Biomonitoring of trace metals in the Black Sea (Romania) using mussels Mytilus galloprovincialis

In a preliminary biomonitoring study, accumulated trace metal concentrations (Cd, Cu, Zn, Hg, Fe, Mn) have been measured in the mussel Mytilus galloprovincialis collected in the Black Sea, at 100 km from the Danube Delta in February 2001 and February 2002. Mussels were collected from four sites. In 2001 metal concentrations were determined in the whole soft body whereas, in 2002, the distribution of metals was evaluated in three different organs (gills, visceral mass and remaining tissues). The results obtained in 2002 confirmed those of 2001. For a given site, concentrations were always higher in the gills and visceral mass of mussels than in the remaining tissues. Principal component analysis allowed separating stations as a function of the metal concentrations in the organs. It is concluded that the mussels M. galloprovincialis are suitable biomonitors to assess changes in metal pollution in this coastal area of the Black Sea.     

Relationship between seawater pollution and qualitative changes in the extracted proteins from mussels Mytilus galloprovincialis

The aim of this study was to find a reliable biomarker of seawater pollution. For this purpose the contents of Zn and Cu, proteins and antioxidant activity in mussels Mytilus galloprovincialis collected from polluted and non-polluted sites of the Bulgarian Black Sea coast were compared. To determine the above-mentioned indices atomic spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, fluorescence, differential scanning calorimetry (DSC), and two antioxidant tests were used. It was found that the amounts of Zn and Cu were significantly higher in the mussel proteins from the polluted than from the non-polluted sites (P<0.05). FT-IR spectroscopy and fluorescence revealed specific qualitative changes in secondary and tertiary structures in mussel proteins in the samples from polluted sites. The thermodynamic properties of proteins and the changes upon denaturation were correlated with the secondary structure of proteins and disappearance of alpha-helix. Purified protein scavenging activity against 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS(*+)) was significantly higher in mussel samples from polluted than from non-polluted sites. Therefore, the changes in Zn and Cu concentration, in protein's secondary and tertiary structures and antioxidant activity in mussels M. galloprovincialis from polluted sites can be a reliable biomarker of the level of the seawater pollution.     

Distribution of arsenic compounds in Mytilus galloprovincialis of the Venice lagoon (Italy)

Samples of Mytilus galloprovincialis collected in different sites of the Venice lagoon (Italy) were investigated for total arsenic concentrations by ICP-AES and for single arsenic species by HPLC-ICP-MS. For this purpose, an analytical procedure for the sensitive and efficient speciation of the arsenic species As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC), and four arsenosugars was optimised. The total arsenic and the single arsenic species were determined in both the hepatopancreas (digestive gland) and the remaining soft tissues in order to verify the different arsenic accumulation in the body parts of mussels. Arsenic compounds were extracted from the mussels with a methanol/water mixture; the extracts were evaporated to dryness, redissolved in water, and chromatographed in an anion-exchange column, a Hamilton PRP-X100. Only small quantities or traces of inorganic arsenic were detected in the mussels. The majority of arsenic compounds detected in the extracts were organic species, with a predominance of arsenobetaine and of an arsenosugar. In addition, a greater arsenic accumulation in the digestive glands of mussels was observed.     

TBT in marine sediments and blue mussels (Mytilus edulis) from central-west Greenland

Concentrations of butyltin compounds were investigated in the bivalve Mytilus edulis (five sites) and marine sediments (three sites) near the largest town, Nuuk, in Greenland. In seven of the eight samples the extremely toxic compound tributyltin (TBT) was detected. The concentrations of tributyltin and degradation products in the bivalves were close to 1 microgram kg-1 wet weight (ww), calculated as Sn, which is lower than those found in Iceland and the Faeroe Islands. In sediments the concentration of TBT ranged from below the limit of detection of 1 microgram kg-1 to 171 micrograms kg-1 dry weight (dw), calculated as Sn, which is comparable to levels found in Europe.     

