CHAPTER-II REVIEW OF LITERATURE

Transcription

1 CHAPTER-II REVIEW OF LITERATURE

2 REVIEW OF LITRATURE The consumption of highly contaminated water and eatables may prove lethal to the human being and may bring genetic disorders. Toxic heavy metals are continuously released to the aquatic bodies in Allahabad as a rapid industrialization. Metals are the problem of magnitude and of ecological significance due to their high toxicity and ability to accumulate in living organisms. Many toxicologists have worked on the analysis and detection of heavy metals in the water bodies, soil, sediments, plankton, fish organs, etc. The main aim of this paper is to provide an in-depth review for the heavy metal concentration in water, fish, sediments, eatables, such as vegetables grown on River beds, etc and to give recommendations to prevent the health hazards against consumption. Due to evolution of technology, the rise of industries at or along the bank of water bodies is one of the main causes of pollution which may cause the health hazards for the population consuming the contaminated water and other related eatables. Many publications are available all around the world consisting the heavy metal detection and have been discussed in the chapter. Due to the number of references collected from the variety of sources, some lacks or omissions are possible. Authors have tried to cover maximum number of information, some of them are briefly discussed below:- In Egypt concentrations of Zn, Cu, Pb and Cd were determined in gills, skin and muscles of two fish species ( M. cephalus and Liza ramada) from five locations in Lake Manzala (Bahnasawy et al., 2009). They indicated that, the values of the metals detected in the fish muscles (the edible part) were within the permissible levels according to According to National Health and Medical Research Council (NHMRC, 1987) limits. (Abdallah, 2008), studied the concentrations of five trace metals namely, Cd, Pb, Cu, Cr and Zn in muscles of some commercially fish species collected from two coastal areas of the Egyptian coast of the Mediterranean Sea west of Alexandria (El- Mex Bay and Eastern Harbour). For all trace element examined, in all fishes zinc was the highest (up to 57 g/g) followed by Cr, Cu, Pb and Cd. The levels of Cr surpassed the maximum permissible concentration in most fish tissues, followed by Pb and Cd Review of Literature Page 22

3 in some species. Cu and Zn concentrations were found to be below the maximum permissible levels proposed by Food and Agriculture Organization. (Saeed et al., 2008) presented a report about concentrations of Fe, Zn, Cu, Mn, Cd and Pb in O. niloticus (Tilapia ) fish tissues, water and sediments in northern Delta Lakes. They found that The edible part of O. niloticus from Lake Edku and Manzala contained the highest levels of Cd while fish from Manzala Lake contained the highest level of Pb. They reported that Nile tilapia caught from these two Lakes may pose health hazards for consumers. In their study to determine the accumulation and the distribution of Cu and Zn in Tilapia zillii and M. cephalus. (Authman et al., 2007) suggested that the consumption of fishes of the lake could pose the health damage to the local population whose diet consist mainly of fish, and they recommended to rescue lake Qarun from these serious ecological problems. In their study to determine the accumulation and the distribution of Cu and Zn in the two fish species, bioaccumulation factor showed that the trend of accumulation of metals in fish organs was apparent in liver, gills and muscles, respectively. Moreover they reported that T. zillii seemed to be more contaminated with Zn and Cu than M. Cephalus. As they mentioned their result was in disagreement with many previous findings which pointed that Mugil species seemed to be more accumulated with heavy metals than Tilapia species. The levels of Fe, Mn, Zn, Cu, Pb and Cd were studied (Ali et al., 2005), in water, sediment, fish and fish diets in some fish farms in El Fayoum province in Egypt. They showed that with exception of zinc the values of heavy metals exceeded that of the permissible limits in water. Heavy metals in the fish flesh showed that Mugil species tended to accumulate more concentration of Cu, Zn, Pb, and Cd than Tilapia species. They were the diets considered as additional ambient heavy metals sources. So, results revealed that the studied fish farms suffered from serious environmental problems such as poor water quality, improper management and absence of scientific monitoring, therefore by time the heavy metals problems cause toxicological effects for the end users and costumers. Review of Literature Page 23

