Oyster <Emphasis Type="Italic">Saccostrea cucullata</Emphasis> as a Biomonitor for Hg Contamination and the Risk to Humans on the Coast of Qeshm Island,Persian Gulf,Iran

A total of 174 individuals of rocky oysters (Saccostrea cucullata) and 35 surface sediment samples were collected from seven stations off the intertidal zones of Qeshm Island, Persian Gulf, in order to study the concentration of mercury in oysters’ tissues, and to investigate whether mercury concentrations in the edible soft tissues are within the permissible limits for public health. The average mercury concentrations were found as 3.44, 50.66 and 2.29 μg kg⁻¹ dw in the sediments, soft tissues and shells of the oysters, respectively. Results indicated that the levels of mercury in sediment differed significantly between the stations. In addition, results confirmed that the soft tissues of oysters could be a good indicator of mercury in the aquatic system. In comparison with food safety standards, mercury levels in oysters were well within the permissible limits for human consumption.     

Mercury in Wetland Birds of Iran and Iraq: Contrasting Resident Moorhen, <Emphasis Type="Italic">Gallinula chloropus,</Emphasis> and Migratory Common Teal, <Emphasis Type="Italic">Anas crecca,</Emphasis> Life Strategies

We document mercury distribution in tissues of two waterfowls; moorhen (Gallinula chloropus; n = 6), and Common Teal (Anas crecca; n = 6) from Shadegan wetlands in Southwestern Iran. Mean value of mercury in moorhen liver was (0.36 Hg μg g⁻¹ dry weight), Common Teal had (4.34 Hg μg g⁻¹ dry weight) mercury. In all tissues, Common Teals had significantly higher mercury concentrations than moorhens (U test, p ≤ 0.05). Mercury was 12, 9, 8, and 6 times higher in liver, muscle, kidney, and feather of Common Teals. These birds have comparable diets but Common Teals are migratory and moorhens are residents of Shadegan wetlands.     

Toxicity of Cadmium,Lead, Mercury and Methyl Parathion on <Emphasis Type="Italic">Euchlanis dilatata</Emphasis> Ehrenberg 1832 (Rotifera: Monogononta)

Acute toxicity tests with Cd, Pb, Hg, and methyl parathion were developed to compare the sensitivity of the rotifer Euchlanis dilatata with other model organisms used in aquatic ecotoxicology. Cd was the most toxic chemical (LC50 = 14.8 μg L⁻¹), while methyl parathion was the least toxic (LC50 = 864.2 μg L⁻¹). E. dilatata was more sensitive that other rotifer species, particularly of the genera Brachionus and Lecane. However, E. dilatata was less sensitive to mercury and methyl parathion than the crustacean, Daphnia magna. The high sensitivity of E. dilatata suggests that it may be an adequate benthic model to use in toxicity assessments of metal-contaminated sediments.     

Comparative Study of Mercury Accumulation in Two Fish Species, (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> and <Emphasis Type="Italic">Sander lucioperca</Emphasis>) from Anzali and Gomishan Wetlands in the Southern Coast of the Caspian Sea

Anzali and Gomishan wetlands are considered as two of the most important wetlands in southern coast of Caspian Sea. To investigate mercury accumulation in these ecosystems, total mercury concentrations were measured in the muscle tissue of two fish species. Higher mercury concentrations were detected in C. carpio, an omnivorous benthic/pelagic species (Anzali wetland: 0.2 μg g⁻¹ wet weight; Gomishan wetland: 0.2 μg g⁻¹ wet weight), than in S. lucioperca, a carnivorous pelagic species (Anzali: 0.06 μg g⁻¹ wet weight; Gomishan: 0.15 μg g⁻¹ wet weight).     