Mytilus galloprovincialis filter feeding on the bacterial community in a Mediterranean coastal area (Northern Ionian Sea, Italy)

This study was carried out seasonally, throughout a year, to evaluate the filtering activity on bacteria of Mytilus galloprovincialis. Six microbiological parameters were researched in the water and mussels samples collected along the coastal area of the Northern Ionian Sea in three stations, S. Vito, Lido Gandoli and Lido Silvana. We detected the densities of culturable heterotrophic bacteria by spread plate on Marine Agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios abundance on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci were determined by the Most Probable Number. Bacterial concentrations at 20 and 37 degrees C as well as vibrios concentrations were higher in the mussel samples compared to the corresponding seawater throughout the year. The results obtained could contribute to improve the information relatively either to the natural processes existing between bacteria and mussels or to the risk of human infections related to the consumption of mussels.     

Presence of vibrios in seawater and Mytilus galloprovincialis (Lam.) from the Mar Piccolo of Taranto (Ionian Sea)

During the spring-summer period, vibrios were detected in water and mussels (Mytilus galloprovincialis) collected in 30 sampling sites located in the Mar Piccolo of Taranto (Ionian Sea, Italy). In order to evaluate the degree of microbial pollution of the investigated area, fecal coliforms and Escherichia coli densities were also determined. Vibrio alginolyticus constituted the predominant component of the total culturable vibrios. Some Vibrio species such as V. mediterranei, V. parahaemolyticus, V. diazotrophicus, V. nereis, and V. splendidus were present in water as well as in mussel samples; selective retention in mussels, however, was demonstrated for other vibrios (V. vulnificus, V. cincinnatiensis, V. orientalis, V. anguillarum, V. marinus, V. hollisae). The isolation of some potential pathogenic vibrio species shows the importance of Vibrio research to estimate water quality and to avoid transmission of infection to man and to other marine organisms.     

Field validation of autometallographical black silver deposit (BSD) extent in three bivalve species from the Lagoon of Venice, Italy (Mytilus galloprovincialis, Tapes philippinarum, Scapharca inaequivalvis) for metal bioavailability assessment

The autometallographic approach was applied to three filter-feeder bivalves from differently polluted sites of the Lagoon of Venice. The area density (AD) values of black silver deposits (BSDs) were therefore seasonally quantified by image analysis in digestive cell lysosomes. Sediments were characterised in terms of grain size, organic content and metal concentrations (Cd, Cu, Ni, Pb, Zn). The physiological status of the bivalves was also evaluated by applying the "survival in air" test as a generic stress index. Chemical results showed that Zn contributed to the total metal load for more than 60% in sediments and for 85%-94% in mussel and clam digestive glands, respectively (data processed from published results obtained on the same samples). Regression analyses between extent of BSDs and both total metal and Zn concentrations in digestive gland followed a linear pattern in mussels and clams, but not in arks. Similarly, in mussels and clams only, BSD amount was significantly correlated with total metal concentrations in sediments according to a logarithmic model. Consequently, results obtained from autometallography can discriminate sites on the basis of their metal pollution levels, like chemical analyses on both sediments and digestive glands, evaluations being supported by the results of the physiological stress index. As a conclusion, it is suggested that autometallography in bivalves may provide overall estimates of metal fractions moving from sediments towards organisms through the ingestion of metal-enriched particles. Future work is needed to define the bioaccumulation model in arks and to clarify their possible use as metal biomonitors.     

