Assessment of heavy metals in water,sediment, Anabas testudineus and Eichhornia crassipes in a former mining pond in Perak,Malaysia

The concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn were analysed in water, sediment, muscle of climbing perch fish (Anabas testudineus), and tissue of water hyacinth plants (Eichhornia crassipes) collected from a former tin-mining pond in Perak, Malaysia. The monitoring was performed during the minimum and maximum rainfall periods. The concentrations of As, Cr, Fe, Ni, Pb and Zn in water exceeded the permissible limits set by the Interim National Water Quality Standards for Malaysia (INWQS). The risk index (RI) values determined for As, Cd, Cr, Cu, Hg, Pb and Zn in sediment presented a low degree of ecological risk. The order of the top three heavy metals measured in fish muscle was Zn?>?Fe?>?Al. The estimated daily intake (EDI) of As and Cr exceeded the allowable limits in both rainfall periods. The bioconcentration factor (BCF) and translocation factor (TF) values of Zn in water hyacinth were 24.865 and 3.214, respectively. The concentrations of Cu and Zn in the plant tissue were significantly correlated (p?<?.05) with the concentrations of heavy metals in water. Overall, climbing perch and water hyacinth are excellent bioindicators of environmental impacts on water bodies.     

Metal accumulation in sediment,water, and freshwater fish in a Dam Lake

Metal concentrations were determined in water, sediment, and freshwater fish samples (Squalus cephalus, Barbus esocinus, and Barbus xanthopterus) collected from Karakaya Dam Lake, Turkey, to estimate the risk of human consumption and pollution. Metal concentrations differed between the species (p??Zn?=?Cu in water and Fe?>?Zn?>?Mn?>?Ni?>?Cu in sediment. In general, the accumulation order of elements in the tissues all of the species sampled were found as Fe?>?Zn?>?Se?>?Mn?>?Cu?>?Ni?>?Cd in muscle, Zn?>?Fe?>?Mn?>?Se?>?Cu?>?Ni?>?Cd in gills, Fe?>?Zn?>?Se?>?Mn?>?Cu?>?Ni?>?Cd in liver and gonad, and Zn?>?Fe?>?Cu?>?Mn?>?Se?>?Ni?>?Cd in kidney. It was concluded that the fish from the dam lake are not heavily burdened with metals, but they should be controlled periodically to avoid excessive intake of trace metals by humans, and to monitoring the pollution of aquatic environment.     

Trace metals in fish of economic interest from the west of Alexandria,Egypt

The concentration of some heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, and Zn) in the muscle, liver, and gills in eight fish species, Caranx crysos, Euthynnus alleferatus, Scomberomorus commerson, Sphyraena viridensis, Sargus sargus, Siganus rivulatus, Mugil species, and Sardinella aurita were collected seasonally from the Mediterranean Sea in the region of Alexandria. The highest concentrations of Cd, Cu, Fe, and Zn were measured in liver tissue, while gill tissue yielded the highest concentrations of Mn, Ni, and Pb. Muscle is the organ of poor accumulation factor for all metals under investigation. Concentration of cadmium in muscle in Mugil species exceeds the permissible limit in summer, while Siganus rivulatus exceeds it in the summer and autumn seasons. On the other hand, copper, nickel, lead, and zinc are still much lower than the permissible levels. The metal pollution index (MPI) for metals was studied, revealing that Siganus rivulatus, Mugil species and Sardinella aurita had the highest MPI. Provisional tolerable daily intake (PTDI) indicates that the concentration levels of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in the muscle of all fish species under investigation are much lower than recommended PTDI values, and accordingly there is no risk for the human consumption of these fish species.     

Trace metals in fish,sediment and water from the south west coast of the Arabian sea,Pakistan

Concentrations of ten metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Hg) in the edible muscle of Arius maculatus captured from eight different near‐shore and off‐shore sites off the south west coast of the Arabian Sea, Pakistan, were determined by atomic absorption spectrophotometry. Relevant water and sediment samples from the sites were also analysed for the metals. Zinc showed the highest metal concentration (6.763 μg/g, wet weight) in the muscle of the fish, while Mn and Hg showed lowest level (0.019 μg/g, wet weight). Of all the metals investigated, largest scatter (measured as σ) was observed for Zn (σ = 2.058 /μg/g) in fish muscle, for Fe and Mn in sediment (σ = 27481 and 44.50 μg/g) and for As in water (σ = 0.270 μg/L). The metal distribution data pertaining to water, fish and sediment were examined on the basis of simple metal correlations. The statistical study revealed that Ni, Cr, Pb and Cu had significant positive correlations (r > 0.830 at ρ = 0.01). The finding substantiated a trace metal concentration gradient in the area, thereby indicating that the local marine environment is contaminated by anthropogenic sources.     