Assessment of Total Mercury Levels in <Emphasis Type="Italic">Clarias gariepinus</Emphasis> from the Sagua la Grande River,Cuba

Total mercury levels (Thg) were quantified in Clarias gariepinus captured from the Sagua la Grande River (Cuba) in the vicinity of an active chlor–alkali plant, and relationships among place of capture; fish size, weight, and sex; and THg levels were assessed. THg levels ranged from 67 to 375 ng/g ww in collected fish, never exceeding the Cuban recommended maximum limit for fish consumption of 500 ng/g ww. No significant correlation was observed between mercury levels and fish allometric characteristics (p < 0.05); however, levels were significantly higher in fish captured below the chlor–alkali facility, suggesting a connection between mercury bioaccumulation and plant discharges.     

Concentrations of Mercury and Other Toxic Elements in Orange Roughy, <Emphasis Type="Italic">Hoplostethus atlanticus</Emphasis>, from the Mid-Atlantic Ridge

Concentrations of the elements mercury, arsenic, cadmium and lead were measured in the muscle tissue of Orange roughy (Hoplostethus atlanticus) obtained from the Mid-Atlantic Ridge during the Mar-Eco expedition in the North Atlantic Ocean in 2004. The age of the fish varied from 1 to 139 years. To the best of our knowledge, the concentration of the heavy metals presented here is for one of the oldest fish in the literature, in addition to the fact that very little information on arsenic in Orange roughy has been previously published. The concentration of mercury in the fillet of the fish varied between 0.06 and 1.1 μg g⁻¹ w.w. Mercury was the only element that was positively correlated to the age. The concentrations of mercury were found to be below the maximum limits for Orange roughy set by EU at 1.0 μg g⁻¹ w.w, except for a 134 year fish sample with a concentration of 1.1 μg g⁻¹ w.w.     

Seasonal Accumulations of Some Heavy Metal in Water,Sediment and Tissues of Black-Chinned Tilapia <Emphasis Type="Italic">Sarotherodon melanotheron</Emphasis> from Biétri Bay in Ebrié Lagoon,Ivory Coast

The seasonal accumulation of cadmium, copper, lead, mercury and zinc was determined in sediments, water, and black-chinned tilapia (Sarotherodon melanotheron; muscle, brain, kidney and liver tissues) collected monthly from Biétri Bay. The mean water concentration of metals (in mg L⁻¹) ranged from 0.01 to 0.30 (mercury), 0.02–0.26 (cadmium), 2.40–4.80 (lead), 9.05–9.68 (copper), and 12.05–19.87 (zinc). The seasonal variations showed a significant difference in the levels of mercury, cadmium and lead among season. The highest mercury (0.30 ± 0.02 μg L⁻¹), cadmium (0.26 ± 0.02 mg L⁻¹) and lead (4.80 ± 1.03 mg L⁻¹) levels were observed during dry season, while the lowest levels (0.21 ± 0.01, 0.02 ± 0.01 and 2.40 ± 0.02 mg L⁻¹, respectively mercury, cadmium and lead) were measured during rainy season. The average cadmium (0.58 ± 0.36 mg L⁻¹), copper (42.15 ± 19.40 mg L⁻¹), lead (58.47 ± 38.10 mg kg⁻¹), mercury (0.79 ± 0.47 μg kg⁻¹) and zinc (187.58 ± 76.99 mg kg⁻¹) concentrations determined in Biétri Bay sediments showed a similar trend as in water. The seasonal variations of mercury, cadmium and lead in tissues revealed that these metals were higher concentrated during dry and swelling seasons. The levels of zinc and copper followed by lead were higher in the tissues. The order of tissues metals concentrations was: kidney > liver > brain > muscle.     

