Metals in edible fish from Vistula River and Dead Vistula River channel, Baltic Sea

Metals including Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were determined in muscle tissue of 12 fish species by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and cold vapour-atomic absorption spectroscopy (CV-AAS). Fish were collected from Vistula River at lower course and Dead Vistula River channel in south of Baltic Sea in Poland. The fish species examined include Round Goby (Neogobius melanostomus), Crucian Carp (Carassius carassius), Bull-rout (Myoxocephalus scorpius), Tench (Tinca tinca), Bream (Abramis brama), Burbot (Lota lot), Perch (Perca perca), Roach (Rutilus rutilus), Silver Carp (Hypophthalmichthys molitrix), Pikeperch (Stizostediun lucioperca), Brown salmon (Salmo trutta m. Trutta) and Eel (Anguilla anguilla). The median values of metal concentrations in fresh muscle tissue of 11 fish species varied as follows: Al < 0.5-60; Ba < 0.05-0.31; Ca 120-1800; Cd < 0.05-0.096; Co < 0.10; Cr < 0.10-0.50; Cu < 0.15-0.77; Fe 1.5-21; Hg 0.0058-0.65; K 1800-4200; Mg 130-560; Mn 0.12-0.59; Na 350-840; Ni < 0.2-0.31; Pb < 0.75; Sr 0.079-2.9; Zn 3.3-23 μg/g fresh weight. The Target Hazard Quotient (THQ) values calculated in this study for Cd and Hg from muscles of fish species collected from Vistula River were low in the range of 0.4 for Hg and 0.8 for Cd.     

The intestinal parasite Pomphorhynchus laevis (Acanthocephala) from barbel as a bioindicator for metal pollution in the Danube River near Budapest, Hungary

Concentrations of As, Al, Ag, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mg, Mn, Ni, Pb, Sb, Sn, Sr, Tl, V and Zn were analyzed by inductively coupled mass spectrometry (ICP-MS) in the intestinal helminth Pomphorhynchus laevis and its host Barbus barbus. The fish were caught in the Danube river downstream of the city of Budapest (Hungary). Ten out of twenty one elements analyzed were found at higher concentrations in the acanthocephalan than in different tissues (muscle, intestine, liver and kidney) of barbel. Considering the fish tissues, most of the elements were present at highest concentrations in liver, followed by kidney, intestine and muscle. Spearman correlation analyses indicate that there is competition for metals between the parasites and the host. The negative relationships between parasite number and metal levels in organs of the barbel support this hypothesis. The bioconcentration factors for Ag, As, Ba, Bi, Cu, Ga, Mn, Pb, Sr, Tl, and Zn showed that the parasites concentrated metals to a higher degree than the fish tissues. They accumulated the metals As, Cd, Cu, Fe, Ni, Pb, Sr and Zn even better than established bioindicators such as the mussel Dreissena polymorpha as revealed by data from the literature. The results presented here emphasize that acanthocephalans of fish are very useful as sentinels for metal pollution in aquatic ecosystems. Ratio of metal concentrations in the parasites and the host tissues provide additional information. Not including acanthocephalans in accumulation bioindication studies with fishes (as still customarily done) may lead to false results.     

Metals in edible fish from Vistula River and Dead Vistula River channel,Baltic Sea

Metals including Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were determined in muscle tissue of 12 fish species by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and cold vapour-atomic absorption spectroscopy (CV-AAS). Fish were collected from Vistula River at lower course and Dead Vistula River channel in south of Baltic Sea in Poland. The fish species examined include Round Goby (Neogobius melanostomus), Crucian Carp (Carassius carassius), Bull-rout (Myoxocephalus scorpius), Tench (Tinca tinca), Bream (Abramis brama), Burbot (Lota lot), Perch (Perca perca), Roach (Rutilus rutilus), Silver Carp (Hypophthalmichthys molitrix), Pikeperch (Stizostediun lucioperca), Brown salmon (Salmo trutta m. Trutta) and Eel (Anguilla anguilla). The median values of metal concentrations in fresh muscle tissue of 11 fish species varied as follows: Al < 0.5–60; Ba < 0.05–0.31; Ca 120–1800; Cd < 0.05–0.096; Co < 0.10; Cr < 0.10–0.50; Cu < 0.15–0.77; Fe 1.5–21; Hg 0.0058–0.65; K 1800–4200; Mg 130–560; Mn 0.12–0.59; Na 350–840; Ni < 0.2–0.31; Pb < 0.75; Sr 0.079–2.9; Zn 3.3–23 μg/g fresh weight. The Target Hazard Quotient (THQ) values calculated in this study for Cd and Hg from muscles of fish species collected from Vistula River were low in the range of 0.4 for Hg and 0.8 for Cd. Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Environmental Science and Health, Part B to view the free supplemental file.     

