Cadmium-Resistance Mechanism in the Bacteria Cupriavidus metallidurans CH34 and Pseudomonas putida mt2

Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 were used as cadmium (Cd)-resistant and -sensitive bacteria, respectively, to study Cd uptake, sorption, intracellular accumulation, metallothionein (MT) induction, and bioremediation potential of both isolates. According to this research work, Cd had a stimulatory effect on the growth of CH34 cells (OD₅₇₈ = 1.43) compared with mt2 cells (OD₅₇₈ = 0.8). Addition of N,N′-dicyclohexylcarbodiimide (DCCD) and 2,4-dinitrophenol (DNP) along with Cd resulted in more cell growth in mt2 (OD₅₇₈ = 0.71) compared with CH34 (OD₅₇₈ = 0.34). DCCD and DNP inhibited this active uptake only in CH34 but not in mt2. Greater Cd interaction with the cell surface was observed in mt2 cells compared with CH34 cells. Intracellular Cd accumulation was interrupted by DCCD and DNP in CH34 (only 1.81 ± 0.04 μg L^?1 at 5 h) but not in mt2 (24.41 ± 0.01 μg L^?1 at 5 h). Intracellular Cd uptake was observed in even killed mt2 cells (7.11 ± 0.05 μg L^?1 at 5 h) compared with CH34 cells (2.50 ± 0.08 μg L^?1 at 5 h). This result showed that the Cd accumulation mechanism in CH34 is ATPase-dependent, whereas in mt2 uptake mechanism is not ATPase-dependent because mt2 ATPase was not inhibited by DCCD and DNP. CH34 removed 93 mg L^?1 of Cd after 8 days from original industrial effluent, which was more than Cd removal by CH34 from distilled water (i.e. 90 mg L^?1 after 8 days). mt2 was able to remove 80 mg L^?1 of Cd after 8 days from original industrial effluent, which was more than Cd removal by mt2 from distilled water (i.e. 77 mg L^?1 after 8 days). Cd did not induce any MT in CH34, but it did so in mt2 (14 kDa), which was thought to be a Cd-resistance mechanism operative in mt2.     

Assessment of Seasonal Variability of Cytochemical Responses to Contaminant Exposure in the Blue Mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Complex)

A selected suite of cytochemical parameters in Mytilus edulis are altered in response to field and laboratory exposure to chemical contaminants. These biomarkers include lysosomal stability, nicotinamide adenine dinucleotide phosphate (NADPH)–ferrihemoprotein reductase activity, liposfuscin deposition, and accumulation of lysosomal and cytoplasmic unsaturated neutral lipid. Normal variations in physiological processes (influenced by exogenous seasonal changes in temperature, salinity, food availability, etc.) may alter the sensitivity of these biomarkers to contaminant exposure. To address this issue, M. edulis (complex) were sampled monthly from a reference nonurban site (Coupeville, Penn Cove) and a polluted urban site (Seacrest, Elliott Bay) in Puget Sound, WA, for a period of 15 months. Physiological measurements including total length, total weight, somatic and mantle weights (an indication of gonadal development and reproductive status), condition index, and the presence or absence of hemic neoplasia (HN, or leukemia) were recorded. Significant differences in lysosomal stability, lysosomal and cytoplasmic unsaturated neutral lipids, lipofuscin deposition, and NADPH–ferrihemoprotein reductase activity in cells of the digestive gland or digestive tubules were generally found in mussels taken throughout the year from Seacrest compared to mussels sampled from Coupeville, consistent with exposure to chemical contaminants. No seasonally influenced suppression of the entire suite of parameters as measures of contaminant exposure was evident. Therefore these biomarkers can be used to evaluate contaminant exposure in mussels throughout the entire year. Received: 16 December 2001/Accepted: 30 May 2002     

Mercury in Different Feather Types from Great Cormorants (<Emphasis Type="Italic">Phalacrocorax carbo</Emphasis> L.) Inhabiting the Vistula Lagoon Ecosystem in Poland

Total mercury levels in different feather types (down, contour, tail and flight) in Great Cormorants (Phalacrocorax carbo L.) were determined using CV-AAS. Feathers from Great Cormorants inhabiting the Vistula Lagoon ecosystem have an average Hg level of 7.14 ± 3.99 (μg/g w.w.). Age-dependent concentrations of Hg were statistically significant (ANOVA Kruskal–Wallis, p < 0.0001). There were also significant differences in Hg levels in different parts of feathers from adults and immature birds (ANOVA Kruskal–Wallis, p < 0.0001). Cormorant chick feathers appear to be a potential biomonitor of Hg pollution in the Vistula Lagoon ecosystem, but this subject requires further research.     

