Pore-water nutrient concentrations variability under different oxygen regimes: A case study in Elefsis Bay, Greece.

Anthropogenic pressures considerably affect coastal areas, increasing nitrogen and phosphorous loads that lead to eutrophication. Eutrophication sometimes results in hypoxic and/or anoxic conditions near the bottom water. Dissolved oxygen (DO) concentrations influence redox-sensitive nutrients, which can alter the benthic flux of nutrients. We retrieved sediment cores from two sites in the eastern and western parts of Elefsis Bay, a semi-enclosed area of the Eastern Mediterranean, Greece, during winter and summer. In the western part, seasonally hypoxic or anoxic conditions occurred. We analysed pore-water samples under normoxic, hypoxic and anoxic bottom water conditions to study the pore-water nutrient concentrations variability under different oxygen regimes. Ex situ incubation experiments were conducted at the site experiencing oxygen deficiency by manipulating the DO concentrations. The pore-water nutrient concentrations showed higher variability at the site experiencing oxygen deficiency. Notably, elevated ammonium concentrations were observed in the pore water during anoxic conditions, in the 2-20-cm sediment layer. However, the benthic fluxes of ammonium and phosphate at the 0-2-cm sediment layer were comparable under hypoxic and anoxic conditions. The results of the incubation experiments demonstrate a direct decrease in nitrate concentrations as the DO concentrations diminished in the overlying water. The incubations after re-oxygenating the overlying water show that phosphate was more efficiently scavenged when anoxic conditions prevailed in the bottom water. The incubation experiments indicate the rapid response of the seafloor to oxygen availability, particularly concerning processes that influence nitrate and phosphate concentrations. These observations highlight the dynamic nature of nutrient cycling in shallow, seasonally anoxic environments, such as Elefsis Bay, and emphasise the sensitivity of the seafloor ecosystem to changes in bottom water oxygen availability.

Trace metal accumulation in Atlantic bluefin tuna and correlations with protein-lipid composition.

This study determines the biochemical composition and metal concentrations (Hg, Fe, Zn, Cu) in muscle tissue of reared Atlantic bluefin tuna and investigates whether protein-lipid composition affects metal accumulation. A significant positive relationship was found between Hg concentrations and protein content, whereas a strong negative relationship between Hg concentrations and lipid content was revealed. Opposite results were obtained, correlating Zn concentrations with biochemical components. No correlations between the concentrations of the other two metals and the protein or lipid components were observed. Evidently, biochemical components may influence the accumulation of certain metals, but not in the same way. Although the analyzed tuna samples represent a rich source of essential metals, Hg may pose a risk to consumers. Our results suggest that a lower level of Hg can be associated with greater lipid and lower protein content. Consumers could reduce the health risk from Hg by choosing constantly high-fat bluefin tuna.

Chromium speciation, mobility, and Cr(VI) retention-release processes in ultramafic rocks and Fe-Ni lateritic deposits of Greece.

Water contamination by geogenic hexavalent chromium is an emerging issue in areas developed on ultramafic rocks and their weathering products. In this study, samples of serpentinites, soil, and laterites were collected and analyzed for the levels of Cr species, distribution into phases of different mobility, mineralogy, Cr oxidation capacity, and leaching of Cr(VI). Total chromium (2176-21,929 mg kg-1) was mainly found in Cr spinels (~ 50% wt as Cr2O3) and Fe (hydr)oxides (2.5% wt). Total Cr(VI) contents (0.49-11.5 mg kg-1) increased from the serpentinites to the soil and lateritic deposit, i.e., during the advanced stages of weathering, which were accompanied by increased Cr mobility. Batch experiments of 500-h duration showed that Cr(VI) released in water at rates of 0.25-1.20 nM h-1. Rates were higher in water of pH 5.7 rather than pH 8.5, because more Cr(VI) was formed during the experimental period. Asbolane-type Mn oxides and Mn-bearing crystalline Fe oxides were responsible for Cr(III) oxidation. Most of the generated Cr(VI) (52-79% of total Cr(VI)) remained solid-bound by adsorption and/or precipitation processes. Because all samples had a self-capacity to oxidize Cr(III), it seems that retention processes will ultimately define the extent of geogenic Cr(VI) contamination of aquatic systems.