Health risk assessment of heavy metals in Cyprinus carpio (Cyprinidae) from the upper Mekong River

The purposes of this research are to quantify the concentration of heavy metals (Zn, Cu, As, Pb, Cd, and Hg) in the water and fish tissues of common carp (Cyprinus carpio) in the upper Mekong River and to thereby elucidate the potential dietary health risks from fish consumption of local residents. Surface water and fish tissues (gill, muscle, liver, and intestine) from four representative sample areas (influence by a cascade of four dams) along the river were analyzed for heavy metal concentrations. Results revealed that the levels of heavy metals in fish were tissue-dependent. The highest Cu and As levels were found in the liver; the highest Zn and Pb levels occurred in the intestine, and the highest Hg level was found in the muscle. The total target hazard quotient (THQ) value for residents is > 1 for long-term fish consumption, and local residents are, therefore, exposed to a significant health risk. Results from the current study provide an overall understanding of the spatial and tissue distribution of heavy metals in water and fish body along the upper Mekong River under the influence of cascade dams and highlight the potential health risk of As for the local residents of long-term fish consumption.

     

Relationship between heavy metals concentrations in egret species,their environment and food chain differences from two Headworks of Pakistan

Concentration of ten metals (Cd, Cr, Co, Cu, Fe, Li, Mn, Ni, Pb and Zn) were analyzed in the egg contents, prey and soil samples of little egret (Egretta garzetta) and cattle egret (Bubulcus ibis) from two Headworks to determine habitat and species-specific differences; to assess the importance of prey and habitat contamination as an exposure source for heavy metals. Concentration of Cu, Mn, Cr and Pb in egg contents, Fe, Co, Cu, Mn, Zn in prey and Fe, Co, Cu, Ni, Li in surface soils were significantly different (P < 0.05). Mean metal concentrations of Cr, Pb and Cd were relatively higher in little egret whereas Cu and Mn were higher in the egg contents of cattle egret. The mean concentrations of Cu, Mn and Zn were higher in prey samples of cattle egrets and Cr, Cd and Pb in prey samples of little egrets. In soil samples collected from little egret heronries metal concentrations were higher except Cu and Ni. Correlation Analysis and Hierarchical Agglomerative Cluster Analysis (HACA) identified relatively similar associations of metals and their source identification. Metals such as Fe, Cu, Mn, and Li were related with geochemical origin from parent rock material as well as anthropogenic input whereas Cr, Cd, Pb, Ni, Co and Zn were associated mostly with anthropogenic activities. The study suggested that eggs are useful bio-monitor of local heavy metal contamination.     

Age-dependent accumulation of heavy metals in a pod of killer whales (Orcinus orca) stranded in the northern area of Japan

Mercury (Hg), cadmium (Cd), iron (Fe) manganese (Mn), zinc (Zn) and copper (Cu) concentrations in the liver, kidney and muscle of nine killer whales (including three calves) that stranded together in the northern area of Japan were determined. The Hg and Cd concentrations were found at trace levels in the calf organs, and increased with age. The Fe concentration in the muscle was significantly lower in the calves than in the mature whales and also increased with age. In contrast, Mn and Cu concentrations in the muscle were significantly higher in the calves than in the mature whales, and changes in the Zn concentration relative to age were unclear. These results suggest minimal mother-to-calf transfer of the toxic metals Hg and Cd and accumulation of these metals in the organs with age, while the essential metals Mn and Cu were found at higher concentrations in the muscle of calves than in mature whales.     