Heavy Metal Levels in Suspended Sediments, Crassostrea gigas, and the Risk to Humans

Wild Pacific oyster (Crassostrea gigas) and sediment, both resuspended and suspended (RSS) samples (<53 μm), were collected over an 8-month period from a coastal estuary in Baynes Sound, BC, Canada. Stable isotope analysis (δ¹³C, δ¹⁵N) was used to determine, first, if RSS sediments was an important dietary source to C. gigas and, second, if so, whether it served as a significant dietary exposure route for Cd, Cu, Pb, and Zn. Although RSS sediments were high in trace metals such as Cd, Pb, Zn, and notably Cu, stable isotope signatures for oyster tissues did not correspond to those of RSS sediments. These results indicate that RSS sediments are not a significant source of metal to the oysters. In addition, we compared the potential risk to humans ingesting C. gigas with levels of Cd, Cu, Pb, and Zn from this study to the current Agency for Toxic Substances and Disease Registry (ATSDR) chronic oral minimal risk levels (MRLs) using current Canadian consumption guidelines of three oysters/week. Cu, Pb, and Zn levels were below MRL levels, with Cd exceeding the recommended 0.2 μg/kg/day MRL level fourfold. Total daily intake levels (TDI) for Cd were additionally calculated and either reached or exceeded the Food and Agriculture Organization/World Health Organization (FAP/WHO) reference dose of 1 μg/kg/day for Cd consumption in Canadians. Our results indicate that the current Canadian Cd consumption guidelines do not protect individuals consuming the maximum recommended levels of wild oysters.     

Total Mercury in Fish, Sediments and Soil from the River Pra Basin, Southwestern Ghana

Total Mercury (Hg) concentrations were determined in soil, river sediments and six (6) species of fish from the River Pra Basin in southwestern Ghana by Cold Vapour Atomic Absorption Spectrometry. Mercury concentration (μg g⁻¹) ranged from 0.042 to 0.145 for soil: from 0.390 to 0.707 for sediments and from <0.001 to 0.370 for fish. All the fish samples had Hg concentration below the World Health Organisation (WHO) permissible limit of 0.5 μg g⁻¹ whereas all the sediment samples had levels higher than the US-EPA value of 0.2 μg g⁻¹. The results obtained from this study showed that fish from River Pra Basin are unlikely to constitute any significant mercury exposure to the public through consumption. No apparent trend of increasing mercury concentration along the main river as it flows downward toward the sea was observed.     

Mercury in Cultured Oysters (Crassostrea gigas Thunberg, 1793 and C. corteziensis Hertlein, 1951) from Four Coastal Lagoons of the SE Gulf of California, Mexico

In order to determine the mercury concentrations in cultured oysters from coastal lagoons (SE Gulf of California), several individuals of Crassostrea gigas and C. corteziensis were collected and their mercury levels were measured with a cold vapor analyzer. The mean concentrations during the rainy and dry seasons, respectively, were 0.70 and 0.15 μg g⁻¹ in C. gigas and 0.56 and 0.18 μg g⁻¹ in C. corteziensis. During the rainy season, elevated mercury contents are apparently related to terrigen transport from the watershed, while during the dry season, the moderate levels are related to upwellings.     

Effect of pH,Sulphate Concentration and Total Organic Carbon on Mercury Accumulation in Sediments in the Volta Lake at Yeji,Ghana

In this study, pH, total organic carbon, sulphate concentration and mercury concentrations of sediment samples from the Volta Lake at Yeji in the northern part of Ghana were determined. The results indicate that pH ranged from 6.32 to 8.21, total organic carbon ranged from 0.17 to 3.02 g/kg and sulphate concentration from 10.00 to 57.51 mg/kg. Total mercury concentrations ranged from 32.61 to 700 ng/g which is below the International Atomic Energy Agency recommended value of 810 ng/g. Humic substance-bound mercury ranged from 81.15 to 481.31 mg/kg in sediments and its two fractions existed as humic acid-bound mercury > fulvic acid-bound mercury with the ratio of humic substance-bound mercury to fulvic acid-bound mercury as 1.62 on the average. Humic substance-bound mercury and the two fractions fulvic acid-bound mercury and humic substance-bound mercury in sediments were favorably determined and found to correlate significantly positive with total organic carbon (r = 0.538) and total mercury (r = 0.574). However, there were poor correlations between SO₄ ²⁻ concentrations and humic substance-bound mercury (r = −0.391) as well as the two fractions; fulvic acid (r = −0.406) and humic acid (r = −0.381). By assuming that methyl mercury is mostly formed in sediments, these significant relations suggest that the efficiency of mercury being methylated from a given inorganic form depends on the amount, and most likely biochemical composition of total organic carbon in the lake sediment but not the SO₄ ²⁻ concentration.     