Physicochemical characteristics and distribution of some metals in the ecosystem of Lake Nasser,Egypt

To know the interrelationship between some metals in different ecosystem components (water, sediment, aquatic plant and fish), many samples from these components were collected from four bights at the Nasser Lake, Egypt, and analyzed for Fe, Mn, Zn, Ca, Mg, Pb, Cd, Ni, Co, Cu and Cr using atomic absorption spectrophotometer. Different distribution factors (bioaccumulation factor – BF, discrimination factor – DF and enrichment factor – EF) were applied on the results of analysis. Data showed that the relatively high concentration of measured metals in water samples are derived from fish farms, and discharge of tourism and trade ships. Applying single leaching sequential technique on sediment samples, using different extracting solutions, revealed a strong ability of trace metals to adsorb on or co-precipitate with amorphous Fe/Mn oxides. High concentrations of Fe, Mn, Co and Ni were measured in the intestine while high Cd and Cr concentrations were recorded in the stomach in both Tilapia (nilotica and galilea). Tilapia galilea accumulated high Pb, Cu and Zn concentrations in their stomach, while in nilotica high concentrations of Pb, Cu and Zn were measured in the intestine, liver and muscles, respectively. Myriophyllum spicatum (an aquatic plant) in the lake recorded high concentrations of Fe, Mn and Zn. Bioaccumulation factors of studied elements in the different bights components indicate that the elevated concentration of measured elements in the aquatic plant and Tilapia (nilotica and galilea) are derived from water, reflecting the increase of human activities in Nasser Lake in recent years. However, the present study concluded that all the elements studied were still below the natural back-ground levels, except Zn and Cu.     

Toxicity of metals to tadpoles of the common Sunda toad,Duttaphrynus melanostictus

Tadpoles of the common freshwater Sunda toad, Duttaphrynus melanostictus (Amphibia, Bufonidae), were exposed for a 4-day period under laboratory conditions to copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminum (Al), and manganese (Mn) at various concentrations. Mortality was assessed and median times of death (LT₅₀) and lethal concentrations (LC₅₀) were calculated. LT₅₀ and LC₅₀ increased with the decrease in mean exposure times and concentrations for all metals. LC₅₀ (96?h) for Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 0.03, 0.3, 4.2, 1.5, 8.8, 0.4, 1.9, and 39?mg?L^?1, respectively. Cu was the most toxic to D. melanostictus, followed by Cd, Fe, Al, Pb, Zn, Ni, and Mn (Cu?>?Cd?>?Fe?>?Al?>?Pb?>?Zn?>?Ni?>?Mn). Duttaphrynus melanostictus is similarly sensitive to these metals as other amphibian tadpoles.     

Environmental impact of leaching of trace elements from fly ash dumps on aquatic ecosystems

Ten sampling points were selected in Kanhan River, situated near the ash dump sites of Koradi Thermal Power Plant, Nagpur. The leaching of trace elements from fly ash dumps was experimentally determined by acid digestion, batch leaching and toxicity characteristic leaching procedure tests. Elemental concentrations in river water, sediment, plankton and five commonly prevailing fish species (Catla catla, Labeo bata, Cyprinus carpio, Cirrhinus reba, Puntius ticto) were determined using a Flame Atomic Absorption Spectrophotometer during the pre-monsoon and post-monsoon seasons. Metal concentrations (Cr, Mn, Zn, Cu, Fe, Ni, Cu and Pb) in river water were higher during the pre-monsoon season compared to the post-monsoon season. Zn (30.65?mg/kg) was observed to be the most predominant metal in plankton during the pre-monsoon season while, during the post-monsoon season, Fe (21.19?mg/kg) showed the maximum concentration. Muscles of C. catla had metal concentrations (Cr, Mn, Zn, Fe, Cu and Pb) above the permissible limits of Food and Agricultural Organization (FAO 1983) during the pre-monsoon season. Bioaccumulation factor (BAF) was found highest for Cr (37.5) in muscles of C. catla during the pre-monsoon season, while BAF was observed to be maximum in L. bata for Cu (28.09), which may be detrimental for human consumption.     