Results of field investigations into the impact of intermittent sewage discharges on the microbiological quality of wild mussels (Mytilus edulis) in a tidal estuary

Field surveys were designed to examine the effects of sewage contamination from storm overflow effluent on faecal coliform and Escherichia coli concentrations in the flesh of wild mussels (Mytilus edulis). Bags containing 30 mussels each were fixed at known inter-tidal locations and retrieved at intervals following discharge from a nearby combined sewer overflow (CSO). Concentrations of faecal coliform bacteria and E. coli were measured in the shellfish flesh and in samples of overlying water prior to collection of the mussel samples. Faecal coliform and E. coli concentrations in shellfish increased rapidly after CSO discharge. E. coli concentrations exceeded the European shellfish hygiene class C limit of 46,000 100g(-1), and decayed during subsequent CSO discharge-free periods. The concentration and depuration response was independent of the magnitude of CSO spill volume. First-order exponential decay functions were fitted to the data. Decay rates were lower than those found in corresponding microcosm experiments. This relates to the repeated pattern of inundation and exposure associated with the tidal cycles in the estuary. Relationships between E. coli and faecal coliform concentrations in the shellfish and overlying water samples were relatively weak (r<0.60), a pattern often seen with data from uncontrolled environmental experiments.     

Temporal trends of Cd, Cu, Hg, Pb and Zn in mussel (Mytilus galloprovincialis) from the Spanish North-Atlantic coast 1991-1999

Temporal trends for heavy metals (Cd, Cu, Hg, Pb and Zn) in mussel (Mytilus galloprovincialis) from the Galician and Cantabrian areas in Spain, where samples were yearly collected from 1991 to 1999, are presented. This study was carried out by the Centro Oceanográfico de Vigo of the Instituto Espa?ol de Oceanografia (I.E.O.) as part of the Spanish contribution to the Joint Assessment and Monitoring Programme (JAMP) of the OSPAR Convention. The experimental work and subsequent statistical treatment, following OSPAR procedures and guidelines, are described. In order to carry out the statistical treatment of the data, median values of the different shell length classes were used for each contaminant, year and area. The Kendall T-b correlation coefficient was used with the purpose of demonstrating the existence of a downward significant temporal trend in the pollution levels, according to the advice of ICES Working Group on Statistical Aspects of Environmental Monitoring. A decrease of copper levels was detected in Vigo, Pontevedra and Arosa, of mercury in Pontevedra and A Coru?a, of lead in Vigo, Pontevedra, A Coru?a and Bilbao and of zinc in Pontevedra and A Coru?a. However, a cadmium positive trend was registered at Ria de Vigo. No significant trends were detected in the other cases.     

The effect of contractor size on mark-up size decision in Saudi Arabia

This study is a part of a larger study addressing the bidding decisions of construction contractors in Saudi Arabia. It examines the mark-up size decisions of small, medium, and large contractors in Saudi Arabia. These groups are found to consider and evaluate many factors subjectively when they set mark-up sizes for projects. However, the importance of these factors varies as the contractor's size changes. Bidding document price, strength in the industry, time allowed for submitting bids and other factors are the greatest contributors to the discrimination between contractor sizes.     

Removal of trace levels of 2-acetylaminofluorene (2-AAF) from wastewater.

An adsorption system is described for the removal of part per billion levels of the chemical carcinogen, 2-acetylaminofluorene (2-AAF), from industrial wastewater. The system consists primarily of filters and activated carbon and non-ionic polymeric adsorbents arranged in tandem. It is highly efficient, operates at low cost, and requires minimal attention. The chemical monitoring of the raw and/or cleaned-up wastewater is based on a highly sensitive and specific spectrophotofluorometric method that allows acceptance or rejection of samples at the 0.2 part per billion level. The system is presented as a model for evaluating the removal of traces of organic chemicals from wastewater prior to recycling or discharging it into the environment. Results of laboratory evaluations of several other approaches to the purification of 2-AAF-containing wastewater are also presented.     