Human serum elements' levels and leukemia: A first pilot study from an adult Greek cohort.

BACKGROUND: The present study focuses on the evaluation of potential relationships between trace elements and acute and chronic types of leukemia, via the determination of their levels in human blood serum. METHODS: A total of 199 serum samples from a Greek cohort were examined, including both leukemia cases and controls. Elements' analysis was carried out using inductively coupled plasma mass spectrometry (ICP-MS) and demographic features such as age, gender, smoking habits and area of residence were recorded and statistically treated applying Shapiro-Wilk, Kolmogorov-Smirnov, Mann Whitney and Kruskal Wallis tests (p < 0.05). Spearman correlation and principal component analysis (PCA) were also performed to investigate possible associations. RESULTS: The results demonstrated significantly higher (p < 0.05) trace elements concentrations in cases' serum compared to that of controls excluding Ba, with Cu (median concentration 1295 µg L-1) being the most abundant in cases. Additionally, concentration of toxic Pb and Cd were found at seven and four fold higher concentrations in cases, respectively. Among the trace elements examined, only Rb (164 µg L-1) was detected in higher concentrations in controls. Ba, Cd and Co presented the lowest concentrations (lower than 1 µg L-1). PCA was performed for overall and classified data, indicating a stronger relation among the toxic As, Cd, Ni and Pb in cases than controls, particularly referring to smokers and industrial sites' residents. Hematological parameters and factors such as age and gender did not present any significant outcome or correlation. CONCLUSIONS: The findings from this pilot study suggest a potential relationship between metals and leukemia, especially concerning the toxic ones. Results from the employed source apportionment tools imply that smoking and atmospheric degradation may be positively related with higher metal serum levels in leukemia patients.

Programmes of measures of the marine strategy framework directive: Are they contributing to achieving good environmental status in the Mediterranean?

The Marine Strategy Framework Directive (MSFD) is the piece of legislation with which the EU aims to achieve Good Environmental Status (GES) of its seas. This Directive requires Member States (MSs) to set up and implement Programmes of Measures (PoMs) to achieve this goal. This paper presents a catalogue as well as the analysis of the 535 measures proposed by the eight Mediterranean EU MSs to combat pollution and non-indigenous species and contribute to the GES of the Mediterranean Sea. The results reiterate the need for better coherence and coordination between MSs, also with non-EU countries in the preparation of the next iteration of PoMs. Only 5% of the measures applied have an effect beyond MSs´ marine waters jurisdiction, and a fifth of them lack linkages with any ecosystem component. The results point to gaps, while desired goals and recommendations will help policy makers to implement the and conceptualise measures.

Mercury concentrations in reared Atlantic bluefin tuna and risk assessment for the consumers: To eat or not to eat?

This study determines the levels of total mercury in muscle tissue from 268 reared Atlantic bluefin tuna in the Mediterranean Sea, detects variations on mercury concentrations in relation to biological parameters and rearing period and evaluates the health risk posed by fish consumption taking into consideration the size, age and rearing period. A total of 30 pooled samples were analyzed. The total Hg concentrations ranged from 0.49 to 1.60 mg/kg w.w. and showed a significant positive relationship with the size and age. It was found that the longer the rearing period, the lower the mercury concentration. The total Hg exceeded the maximum level defined by the European Commission Decision in a proportion of 40.0%. Since the value of Target Hazard Quotient was higher than 1 in all different groups (medium, large, 6 months and 18 months reared specimens), the maximum possible safe weekly consumption (400 g) is suggested.

Copper Complexing Capacity and Trace Metal Content in Common and Balsamic Vinegars: Impact of Organic Matter.