Organochlorine Pesticides in Green Mussel, <Emphasis Type="Italic">Perna viridis,</Emphasis> from the Cienfuegos Bay,Cuba

The green mussel, Perna viridis, was used to measure bioaccumulated levels of organochlorine pesticides in the marine environment of Cuba. Samples were collected in the Cienfuegos Bay between January and December 2010. The organochlorine pesticides (i.e. DDT, Dieldrin, Chlordane, Endosulfan, HCB, Aldrin, Heptachlor and Lindane) were quantified by gas chromatography. The sum of all organochlorine pesticides in P. viridis was 6.31 ng g⁻¹. The concentration ranged from 3.53 to 4.42 ng g⁻¹ dry weight (dw) for DDTs (i.e. sum of pp’ DDT, pp’ DDD, op’ DDE and pp’ DDE); 1.7–1.9 ng g⁻¹ dw for Dieldrin; 0.17–0.20 ng g⁻¹ dw for Chlordanes; 0.14–0.16 ng g⁻¹ dw for Endosulfan; 0.11–0.17 ng g⁻¹ dw for HCB; 0.07–0.11 ng g⁻¹ dw for Aldrin; 0.046–0.054 ng g⁻¹ dw for Heptachlor and 0.035–0.039 ng g⁻¹ dw for Lindane. These levels can be considered as low when compared to reported values from similar studies conducted elsewhere in the world. The concentrations of all organochlorines residues detected in this study fell below the EU Maximum Residue Limits.     

Mercury and Selenium Content in <Emphasis Type="Italic">Otolithes ruber</Emphasis> and <Emphasis Type="Italic">Psettodes erumei</Emphasis> from Khuzestan Shore,Iran

In this paper the level of selenium and mercury is analyzed in edible part and liver of Psettodes erumei and Otolithes ruber two commercial fish in Persian Gulf. The average concentration of Hg and Se in edible parts of P. erumei was 0.077 ± 0.062 and 0.044 ± 0.018 (μg g⁻¹ww), and in liver was 0.127 ± 0.122 and 0.132 ± 0.610 (μg g⁻¹ww) respectively. In O. ruber, the average concentration of Hg and Se in edible parts was 0.348–0.27 and 0.06 ± 0.021 (μg g⁻¹ww) and in liver was 0.176 ± 0.174 and 0.093 ± 0.022 (μg g⁻¹ww), respectively. P. erumei has higher mean molar ratio Se/Hg (1.98) compared to O. ruber (0.88).     

Mercury and Selenium in a Top-Predator Fish, <Emphasis Type="Italic">Trichiurus lepturus</Emphasis> (Linnaeus, 1758), from the Tropical Brazilian Coast,Rio de Janeiro

Muscular mercury and selenium were assessed in a voracious fish from three Brazilian coastal areas with different environmental conditions. Mercury was higher in specimens from Ilha Grande Bay (0.35 ± 0.17 μg g⁻¹) than in cutlassfish from Guanabara Bay (0.30 ± 0.15 μg g⁻¹) and Buzios coast (0.13 ± 0.08 μg g⁻¹), respectively. No difference was found regarding selenium among these areas. Mercury was positively correlated with fish length and size intervals (sub-adult, small and large adult), suggesting that larger and older fish bioaccumulated more mercury. A large excess of molar selenium in relation to mercury was observed.     