4 In Jordan, Levels of Cd, Cu and Zn in three fish species, Oreochromis aureus, Cyprinus carpio and Clarias lazera, Collected from the Northern Jordan Valley were investigated by (Al-Weher, 2008). He found that levels of these heavy metals in muscles of the three fish species were within acceptable limits by FAO standards, except for the Zn concentration in muscles of Oreochromis aureus ( g/g dry wt.) which were attributed to the increase of agricultural influx and some other anthropogenic activity in that area. The distribution of eight heavy metals, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in muscles, gills, livers and bones of five fish species namely, Sargus sargus, Siganus rivulatus, Mugil cephalus, Caranx crysos and Scomberomorus commerson collected from El- Mex Bay Alexandria, Egypt were studied by (Khalid, 2004). Results for weekly intake demonstrated that the concentrations of Cd, Cu, and Pb in muscles of the five fishes were lower than the Provisional tolerable weekly intake (PTWI) values set by international organization and accordingly there is no risk for human consumption of flesh of these fishes. In a study performed by (Rashed, 2001), results indicated that T. niloticus is one of the aquatic organisms affected by heavy metals. He showed that according to the Egyptian Organization for Standardization, concentrations of Cr, Cu, Fe, Mn, Ni, Co, Zn and Sr in the edible parts of the investigated fish were in the safety permissible level for human uses. In Saudi Arabia, vanadium (V), Cd, Zn, arsenic (As), Ni, Pb and mercury (Hg) levels in most common available fish species in Saudi markets were determined by (Al- Bader, 2008). Results showed that the concentrations of metals were below the maximum allowed limit by the Saudi and international legislations for fish human consumption permissible limit. In Libya, (Khalifa et al., 2010) determined concentrations of Co, Cd, Pb, Fe and Cu in different tissues of six samples of fishes of the Mediterranean sea. They found that the concentrations of Co, Cd and Pb in all examined tissues were more than the allowed literature values by WHO. In Yemen, distribution of seven trace metals namely Zn, Mn, Cd, Cu, Co, Ni, and Pb in Mullet and other commercial fish species along the coast of Al-Hodiedah Red Sea Review of Literature Page 24

5 coast was investigated by (Hassaan et al., 2007). They found that the values of trace metals observed in their study were within the acceptable worldwide range, however they were lower than those reported elsewhere. They recommended carrying out continuous monitoring program for the Red sea coast of Yemen, and that the levels of heavy metals must remain within the prescribed worldwide ratio. In Turkey, concentrations of Zn, Cu, As, Cd, Hg and Pb in seven popular fish species of Ataturk Dam Lake (Euphrates, Turkey) were i nvestigated by (Mol et al.,2010). They found that the fish from Ataturk Dam Lake are not heavily burdened with metals, but they should be controlled periodically to avoid excessive intake of trace metals by human, and to monitoring the pollution of aquatic environment. In a study performed by (Yilmaz, 2009 ), to compare concentrations of Cd, Cu, Mn, Pb, and Zn in tissues of three economically important fish ( Anguilla anguilla, M. cephalus and O. niloticus) inhabiting Koycegiz Lake-Mugla (Turkey), th e highest concentration of trace metals in the tissues of M.cephalus in lake was attributed to the trophic characteristics of this species, that M.cephalus reflects the metal concentrations in surface and suspended particulate matter, showing high metal concentrations.he considered M. cephalus as an adequate and most suitable species for use as biomonitors of trace metals pollution in the Koycegiz Lake. Consequently, he recommended the use of these species as biological indicators as a tool for future monitoring programs, to evaluate the evolution of heavy metal pollution in that area. Results indicated that, concentrations of Pb and Zn for O. niloticus; Pb, Zn and Cd for A. anguilla; and Cd and Zn for M. cephalus were found higher than the Turkish Food Codex, European Units and WHO limits for human consumption in edible parts of the fish samples and posed a risk for human health. In another search, (Yilmaz et al., 2007) measured the concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn in muscle, gill and liver of two fish species ( Leuciscus cephalus and Lepomis gibbosus) that caught from Saricay, South-West Anatolia (Turkey). Results indicated that the concentrations were below the limits for fish proposed by FAO/WHO, EU and Turkish Food Codes and safe within the limits for human consumption in the edible parts of fish species in that region. Review of Literature Page 25