Complex formation is among the mechanisms affecting metal bioaccessibility. Hence, the quantification of organic metal complexation in food items is of interest. Organic ligands in solutions of environmental and/or food origin function as buffering agents against small changes in dissolved metal concentrations, being able to maintain free metal ion concentrations below the toxicity threshold. Organic matter in vinegars consists of bioactive compounds, such as polyphenols, Maillard reaction endproducts, etc., capable of complexing metal ions. Furthermore, transition metal ions are considered as micronutrients essential for living organisms exerting a crucial role in metabolic processes. In this study, differential pulse anodic stripping voltammetry (DPASV), a sensitive electrochemical technique considered to be a powerful tool for the study of metal speciation, was applied for the first time in vinegar samples. The concentrations of Cu complexing ligands (LT) in 43 vinegars retailed in Greece varied between 0.05 and 52 µM, with the highest median concentration determined in balsamic vinegars (14 µM), compared to that of common vinegars (0.86 µM). In 21% of the vinegar samples examined, LT values were exceeded by the corresponding total Cu concentrations, indicating the presence of free Cu ion and/or bound within labile inorganic/organic complexes. Red grape balsamic vinegars exhibited the highest density of Cu ligands per mass unit of organic matter compared to other foodstuffs such as herbal infusions, coffee brews, and beers. Among the 16 metals determined in vinegars, Pb is of particular importance from a toxicological point of view, whereas further investigation is required regarding potential Rb biomagnification.

Trace elements, polycyclic aromatic hydrocarbons, mineral composition, and FT-IR characterization of unrefined sea and rock salts: environmental interactions.

Unrefined sea salt originates from seawater, typically by natural evaporation. Being minimally processed, it contains the natural minerals and impurities of seawater. Despite the wide applications of salt for culinary and food preservation purposes, the available composition data is particularly limited. Since seawater often contains various harmful substances at a trace or ultra-trace level, their determination in unrefined salt is significant in terms of quality control and food safety. Twenty-four (24) samples of unrefined sea and rock salts retailed in Greece were studied in terms of their trace metals and polycyclic aromatic hydrocarbon (PAH) content, which constitute the usual pollutants examined in seawater. In addition, samples' color and mineralogy were recorded and their attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectra were obtained. No statistically significant differences were found between sea and rock salts regarding their trace metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) content (excluding V) and the 15 PAHs examined. ATR FT-IR succeeded to discriminate among sea, rock, flower, and underground salty water salts. Compared with the typical trace metal concentrations in seawater, quite high Pb values were determined in both sea and rock salts, whereas outliers in the rest of the trace elements examined were scarce. Median values of the sum of PAH (ΣPAHs) concentrations were calculated equal to 2.1 and 2.6 ng g-1 for sea and rock salts, respectively. Environmental interactions of salt production with trace elements and PAHs are also discussed.

Dynamics of trace metals in the system water - soil - plant - wild rats - tapeworms (Hymenolepis diminuta) in Maglizh area, Bulgaria.