Metal Concentrations in Two Bioindicator Fish Species, <Emphasis Type="Italic">Merlangius merlangus</Emphasis>, <Emphasis Type="Italic">Mullus Barbatus</Emphasis>, Captured from the West Black Sea Coasts (Bartin) of Turkey

The Black Sea is very vulnerable to originating from land based human activities and its health is equally dependent on the coastal and non-coastal states of its basin. Total concentrations of cadmium, copper, zinc, lead, nickel, aluminum, iron, manganese, boron and chromium concentrations were determined in Merlangius merlangus (whiting) and Mullus barbatus found in Amasra in the West Coast of the Black Sea (Turkey). The metal contents that were measured in head and muscle was expressed in μg g⁻¹ wet weight. On average, while the highest Fe (344.25 μg g⁻¹), Mn (10.35 μg g⁻¹), Cr (0.96 μg g⁻¹) and Al (76.77 μg g⁻¹) concentrations were measured in the heads of M. merlangus and the highest Zn (77.99 μg g⁻¹), Cu(8.53 μg g⁻¹), B (44.83 μg g⁻¹), Ni (1.96 μg g⁻¹), Cd (0.40 μg g⁻¹) and Pb (6.80 μg g⁻¹) concentrations were detected in the muscles of M. merlangus. There were significant differences between metal levels of muscles in these two species. In terms of permissible levels reported by WHO FAO and TSE, there is not any risk for human consumption for both M. merlangus and M. barbatus, for Pb.     

Heavy-Metal Concentrations in Soft Tissues of the Burrowing Crab Neohelice granulata in Bahía Blanca Estuary, Argentina

Copper (Cu), cadmium (Cd), and chromium (Cr) in soft tissues of male and female burrowing crab Neohelice granulate, as well as their eggs, were measured in two different locations in the Bahía Blanca estuary, a moderately polluted ecosystem, from October 2008 to August 2009. Differences between sexes, sites, and seasonality were assessed. Furthermore, metal levels in eggs were compared with metal levels in female crabs. The results showed no significant differences for Cu and Cd between sexes (Student t test p > 0.25 for both sites) and sites (two-way analysis of variance: Cu p = 0.82 and Cd p = 0.29). Nevertheless, seasonality was found, with winter having significantly lower concentrations for both metals. The range of Cu concentrations was between 96.92 and 152.18 μg g⁻¹ dry weight (dw), and the range of Cd concentrations was between 6.09 and 10.41 μg g⁻¹ dw. Cr concentrations could not be assessed because most of the values were lower than the detection limit. Although heavy metals in sediments were not measured in this study, a bioaccumulation process may be occurring for Cd because levels found during the entire sampling period were greater than levels in sediment from previous years. For Cu, a regulation process may be occurring considering that this is an essential metal and levels of Cu in N. granulata found in this study were between 1 and 2 orders of magnitude greater than levels in sediments. Finally, Cu and Cd levels in eggs were detectable, but they were lower than levels in female crabs. The importance of these findings is linked to the fact that metal accumulation seems to be occurring before hatch. The presence of heavy metals in soft tissues as well as in eggs of N. granulata is of great importance considering that this is a key species within the Bahía Blanca estuary; therefore, it plays a major role in the transference of pollutants to greater trophic levels.     

Relationship Between Gonad Maturation and Heavy Metal Accumulation in the Clam, <Emphasis Type="Italic">Galatea paradoxa</Emphasis> (Born 1778) from the Volta Estuary,Ghana

The relationship between gonadal development and the concentrations of four heavy metals Mn, Zn, Fe and Hg in the tissues of the clam Galatea paradoxa was evaluated at the Volta estuary, Ghana, over an 18-month period. Metal concentrations in the clam tissues were highly variable over the sampling period and seemed to be influenced by the reproductive cycle of the clam. Mn concentrations varied over a wide range from 49 to 867 μg/g and exhibited a significant positive correlation with gonadal development (p = 0.0146, r² = 0.3190). Zn and Fe concentrations ranged from 13 to 59 μg/g and 79 to 484 μg/g, respectively and both revealed negative relationships between gonad development and metal accumulation (Zn (p = 0.0554, r² = 0.0554) and Fe (p = 0.1040, r² = 0.1567)). Hg concentrations ranged from 0.026 to 0.059 μg/g over the sampling period and exhibited a slight positive relationship between gonadal development and metal accumulation (p = 0.0861, r² = 0.1730).     