6 A comparison of Fe, Cu, Ni, Cr, Pb and Zn levels of Grey Mullet (M. cephalus ) and Sea bream (S.aurata ) caught in Iskenderun Bay (Turkey) was made by (Yilmaz, 2005). Generally, Results indicated that M. cephalus showed higher levels of metal contamination than S. aurata which attributed to the difference in foraging habits of the two species. Levels of Fe, Cu, Ni, Cr, Pb, and Zn were determined in the muscle, skin and gonads in M. cephalus and Trachurus mediterraneus species from Iskenderun Bay in Turkey by (Yilmaz, 2003) The results of this study showed that metals seem to be more concentrated in M. cephalus than in that of T. mediterra- neus. He reported that concentrations of some metals in some tissues exceeded the acceptable levels for a food source for human consumption designated by various health organizations. In France, (Shinn et al., 2009) assessed heavy metals contamination in River Lot between 1987 and The concentration of Cu, Zn, Cd and Pb were quantified in muscle and liver of fish species from the river as well as in water, sediment and moss. The results showed that the average concentrations of Cd in fish muscle in 2007 were above the maximum safe level for human consumption defined by the EC. In Nigeria, (Alinnor et al., 2010) performed a study to examine trace metal (Pb, Fe, Cd, Mn, Hg, Cu and Zn composition in fish samples from Nworie River and in frozen fish samples purchased from Ekeonunwa. They pointed out that untreated waste products discharged into Nworie river contaminated the biota in the aquatic system with these elements which it's toxicants will be transferred to man by consumption of fish obtained from the river. Also they found that frozen fish samples purchased from Ekeonunwa market were contaminated with heavy metals. Furthermore, (Olowu et al., 2010), determined the concentrations of Zn, Ni and Fe in tissues of two fish species, Tilapia and Cat fish from two stations in Lagos, Nigeria. They concluded that both fish species may be considered safe for consumption, but the need for continuous monitoring to prevent bioaccumulation is necessary. In another study in Nigeria (Christopher et al., 2009), studied the Distribution of Pb, Zn, Cd, As and Hg in Bones, Gills, Livers and Muscles of Tilapia (O. niloticus) from Henshaw town beach market in Calabar. The results showed that the muscle of Tilapia contained the least concentrations of the heavy metals determined. Review of Literature Page 26

7 (Obasohan et al., 2008) investigated accumulation levels of Cu, Mn, Zn, Cd, Ni and Pb in a freshwater fish (Erpetoichthys calabaricus) from Ogba river, Nigeria, during dry and rainy seasons. Findings showed that the accumulation levels in fish exceeded the levels of the metals in water and indicated bioaccumulation in fish and no significant differences of metal levels between the dry and rainy season. Findings also showed that both dry and rainy season mean levels of Cu, Mn and Ni in fish exceeded WHO recommended limits in food, suggested that the fishes of the river are not suitable for human consumption. They recommended that a close monitoring of metal pollution of Ogba river is strongly advocated, in view of the possible risks to health of consumers of fish from the river. Another study performed by (Sivaperumal et al., 2007), evaluated concentrations of Cd, Pb, Hg, Cr, As, Zn, Cu, Co, Mn, Ni, and Se in commercially important species of fish, shellfish and fish products from fish markets in and around the Cochin area, India. Results showed that different metals were present in the samples at different levels but within the maximum residual levels prescribed by the European Union (EU) and USFDA and the fish and shellfish from that areas, in general, were safe for human consumption. In USA, an investigation of As, Cd, Mn, Pb, Hg, and Se levels in commercial fish in New Jersey were performed by (Burger et al., 2005). They reported that the levels of most metals were below those known to cause adverse effects in the fish themselves. However, the levels of As, Pb, Hg, and Se in some fish were in the range known to cause some sub-lethal effects in sensitive predatory birds and mammals and in some fish exceeded health-based standards set by FAO, Environmental Protection Agency (EPA), WHO, FDA. In Argentina, (Marcovecchio, 2004) considered M. furnieri fish as good bio-indicator of heavy metal pollution in ecosystem. A marked relationship between metal contents of the studied species and their trophic and ecological habits was observed. The results indicated that levels of Hg, Cd and Zn found in edible muscle tissue were lower than the international standards for human consumption. In Uruguay M. furnieri, is considered as one of fish species which local population commonly uses for consumption. (Viana et al., 2005) determined concentrations of Review of Literature Page 27