BACKGROUND: The impact of chemical elements on the biosphere is a function of their concentration and chemical form. Elucidation and prognosing of the latters in water basins and soil extracts is of particular significance for the assessment of their bioaccumulation in plants and animals. OBJECTIVES: Trace metals dynamics in the system water - soil-plant-wild rats - Hymenolepis diminuta in two agro-industrial zones (East and West) around Maglizh city, Bulgaria were investigated through experimental studies and thermodynamic modelling of the chemical species. METHODS: Samples from surface waters of rivers, their nearby uncultivated soils, meadow uncultivated vegetation (Ranunculus acris and Gramineae) and field rats were collected. In situ measurements and laboratory analyses were performed for the determination of the physico-chemical characteristics and total concentrations of Al, Fe, Mn, Ni, Cu, Zn and Pb. The distribution of their dissolved chemical species in water samples and in the aqueous soil extracts was calculated using a thermodynamic approach. The relationship chemical species - bioaccumulation was discussed. RESULTS: Waters and soils in the East zone of Maglizh area were found to be more polluted compared to those in the West one, regarding Ni, Mn, Zn, Pb and Cu, while Mn and Cu displayed the highest mobility in West zone soils. Trace metals contents in Ranunculus acris exceed that in Gramineae, since the highest accumulation factors were calculated for Cu and Zn. The highest accumulation in rats was found for Zn followed by Cu, being higher in the West zone. Thermodynamic modelling shows that Mn2+ free ions are dominant in both waters and aqueous soil extracts. Ni2+ and Zn2+ ions followed by metal-organic complexes are dominant in waters of East zone while metal-organic complexes followed by free ions are dominant in waters of West zone and both soil extracts. Metal-organic complexes are dominant for Fe, Cu and Pb in all samples studied, while mainly hydroxy forms (Al(OH)4-) followed by metal-organic complexes are typically for Al depending on pH. CONCLUSIONS: Experimentally established bioaccumulation of trace metals in the studied vegetation and rats is a consequence of the total concentration of trace metals in waters and soils, their mobility and chemical species. The dominance of organic complexes of trace metals is a prerequisite for their bioaccumulation in plants. Rats are in direct contact with the soil solution and therefore, of importance is the content of free ions of Mn2+, Ni2+, Zn2+, which are easily absorbed through the skin. The host-helminth system wild rat/H. diminuta could be used as a bioindicator for trace metals pollution.

Evaluation of Plasma Trace Elements in Different Stages of Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome. Its global prevalence is estimated between 25 and 45%, occurring mainly in overweight individuals with unhealthy dietary habits and low levels of physical activity. Many studies have investigated the association of trace elements with liver diseases, though not with NAFLD. In this work, we investigated trace element levels in plasma of patients and not-patients and their possible association with various stages of the disease. Inductively coupled plasma mass spectrometry (ICP-MS) was employed for the determination of As, Ba, Cd, Co, Cs, Cu, Fe, Rb, Sr, Tl, and Zn in the plasma of 189 free-living residents of Athens, Greece, either healthy or patients with mild, moderate, or severe NAFLD. The disease was diagnosed by abdominal ultrasound; blood samples were analyzed for total, HDL and LDL cholesterol, triglycerides, fasting glucose, fasting insulin, and liver enzymes, namely aspartate aminotransferase (AST), alanine transaminase (ALT), and γ-glutamyltransferase (Gamma-GT); insulin resistance was determined by the homeostatic model assessment (HOMA-IR). Zinc exhibited a statistically significant negative association with the severity of the disease, while cesium showed a statistically significant positive association. Moreover, thallium and iron were inversely associated with insulin levels. Trace element determination in plasma could be useful for establishing relationships with NAFLD status of patients. Further research is required for the verification and interpretation of these findings.

Trace metals pollution of waters and soils in Kardjali region, Bulgaria.

Trace metals pollution of surface waters and their nearby soils in the metallurgically polluted Kardjali region, Bulgaria, were studied. Thermodynamic modeling including the dissolved organic carbon (DOC) was carried out for evaluating the distribution of metal species in waters and soil solutions. Zn was found to be the most widespread pollutant in the water samples, followed by Cu, Mn, and Cd. Geoaccumulation indices of trace metals for the tested soils were calculated, indicating that regarding Al, Fe, Co, Ni, and Cu all soils are "uncontaminated". The most significant soil pollutant was found to be Cd, with all soils being either "extremely contaminated" by this metal or close to the limit, followed by Pb and Zn. The dynamics of trace metal chemical species distribution in surface waters and in the water-soluble soil fractions, as a result of possible spontaneous precipitations, was calculated by applying different thermodynamic models. Regarding Mn, Co, Ni, and Cd in waters and aqueous soil extracts and Zn in aqueous soil extracts, their free ion species prevailed, being more labile and hence toxic for the ecosystem. In the case of Al, Fe, Cu, Cd, and Pb in the waters and aqueous soil extracts and of Zn in waters, stable organic complexes with bidentate bonds, Me(OH)4- or Me(OH)02 prevailed.