Mercury Contamination in the Topsoil and Subsoil of Urban Areas of Beijing, China

Mercury contamination is a serious problem in Chinese cities. In the present study, mercury contamination was evaluated in topsoil and subsoil samples collected in an urban area of Beijing. The level of total mercury in topsoil ranged from 12.1 to 8,487 ng g⁻¹, and a significant correlation (R = 0.58145, p < 0.0001) with polycyclic aromatic hydrocarbons was observed. Higher levels were generally observed in the suburbs and urban centers, with the highest levels being observed in the urban centers. The fraction of water soluble, ion exchangeable, Fe-Mn in the oxide-bound and organic phase was 0.78%, 0.18%, 0.25% and 3.42%, respectively. For subsoils, the level of total mercury ranged from 7.0 to 924.6 ng g⁻¹, and the higher levels were primarily located in the suburbs. This study showed that mercury has possibly affected the environmental quality of soil and groundwater in urban areas of Beijing.     

Survival,Growth, and Body Residues of <Emphasis Type="Italic">Hyalella azteca</Emphasis> (Saussure) Exposed to Fipronil Contaminated Sediments from Non-Vegetated and Vegetated Microcosms

We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g⁻¹) ranged from 0.72–1.26, 0.01–0.69, 0.07–0.23, and 0.49–7.87 for fipronil, fipronil-sulfide, fipronil-sulfone, and fipronil-desulfinyl, respectively. No significant differences in animal survival or growth were observed between non-vegetated and vegetated microcosms during wet or dry exposures. Mean animal body residue concentrations (ng g⁻¹) ranged from 28.4–77.6, 0–30.7, and 8.3–43.8 for fipronil, fipronil-sulfide, and fipronil-sulfone. Fipronil-desulfinyl was not detected in any animal samples.     

The Influence of Diet on Mercury Intake by Little Tern Chicks

We assessed mercury levels in the feathers of little tern (Sternula albifrons) chicks from hatching to fledging and in their prey captured by adults in three main foraging habitats: lagoon, salinas, and adjacent sea. These data were used to model mercury concentration in chick feathers through food ingestion, in order to explore the effects that changes in diet would have on the mercury burden of chicks as they aged. The mercury concentration in feathers of chicks raised in sandy beaches was higher than in those raised in salinas. Lagoon prey had a significantly higher mercury concentration (0.18 ± 0.09 μg g⁻¹ dry weight [d.w.]) than prey from salinas and the adjacent sea (both 0.06 ± 0.03 μg g⁻¹ d.w.). In relation to prey species group, mercury content was significantly higher for bottom fish (0.17 ± 0.10 μg g⁻¹ d.w.) than for pelagic (0.08 ± 0.06 μg g⁻¹ d.w.), euryhaline fish (0.04 ± 0.02 μg g⁻¹ d.w.), and crustacea (0.08 ± 0.03 μg g⁻¹ d.w.). To understand the importance of mercury content of each prey group, we ran several theoretical scenarios assuming that chicks were fed on only one species at a time. Considering a diet restricted to lagoon (mostly benthic) prey, A- and B-chicks may encounter health problems with an excess of mercury. On the contrary, a diet restricted to marine (mostly pelagic) prey would decrease the mercury concentration in chick feathers; the fast growth rate and the related mercury dilution effect in little tern chicks seem to decrease mercury levels in their feathers. Our study supports the fact that marine pelagic prey are important for estuarine seabirds because they provide a food resource with lower contamination levels. This model may have a wider application in similar seabird species and coastal environments.