Effects of pyrene on mussels in different experimental conditions

The toxicity of the polyaromatic hydrocarbon pyrene to Mytilus edulis and Mytilus galloprovincialis was investigated in experiments conducted in the United Kingdom for M. edulis and in Turkey for M. galloprovincialis. Experimental conditions of temperature and salinity were chosen to be appropriate to the ambient conditions in which the mussels typically live. The effect of different feeding regimes on pyrene bioaccumulation and toxicity was also investigated. Feeding rate and neutral red retention biomarker techniques were used for toxicity assessment. An experiment with M. edulis demonstrated that mussels exposed to pyrene accumulated increasing amounts of this compound throughout a 15-day exposure period and that accumulation increased in relation to exposure concentration and with increasing concentration of unicellular algal food material. However, in these experiments, which were protected from UV light, there was no clear relationship between pyrene concentration in tissues and feeding rate. A clear concentration-response relationship was observed between tissue concentration and neutral red retention for days 1 and 7 of the experiment, but this relationship was lost by day 15, with evidence of the cells recovering. A similar experiment was conducted with M. galloprovincialis at a single (high) pyrene concentration in darkness. The feeding rate of the exposed mussels was always lower than the feeding rate of the control mussels, although the difference was insignificant at 7-day exposure. A decreasing trend in health status of the mussels was indicated by the neutral red retention assay results after 7 and 15 days of exposure to pyrene. In a third experiment (with M. galloprovincialis), an illuminated algal chemostat system containing pyrene was inserted in the exposure system as the food source for the mussels. Both biomarker results showed conclusively that toxic effects correlated with pyrene bioaccumulation, though there was no clear evidence for light-enhanced toxicity. These experiments showed that experimental conditions such as salinity, temperature and feeding regime and perhaps the species of mussel used may influence whether pyrene is perceived as being a toxic molecule.     

Lead and cadmium biosorption by extracellular polymeric substances (EPS) extracted from activated sludges: pH-sorption edge tests and mathematical equilibrium modelling

The sorption of Cd and Pb by extracellular polymeric substances (EPS) extracted from activated sludges originated from wastewater treatment plants (WWTPs) or Lab-scale bioreactors was investigated as a function of pH. The study was carried out using a polarographic method in the SMDE (stripping mercury dropping electrode) mode which is suited to determine labile metals in solution containing soluble ligands such as EPS. The results obtained provide evidence of the presence of a pH-sorption/desorption edge for Cd and Pb by EPS. The use of Kurbatov’s model gives information on the mechanisms involved through the determination of “relative complexation constants” (operationally defined) and the number of protons exchanged. The use of this model demonstrates that proton exchange with metals is not the only mechanism involved in metal biosorption by EPS. Other mechanisms such as cation exchange with Ca or Mg, global electric field surrounding the ligand or micro-precipitation of metals could be involved in metal sorption by EPS. The position of the pH-sorption edge curves and the “relative complexation constants” show that Pb displays a greater affinity for EPS than Cd. The studied EPS have large differences regarding binding strength of Cd and Pb. These differences are not correlated with the organic parameters measured to characterize the EPS, however the mineral fraction of the EPS could be involved to a large extent in the sorption of metal.     

A spatial scan statistic for zero-inflated Poisson process

The scan statistic is widely used in spatial cluster detection applications of inhomogeneous Poisson processes. However, real data may present substantial departure from the underlying Poisson process. One of the possible departures has to do with zero excess. Some studies point out that when applied to data with excess zeros, the spatial scan statistic may produce biased inferences. In this work, we develop a closed-form scan statistic for cluster detection of spatial zero-inflated count data. We apply our methodology to simulated and real data. Our simulations revealed that the Scan-Poisson statistic steadily deteriorates as the number of zeros increases, producing biased inferences. On the other hand, our proposed Scan-ZIP and Scan-ZIP+EM statistics are, most of the time, either superior or comparable to the Scan-Poisson statistic.     