Nutrient dynamics and eutrophication in the Sea of Marmara: Data from recent oceanographic research.

This work was implemented to study the physicochemical and biological characteristics of the Sea of Marmara and the Turkish straits (TSS: Bosporus and Dardanelles straits) for the period 2010-2013 and to calculate winter and summer fluxes of nutrients (nitrates, phosphates) between the Aegean and Black Seas through the TSS. The brackish Black Sea waters reach the Dardanelles Strait with modified biochemical properties. The salinity and phosphates of the surface waters increased westwards. Biologically labile nutrients of Black Sea origin are utilized through biological processes in the Marmara Sea. On the other hand, increase of nutrients due to land based sources has led to eutrophication problems in the area. The sub surface water layer of Mediterranean origin is oxygen depleted (saturation<30%) and rich in nutrients. Higher oxygen values indicated water mixing of the Sea of Marmara during winter 2012. Ammonium was the predominant form of inorganic nitrogen. The study area has been classified from Moderate to Bad trophic status. Izmit Bay also faced serious eutrophication problems together with hypoxic conditions below the halocline. Nutrient fluxes through the TSS showed temporal variation in the upper and lower layers related to changes in both nutrient concentrations and the water mass volume fluxes. Surface nitrates and phosphates outflux from the Sea of Marmara to the Aegean Sea was higher than the influx from the Black Sea through Bosporus strait, indicating high enrichment of nutrients in the Sea of Marmara from anthropogenic sources.

Organic complexation of copper in throughfall and open field bulk deposition: Influence of the tree canopy of Mediterranean forest ecosystems.

The complexing capacity for Cu ions (LT) and the apparent stability constant values (logKapp) were measured in throughfall (TF) and open field bulk deposition (BD), at two Mediterranean forest ecosystems of western Greece. LT was measured for the first time in the TF of natural forests. Concentrations of LT were three-to-four-fold higher in TF (mean ± st.dev: 2014 ± 769 nM for Varetada and 1565 ± 595 nM for Karpenissi) compared to those in BD (531 ± 517 nM and 468 ± 321 nM, respectively). In all TF and BD samples, LT concentrations were significantly higher than the corresponding total Cu concentrations, indicating that Cu was fully complexed. The LT/TOC ratios in TF were found comparable between the two study sites (235 ± 149 nM mg-1 C for Varetada and 256 ± 233 nM mg-1 C for Karpenissi) and with those of BD (226 ± 257 and 163 ± 163 nM mg-1 C, respectively). The determined mean logKapp values were almost identical in TF (6.8 ± 0.7 at Varetada; 6.8 ± 0.6 at Karpenissi) and BD (6.5 ± 0.6 at Varetada; 6.8 ± 0.3 at Karpenissi), pointing to the fact that regardless of the enrichment of TF in ligands (LT(TF) > LT(BD)) the type of binding sites remain the same. The logKapp values which were obtained herewith are similar to those obtained for humic-like substances (HULIS), indicating them as the most widespread type of ligands in BD and TF.

Predictors of cadmium and lead concentrations in the blood of residents from the metropolitan area of Athens (Greece).

