Slavka Stanković

Trace metal concentrations in Mediterranean blue mussel and surface sediments and evaluation of the mussels quality and possible risks of high human consumption

The concentrations of trace metals (Fe, Zn, Mn, Ni, Cu, Co and Cr) were determined for the first time in Mediterranean blue mussels (Mytilus galloprovincialis) and surface sediments. The mussel and sediment samples were collected from five sites on the Montenegrin coastal area (southeastern Adriatic Sea) in the fall of 2005 and 2006. The collected samples were digested with a microwave digestion system. The maximum Fe, Zn, Mn, Ni, Cu, Co and Cr mean concentrations in the mussel samples were 603.0, 345.0, 85.0, 18.9, 17.2, 9.1 and 4.2mg/kg of sample dry weight, respectively. The maximum Fe, Mn, Cr, Ni, Zn, Cu and Co concentrations in the sediment samples were 40867, 943.0, 382.0, 336.0, 67.2, 24.8 and 16.9mg/kg of sample dry weight, respectively. A correlation between the metal levels found in the mussel soft tissues with those found in sediments, for both 2005 and 2006, could be established, except for the levels of Zn observed.

Biota as toxic metal indicators

Metal in the environment arises from both natural sources and human activities. Toxic metals in air, soil, and water have become a global problem. They are potential hazards to aquatic, animal, and human life because of their toxicity, bioaccumulative, and non-biodegradable nature. The major impacts of metal pollutants can be stated as ecosystem contamination and health problems of exposed human populations. Those problems have been a cause of increasing public concern throughout the world. Some trace metals are used by living organisms to stabilize protein structures, facilitate electron transfer reactions, and catalyze enzymatic reactions. But even metals that are biologically essential can be harmful to living organisms at high levels of exposure. An increasing concentration of heavy metals in the environment can modify mineral and enzyme functions of human beings. During the last two decades, the interest in using bioindicators as monitoring tools to assess environmental pollution with toxic metals has increased. Bioindicators are flora and fauna members, which are collected and analyzed to measure the levels of metal contaminants. Bioindicators therefore identify health hazards. Various living organisms, such as microbes, fungi, plants, animals, and humans, are used to monitor toxic metals from air, water, sediment, soil, and food chain. Here, we review recent bioindicators, toxicity assessment, and ecological effects.

Human exposure to trace metals and possible public health risks via consumption of mussels Mytilus galloprovincialis from the Adriatic coastal area

Considering the growing concern due to different levels of anthropogenic loadings, the main purpose of this study was to identify the levels of trace metals (Fe, Mn, Cu, Zn, Co, Ni, Cd, Pb and Hg) in the mussels Mytilus galloprovincialis sampled along the marine coast of Boka Kotorska Bay, Montenegro. In comparison with the permissible limits set by the EU and the US FDA, all trace metal concentrations found in the mussels from the coastal area of Boka Kotorska Bay were lower than the prescribed limits. Generally, the trace metal concentrations found in Montenegrin mussels are within the range of trace metal concentrations determined in low to moderately polluted Adriatic areas. Based on these and other available literature data published by other authors for Adriatic region, the public health risks associated with the consumption of mussels in relation to reported trace metal concentrations were evaluated. In terms of the obtained trace metals concentrations in mussels and the provisional tolerable weekly intake prescribed by the JECFA and oral reference doses by the US EPA, the Pb and Cd concentrations and the Co and Cd concentrations were recognized as the limiting factor for the consumption of mussels from some Adriatic areas, respectively.

Heavy Metals in Seafood Mussels. Risks for Human Health

Life on earth is threatened both by environmental pollution and overpopulation. Natural phenomena contributing to pollution have always existed but anthropogenic activities are increasing contamination of air, soil and water. Waters are especially polluted by metals. The main threats to life from toxic metals are associated with exposure to Pb, Cd, Hg and As, which accumulate in organisms. Overpopulation means more food is required but the amount of arable land is declining due to human requirements. One way of overcoming these consequences of overpopulation is to exploit seas and oceans. Thus, the consumption of seafood has increased in recent years, especially in coastal regions. However, as many traditional fishing grounds have been over-fished, aquaculture seems a viable solution to these problems. Marine mussels are an excellent candidate for aquaculture. However mussels accumulate a wide range of metals in their soft tissue. Thus, the determination of the concentrations of potentially toxic substances in mussels is essential because of their usage as seafood and the potential adverse effects of their consumption on human health. Moreover, as contamination by metal pollutants continues and is even increasing in some parts of the world, particularly in less developed countries, it is also important to determine the level of pollution in the marine environment, especially in regions where aquaculture is foreseen and where the local population consumes large amounts of mussels.

Bioindicators of Toxic Metals

Growing social concern about environmental quality has been observed in recent years, on global and local scales. As the world’s population continues to grow, it becomes imperative to understand the dynamic interactions between human activities and the environment. With the growth of all aspects of the activities of modern man, warning signs appeared that the sources of the basic environmental components, air, water, and land are not unlimited. The advent of an increasing number of contaminants reduces the power of self-purification of these media, and degradation of nature and biosphere continues infinitely, consequently acting on the man.