8 Cu, Hg and Zn in muscle tissue of seven fish species including M. furnieri, from coastal waters of Uruguay. Results showed that the fish studied were acceptable for human consumption. Nejem et al., 2009, performed a study to detect some heavy metals ( Zn, Cu, Ag, Pb, Hg and Cd ) levels in some fruit and leaves grown in the polluted soil due to sewage water diffusion into planted land of Um Al Nasser village. Results showed a significant pollution of plants with some of the studied metals, which exceeded in some cases the allowed values approved by WHO and FAO. Mourtaja, 2008 determined concentrations of Zn, Cr, Cd, Pb and Cu in three marine fishes namely, Grey mullet, Barracuda and Sigan species. The average concentrations of these heavy metals in muscles of Grey mullet were for Zn:4.675; Cr: 0.120; Cd: 0.096; Pb: and Cu: ( g/g dry wt.). In Barracuda the average concentrations were 6.030, 0.151, 0,092, and 0.247( g/g dry wt.), respectively. In Sigan fish the averages were 6.258, 0.141, 0.123, and ( g/g dry wt.), respectively. Concentrations of Cu, Mo, Pb, Cd, Cr, Hg, Co, Zn and Fe were determined in some groundwater wells in Gaza strip by (El-Nahhal, 2006). Results in some wells showed that concentration of lead, cadmium, iron, and chromium were above EPA standards. In 2001 Palestinian ministry of environmental affairs (MEnA, 2001) assessed pollution sources in Gaza strip, it reported that the seawater quality of Gaza Strip has been highly polluted by sewage, sediments, nutrients, pesticides, litter and marine debris, and toxic wastes during thirty years of Israeli occupation. And this has left the coastal area in a bad and neglected state. Also it reported that lab analyses of the wastewater of some polluting industries in Gaza Strip showed that it contains some heavy metals with concentrations exceeding the permissible limits. This wastewater contains quantities of water used by the human population, whether for domestic or industrial purposes which are transported by the sewer system to the wastewater treatment plants and finally discharged with or without partial treatment into the Mediterranean Sea, contaminating the coastal waters. Review of Literature Page 28

9 Twelve elements included Ag, Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were analyzed by (Shomar et al., 2010) in 120 wastewater samples. The results revealed that domestic wastewater influent contains considerable amounts of metals. Schierup et al., 1981a investigated P. australis cycling of zinc, copper, lead, and cadmium in two Danish lakes, one being polluted, the other not. They found that uptake of these heavy metals by population of P. australis was greater in the unpolluted lake than in the polluted lake. They indicated that a differentiation in uptake could be established between real uptakes of heavy metals and chelation, compared to active functional groups in the cell walls and phenolic OH groups. The difference in uptake was dependent on edaphic factors rather than on the amount of heavy metals present in the sediment. Two of the edaphic factors thought to influence heavy metal availability are sediment ph, and sediment oxidation reduction (redox). The status was sufficiently different between the two lakes to explain the difference in uptake, i.e. uptake increased as redox increased or ph decreased. Widianarko et al., 2000 studied the relationship among sediment, water and fish for their metal concentrations in urban streams of Semarang, Indonesia and found a significant declining trend of lead concentrations with increasing organism size, whereas for two other metals, Zn and Cu, the concentrations did not depend on the body weight. However, metal concentration in the sediment was the most important factor governing the toxicity of metal in fish body. The fish living in highly polluted sites have also developed a physiological adaption by accumulating a large quantity of metals. Tole et al., 2003 carried out a study to establish the concentrations of Pb, Cd, As and Se in Lake Victoria waters, sediments and fish in order to assess the current threats to human health from heavy metal pollution, and also compare the current status with previous studies conducted in the Lake, so that current trends in heavy metal pollution in the Lake waters, sediments, and fish can serve as a pointer to future status. Nnaji et al., 2007 used flame Atomic Absorption Spectrometer (AAS). The Oreochromis niloticus and Synodontis schall were caught with cast net from twenty sampling points. The fish samples were dissected to separate the fish head/viscera Review of Literature Page 29

10 from other parts after weighing. The samples were digested with concentrated acid solution and the digests were analysed. Mean metal contents in the fish head/viscera of O. niloticus in the upstream and downstream area were calculated. After comparison of these values with FAO limits in fish tissue the study suggested that it is unsafe to consume the fish head/viscera of both fish species from River Galma. Abdallah, 2008 studied the concentrations of Cd, Pb, Cu, Cr and Zn in muscles of some commercially fish species collected from two coastal areas of the Egyptian coast of the Mediterranean Sea west of Alexandria (El-Mex Bay and Eastern Harbour). For all trace element examined, in all fishes zinc was the highest followed by Cr, Cu, Pb and Cd. The levels of Cr surpassed the maximum permissible concentration in most fish tissues, followed by Pb and Cd in some species. Cu and Zn concentrations were found to be below the maximum permissible levels proposed by Food and Agriculture Organization. In Saudi Arabia V, Cd, Zn, As, Ni, Pb and Hg levels in most common available fish species in Saudi markets were determined by (Al-Bader, 2008). Results showed that the concentrations of metals were below the maximum allowed limit by the Saudi and international legislations for fish human consumption permissible limit. Mourtaja, 2008 determined concentrations of Zn, Cr, Cd, Pb and Cu in three marine fishes namely, Grey mullet, Barracuda and Sigan species. The average concentrations of these heavy metals in muscles of Grey mullet were for Zn: 4.675; Cr: 0.120; Cd: 0.096; Pb: and Cu: (g/g dry wt.). In Barracuda the average concentrations were 6.030, 0.151, 0,092, and 0.247( g/g dry wt.), respectively. In Sigan fish the averages were 6.258, 0.141, 0.123, and (g/g dry wt.), respectively. Obasohan et al., 2008 investigated accumulation levels of Cu, Mn, Zn, Cd, Ni and Pb in a freshwater fish (Erpetoichthys calabaricus) from Ogba River, Nigeria, during dry and rainy seasons. Findings showed that the accumulation levels in fish exceeded the levels of the metals in water and indicated bioaccumulation in fish and no significant differences of metal levels between the dry and rainy season. Findings also showed that both dry and rainy season mean levels of Cu, Mn and Ni in fish exceeded WHO Review of Literature Page 30