Cadmium Concentration and Subcellular Distribution in Organs of the Mussel Crenomytilus Grayanus from Upwelling Regions of Okhotsk Sea and Sea of Japan

Cadmium (Cd) accumulation and subcellular distribution in the digestive gland and kidney of mussel Crenomytilus grayanus from naturally Cd elevated areas was studied. Mussels were collected from three sites of Okhotsk Sea and Sea of Japan: control area (site 1), seasonal upwelling region (site 2), and stationary upwelling region (site 3). Mussel from site 3 was shown to accumulate a significantly increased Cd concentration in the digestive gland and an extremely high Cd concentration (1780 ± 732 μg g⁻¹ dry weight) in the kidney. Cd was mainly sequestered into the kidney cytosol of the mussels from both upwelling regions and control sites (73% to 96%). However, digestive gland cytosol bound about 55% of Cd for the mussels from sites 1 and 2 and only 22.4% of Cd for the mussel from site 3. In the organs of the mussels from upwelling regions, the most of cytosolic Cd was associated with the protein fraction corresponding to molluscan metallothioneins. MTLP was isolated from kidney cytosol of the mussels from site 3 (powerful upwelling regions) by gel filtration chromatography, whereas in the organs studied of the mussels from other sites, MTLP content was below the detection limit.     

Trace Element Accumulation in Bivalve Mussels Anodonta woodiana from Taihu Lake, China

Data are presented for 13 trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, and Pb) in 38 bivalve mussels Anodonta woodiana from four separate sites (Huzhou, Dapu, Sansandao, and Manshan) around the Taihu Lake of China. All elemental concentrations generally ranked in decreasing order, Mn > Fe > Zn > As ≈ Cu ≈ Cd ≈ Se > Pb > Mo ≈ Ag, except that Cr, Co, and Ni were not detected. Anodonta woodiana was able to bioaccumulate essential Mn and toxic Cd to the extremely high level of 19,240 and 53 mg/kg dry weight, respectively. Geographical differences in the concentrations of trace elements were usually significant between sampling sites except for As and Pb, and the mussels from Sanshandao site had mostly accumulated or were contaminated with essential and toxic elements. The residue level of Cd in A. woodiana from the Sanshandao and Manshan sites appeared to be even higher than those of the essential elements Cu and Se, and exceeded the corresponding maximum residue limits of China. The present study provides the most recent information on trace element bioaccumulation or contamination in Taihu Lake and, further, suggests that A. woodiana can be used as a suitable bioindicator for inland water environmental monitoring.     

Removal and Accumulation of As, Cd and Cr by Typha latifolia

The removal from the solution and the accumulation of As, Cd and Cr by Typha latifolia was studied. Small plants of T. latifolia, collected from a non-contaminated site, were exposed to individual concentrations of As, Cd and Cr for 10 days. The ability of T. latifolia for the removal of toxic elements ranged from 23 % to 54 % for As, 43 %–55 % for Cd and 28 %–73 % for Cr. The accumulation of toxic elements in T. latifolia occurred mainly in the roots. The results suggest that T. latifolia can be considered as an interesting alternative for treating aquatic effluents polluted with toxic trace elements.     

Tissue Injury and Cellular Immune Responses to Cadmium Chloride Exposure in the Common Mussel Mytilus edulis: Modulation by Lipopolysaccharide