Contamination of the River Ganga and its toxic implication in the blood parameters of the major carp Labeo rohita (Ham)

A field study was conducted to examine different physicochemical properties of water and various haematological and biochemical parametres of the fish Labeo rohita collected from the Ganga River (National river of India) at Varanasi district, India. The water was found to be greatly contaminated with a number of dissolved metals (Fe, Cr, Zn, Cu, Mn, Ni and Pb) whose concentrations were above the safe limits suggested by Bureau of Indian Standard (BIS 1991) for drinking water (Fe, 1,353.33 %; Cr, 456 %; Mn, 553.33 %; Ni, 4,490 % and Pb, 1,410 %). The metal accumulation in the fish blood was very high (Fe, 2,408 %; Cr, 956.57 %; Zn, 464.90 %; Cu, 310.57 %; Mn, 1,115.48 %) in comparison to the control fish maintained under strict quality control. Lower values of the various haematological parameters (total erythrocytes count, haemoglobin, haematocrit, mean corpuscular volume and O₂-carrying capacity) in the river fish in comparison to the control indicate toxic manifestation exerted by the contaminated river water on the fish. The higher level of total leucocytes count further illustrates stressed condition of the river fish. The toxic impact of the Ganga water is also expressed in the fish by the presence of higher levels of cholesterol, glucose, elevated activities of the enzymes aspartate amino transferase and alanine amino transferase, and lowered protein concentration.     

Trace elements and butyltins in a Dall's porpoise (Phocoenoides dalli) from the Sanriku coast of Japan

Concentrations and body burdens of 14 trace elements (Hg, Cr, Mn, Co, Cu, Zn, Sr, Ag, Cd, V, Se, Pb, Mo, and Fe) and butyltins (BTs) (tributyltin TBT, dibutyltin DBT, and monobutyltin MBT) were determined in various tissues of a mature male Dall's porpoise (Phocoenoides dalli) collected off the Sanriku coast of Japan. Selective accumulation in this porpoise was observed for Hg, Mn, Cu, Ag, Mo, Fe, and total BTs (TBT, DBT, and MBT) in the liver, Cd in the kidney, Zn, Sr, V, Pb, and Co in the bone, and Se in the skin. In contrast, Cr concentrations in all tissues were similar. This distribution pattern in this mature porpoise was in general agreement with the accumulation characteristics of trace elements and butyltins reported for other marine mammals. The whole body of the porpoise contained approximately 62 g Fe, 8.8 g Zn, 4.0 g Sr, 0.6g Se, 0.41 g Cu, 0.19 g Hg, 0.17 g Cd, 0.16 g Mn, 0.05 g Cr, 0.009 g Ag, 0.008 g Mo, 0.005 g Pb, 0.004 g Co, and 0.7 mg of BTs (0.4 mg TBT, 0.2 mg DBT, and 0.1 mg MBT). Metabolism of TBT to its breakdown products of this porpoise seems to be limited, since TBT still accounted for about half of the total burden of BTs. As in the cases of Hg, Mn, Cu, Se, and Fe, the muscle was the most important reservoir (43%) for the whole body burden of total BTs, 80% of which was TBT, and thus muscle played a crucial role in the higher body composition of TBT in this Dall's porpoise.     

Trace elements in sediments,blue spotted tilapia Oreochromis leucostictus (Trewavas, 1933) and its parasite Contracaecum multipapillatum from Lake Naivasha,Kenya, including a comprehensive health risk analysis

This study presents the distribution of 15 major and trace elements in sediments and fish and their pericardial parasites from Lake Naivasha, Kenya. The lake is one of the few freshwater lakes in the Great Rift Valley and is under strong anthropogenic pressure mainly due to agricultural activities. Its fish provide a valuable protein source for approximately 100,000 people in the area. Fish and their parasites have been acknowledged as indicators of environmental quality due to their accumulation potential for both essential and nonessential trace elements. A total of 34 specimens of the blue spotted tilapia Oreochromis leucostictus and pooled samples of their pericardial parasite, the anisakid nematode Contracaecum multipapillatum (larvae 3), were examined. Element concentrations were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and graphite furnace atomic absorption spectrometry (GF-AAS). The concentrations of elements in the sediments reflected the geology of the area and did not point to pollution: none of the investigated trace elements, including Pb, Cd, Cu, and Zn, showed elevated values. In contrast, concentrations in the fish muscle were elevated for Li, Sr, Cd, and Zn, with high target hazard quotients (THQ?>?0.1) indicating a potential health risk to the consumers of this fish. Fish liver showed significantly higher concentrations of the trace elements Fe, Mn, Cd, and Cu compared to the muscle and C. multipapillatum. In the parasite, Zn had the highest concentration, but the worms only minimally accumulated trace elements in relation to their fish host.     