11 recommended limits in food, suggested that the fishes of the River are not suitable for human consumption. They recommended that a close monitoring of metal pollution of Ogba River is strongly advocated, in view of the possible risks to health of consumers of fish from the River. Prasath et al., 2008 used Atomic Absorption Spectrophotometer for the detection of accumulation of heavy metals (Zn, Cu, Fe, Mn, Co, Pb, Cd and Ni) in water, sediments and fish ( Mugil cephalus) at Poompuhar coast (southeast coast of India) before and after Tsunami. Accumulation of heavy metals was observed in the order of Sediments > Fish > Water. In water, the order was found to be Mn > Fe > Zn > Cu > Ni > Cd > Co > Pb; Mn recorded a maximum of 506.9µ.L-1 and Pb recorded a minimum of µ.l-1 In sediments, the order was Mn > Fe > Cu > Zn > Pb Co Cd Ni; Mn recorded a maximum of 851.1µg.g-1 and a minimum of below detectable levels were found in Pb, Co, Cd and Ni. In fish, the order was found to be Fe > Zn > Mn > Cu > Ni > Co Pb Cd; Fe recorded a maximum of µg.g-1 and a minimum of below detectable levels were found in Pb and Cd. Saeed et al., 2008 presented a report about concentrations of Fe, Zn, Cu, Mn, Cd and Pb in O. niloticus (Tilapia) fish tissues, water and sediments in northern Delta Lakes. They found that the edible part of O. niloticus from Lake Edku and Manzala contained the highest levels of Cd while fish from Manzala Lake contained the highest level of Pb. They reported that Nile tilapia caught from these two Lakes may pose health hazards for consumers. Vinodhini et al., 2008 determined the bioaccumulation of heavy metals in various organs of the fresh water fish exposed to heavy metal contaminated water system using Atomic Absorption Spectrophotometer. The experimental fish was exposed to Cr, Ni, Cd and Pb at sub lethal concentrations for periods of 32 days. The results were given as µg/g dry wt. The accumulation of heavy metal gradually increases in liver during the heavy metal exposure period. All the results were statistically significant at p < The order of heavy metal accumulation in the gills and liver was Cd > Pb > Ni > Cr and Pb > Cd > Ni > Cr. Similarly, in case of kidney and flesh tissues, the order was Pb > Cd > Cr > Ni and Pb > Cr > Cd > Ni. In all heavy metals, the Review of Literature Page 31

12 bioaccumulation of lead and cadmium proportion was significantly increased in the tissues of Cyprinus carpio (Common carp). Rauf et al., 2009 carried out a study to determine heavy metal (cadmium and chromium) concentrations in gills, kidneys, liver, skin, muscles and scales of three fish species (Catla catla, Labeo rohita and Cirrhina mrigala). The sample collection was carried out from three places viz. Lahore Siphon (Up-stream), Shahdera Bridge and Baloki Headworks (Down stream) in the River Ravi, Pakistan. The res ults showed that Heavy metal concentrations varied significantly depending upon the type of fish tissues and locations. The concentrations of Cd and Cr differed significantly (p<0.001) among five fish organs and three sites and non-significantly between the three fish species. Fish liver appeared to have significantly higher tendency for the accumulation of cadmium and chromium (4.26 ± 1.57 and 6.23 ± 1.14 µgg-1), while gills had minimum concentrations (1.10 ± 0.53 and 1.46 ± 0.52 µgg -1) of these metals. Generally, Catla catla showed higher levels of metal concentrations than Labeo Rohita and Cirrhina mrigala. Metal contamination was highest at Baloki Headworks, probably due to inclusion of more effluents from industrial and sewage water. Lakshmanan et al., 2009 carried out a study on the detection of accumulated heavy metals in the fishes of Parangipettai coastal waters. The fishes are important from the commercial point of view and analyzed for the Zn, Pb, Cr, Co and Cd concentrations in the muscles. The statistical results suggested that there is no significant speciesspecific difference. The highest concentration of Cr and Zn whereas lowest concentration of Pb<Cd<Co in the five species of fish tissues were detected. The concentration of elements in muscles is reported as 0.415± ±1.49, 0.103± ±0.13, 0.114±0.14 and 0.006± ±0.00 ppm for Cr, Zn, Pb, Cd and Co respectively. Cd, Co and Pb were found highly concentrated in muscles of The Anchoviella commersonii fish comparative to other fish studied. However, the Upeneus vittatus contained the highest concentrations of Zn and lowest concentration of most of the metals. The authors suggested that there is no hazard to human being on consuming these fishes as the metal concentrations found in there study were Review of Literature Page 32