The immunotoxic effects of cadmium (Cd) exposure in bivalves are poorly understood and whether or not stimulation of the immune system exacerbates Cd toxicity is unclear. The mussel Mytilus edulis was exposed to 20 or 50 μg/l total Cd for up to 11 days compared to no added Cd controls to assess immune and other physiological responses. Selected experiments were then repeated in the presence of a lipopolysaccharide (LPS) challenge with and without subsequent Cd exposure. Immune functions of hemocytes, hematology, hemolymph glucose and ion content, as well as superoxide dismutase (SOD) activity and organ pathology were measured. Cd accumulated mainly in digestive gland and gills and to a lesser extent in the adductor muscle. Exposure to 20 μg/l Cd alone caused a transient modulated of phagocytosis and increased neutral red retention (Kruskal–Wallis, p = 0.002). The higher Cd concentration also increased cytotoxicity, and decreased hemocyte count. Changes in hemolymph Na⁺, K⁺, and glucose were small or negligible. Histopathological examination showed tissue injuries consistent with inflammation and necrosis in the gills, digestive gland, and adductor muscle during Cd exposure alone. LPS injection alone and LPS + Cd caused an increase in the number of circulating hemocytes by the end of the experiment (Kruskal–Wallis, p = 0.01) and a transient rise in phagocytosis at day 4 (analysis of variance (ANOVA), p = 0.001). The LPS + Cd treatment also caused transient changes in neutral red retention and in the cytotoxicity of hemocytes compared to controls. Intracellular SOD activity did not change in hemocytes under any treatment. Tissue inflammation and pathology was greatly increased by the effect of Cd exposure with an LPS injection compared to either treatment alone. We conclude that immunostimulation with LPS can greatly increase Cd-related organ pathologies but does not necessarily alter the responses of hemocytes.     

Accumulation and Distribution Characteristics of Zinc and Cadmium in the Hyperaccumulator Plant Sedum plumbizincicola

Accumulation and distribution of Zn and Cd in the hyperaccumulator plant Sedum plumbizincicola were investigated in a hydroponic experiment. Mean Cd and Zn concentrations in shoots (7,010 and 18,400 mg kg^?1) were about sevenfold and fivefold higher than those in roots (840 and 3,000 mg kg^?1) after exposure to 100 μM CdSO₄ and 600 μM ZnSO₄, respectively. Cd and Zn concentrations in young leaves (4,330 and 9,820 mg kg^?1) were about sixfold and twofold higher than those in mature leaves (636 and 2,620 mg kg^?1), respectively. MicroPIXE analysis showed that Zn was predominantly localized in epidermal cells in both young and mature leaves, but large amounts of Zn occurred in mesophyll cells in young leaves. Leaf tissue fractionation showed that soluble and cell wall fractions were different at the two stages of leaf growth. Young and mature leaves of S. plumbizincicola also showed different accumulation and distribution characteristics for Zn and Cd.     

Cadmium bioavailability to three estuarine animals in relation to geochemical fractions to sediments

The effects of sediment characteristics and geochemical fractions on the biological availability of cadmium to estuarine animals were studied. Grass shrimp (Palaemonetes pugio), blue mussels (Mytilus edulis) and a polychaete (Nereis virens) were exposed to Cd-treated sediment for 14 days. The test populations were evaluated for mortalities, oxygen consumption (exceptN. virens), and bioaccumulation of Cd. Sediment Cd was extracted sequentially to determine the exchangeable (EP), easily reducible (ERP), organic-sulfide (OSP), moderately reducible (MRP), and acid extractable (AEP) geochemical phases.The shrimp displayed significant respiration effects; the shrimp and mussels bioaccumulated Cd, particularly in the Cd-sand treatments. The polychaete did not bioaccumulate Cd. The OSP contained the greatest concentrations of Cd in all treatments. The Cd-sands were characterized by relatively higher levels of EP and ERP than for silts or clays. A statistical model was developed that describes the bioaccumulation of Cd as a function of EP and ERP geochemical fractions of sediment Cd forM. edulis.     

Concentrations of Heavy Metals (Cu, Cd, Zn and Ni) and PAHs in Perna viridis Collected from Seaport and Non-seaport Waters in the Straits of Johore

In this study, the ranges of pollutants found in the soft tissues of Perna viridis collected from Kg. Masai and Kg. Sg. Melayu, both located in the Straits of Johore, were 0.85–1.58 μg/g dry weight (dw) for Cd, 5.52–12.2 μg/g dw for Cu, 5.66–8.93 μg/g dw for Ni and 63.4–72.3 μg/g dw for Zn, and 36.4–244 ng/g dry weight for ∑PAHs. Significantly (p < 0.05) higher concentrations of Cd, Cu, Ni, Zn and ∑PAHs in the mussels were found in the water of a seaport site at Kg. Masai than a non-seaport site at Kg. Sg. Melayu population. The ratios of low molecular weight/high molecular weight hydrocarbons (2.94–3.42) and fluoranthene/pyrene (0.43–0.45) in mussels from both sites indicated the origin of the PAHs to be mainly petrogenic. This study has demonstrated the utility of using the soft tissues of P. viridis as a biomonitor of PAH contamination and bioavailability in the coastal waters of Peninsular Malaysia.     