Can the origin of some metals in the seagrass Posidonia oceanica be determined by the indexes of metals pollutions

To assess metal pollution, Fe, Mn, Cu, Zn, Pb, Ni, Co, As, Cd, and Hg contents in samples of the seagrass Posidonia oceanica and surface sediment, collected at eight locations along the Montenegrin coast, were determined. The metal pollution index (MPI) and metal enrichment factor (EF) were then calculated. MPI and EF were lower in sediment than in P. oceanica at the same locations. This was very evident for EF values of Hg and Cd. Based on the Pearson’s correlations and EF values, it was possible to conclude that the last two metals’ content in the seagrass did not originate from the crustal sources or natural weathering processes.

The kinetics of the hydrogen evolution reaction on zinc in EDTA solutions in the pH 3 /10 range

Abstract Polarization curves of the hydrogen evolution reaction on zinc were obtained in Ethylenediaminetetraacetic acid (EDTA) solutions of different total molar concentrations (0.05, 0.10, 0.15 and 0.20 mol dm−3), the pH values of which were systematically varied (pH 3.0–10.0). The Tafel slopes of the cathodic polarization curves are −120 to −145 mV dec−1 at lower currents densities (approximately 10−5–5×10−4 A cm−2), while the higher current densities (approximately 5×10−4–10−4 A cm−2) the slopes are in the range −190 to −370 mV dec−1. The apparent cathodic reaction orders with respect to the hydrogen ions and EDTA, which were obtained from the cathodic polarization curves at the lower current densities, are z−(H+)≅1/2 and z−(H4Y)≅1, respectively. On the basis of these results, a mechanism of the hydrogen evolution reaction on zinc in the EDTA solutions examined, where protonated EDTA species (the protonated EDTA anions and the acid itself) participate directly as reactants is proposed. The unusual polarization behavior of the zinc electrode in the higher current density range is discussed.

Elemental analysis of mussels and possible health risks arising from their consumption as a food: The case of Boka Kotorska Bay, Adriatic Sea

The present study investigated the essential and non-essential elements in cultivated and wild mussels and assessed the health risk arising from their consumption as an impact of rapid growth and intensive production of Mytilus galloprovincialis in the mussel farms of the Boka Kotorska Bay. The concentrations of macro, micro, nonessential and even the small amounts of potentially toxic elements in the cultivated and wild mussels were influenced by industry, tourism and the geohydrology of the Bay. In the case of cultivated mussels, the limiting factor, i.e., the element the elevated concentration of which restricts mussels consumption, was Zr, while in the case of wild mussels the limiting factors were Cr and As. The sites with cultivated mussels stand out as sites with the highest calculated element pollution index, the total hazard index and with higher estimated risk to the health of consumers.

Analysis of trace elements in surface sediments, mussels, seagrass and seawater along the southeastern Adriatic coast – a chemometric approach

Abstract Surface sediments, mussels, seagrass, surface and bottom seawater samples were collected from the costal area of the southeastern Adriatic Sea and analyzed in order to determine the concentration and origin of the following elements: Fe, Mn, Zn, Ni, Cu, Ni, Co, As, Cd, Cr and Hg. The complexity of the obtained data was reduced by principal component analysis (PCA) and cluster analysis (CA), methods well known and accepted for the identification of the quality of marine environments. Both PCA and CA analysis were used to discriminate groups of samples according to the similarity of their chemical composition. The results revealed good diversity between the various samples, expressed by their distinctive positions of points in factor space. PCA indicated that the first two PC components explained about 73, 48, 43, 48, and 50 % of the total variance of the data for sediments, mussels, seagrass, and surface and bottom water, respectively. The results showed good discrimination capabilities between the samples taken from different locations, and also different seasons, which was especially evident in the surface and bottom water samples. Simultaneously, PCA/CA analysis of the amounts of trace elements found in the marine organisms could explain the manner of their bioaccumulation.

The geochemistry model of the surface sediment determined by using ED-XRF technique: a case study of the Boka Kotorska bay, Adriatic Sea.

The spatial distribution of major oxides (Na2O, K2O, SiO2, Al2O3, Fe2O3, CaO, MgO, MnO, TiO2, P2O5) and numerous elements (Cr, Co, Ni, Cu, Zn, As, Se, Pb, Sn, Sb, Ba, Sr, Br, Rb, Zr, Mo, Cs, Y, V, Ga, La, U, Th, Nb, W, Sc, Ge, Gd, Yb, Hf, and Ce) was determined by using energy dispersive X-ray fluorescence spectrometry on the basis of previously measured organic matter and carbonates. The optimal measuring variables for the investigated oxides and elements were determined by using five standard reference materials. The carbonated sediment type can be determined on the basis of the highest Sr, Sc, La, Nb, Hf, and Yb concentrations followed with the lowest concentrations of the remaining elements and the negative Ce anomaly. The complexity of the obtained data was also examined by principal component analysis (PCA) and cluster analysis (CA) in the identifying geochemical composition of the surface sediment. Boka Kotorska bay’s geographical position, orographical configuration, and hydrographic characteristics influence the geochemistry model of the surface sediment, quite different from the open sea.