13 similar to the metal levels of the fishes collected from pitchavaram mangroves and mudasalodai landing centre. In India, (Raja et al., 2009), determined the concentrations of Cr, Cd, Cu, Fe, Mg, Mn, Ni, Co, Zn and Al in four commercially available marine edible fish species from Parangipettai coast. They reported that metal levels in edible parts of the investigated fish was in the permissible safety levels for human uses according to FAO, 1983; EC, 2001; Food and Drug Administration, 2001 standards. Mandour et al., 2011 used atomic absorption spectrophotometer for the analysis of Fifty-four drinking groundwater samples collected in April 2010 from some districts of the Dakahlyia governorate, Egypt. The water samples were analyzed for Fe. Mn, Pb, Ni, Cr, Zn, Cu, Co and Cd concentrations. Two were found suitable for drinking; from the water sample from Aga district showed slightly higher levels of Cd and Ni (Ikhtab and Feshbena) than other areas; the concentrations were higher than the permissible limits of Egyptian Ministry of Health and WHO. Sabra et al., 2011 carried out the sequential extraction study on the sample of sediment of Deule canal. The sediments were subjected to a physico-chemical characterization comprising particle size classification and heavy metals sequential extraction studies. Study reported the total metallic concentrations of several metals such as Cd, Zn, Pb or Cu exceeded from the limit permitted by French standards. Particles that are less than 53 µm in size contains as an average, 92% of the total weight of each metal. These particles represent about 85% of the suspended matter dry weight. This sequential extraction study revels that most of the studied metals are strongly linked to the sediments because of their association with the sulphides and with the organic matter. Kaur et al., 2012 used ICP-MS for the monitoring of seasonal variation (Year 2011) of the heavy metals concentration of water of Yamuna River flowing through Delhi. The analysis was carried out for the heavy metals Pb, Fe, Zn, Mn, Cd, Co, Cu, Cr and Ni. For this purpose, sampling was done from ten selected study sites (most likely to be affected by industrial & anthropogenic activities) during two seasons i.e. summer Review of Literature Page 33

14 (May) and winter (January). Result shows broad variation in the heavy metal levels varying from high concentration during summer and low concentrations during winter season. The concentration of Pb, Cd, Cr, Cu, Zn and Co was detected under the permissible limits of ICMR, CPCB, WHO and EPA. Eminent concentrations of Fe, Ni & Mn were reported at Boat club, Yamuna Bazaar, Nigambodh Ghat, Delhi old Bridge, ITO, Nizamuddin Bridge and Mayur Vihar. Also, Pb, Cd, Cu and Co have shown significant variation (p<0.05) in their concentratio n between summer and winter seasons, with less accumulation during winter and high during summers. Authors discussed that high heavy metal concentration during summer may be attributed to increased water temperature during summer that may result in increased metal toxicity. Shabanda et al., 2012 used atomic absorption spectrophotometer for the detection of Cd, Cr, Pb, Mn and Al in water, sediments, gills and flesh of both Synodntissorex and Bagrus filamentosus from River Jega in Kebbi State, Nigeria. The pattern of distribution of the heavy metals showed a preponderance of Cr and Mn over other metals in the organs of the two fish species as well as in the water and sediment samples. Al was not detected in the organs of fish species, water and sediment. The concentration of Mn was found highest in the sediment and lowest in water. The unexpectedly high concentration value obtained for Cr and Mn calls for medical alertness since it exceeded the WHO recommended acceptable limits for consumption. Cd and Pb distribution in all the samples was lower than the WHO and USEPA recommended acceptable limits for consumption. Rios-Arana et al., 2003 studied the presence or impacts of heavy metals (Cr, Cu, Cd, Ni, Pb, and Zn) and arsenic in ecosystem due to anthropogenic activities at the Rio Grande located along the US Mexico border. Zinc and lead were found as both total and dissolved metals in most of the samples, with concentrations of total recoverable metals reaching up to 105 and 70 µg/l, respectively. Most metals were found in sediment samples. The highest Cu concentration (35 mg/l) was found at the American Dam site. Concentrations of metals found through this survey will be used as a reference for future studies in monitoring arsenic, heavy metals, and their impacts in the Rio Grande. Review of Literature Page 34