Correlation and toxicological inference of trace elements in tissues from stranded and free-ranging bottlenose dolphins (Tursiops truncatus)

The significance of metal concentrations in marine mammals is not well understood and relating concentrations between stranded and free-ranging populations has been difficult. In order to predict liver concentrations in free-ranging dolphins, we examined concentrations of trace elements (Al, As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sn, total Hg (THg), V, Zn) in skin and liver of stranded bottlenose dolphins (Tursiops truncatus) from the South Carolina (SC) coast and the Indian River Lagoon, Florida (FL) during 2000-2008. Significantly higher concentrations of Zn, Fe, Se, Al, Cu and THg were found in skin while liver exhibited significantly higher Cu, Fe, Mn and THg concentrations for both study sites. Mean skin concentrations of Cu and Mn were significantly higher in SC dolphins while higher concentrations of THg and V were found in FL dolphins. In addition, liver tissues in SC dolphins exhibited significantly higher As concentrations while higher Fe, Pb, Se, THg, and V levels were found in FL dolphins. Two elements (Cu and THg) showed significant age-related correlations with skin concentration while five elements (Cu, Se, THg, Zn and V) showed age-related correlations with liver concentrations. Geographic location influenced age-related accumulation of several trace elements and age-related accumulation of THg in hepatic tissue was observed for both sites to have the highest correlations (r² = 0.90SC; r² = 0.69FL). Mean THg concentration in liver was about 10 times higher in FL dolphins (330 μg g⁻¹ dw) than those samples from SC dolphins (34.3 μg g⁻¹ dw). The mean molar ratio of Hg to Se was 0.93 ± 0.32 and 1.08 ± 0.38 for SC and FL dolphins, respectively. However, the Hg:Se ratio varied with age as much lower ratios (0.2-0.4) were found in younger animals. Of the 18 measured elements, only THg was significantly correlated in skin and liver of stranded dolphins and skin of free-ranging dolphins from both sites suggesting that skin may be useful in predicting Hg concentrations in liver tissue of free-ranging dolphins. Results indicate that 33% of the stranded and 15% of the free-ranging dolphins from FL exceed the minimum 100 μg g⁻¹ wet weight (ww) (∼400 dw) Hg threshold for hepatic damage while none from SC reached this level. Hepatic concentrations of As in SC dolphins and V in FL dolphins were also highly correlated with skin concentrations which may have some regional specificity predictive value. The present study provides the first application of trace element concentrations derived from stranded bottlenose dolphins to predict liver concentrations in free-ranging populations.     

Comparison of trace element accumulation in Baikal seals (Pusa sibirica), Caspian seals (Pusa caspica) and northern fur seals (Callorhinus ursinus)

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Cs, Hg, Tl and Pb) were determined in liver, kidney, muscle and hair of Baikal seals, Caspian seals and northern fur seals. All the three species showed the highest concentrations of Hg, V, Mn, Se and Ag in liver, Cd, Co and Tl in kidney, and Cs in muscle among the soft tissues examined. The highest burdens of Zn, Rb and Cs were observed in muscle, Mo and Ag in liver, and Sb and Pb in hair in all the three species. Concentrations of non-essential elements, Rb, Cd, Cs and Hg, showed significant positive correlations among liver, kidney and muscle, whereas correlation coefficients for essential elements, Mn, Co, Cu, Zn and Se, between the three tissues were generally low for all the species, suggesting that homeostasis controls the concentrations of essential elements but not the non-essential elements in the tissues of these animals. Significant age-dependent increase was found in the concentrations of V, Se and Ag in liver and Hg in liver and kidney of all the three species. Hair concentrations showed significant positive correlations with Zn levels in liver and kidney and Hg in muscle for Caspian seals, Hg in liver and kidney for Baikal seals, and Pb in liver for northern fur seals. Furthermore, regression analysis using the data in the present study and in the literature showed significant positive correlations between Hg levels in hair, and liver, kidney and muscle for various species of pinnipeds. These results indicate the possibility of using hair samples for monitoring these trace elements in pinnipeds.     