Metal Pollution (Cd,Pb, Zn,and As) in Agricultural Soils and Soybean,Glycine max,in Southern China

Crops produced on metal-polluted agricultural soils may lead to chronic toxicity to humans via the food chain. To assess metal pollution in agricultural soils and soybean in southern China, 30 soybean grain samples and 17 soybean-field soil samples were collected from 17 sites in southern China, and metal concentrations of samples were analyzed by graphite furnace atomic absorption spectrophotometer. The integrated pollution index was used to evaluate if the samples were contaminated by Cd, Pb, Zn and As. Results showed that Cd concentration of 12 samples, Pb concentration of 2 samples, Zn concentration of 2 samples, and As concentrations of 2 samples were above the maximum permissible levels in soils. The integrated pollution index indicated that 11 of 17 soil samples were polluted by metals. Metal concentrations in soybean grain samples ranged from 0.11 to 0.91 mg kg^?1 for Cd; 0.34 to 2.83 mg kg^?1 for Pb; 42 to 88 mg kg^?1 for Zn; and 0.26 to 5.07 mg kg^?1 for As, which means all 30 soybean grain samples were polluted by Pb, Pb/Cd, Cd/Pb/As or Pb/As. Taken together, our study provides evidence that metal pollution is an important concern in agricultural soils and soybeans in southern China.     

Intersex in Littorina littorea and DNA damage in Mytilus edulis as indicators of harbour pollution

Intersex in snails (Littorina littorea) and DNA damage in blue mussels (Mytilus edulis) were analysed to assess how these bio-indicators reflected the level of chemical contamination at two sites in a highly contaminated harbour in Denmark. The comet assay using mussel gill cells was an indicator of exposure to genotoxic chemicals, and the intersex index (ISI) observed in snails was an indicator of exposure to butyltin (BT) compounds. Biota and sediments were analysed for heavy metals (Cd, Cu, Pb and Zn), butyltin compounds (TBT, DBT and MBT), nine PCB congeners and 19 PAH compounds. The biological effects were found to reflect the levels of the chemicals, and it was concluded that intersex in L. littorea and DNA damage in M. edulis can be used as bio-indicators of harbour pollution.     

Selected Heavy Metals and Selenium in the Blood of Black Sea Turtle (Chelonia mydas agasiizzi) from Sonora, Mexico

The concentration of heavy metals (Zn, Cd, Ni, Cu, Mn) and selenium (Se) was analyzed in blood collected from 12 black turtles (Chelonia mydas agasiizzi) captured in Canal del Infiernillo, Punta Chueca, Mexico. The most abundant metals were Zn (63.58 μg g^?1) and Se (7.66 μg g^?1), and Cd was the lower (0.99 μg g^?1). The sequential concentrations of trace metals were Zn > Se > Cu > Mn > Ni > Cd. In conclusion, this information is important as a baseline when using blood as tissue analysis of heavy metals; however, these levels could represent recent exposure in foraging grounds of black turtles in the Sea of Cortez.     

Phytoremediation of Water Polluted by Thallium,Cadmium, Zinc,and Lead with the Use of Macrophyte Callitriche cophocarpa

The objective of the present work was to study the phytoremediation capacity of Callitriche cophocarpa concerning water contaminated with thallium (Tl), cadmium (Cd), zinc (Zn), and lead (Pb) derived from the natural environment. We found that after a 10-day incubation period, shoots of C. cophocarpa effectively biofiltrated the water so that it met (for Cd, Zn, and Pb) appropriate quality standards. The order of accumulation of the investigated elements by shoots (mg kg^?1 dry weight) were as follows: Zn (1120) < Tl (251) < Cd (71) < Pb (35). The order of bioconcentration factors were as follows: Cd (1177) < Tl (1043) < Zn (718) < Pb (597). According to Microtox bioassay, C. cophocarpa significantly eradicated polluted water toxicity. During the experiment, the physiological status of plants was monitored by taking measurements of photosystem II activity (maximum efficiency of PSII, photochemical fluorescence quenching, nonphotochemical fluorescence quenching, and quantum efficiency of PSII), photosynthetic pigment contents, and shoot morphology. Plants exposed to metallic pollution did not exhibit significant changes in their physiological status compared with the control. This work is potentially applicable to the future use of C. cophocarpa in the phytoremediation of polluted, natural watercourses.     