15 Chobtang (2002) studied six heavy metal residues as Hg, Pb, Cd, Cr, Ni a nd As in water collected in the mangrove at Royal Laem Phak Bia Environmental Research and Development Center, Amphoe Ban Laem, Phetcha Buri province. The results indicated that heavy metal levels before entering the mangrove forest were mostly within the standard criteria of coastal zone area except for Hg and the heavy metal levels which came out of the mangrove forest were higher than those before entering the mangrove forest. The heavy metal levels in both areas were within the standard criteria except for Hg and Cd. The statistical test of each heavy metal at three sites found that the difference was statistically significance (p < 0.05) for Cd. For Ni it was found that the levels found in the water and sediments were in the same direction. Hg had a relation in the opposite direction. In sediments the results showed that the mangrove forest near the wastewater releasing point had higher heavy metal levels (except for Hg and As) than the area far from releasing point. The mangrove forest at Ban Laem Phak Bia had higher heavy metal levels (except As) than the mangrove forest at Ban Laem Phanoen. The heavy metal levels in both areas were within the standard criteria. The statistical test of each heavy metal at three sites found that the difference was not statistically significance (p < 0.05) for all heavy metals. Pb, Cd, and Ni levels in sediments and crabs had a relation in the same direction while Cr and As levels had a relation in the opposite direction. Bunsong (2003) studied the accumulation of eight heavy metals (Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) in water, sedim ent, and selected tissues of aquatic organisms in Klong phasicharoen from May 2002 to April Samples of water, sediment, plankton, aquatic plants, mollusks and fish were taken once a month at three sampling sites: Phasicharoen, Nongkham and Kratumbaen. The dry samples were digested with concentrated nitric acid in microwave digestion system and determination for heavy metals was carried out by using Flame Atomic Absorption Spectrometer (FAAS). The results were found that the concentrations of dissolved Fe, Mn and Zn in surface water showed the most variation and were highest at Kratumbaen. Concentrations of Cr, Cu, Fe, Pb, Mn and Ni in sediment were high at Nongkham. Plankton and water hyacinth from Nongkham and Kratumbaen contained very high concentrations of Cr, Cu, Ni and Zn, while concentrations of Fe and Pb were considerably high at Phasicharoen. In addition, the accumulation of heavy metals in target tissues of fish and mollusk was found at high concentrations at these areas as well. These heavy Review of Literature Page 35

16 metals were higher in the roots of water hyacinth than in the leaves. Fish livers and kidneys accumulated high levels of Fe, Zn and Cu while Mn and Zn were detected in the gills at high concentrations. Mollusk accumulated high levels of Fe, Zn and Cu in the foot, while Mn was at high levels in the gills. Fe, Zn and Cu accumulated at high levels in both the foot and the gills, whereas the mantle had the lowest concentrations of these heavy metals. The result showed that bioaccumulation of heavy metals occured in the organisms at the lower levels of the food chain and no biomagnification was detected at the upper levels, except for Cu in mollusks and fish. This study indicated that copper showed bioaccumulation and biomagnification through the higher trophic levels. Deng et al., 2004 studied the accumulation of Pb, Zn, Cu and Cd accumulated in 12 wetland plant species thriving in metal-contaminated sites in China. The results showed that metals accumulation by wetland plants differed among species, populations and tissues. Populations grown in substrata with elevate metals contained significantly higher metals in plants. Metals accumulated by wetland plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. The factors affecting metal accumulation by wetland plants include metal concentrations, ph and nutrient status in substrata. Copper is necessary trace element that at low level can result in anemia, gastrointestinal disturbances, bone development abnormalities and death (Eisler, 1997). However, at higher levels in fish, copper can cause sublethal effects on respiration, osmoregulation, behavior, growth, metabolism and death (Handy, 1993). Chobtang (2002) studied six heavy metal residues as Hg, Pb, Cd, Cr, Ni and As in water collected in the mangrove at Royal Laem Phak Bia Environmental Research and Development Center, Amphoe Ban Laem, Phetcha Buri province. The results indicated that heavy metal levels before entering the mangrove forest were mostly within the standard criteria of coastal zone area except for Hg and the heavy metal levels which came out of the mangrove forest were higher than those before entering the mangrove forest. The heavy metal levels in both areas were within the standard criteria except for Hg and Cd. The statistical test of each heavy metal at three sites found that the difference was statistically significance (p < 0.05) for Cd. For Ni it was found that the levels found in the water and sediments were in the same direction. Hg Review of Literature Page 36