Patterns of mercury and methylmercury bioaccumulation in fish species downstream of a long-term mercury-contaminated site in the lower Ebro River (NE Spain)

Since the 19th century, large amounts of industrial waste were dumped in a reservoir adjacent to a chlor-alkali plant in the lower Ebro River (NE Spain). Previous toxicological analysis of carp populations inhabiting the surveyed area have shown that the highest biological impact attributable to mercury pollution occurred downstream of the discharge site. However, mercury speciation in fish from this polluted area has not been addressed yet. Thus, in the present study, piscivorous European catfish (Silurus glanis) and non-piscivorous common carp (Cyprinus carpio) were selected, to investigate the bioavailability and bioaccumulation capacities of both total mercury (THg) and methylmercury (MeHg) at the discharge site and downstream points. Multiple Correspondence Analysis (MCA) was applied to reduce the dimensionality of the data set, and Multiple Linear Regression (MLR) models were fitted in order to assess the relationship between both Hg species in fish and different variables of interest. Mercury levels in fish inhabiting the dam at the discharge site were found to be approximately 2-fold higher than those from an upstream site; while mercury pollution progressively increased downstream of the hot spot. In fact, both THg and MeHg levels at the farthest downstream point were 3 times greater than those close to the waste dump. This result clearly indicates downstream transport and increased mercury bioavailability as a function of distance downstream from the contamination source. A number of factors may affect both the downstream transport and increased Hg bioavailability associated with suspended particulate matter (SPM) and dissolved organic carbon (DOC).     

Trophic transfer and accumulation of mercury in ray species in coastal waters affected by historic mercury mining (Gulf of Trieste,northern Adriatic Sea)

Total mercury (Hg) and monomethylmercury (MMHg) were analysed in the gills, liver and muscle of four cartilaginous fish species (top predators), namely, the eagle ray (Myliobatis aquila), the bull ray (Pteromylaeus bovinus), the pelagic stingray (Dasyatis violacea) and the common stingray (Dasyatis pastinaca), collected in the Gulf of Trieste, one of the most Hg-polluted areas in the Mediterranean and worldwide due to past mining activity in Idrija (West Slovenia). The highest Hg and MMHg concentrations expressed on a dry weight (d.w.) basis were found in the muscle of the pelagic stingray (mean, 2.529 mg/kg; range, 1.179–4.398 mg/kg, d.w.), followed by the bull ray (mean, 1.582 mg/kg; range, 0.129–3.050 mg/kg d.w.) and the eagle ray (mean, 0.222 mg/kg; range, 0.070–0.467 mg/kg, d.w.). Only one specimen of the common stingray was analysed, with a mean value in the muscle of 1.596 mg/kg, d.w. Hg and MMHg contents in the bull ray were found to be positively correlated with species length and weight. The highest MMHg accumulation was found in muscle tissue. Hg and MMHg were also found in two embryos of a bull ray, indicating Hg transfer from the mother during pregnancy. The number of specimens and the size coverage of the bull rays allowed an assessment of Hg accumulation with age. It was shown that in bigger bull ray specimens, the high uptake of inorganic Hg in the liver and the slower MMHg increase in the muscle were most probably due to the demethylation of MMHg in the liver. The highest Hg and MMHg contents in all organs were found in the pelagic stingray, which first appeared in the northern Adriatic in 1999. High Hg and MMHg concentrations were also found in prey species such as the banded murex (Hexaplex trunculus), the principal prey of the eagle rays and bull rays, the anchovy (Engraulis encrasicholus) and the red bandfish (Cepola rubescens), which are preyed upon by the pelagic stingray, as well as in zooplankton and seawater. Based on previously published data, a tentative estimation of MMHg bioamagnification was established. The average increase in MMHg between seawater, including phytoplankton, and zooplankton in the Gulf was about 10⁴, and MMHg in anchovy was about 50-fold higher than in zooplankton. The bioaccumulation of MMHg between seawater and small pelagic fish (anchovy) amounted to 10⁶ and between water and the muscle of larger pelagic fish (pelagic stingray) to 10⁷. The MMHg increase between surface sediment and benthic invertebrates (murex) and between benthic invertebrates and small benthic fish was 10². Ultimately, the trophic transfer resulted in a 10³ accumulation of MMHg between water and muscle of larger benthic fish (bull ray, eagle ray, common stingray), suggesting lower bioaccumulation by benthic feeding species.     

