346 365. Pintaeva, E.Ts., S.V. Bazarsadueva, L.D. Radnaeva, E.A. Pertov, and O.G. Smirnova. 2011. “Content and Character of Metal Accumulation in Fish of the Kichera River (a Tributary of Lake of Baikal).” Contemporary Problems of Ecology 4: 64 68. Plaskett, D., and I.C. Potter. 1979. “Heavy Metal Concentrations in the Muscle Tissue of 12 Species of Teleost from Cockburn Sound, Western Australia.” Australian Journal of Marine and Freshwater Research 30: 607 616. Prasad, A.S. 1983. “The Role of Zinc in Gastrointestinal and Liver Disease.” Clinics in Gastroenterology 12: 713 741. Rahman, M.S., A.H. Molla, N. Saha, and A. Rahman. 2012. “Study on Heavy Metals Levels and Its Risk Assessment in Some Edible Fishes from Bangshi River, Dhaka, Bangladesh.” Food Chemistry 134: 1847 1854. Raphael, E.C., O.C. Augustina, and E.O. Frank. 2011. “Trace Metals Distribution in Fish Tissues, Bottom Sediments and Water from Okumeshi River in Delta State, Nigeria.” Environmental Research Journal 5: 6 10. Reddy, M.S., B. Mehata, S. Dave, M. Joshi, L. Karthikeyan, and V.K.S. Sharma. 2007. “Bioaccumulation of Heavy Metals in Some Commercial Fishes and Crabs of the Gulf of Cambay, India.” Current Science 92: 1489 1491. Sharif, A.K.M., M. Alamgir, A.I. Mustafa, M.A. Hossain, and M.N. Amin. 1993. “Trace Element Concentrations in Ten Species of Freshwater Fish of Bangladesh.” Science of the Total Environment 138: 117 126. Shue, M.-F., W.-D. Chen, C.-C. Su, and M.-C. Lu. 2014. “Heavy Metals in Bivalve Mollusks Collected from Da-Peng Bay Lagoon in South-Southwestern Taiwan.” Journal of Toxicology and Environmental Health A 77: 214 222. Sivaperumal, P., T.V. Sankar, and P.G.V. Nair. 2007. “Heavy Metal Concentrations in Fish, Shellfish and Fish Products from Internal Markets of India vis-a-vis International Standards.” Food Chemistry 102: 612 620. Teodorovic, N.D., S.B. Maletin, and M.N. Jugovac. 2000. “Metal Pollution Index: Monitoring Based on Trace Metal Accumulation in Fish.” TISCIA 32: 55 60. 16 S. Mahboob et al. Downloaded by [S. Mahboob] at 21:51 11 October 2014 Turkmen, M., A. Turkmen, Y. Tepe, Y. Tore, and A. Ates. 2009. “Determination of Metals in Fish Species from Aegean and Mediterranean Seas.” Food Chemistry 113: 233 237. Underwood, E.J. 1977. Trace Elements in Human and Animal Nutrition. 4th ed., 258 270. New York, NY: Academic Press. USFDA. 1993. Food and Drug Administration. Guidance Document for Chromium in Shellfish. Washington, DC: DHHS/PHS/FDA/CFSAN/Office of Seafood. Vosyliene, M.Z., and A. Jankaite. 2006. “Effect of Heavy Metal Model Mixture on Rainbow Trout Biological Parameters.” Ekologija 4: 12 17. WHO. 1996. Guidelines for Drinking Water Quality. Vol. 2, 2nd ed. Geneva: World Health Organization. Xie, W.P., K.C. Chen, X.P. Zhu, X.P. Nie, G.M. Zhen, and D.B. Pan. 2010. “Evaluation on Heavy Metal Contents in Water and Fishes Collected from the Waterway in the Pearl River Delta, South China.” Journal of Agro-Environment Science 29: 1917 1923. Ylmaz, A.B., M.K. Sangun, D. Yag, and C. Turan. 2010. “Metals (Major, Essential to Non-essential) Composition of the Different Tissues of Three Demersal Fish Species from Iskenderun Bay, Turkey.” Food Chemistry 123: 410 415.