Heavy metal concentration in water,sediment, and tissues of fish species (Heteropneustis fossilis and Puntius ticto) from Kali River,India

The river Kali has been one of the major recipients of industrial effluents in the Muzaffarnagar district of western Uttar Pradesh. The present studies revealed the occurrence and bioaccumulation of heavy metals (Cd, Cr, Pb, Zn, Mn) in riverine water, sediment, and muscles of two fish species, Heteropneustis fossilis and Puntius ticto. Data showed that the order of occurrence of heavy metals was Pb > Zn > Mn > Cr > Cd in river water, Mn > Zn > Pb > Cr > Cd in sediment, Zn > Mn > Cr > Cd > Pb in Puntius ticto and Cr > Zn > Mn > Cd > Pb in Heteropneustis fossilis. Results indicate that the concentrations of Cd, Pb, and Zn in river water, Pb, Zn, and Mn in sediment, Cd, Cr, Pb, and Zn concentration in muscles of Puntius ticto and Cr, Pb, and Zn concentration in in muscles of Heteropneustis fossilis are higher than the permissible standard limits. The presence of heavy metals contributed to toxicity in different organs of fish in River Kali. The bioaccumulation of heavy metals in different biotic organisms in river ecosystem may have adverse consequences on humans and livestock.     

Observations on metal concentrations in commercial landings of two species of tilapia (Oreochromis mossambicus and Oreochromis niloticus) from reservoirs in six river basins in Sri Lanka

Samples of the muscle of two species of tilapia (Oreochromis mossambicus and O. niloticus; 17–20 cm length) were obtained from at least one reservoir in each of the six river basins (Aruvi Aru, Kala Oya, Kirindi Oya, Ma Oya, Mahaweli, and Walawe Ganga catchments) in Sri Lanka. The metals Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were consistently detected in the muscle tissue. Overall, there were few differences in the concentration of metals between the two species of fish, although there were also some statistically significant differences (p < 0.05) in the concentrations of some metals in fish obtained from some of the reservoirs. Aruvi Aru stands out as a river basin in which the two fish species have significantly lower concentration of metals when compared to other river basins. The concentration of the metals studied were below WHO and FSANZ guideline values for fish, suggesting that the consumption of the metals found in tilapia from these reservoirs poses little risk to human health.     

Trace elements and organochlorine pollutants in selected fish species from Lake Phewa,Nepal

Lake water and fish livers and gills of sahar (Tor putitora), spiny eel (Mastacembelus armatus), African magur (Clarias gariepinus), and tilapia (Oreochromis niloticus) from Lake Phewa, Nepal, were assessed for the concentrations of trace metals/elements and persistent organic pollutants. The lake water was neutral with low ionic and metallic concentrations as compared to high-altitude lakes of Nepal. The four elements Cu, Zn, Se, and Cd had highest concentrations in livers, indicating uptake from diet, whereas four other metallic elements Cr, Mn, Ni, and Pb had highest concentrations in gills, indicating uptake from lake water. O. niloticus tended to have most of trace metals in the liver at higher concentrations than the other species but significant differences among the different species were found only for Mn, Ni, and Zn in the gills. A pilot study on the concentrations of persistent organic pollutants in muscle revealed that dichlorodiphenyltrichloroethane and related compounds were the dominant organochlorine pesticides, having highest concentrations in C. gariepinus and lowest in O. niloticus.     

Methylmercury, total mercury and total selenium in four common freshwater fish species from Ya-Er Lake, China