Trace metals in Ganges soft-shell turtle (Aspideretes gangeticus) from two barrage: Baloki and Rasul, Pakistan

The concentration of nine metals was measured in liver, kidney, heart, muscle, plastron, and carapace of Aspideretes gangeticus from Rasul and Baloki barrages, Pakistan. The results indicated that metal concentration were significant different among tissues of Ganges soft-shell turtles. However, higher concentrations of Co (5.12 μg/g) and Ni (1.67 μg/g) in liver, Cd (0.41 μg/g) in heart, Fe (267.45 μg/g), Cd (2.12 μg/g) and Mn (2.47 μg/g) in kidney, Cd (0.23 μg/g), Cu (2.57 μg/g), Fe (370.25 μg/g), Mn (5.56 μg/g), and Pb (8.23 μg/g) in muscle of A. gangeticus were recorded at Baloki barrage than Rasul barrage. Whereas mean concentrations of Pb (3.33 μg/g) in liver, Co (1.63 μg/g), Cu (11.32 μg/g), Pb (4.8 μg/g) and Zn (144.69 μg/g) in heart, Co (4.12 μg/g) in muscle, Ni (1.31 μg/g), Pb (2.18 μg/g), and Zn (9.78 μg/g) in carapace were recorded higher at Rasul barrage than Baloki barrage. The metals followed the trend Fe > Zn > Ni > Cu > Mn > Pb > Cr > Co > Cd. Metals of toxicological concern such as Cr, Pb, and Cd were at that level which can cause harmful effects to turtles. The results provide baseline data of heavy metals on freshwater turtle species of Pakistan.     

Metal accumulation in tissues of seabirds from Chaun, northeast Siberia, Russia

Concentrations of four essential elements (Fe, Mn, Zn, and Cu) and two toxic metals (Cd and Hg) were determined in selected tissues of 11 seabird species collected in Chaun, northeast Siberia. In oldsquaw, arctic tern and herring gull, zinc concentrations were correlated with Cd concentrations. Cadmium concentrations in all the species were highest in kidney and Hg in liver. Cd levels in the liver and kidney of herring gulls were higher than those observed from other breeding areas. Similarly, Hg concentrations were also high in the liver of herring gull. High concentrations of Cd and Hg found in some birds from Chaun might have arisen from exposure on migration.     

Relevance of biotic parameters in the assessment of the spatial distribution of gastrointestinal metal and protein levels during spawning period of European chub (Squalius cephalus L.)

The present field study, conducted during the spawning period (April/May) of European chub (Squalius cephalus L.) from the Sava River in Croatia, indicates that seasonal changes of fish physiological state might cause variability in gastrointestinal metal (Cd, Cu, Fe, Mn and Zn), total cytosolic protein and metallothionein (MT) levels. During the period of fish spawning and increased metabolic activity, a significant relationship with chub hepatosomatic index was evident for Fe and Mn in gastrointestinal tissue (r?=?0.35 and 0.26, respectively) and in cytosolic fraction (r?=?0.32 and 0.41, respectively) and for Zn and Fe in the gut content (r?=?0.36 and 0.31, respectively). Total cytosolic protein and MT concentrations followed the same spatial distribution as Fe and Mn in all gastrointestinal fractions and as Zn in the sub-cellular fractions, with higher levels at upstream locations. Due to the role of essential metals in metabolic processes and gonad development, increased feeding and spawning activity in April/May resulted in higher gastrointestinal essential metal (Fe, Mn and Zn) and MT concentrations, which probably follow an increase in Zn concentrations, known as the primary MT inducer. Therefore, biotic factors should be considered as important confounding factors in metal exposure assessment, while their influence on gastrointestinal metal and protein levels should be interpreted depending on the season studied.     

Heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in seven fish species in relation to fish size and location along the Yangtze River

Purpose

The objective of this paper is to assess the regulation of the accumulation of heavy metals in the aquatic environment and different fish species.

Methods

Water and fish samples were collected from upper to lower reaches of the Yangtze River. The heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in the muscle tissue of seven fishes were measured. Additionally, the relationships between heavy metal concentrations in fish tissue and fish size (length and weight), condition factor, water layer distribution, and trophic level were investigated.