The Cd and Pb blood contents of healthy adult subjects who are non-occupationally exposed and living in the metropolitan area of Athens (Greece) have not been assessed thus far. Additionally, Greeks rank first among EU27 in terms of smoking habits. To fill the existing gap, we aimed to evaluate the predictors and propose reference values (RVs) of the Cd (CdB) and Pb (PbB) blood concentrations in residents of the metropolitan area of Athens (Greece). Age, sex, smoking, alcohol drinking, educational status and nutritional habits were used as variables, with an emphasis on smoking. CdB and PbB determinations were performed directly by graphite furnace atomic absorption spectrometry (GFAAS) following the appropriate dilution of the samples with Triton-X-100. The RVs of CdB and PbB proposed for the general adult population of the Metropolitan area of Athens, Greece (upper limit of the 95% CI of the 95th percentile of the distribution of values), were 2.3 and 88µgL(-1) (P95: 1.8 and 77µgL(-1); 95% CI (P95): 1.5-2.3 and 70-88µgL(-1)), respectively. Males had a higher median CdB (0.69µgL(-1)) than females (0.55µgL(-1)). Subjects aged <40years had a lower median CdB (0.51µgL(-1)) than the elderly (≥60years; 0.60µgL(-1)). The CdB in smokers (1.2µgL(-1)) was almost threefold higher than in non-smokers (0.46µgL(-1)). The PbB levels were higher in males (31µgL(-1)) than females (20µgL(-1)). Subjects aged <40years had a lower median PbB (17µgL(-1)) than the elderly (≥60years; 32µgL(-1)). A multiple linear regression analysis demonstrated that the predictor variables for the CdB levels were the standardized beta weight, smoking, age, alcohol consumption, and intake of leafy vegetables, whereas for the PbB levels they were sex and age.

Do fattening process and biological parameters affect the accumulation of metals in Atlantic bluefin tuna?

The objective of this study was to determine the current levels of heavy metals and trace elements in Atlantic bluefin tuna muscle tissues and how they are influenced by the fattening process and various life history parameters to ascertain whether the concentrations in muscle tissue exceed the maximum levels defined by the European Commission Decision and to evaluate the health risk posed by fish consumption. A total of 20 bluefin tuna reared in sea cages, ranging from 160 to 295 cm in length and from 80 to 540 kg in weight, were sampled from a bluefin tuna farm in the Ionian Sea. The condition factor K of each specimen was calculated and their age was estimated. Heavy metal and trace element (Hg, Zn, Fe and Cu) contents were determined in muscle tissue using cold vapour atomic absorption spectrometry and flame and graphite furnace atomic absorption spectrometry. The total Hg concentrations ranged from 0.28 to 1.28 mg kg(-1) w/w, Zn from 5.81 to 76.37 mg kg(-1) w/w, Fe from 12.14 to 39.58 mg kg(-1) w/w, and Cu from 0.36 to 0.94 mg kg(-1) w/w. Only 5% of the muscle samples of tuna contained Hg above the maximum level laid down by the European Commission Decision. Moreover, 15% of the muscle samples contained Zn above the maximum level, while Fe and Cu concentrations were within the acceptable tolerable guideline values. The reared bluefin tuna had lower concentrations of Hg than the wild ones from the Mediterranean Sea. Hg and Fe concentrations showed a positive relationship with size and age of bluefin tuna, whereas negative relationships were found for the concentrations of Zn and Cu. The estimated dietary intake values of the analysed metals were mostly below the derived guidelines.

Levels of perfluorinated compounds in raw and cooked Mediterranean finfish and shellfish.

Perfluorinated compounds (PFCs) were analyzed in several species of small Mediterranean fish and shellfish, all of which are popular in Greek diet. Analysis was conducted in raw samples and in samples cooked by the two ways preferred in Greek cuisine, i.e. fried in olive oil and grilled. PFCs above the detection limit were found in all raw samples except sardine, mussel and squid. The predominant PFC was PFOS (perfluorooctane sulfonate), the highest concentration of which was measured in picarel (20.4 ng g(-1) fresh weight). The PFOS values for the rest of the samples were between

Copper complexing properties and physico-chemical characterisation of the organic matter in Greek herbal infusions.

Complex formation is among the mechanisms affecting metals' bioaccessibility. Evaluating the extent of interactions between trace elements and several constituents of food items is of great interest. This paper examines the release of copper-complexing ligands in herbal infusions of 13 aromatic plants commonly used in Greece. The concentration of ligands (LT) and the copper-binding strength (logKapp) of herbal infusions were determined with Differential Pulse Anodic Stripping Voltammetry (DPASV). All herbal infusions were found to release Cu complexing ligands, at concentrations ranging from 8.8 to 112.5 µM in rosemary and marjoram, respectively. In all infusions the total copper concentrations were lower than the corresponding LT values, indicating that Cu is fully complexed. Aiming to partially characterise the physico-chemical properties of the released organic material, the surface active substances (SAS), reduced sulphur species (RS) and catalytically active compounds (CAC) were measured, for the first time, in herbal infusions by sensitive electrochemical techniques.