The effect of pH and hardness metal ions on the competitive interaction between trace metal ions and inorganic and organic complexing agents found in natural waters

The effect of pH and hardness metal ions on the interactions between trace metals and both inorganic and organic complexing agents has been studied under conditions simulating natural aquatic conditions, by employing anodic stripping voltammetric titration techniques. The complexation of Bi(III), Cd(II), Cu(II), Pb(II), and Tl(I) with the hydroxo- and carbonato-ligands found in a carbonate medium has been observed to generally increase with increasing pH. Both labile and nonlabile interactions have been observed. Nonlabile interactions are predominant at low pH and labile interactions generally increase with increasing pH. Neither calcium nor magnesium affects these interactions. The complexation of humic acids with trace metals in a carbonate medium was found to be more intense than metal ion-inorganic complexation. Both labile and nonlabile complexation was found; however, no generalizations can be made concerning the type and extent of complexation because of the individual nature of the interactions of each trace metal. Calcium was found to be more effective than magnesium in inhibiting trace metal-organic complexation. The effect of calcium is to inhibit labile complexation and is most pronounced with the cadmium-humic acid system.     

The application of high resolution spark source mass spectroscopy for the determination of trace elements in mussels

The applicability of high resolution spark source mass spectrometry to the determination of some selected trace elements in dried mussel samples is described. In this study it is shown that when using high resolution mass spectrometry, element spectral lines can be measured which are normally partly or completely overlapped by complex ions, polyatomic ions, etc.Ten trace elements are determined for each mussel sample. The sampling was carried out at various locations along the English and Welsh coast at different times over a period of two years.     

The use of physical separation techniques in trace metal speciation studies

Size fractionation techniques used in speciation studies of trace metals in natural waters have been reviewed. Centrifugation, filtration, ultrafiltration (UF), dialysis and gel filtration chromatography (GFC) have been considered with respect to trace metal contamination, adsorption effects and size selectivity. Size differentiation during centrifugation is impeded due to density effects on particle settling rates. Filtration is the most commonly used method to fractionate trace metal species, but often only “issolved” and “particulate” fractions are identified. Filters may be decontaminated with dilute nitric acid and adsorption effects may be minimised by preconditioning with a dilute calcium nitrate solution. Several studies concerning the size selectivity of filters indicate that at present only Nuclepore polycarbonate filters are suitable for size spectrum investigations. Those difficulties outlined above are also experienced with UF methods but generally have not been so well resolved. particularly with respect to adsorption. Adsorption during UF causes an overestimation of the molecular size of metal complexes. Dialysis techniques have been utilized with some success in order to isolate trace metal species in true solution but have seen only limited applications in comprehensive speciation schemes. GFC offers considerable potential in physicochemical speciation studies. The major advantage lies with the ability to determine metal concentrations over a continuous size spectrum rather than at discrete size ranges. In contrast to other methods, adsorption during GFC will cause the molecular weight of organometallic complexes to be underestimated. Several examples of the environmental application of each technique have been considered, thereby illustrating the value of examining the size distribution of metal species in natural waters.     

Detection of DNA damage in haemocytes of Mytilus galloprovincialis in the coastal ecosystems of Kastela and Trogir bays, Croatia

Coastal waters are burdened with different contaminants of anthropogenic origin due to intensive urbanisation and economical development. Bays, semi-enclosed areas with limited water renewal ability, are particularly endangered by contaminant inputs. Kastela Bay (Dalmatia, Eastern Adriatic) has earlier been identified as an area loaded with diffuse sources of pollution, including genotoxic agents. However, there is lack of data on the effects of these contaminants on the local marine fauna. The aim of this study was to assess genotoxic impacts in Kastela Bay and the neighbouring Trogir Bay using the micronucleus test and Comet assay with mussel (Mytilus galloprovincialis) haemocytes. Native and caged mussels were included in the studies. Our results confirmed that mussels in Kastela and Trogir Bays are affected by genotoxic contaminants. In addition to mussels from the most known polluted site (Vranjic), there was evidence for genotoxic effects in mussels collected at other locations. The response in the micronucleus test and the Comet assay differed somewhat between sites, the latter apparently being more sensitive, but the two methods complement each other and it is therefore desirable to use them both in monitoring the impacts of genotoxic pollution in coastal waters.     