Tracing cadmium contamination kinetics and pathways in oysters (Crassostrea gigas) by multiple stable Cd isotope spike experiments

Laboratory experiments using stable Cd isotopes (¹¹⁰Cd and ¹¹²Cd) were conducted to separately and simultaneously characterize Cd accumulation in different tissues of Pacific oysters (Crassostrea gigas) via the (i) trophic and (ii) direct pathways. For this, we exposed juvenile oysters to ¹¹⁰Cd-spiked seawater (¹¹⁰Cd: 2 μg l⁻¹; constant level) and ¹¹²Cd-spiked food (Thalassiossera weissflogii, ¹¹²Cd: 2 μg l⁻¹ in 35×10³ cells/oyster/L) in four experimental treatment groups, each containing 6 oysters, for 21 days with constant trophic feeding. These Cd contamination levels were ∼10 times lower than those typically used in experimental accumulation studies. Three oysters per treatment group were dissected every 7 days with separate sampling of the gills, digestive gland and the rest of the body. Metallothioneins were analysed in the digestive gland and gills. Cadmium concentrations and isotope ratios were measured in water (daily) and tissues (weekly) by GF-AAS and ICP-MS. The observed time-dependant evolution in Cd concentrations and ¹¹⁰Cd/¹¹⁴Cd and ¹¹²Cd/¹¹⁴Cd isotope ratios clearly revealed the bio-accumulation short-term kinetics and pathways of Cd contamination in the different tissues. Under the experimental conditions, significantly changed isotope ratios in gills and the digestive gland of oysters suggested rapid and efficient contamination by ¹¹⁰Cd derived from direct exposure followed by internal Cd transfer between organs. Trophic contamination became measurable after 14 days of exposure corresponding to a trophic transfer rate of 1%. Constant metallothionein levels during the experiment suggested that the initially present metallothionein levels were sufficient to deal with the experimental Cd exposure.     

Assessing of Heavy Metal Concentrations in the Tissues of Rutilus rutilus caspicus and Neogobius gorlap from Miankaleh International Wetland

The concentrations of four heavy metals (Pb, Cd, Ni and Cr) were measured in tissues of pelagic (Rutilus caspicus) and benthic (Neogobius gorlap) fishes from the Miankaleh international wetland. The maximum concentrations of Pb, Cd, Ni, and Cr (2.06, 1.20, 1.14 and 0.70 μg g^?1, respectively) were measured in the liver of N. gorlap, while the lowest concentrations were measured in muscle tissue collected from R. caspicus (Pb 0.67; Cd 0.25; Ni 0.21 and Cr 0.08 μg g^?1). The mean concentrations of metals in liver of R. caspicus and N. gorlap followed a trend where Pb > Cd > Ni > Cr, whereas in R. caspicus and N. gorlap gills and N. gorlap muscle the following trend was observed Pb > Ni > Cd > Cr. The data of presented study show that the liver and gill tissues have higher metal concentrations than muscle and also the metal concentrations in tissues of N. gorlap (benthic) were higher in comparison with R. caspicus (pelagic).     

Acute Toxicity of Copper,Zinc, and Ammonia to Larvae (Glochidia) of a Native Freshwater Mussel Echyridella menziesii in New Zealand