Copper complexing properties of exudates and metabolites of macroalgae from the Aegean Sea.

Macroalgae are a significant source of extracellular organic material in the coastal areas of the Mediterranean, including organic ligands which serve as modulators of metal complexing capacity. This paper examines the release of copper-complexing ligands by 24 macroalgal species, including chlorophyta, rhodophyta, ochrophyta as well as Posidonia oceanica, common throughout the Mediterranean. Metabolites isolated from the algae Dictyota dichotoma and Pterocladiella capillacea were examined for the first time regarding their Cu-complexing properties. The concentration of ligands (LT) and the copper-binding strength (logKapp) of exudates and metabolites were determined by electrochemical methods. All algal species released ligands giving LT concentrations ranging from 109 to 744 nM in unfiltered samples. An increase in the concentration of ligands up to 15 times in comparison to the blank was observed after 48 h of culturing macroalgae in artificial seawater. The binding strength (log Kapp) varied among species from 7.0 to 8.6, except for the metabolites for which it was lower (log Kapp=6). Most of the ligands released were in the dissolved phase, with the contribution of particulate and/or colloidal organic matter (up to 46% of total ligands) appearing to be important only in specific macroalgal species.

Bioaccumulation of metals (Cd, Cu, Zn) by the marine bivalves M. galloprovincialis, P. radiata, V. verrucosa and C. chione in Mediterranean coastal microenvironments: association with metal bioavailability.

The concentrations of Cd, Cu and Zn in both the whole soft tissue and separate organs (gills, mantle, muscle and digestive gland) of wild bivalves (Mytilus galloprovincialis, Pinctada radiata, Venus verrucosa and Callista chione) from three different coastal microenvironments of Greece were monitored from 2003 to 2004. In parallel, by employing appropriate analytical protocols for metal partitioning, the labile fraction of the metals was determined in the dissolved phase, suspended particulate matter and sediments. Differences in the metal levels were detected both among the study areas as well as among the bivalves examined. Significant bioaccumulation was demonstrated regarding Zn in M. galloprovincialis specimens from the highly industrialized Gulf of Elefsis and Cd in P. radiata and V. verrucosa from the Maliakos Gulf, which is influenced by extended agricultural activity occurring at the neighbouring area and a river outflow. Data of the metal levels in the various environmental phases were correlated with their concentrations in bivalves' tissues. The clear relationships obtained in many cases among the labile metal concentrations and the bioaccumulated concentrations in bivalves point out that the labile fraction of a metal is the most bioavailable. The lack of positive correlation for C. chione confirms the occurrence of effective mechanisms of internal regulation of metal concentrations.

Heavy metals in raw, fried and grilled Mediterranean finfish and shellfish.

The effect of domestic pan-frying and grilling on Cd, Cr, Cu, Fe, Hg, Ni, Pb and Zn content of popular small Mediterranean finfish and shellfish was studied. The species selected -namely anchovy, bogue, hake, picarel, sardine, sand smelt, stripped mullet, Mediterranean mussel, shrimp and squid- are among the most commonly marketed and consumed in Greece and most of the Mediterranean countries. Both culinary practices examined resulted in increased metals concentrations compared to those of raw samples, the increment being inversely related to fish size and -in most cases- being more extended in pan-frying. The consumption of cooked seafood is expected to provide significant amounts of Fe and Zn followed, in decreasing order, by Cr, Cu and Ni. In addition, the estimation of (a) weekly intakes and (b) target hazard quotients for the toxic elements Cd, Hg and Pb revealed that the cooked fish and shellfish do not pose any health risk for the consumers.