17 had a relation in the opposite direction. In sediments the results showed that the mangrove forest near the wastewater releasing point had higher heavy metal levels (except for Hg and As) than the area far from releasing point. The mangrove forest at Ban Laem Phak Bia had higher heavy metal levels (except As) than the mangrove forest at Ban Laem Phanoen. The heavy metal levels in both areas were within the standard criteria. The statistical test of each heavy metal at three sites found that the difference was not statistically significance (p < 0.05) for all heavy metals. Pb, Cd, and Ni levels in sediments and crabs had a relation in the same direction while Cr and As levels had a relation in the opposite direction. Guhathakurta (2000) studied heavy metal concentration in water, sediment, shrimp (Penaeus monodon) and mullet ( Liza parasia) in some brackish water ponds of Sunderban, India. Concentrations of Cd, Zn, Pb and Fe were determined in the brackish water ponds of Sunderban mangrove system of India at five different localities. Concentration of the metals in pond water were in the descending order of Fe > Zn > Pb > Cd, whereas in the accumulation of metals in the pond sediment, There was a significant variation of Zn and Fe concentrations in the sediment among the localities. In the surface layer of the sediment (upto 10.0 cm depth) was found that the concentrations of Fe were higher than Zn. Background concentration of Fe in the sediment (30.0 cm deep stratum) was very high in all the localities All the metals in the surface layer of sediment showed a characteristic pattern of partitioning among various chemical fractions of the sediment. Lertprasert ( 2006) studied the accumulation and distribution of heavy metals in water, sediment, I. aquatica and R. apiculata in the Phi Lok canal system, Samut Songkhram province. The results showed that five heavy metal concentrations in water can be presented in descending order as follows: Fe > Zn > Cu > Pb > Cd while the average heavy metal concentrations in sediment can be presented in descending order as follows: Fe > Zn > Pb > Cu > Cd, and the average heavy metal concentrations in shoots and roots of R. apiculata and I. aquatica can be presented in descending order as follows: Fe > Zn > Cu > Pb > Cd. When comparing heavy metal concentrations among water, sediment, shoots and root, it was found that for five heavy metals, each of the average concentrations can be presented in descending order as follows: Cd : root > sediment > shoots > water, Cu: sediment > root > shoots Review of Literature Page 37

18 > water, Fe : sediment > root > shoots > water, Pb: sediment > root > shoots > water, Zn: sediment > root > shoots > water. When comparing the heavy metal concentrations in monthly variations in water, the results showed different trends in concentration. The present study showed that the mean difference is significant in concentrations of Cd, Cu, Fe, Pb and Zn in the periods of collection; whereas in sediment, it was found that the mean difference is significant in concentrations of Cd, Cu, Fe, Pb and Zn in the periods of collection, for the aquatic plants, the mean difference of Cd, Cu, Pb and Zn in roots was found, while significantly different mean concentration of Fe, Cu, Pb and Zn concentrations were found in shoots. Rai and Sinha (2001) studied the distribution of metals in aquatic edible plants: Trapa natans (Roxb.), Makino and Ipomoea aquatica Forsk. Most of the water bodies being used for the cultivation of edible aquatic plants ( T. natans and I. aquatica) in Lucknow district, U.P., India, were found to be contaminated with a variety of toxic metals (Fe, Cu, Cr, Mn and Pb). The edible parts of these plants bioconcentrated metals from their surrounding water significantly. Despite varying levels of metals found in various fruit parts of T. natans, the metal accumulation in kernel was alarming. However, metal content decreased significantly in various parts after boiling the fruit. Similarly, I. aquatica also accumulated significantly higher amounts of these metals in leaves; however the metal accumulating potential varied considerably depending upon level of metal contamination in the water body in which they were growing. The importance of these findings in the exploitation of these aquatic crops to meet the demand of food and health perspectives for human beings is highlighted. Review of Literature Page 38