Results

Metal concentrations (milligrams per kilogram wet weight) were found to be distributed differently among different fish species. The highest concentrations of Cu (1.22?mg/kg) and Zn (7.55?mg/kg) were measured in Pelteobagrus fulvidraco, the highest concentrations of Cd (0.115?mg/kg) and Hg (0.0304?mg/kg) were measured in Silurus asotus, and the highest concentrations of Pb (0.811?mg/kg) and Cr (0.239?mg/kg) were measured in Carassius auratus and Cyprinus carpio. A positive relationship was found between fish size and metal level in most cases. The variance of the relationships may be the result of differences in habitat, swimming behavior, and metabolic activity. In this study, fishes living in the lower water layer and river bottom had higher metals concentrations than in upper and middle layers. Benthic carnivorous and euryphagous fish had higher metals concentrations than phytoplankton and herbivorous fish. Generally, fish caught from the lower reach had higher metals concentrations than those from the upper reach.

Conclusions

Cadmium and lead concentrations in several fishes exceeded the permissible food consumption limits, this should be considered to be an important warning signal.     

Heavy metal accumulation in edible fish species from Rawal Lake Reservoir, Pakistan

The aim of the present study was to describe the accumulation of trace metals in the liver, kidney, gills, muscles, and skin of four edible fish species (Tor putitora, Cirrhinus mrigala, Labeo calbasu, and Channa punctatus) of Rawal Lake Reservoir, Pakistan. The fish samples were collected in the pre-monsoon (May 2008) and post-monsoon (October 2007) seasons and were analyzed for heavy metals by using an atomic absorption spectrometer. Kidney and liver showed relatively high concentrations of heavy metals. The accumulation of metals in the different organs of the fish (skin, muscles, and gills) in post-monsoon was higher than in pre-monsoon. In pre-monsoon, the metals followed the trend Zn > Pb > Fe > Cr > Ni > Mn > Co > Cu > Cd > Li, while in the post-monsoon season, the trend was Fe > Pb > Cr > Ni > Zn > Cu > Co > Mn > Cd > Li. The concentrations of Ni, Cr, and Pb in the muscle of all fish species were higher than the WHO guideline values of heavy metals in fishes for human consumption except in T. putitora. Cu level was nearly equal to the WHO maximum levels in C. mrigala and L. calbasu, while it was lower in T. putitora and C. punctatus. It is strongly advocated that risk assessment studies should be conducted and there is an urgent need for water quality restoration and management of Rawal Lake Reservoir.     

Long-term effect of temperature on bioaccumulation of dietary metals and metallothionein induction in Sparus aurata

Previous studies have demonstrated that the commercial feed of aquacultured fish contains trace amounts of toxic and essential metals which can accumulate in tissues and finally be ingested by consumers. Recently rising temperatures, associated to the global warming phenomenon, have been reported as a factor to be taken into consideration in ecotoxicology, since temperature-dependent alterations in bioavailability, toxicokinetics and biotransformation rates can be expected. Sparus aurata were kept at 22 °C, 27 °C and 30 °C for 3 months in order to determine the temperature effect on metallothionein induction and metal bioaccumulation from a non-experimentally contaminated commercial feed. A significant temperature-dependent accumulation of cadmium (Cd), copper (Cu), mercury (Hg), zinc (Zn), lead (Pb) and iron (Fe) was found in liver, together with that of manganese (Mn), Fe and Zn in muscle. Hg presented the highest bioaccumulation factor, and essential metal homeostasis was disturbed in both tissues at warm temperatures. An enhancement of hepatic metallothionein induction was found in fish exposed to the highest temperature.     

Trace elements in two marine fish cultured in fish cages in Fujian province, China

Two cultured marine fish, the Japanese seabass (Lateolabrax japonicus) and red seabream (Pagrus major) were collected from eight fish cage sites along the coast of Fujian province in China. The concentrations of Ag, As, Cd, Co, Cu, Fe, Mn, Se, and Zn in their muscle, stomach and liver tissue were quantified. The risk of these trace elements to humans through fish consumption was then assessed. The highest concentrations of As, Cd, Se and Zn in fish feed from fish cages were found in Dongshan Station. Moreover, the As levels in the muscles of both species at all sites were generally higher than China's national standard (>1.0 μg/g). Trace element concentrations in two marine fish followed the order of livers > stomachs > muscles. Although the As levels in two marine caged fish exceeded the permissible standards, the estimated daily intake of As did not exceed the reference dose guideline established by US EPA. For other trace elements examined in this study, their concentrations did not exceed the permissible concentrations of the international standards.