Adult New Zealand freshwater mussel Echyridella menziesii were collected from three locations in the North Island of New Zealand. In a series of tests that followed standard test guidance, glochidia were exposed to either dissolved copper (Cu), zinc (Zn), or total ammonia nitrogen (TAN) for 6, 24, or 48 h (20 °C, pH 7.8, water hardness 30 mg L^?1 as CaCO₃, dissolved organic carbon [DOC] 2.0–2.9 mg L^?1). Of the three contaminants and tests that met control survival criteria, mussel larvae (glochidia) were most sensitive to Cu exposure (48-h EC₅₀ = 1.7–3.4 μg L^?1, 48-h no observed effect concentrations (NOEC) of 1.3–2.6 μg L^?1). The Zn 48-h EC₅₀ concentrations were 229–337 μg L^?1 and the 48-h NOEC values were 128–240 μg L^?1. Compared with other native New Zealand species, glochidia were also relatively sensitive to TAN exposure (48-h EC₅₀ 12–15 mg TAN L^?1 [pH 7.8], 48-h NOEC 8–10 mg TAN L^?1). Comparison of our data with those of previous studies on North American freshwater mussels indicates that (1) E. menziesii are among those aquatic species most sensitive to acute Cu or TAN exposure; and (2) E. menziesii juveniles would not be adequately protected by current ANZECC water quality guidelines for TAN or Cu. Inclusion of North American juvenile mussel data in a revision of the current ANZECC water-quality guideline (95th percentile) for chronic ammonia exposure results in a decrease from 0.9 mg to 0.2 mg TAN L^?1 (pH 8).     

Involvement of an Antioxidant Defense System in the Adaptive Response to Cadmium in Maize Seedlings (Zea mays L.)

Chemical and biological analyses were used to investigate the growth response and antioxidant defense mechanism of maize seedlings (Zea mays L.) grown in soils with 0–100 mg kg^?1 Cd. Results showed that maize seedlings have strong abilities to accumulate and tolerate high concentrations of Cd. For soil with 50 mg kg^?1 Cd, the Cd contents in roots and shoots of maize seedlings are as large as 295.6 and 153.0 mg kg^?1 DW, respectively, without visible symptoms of toxicity. Lower soil Cd concentrations lead to a decrease in reduced glutathione (GSH) content in leaves of maize seedlings, whereas higher soil Cd concentrations resulted in an increase in the activities of superoxide dismutase, guaiacol peroxidase, catalase, and ascorbate peroxidase. Maize seedlings have strong capacities to adapt to low concentrations of Cd by consuming GSH and to develop an antioxidative enzyme system to defend against high-Cd stress.     

Cnesterodon decemmaculatus Juveniles as Test Organisms in Toxicity Assessment: Cadmium Case

The poeciliid Cnesterodon decemmaculatus is one of the native species of southern South America recently recommended for use as a test species in biomonitoring. Therefore, it is important to characterize its responses to stress conditions caused by pollution. The aim of this work was to determine the toxicity of the reference toxicant cadmium (Cd) and to evaluate the lethality response of juveniles of C. decemmaculatus exposed to an environmental sample with a high degree of pollution (Luján River, Buenos Aires, Argentina). The LC₅₀ values at 24 and 96 h were 6.00 and 2.27 mg Cd/L, respectively. The uptake of Cd was significantly greater in the first 24 h in relation to the total time of exposure in the bioassay. The toxicity of the water was in agreement with the level of contamination. A Cd contaminant pulse exerted an important additive effect on the toxicity of the environmental sample. The results provide information regarding the sensitivity of a native species to be used as a test organism in environmental monitoring.     

Spatial and Seasonal Distribution of Trace Metal Concentrations in Mussel (Mytilus galloprovincialis) and Sediment of Bosphorus and Golden Horn

The Golden Horn Estuary and Bosphorus Strait are two major marine environments of metropolitan Istanbul which have been exposed to intensive industrial discharges for more than 50 years. In the present study, concentrations of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) were measured in mussel tissue and sediment samples by using inductively coupled plasma-atomic emission spectroscopy to assess the current status of metal pollution in the Golden Horn and Bosphorus Strait. Ranges of Cd, Cr, Cu, Pb and Zn concentrations in soft parts of the mussels were BDL-2.59; BDL-7.35; 3.96–20.90; BDL-10.0; and 124.8–293.2 μg g^?1 dry weight (dw), respectively, while the ranges of Cd, Cr, Cu, Pb and Zn in <63 μm sediment fractions were BDL, 19.5–300.3, 16.9–724.7, 10.5–260.9, and 39.3–793.1 μg g^?1 dw, respectively. Ranges of Cd, Cr, Cu, Pb and Zn in >63 μm sediment fractions were BDL, 4.73–52.81, 3.45–481.87, 3.13–174.67 and 10.7–241.2 μg g^?1 dw, respectively. Trace metal concentrations found in sediment of the Golden Horn were 5–10 times higher than average literature values obtained in Mediterranean marine environment, whereas those of the Bosphorus Strait were consistent with or slightly higher than average literature values.