Snakehead fish (Ophiocephalus argus cantor), silver carp (Hypophthalmichthys molitrtix), crucian carp (Carassius carassius), and common carp (Cyprinus carpio) are four common freshwater fish species in China. In this study, the level of methylmercury (MeHg), total mercury (T-Hg), and total selenium (T-Se) in muscle samples of these four fish species from Ya-Er Lake, China, were analyzed using atomic fluorescence spectrometry coupled with high-performance liquid chromatography, and inductively coupled plasma mass spectrometry. The concentrations of MeHg in all the fish species were significantly correlated with those of T-Hg. Higher T-Hg and MeHg concentrations had accumulated in the snakehead fish, which is a strongly predatory fish, than in the other three species. The concentration ratios of MeHg and T-Hg in the muscles of these four fish species were almost equal. Conversely, there was negative correlation between the concentrations of T-Hg and T-Se, which implies that there is a competition between these two elements with respect to bioaccumulation. It is noteworthy that of all the muscle samples tested, the level of T-Hg exceeded the maximum allowable limit in fish [0.4 mg kg⁻¹ (w/w) recommended by the World Health Organization] in 38.46% of those of the silver carp, 18.18% of those of the crucian carp, and 100% of those of snakehead fish. These results show that the consumption of contaminated fish is a potential threat to human health and that necessary preventive measures to safeguard public health should be emphasized.     

A study on the accumulation of nine heavy metals in some important fish species from a natural reservoir in Riyadh,Saudi Arabia

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.     

Interactions between metals accumulated in the narrow-clawed crayfish Astacus leptodactylus (Eschscholtz, 1823) in Dikilitaş Lake,Turkey

The accumulations of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn in the exoskeleton, gills, hepatopancreas and abdominal muscles of crayfish Astacus leptodactylus (Eschscholtz, 1823) were determined. The strongest correlation observed was between Cr and Ni in the gills (r?=?0.904); moderate to strong correlations between Al, Cr, Fe, Ni and Cu were also observed in gill tissue. Disregarding the gills, the strongest correlation was found between Cu and Zn in the hepatopancreas (r?=?0.808); the correlation between these two metals might have been a result of metallothionein activity. The accumulation of Pb was found to correlate with that of Cd in the exoskeleton, Cd and Zn in the gills, Zn and Cu in the hepatopancreas and Cu in the abdominal muscle. None of these correlations were present in lakewater and sediment samples, suggesting that the crayfish metabolism may be responsible for the co-accumulation of metal–metal pairs. As all correlations in non-gill tissues are observed between divalent metals, a shared transporter such as divalent metal transporter 1 might be involved in the accumulation of these metals.     

滦河流域鲫鱼体内重金属分布及风险评价

采集滦河流域鲫鱼样本并分析重金属元素(Cu、Zn、Cr、Pb、As、Cd)在其体内的分布特征及食用风险。实验结果表明鲫鱼体内重金属含量由高到低顺序为ZnCrCuPbAsCd,蓄积器官主要为肝脏和鳃部,Cu和Cr主要蓄积在肝脏,Zn、Pb、Cd主要富集在鳃部,As的蓄积器官随地域变化,而且下游样本中各组织器官重金属含量下游高于上游。针对鲫鱼肌肉的评价表明,Zn、Cr、Pb含量超出《无公害食品水产品中有毒有害物质限量》(NY5073—2006)、《食品污染物限量》(GB2762—2012)和《食品中锌限量卫生标准》(GB 13106—1991)规定的标准限值,超出倍数依次为Cr(3.34)Pb(2.24)Cd(1.15)。基于目标危险系数法(THQ)评价结果表明鲫鱼肌肉组织单一重金属THQ值均小于1,As导致的健康风险最高,Cr最低;总风险系数(TTHQ)显示下游的溯河(TTHQ=1.263)与陡河(TTHQ=1.381)存在食用风险,风险比重较高的元素是As、Pb、Zn。     

Levels of heavy metals in blue whiting caught from the eastern Black Sea area of Turkey

This paper presents data on the concentrations of 5 metals, copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn) and lead (Pb) in Blue Whiting sampled from the Eastern Black Sea coast of Turkey. The highest metal concentrations of Cu, Cd, Fe, Zn and Pb were recorded in Blue Whiting with the values of 2.71, 0.601, 14.137, 15.322 and 1.078 μg g^‐1 dry weight, respectively. On average the metal concentrations in Blue Whiting followed the order of Zn > Fe > Cu > Pb > Cd. Temporal differences of concentrations of these metals were significant (p < 0.05). Spatial fluctuations of Cu, Cd, Fe, Zn and Pb concentrations in Blue Whiting were also significant (p < 0.01). It was found that the concentrations of Cu, Cd, Fe, Zn and Pb in the muscle in Blue Whiting were below the limit of Public Health Regulation in Turkey.     