Phosphorus addition reverses the positive effect of zebra mussels (Dreissena polymorpha) on the toxic cyanobacterium, Microcystis aeruginosa

We tested the hypothesis that zebra mussels (Dreissena polymorpha) have positive effects on the toxin-producing cyanobacterium, Microcystis aeruginosa, at low phosphorus (P) concentrations, but negative effects on M. aeruginosa at high P, with a large-scale enclosure experiment in an oligotrophic lake. After three weeks, mussels had a significantly positive effect on M. aeruginosa at ambient P (total phosphorus, TP ∼10 μg L⁻¹), and a significantly negative effect at high P (simulating a TP of ∼40 μg L⁻¹ in lakes). Positive and negative effects were strong and very similar in magnitude. Thus, we were able to ameliorate a negative effect of Dreissena invasion on water quality (i.e., promotion of Microcystis) by adding P to water from an oligotrophic lake. Our results are congruent with many field observations of Microcystis response to Dreissena invasion across ecosystems of varying P availability.     

Estimating sludge loadings to land based on trace metal sorption in soil: effect of dissolved organo-metallic complexes

This paper describes the results of research examining the effect of dissolved organo-metallic complexes of copper (Cu) and zinc (Zn) from sewage sludge leachate on sorption by a humic-gley soil A-horizon, and the influence of such complexes on resultant sludge loading estimates. Sorption was described with Linear, Freundlich or Langmuir equations, and compared between a sample of sludge leachate (containing 97.4% of Cu and 63.2% of Zn as dissolved organo-metallic complexes) and a reference solution (which mimicked the leachate, except for a lack of dissolved organic material). This comparison revealed that dissolved organo-metallic complexes significantly depressed Cu and Zn sorption in the study soil. The isotherm equations were then used to estimate sludge-derived Cu and Zn loadings to soil in order to result in an "allowable" output concentration from the soil solution to the surrounding environment. These loadings, together with soil bulk density and "availability" of sludge Cu and Zn, were incorporated in a preliminary model to estimate sludge application rates which are acceptable in terms of off-site movement of these metals through leaching losses. In the absence of dissolved organo-metallic complexes (sorption from the reference solution), levels of Cu and Zn sorption in the study soil indicated a sludge application rate of approximately 3500 kg/ha. However, when Cu and Zn sorption from the sludge leachate with dissolved organo-metallic complexes was considered, calculated loading rates were reduced to approximately 690 kg-sludge/ha. This suggests that for sludge loading estimates based on soil sorption characteristics to be relevant to environmental protection, the sorption depressing effect of dissolved organo-metallic complexes should be quantitatively considered.     

Risso's dolphin (Grampus griseus) stranding on the coast of Israel (eastern Mediterranean). Autopsy results and trace metal concentrations

Radon-222 concentration measurements using the charcoal adsorption technique were made continuously over periods of up to 2 years in three houses, two rural and one urban. The measurement records for all houses show a variation in radon concentration on a seasonal scale on which is superimposed shorter periods of relatively large magnitude fluctuations on a scale longer than the typically 4-5-day measurement duration. Regression analysis using meteorological data from a weather station remote from the houses shows that much of the variation in both monthly and 3-day mean radon concentration can be explained by regional scale external temperature variation. Wind speed, rainfall and barometric pressure apparently influence the 3-day values to a much smaller degree. Differences in the radon levels between the houses reflect the different geological radon potential of the two areas, with notably higher levels over limestone than glacial till and sandstone. Other differences within and between houses reflect house construction and occupancy factors.     

The discriminatory power of two biomonitors of trace metal bioavailabilities in freshwater streams

The relative discriminatory powers of two trace metal biomonitors in European streams (the amphipod crustacean Gammarus fossarum and mayfly larvae of the genus Baetis-B. rhodani and B. vernus) are compared by discriminant function analysis using data from streams draining a zinc and lead mining area of Upper Silesia, Poland. The mayfly larvae (whether or not distinguished into the two separate species) had the better discriminatory power to distinguish between sites on the basis of local bioavailabilities of cadmium, copper, iron, lead and zinc. The bioavailabilities of the two metals lead and cadmium were the major local contributing factors to the stronger discrimination shown by the Baetis larvae.