Pollution assessment of the lower basin of Lakes Kainji/Jebba, Nigeria: heavy metal status of the waters, sediments and fishes

The objective of this investigation was to examine the heavy metal status of the lower basin of Kainji dam (used for hydroelectricity generation), which includes Lakes Kainji/Jebba, Nigeria, and the potential for human exposure to heavy metals from eating fish caught in the lakes. Water, sediments and fish were sampled from the lakes and evaluated for As, Cu, Co, Cr, Fe, Hg, Mn, Ni, Pb, Sb, Ti, V and Zn using the EDXRF technique. Fe and Mn were found to be present at high mean concentrations in the water (13 and 9 μg L^-1), sediment (7092 and 376 μg g^-1) and fish (11.4 and 4.6 μg g^-1) samples. Sb (3.2 μg L^-1), Ti (4.1 μg L^-1), Cr (2.2 μg L^-1), Co (1.2 μg L^-1), Cu (1.3 μg L^-1) and Pb (1.2 μg L^-1) in the water samples and Sb (29 μg g^-1), Ti (27 μg g^-1), V (27 μg g^-1), Cr (27 μg g^-1), Co (40 μg g^-1), Ni (33 μg g^-1), Cu (25 μg g^-1), Zn (59 μg g^-1) and Pb (19 μg g^-1) in the sediment samples were found to be of medium mean concentrations. The other metals were present at trace levels (<1 μg), including As and Hg in the fish and sediment samples. There was an appreciable increase in␣metal concentrations in going from the water to the sediment samples. The probable source of the pollutants is anthropogenic, arising from agricultural activities, corrosion/abrasion of the ferrous steel material and additives in the lubricants and insulation used for auxiliary services on the turbine floor of the dam constructed on the lakes. However, natural geological sourcing from the underlying lake rock cannot be totally ignored, particularly the high levels of Fe and Mn in the sediment samples. The potential risk for human exposure to these metals emanates from the fish caught in the lakes and subsequently consumed, as there are already significant levels of these metals in the two fish species analysed, Tilapia (Oreochromis niloticus) and Chrysicthys (Chrysicthys auratus).     

A Screening-Level Assessment of Lead, Cadmium, and Zinc in Fish and Crayfish from Northeastern Oklahoma, USA

The objective of this study was to evaluate potential human and ecological risks associated with metals in fish and crayfish from mining in the Tri-States Mining District (TSMD). Crayfish (Orconectes spp.) and fish of six frequently consumed species (common carp, Cyprinus carpio; channel catfish, Ictalurus punctatus; flathead catfish, Pylodictis olivaris; largemouth bass, Micropterus salmoides; spotted bass, M. punctulatus; and white crappie, Pomoxis annularis) were collected in 2001--2002 from the Oklahoma waters of the Spring River (SR) and Neosho River (NR), which drain the TSMD. Samples from a mining-contaminated site in eastern Missouri and from reference sites were also analyzed. Individual fish were prepared for human consumption in the manner used locally by Native Americans (headed, eviscerated, and scaled) and analyzed for lead, cadmium, and zinc. Whole crayfish were analyzed as composite samples of 5--60 animals. Metals concentrations were typically higher in samples from sites most heavily affected by mining and lowest in reference samples. Within the TSMD, most metals concentrations were higher at sites on the SR than on the NR and were typically highest in common carp and crayfish than in other taxa. Higher concentrations and greater risk were associated with fish and crayfish from heavily contaminated SR tributaries than the SR or NR mainstems. Based on the results of this and previous studies, the human consumption of carp and crayfish could be restricted based on current criteria for lead, cadmium, and zinc, and the consumption of channel catfish could be restricted due to lead. Metals concentrations were uniformly low in Micropterus spp. and crappie and would not warrant restriction, however. Some risk to carnivorous avian wildlife from lead and zinc in TSMD fish and invertebrates was also indicated, as was risk to the fish themselves. Overall, the wildlife assessment is consistent with previously reported biological effects attributed to metals from the TSMD. The results demonstrate the potential for adverse effects in fish, wildlife, and humans and indicate that further investigation of human health and ecological risks, to include additional exposure pathways and endpoints, is warranted.This study was conducted by the Columbia Environmental Research Center (CERC) of the U.S. Geological Survey (USGS) and cooperating organizations and government agencies. All field and laboratory procedures conformed to the “Guidelines for the use of fishes in research” of the American Fisheries Society (AFS), Institute of Fishery Research Biologists (AIFRB), and American Society of Ichthyologists and Herpetologists (ASIH) Use of Fishes in Research Committee (AFS, AIFRB, and ASIH 2004), and with all USGS and CERC guidelines for the humane treatment of test organisms during culture and experimentation. Use of trade names does not constitute USGS or U.S. government endorsement.     

Trends in sediment metal concentrations in the River Avoca, South-East Ireland

Variation in sediment metal concentrations in the River Avoca, which is severely polluted by acid mine drainage (AMD) discharged from the abandoned sulphur and copper mines in Avoca, is reported. A survey of surface and subsurface sediments was repeated after seven years during exceptionally low flow conditions in 2001. The present study found that the reference (up-stream) site used in the original 1994 study was itself impacted by AMD, showing sediment metal enrichment by AMD to be greater than originally thought. The new reference site contained elevated Pb (570 µg g^–1) in the subsurface sediment due to abandoned Pb-Zn mines 25 km further upstream. Concentrations of Cu (43 µg g^–1), Zn (349 µg g^–1) and Fe (4.0%) were normal for uncontaminated rivers. All the downstream sites showed sediment metal enrichment arising from the AMD (Cu and Zn p < 0.001; Fe p < 0.01). Subsurface concentrations of metals immediately below the mixing zone were Cu 904 µg g–1 (sd 335), Zn 723 µg g–1 (sd 93), Fe 6.3% (sd 1.5) and Pb 463 µg g^–1 (sd 279). Monthly variation in metal concentrations at sites was not significantly different (p > 0.05). Although surface sediment metal concentrations were more variable, they followed similar trends to subsurface sediment. There were no significant differences in the subsurface sediment concentrations for either Cu or Zn over the period 1994 and 2001 immediately below the mines, although at the lowest site Zn had decreased by 35% over the period (p < 0.01). However there was a significant (p < 0.01) decrease over the period in the Fe concentration at all the impacted sites. This corresponds to a reduction in Fe concentration in the AMD and indicates that some remediation has occurred in the river since 1994.     

Concentrations of cadmium,manganese, copper,zinc, and lead in the tissues of the oyster (Crassostrea iredalei) obtained from Setiu Lagoon,Terengganu, Malaysia

Heavy metals pollution in aquatic environments is a major problem contributing to human health issues. The study of these pollutants through bioindicators such as the oyster Crassostrea iredalei is important for (1) determining the levels and sources and (2) regulating the quantity of pollutants. The concentrations of cadmium (Cd), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) in tissues of C. iredalei, sediment and surrounding water was measured, and data was analyzed to determine the relationship between sampling periods and between oyster tissue, sediment, and water. The highest concentration of metals in oyster tissue was Zn, followed by Cu, Mn, Cd, and Pb. Concentrations of Cd, Cu, and Zn exceeded the maximum level allowed according to the Malaysian Food Act of 1983, which is equivalent to the WHO recommended levels of heavy metals in organisms used for consumption. The highest metal concentration in sediment was Mn followed by Zn, Pb, Cu, and Cd. Concentrations of heavy metals in surrounding water were Zn, Pb, Cu, Mn, and Cd. There was no correlation between metal concentration in oyster tissue and in sediment for all five metals.     

Sources and Distribution of Heavy Metals in East China Sea Surface Sediments

Box cores and surficial sediments collected from the shelf, slope and Okinawa Trough of the East China Sea were analyzed for loss on ignition, and concentration and speciation of Al, Fe, Mn, Pb, Cd, Cu and Zn. in general, concentrations of these metals are higher in the inner shelf and lower in the midshelf, but the highest LOI, Cd and Mn levels are found in the Okinawa Trough. Spatial distributions of these metals in surficial sediments indicate that the Yangtze River is the major source for materials deposited in the inner shelf. the results of a six-stage sequential leaching experiment indicate that the fluvial input includes natural (e.g., Al and Fe) and anthropogenic (e.g., Pb) materials. the depletion concentration of these metals in the midshelf sediments reflects the dominance (～ 70%) of coarse, relict sand, while the enrichments in the inner shelf and the Okinawa Trough sediments are due to the fine grained, organic-rich sediments. the speciation of Mn in the sediments of the Okinawa Trough indicates that its distribution is diagentically or hydrothermally controlled.