Levels of heavy metals in blue whiting caught from the eastern Black Sea area of Turkey

This paper presents data on the concentrations of 5 metals, copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn) and lead (Pb) in Blue Whiting sampled from the Eastern Black Sea coast of Turkey. The highest metal concentrations of Cu, Cd, Fe, Zn and Pb were recorded in Blue Whiting with the values of 2.71, 0.601, 14.137, 15.322 and 1.078 μg g^‐1 dry weight, respectively. On average the metal concentrations in Blue Whiting followed the order of Zn > Fe > Cu > Pb > Cd. Temporal differences of concentrations of these metals were significant (p < 0.05). Spatial fluctuations of Cu, Cd, Fe, Zn and Pb concentrations in Blue Whiting were also significant (p < 0.01). It was found that the concentrations of Cu, Cd, Fe, Zn and Pb in the muscle in Blue Whiting were below the limit of Public Health Regulation in Turkey.     

Antiaggregant and toxic properties of different solutions on hemocytes of three freshwater bivalves

Hemocytes are main blood components of bivalves playing important roles in toxicological and immune responses. Consequently, a study on these cells may be useful to understand the invertebrate immunological systems. The aim of the present study was to find the best antiaggregant solution, based on its capacity of preserving the natural morphology and viability of hemocytes from the freshwater bivalves, Anodonta cygnea, Unio delphinus, and Corbicula fluminea. Hemocytes from the three species were collected and maintained in different antiaggregant solutions, i.e., ethylenediaminetetraacetic acid (EDTA), EDTA-citrate, modified Alsever solution (MAS), N-ethylmaleimide (NEM), NEM-NaCl, and heparin. The cell morphology and viability were analyzed periodically with light microscopy techniques. Between these assays with various antiaggregant solutions, the best results were obtained with NEM at a concentration of 0.05 mol·L^?1. It is also shown that, as expected, the osmolarity of the antiaggregant solutions plays a very important role in cell viability. Based on this study, NEM at 0.05 mol·L^?1 was considered an adequate antiaggregant solution for future research on immunological and toxicological responses and other physiological studies of freshwater bivalve hemocytes.     

Reproductive biology of the deep-sea octocoral Drifa glomerata in the Northwest Atlantic

The present study examined the mode and timing of reproduction of poorly understood deep-water octocorals and the environmental factors that may influence their reproductive patterns. Data on reproductive characteristics of the octocoral Drifa glomerata (Alcyonacea: Nephtheidae) collected between 2004 and 2007 at ca. 100–330 m depth off Newfoundland and Labrador (eastern Canada) were compared among years, months and depth ranges. No male gonad was ever observed during the study. The ratio of fertile colonies possessing large pinkish polyps with oocytes/planulae was >50% throughout the year. The number of brooded planula larvae within a single fertile polyp varied between 1 and 10 for a total of approximately 40–3,000 in a whole colony. The size of oocytes and/or planulae was consistently greater in the polyps than in the branchlets, indicating that the development pathway of oocytes to planulae is from the branchlets to the polyps. Although larval production seemed to persist year round, the onset of major planulation events occurred in December–January of two consecutive years, when large mature planulae were released in correlation with the first increase of photoperiod and maximum temperature at 150 m. A second peak in planulation between April and early June followed the phytoplankton bloom. Seasonal trends were more apparent in colonies from <200 m, and the planula index varied among sampling depths and years. Larval release in a live colony under laboratory conditions occurred between January and June 2008, closely following predictions based on field samples.     

A ‘coastal-hazard GIS’ for Sri Lanka

Following the 2004 tsunami disaster in Sri Lanka, it was apparent that mapping the coast’s vulnerability was essential for future protection of the local populations. We therefore developed a prototype ‘Coastal-hazard GIS’ for Sri Lanka so as to provide an effective tool for decision makers to limit the impact of natural coastal hazards such as sea level rise, tsunamis, storm surges and coastal erosion, and thus protect the exposed assets (population, property, settlements, communications networks, etc.). The prototype was developed on a pilot site in Galle through building up homogeneous data on the land/sea interface from studies conducted on the exposure of the coastal populations, the aim being to enable an evaluation of the hazards combined with the vulnerability and thus an analysis of the risks. Coastal risk scenarios are developed so as to estimate the impacts and consequences of an event (tsunami, storm, etc.) on the assets, the principle behind this being that if, in general, the coastal hazard cannot be decreased, then a better knowledge of it through simulation should make it possible to limit the vulnerability and thus the risk. The Coastal-hazard GIS will also provide a planning tool in terms of locating new settlements, expanding urban areas, siting coastal protection works, etc.     

Investigations on the binding mechanism of the herbicide simazine to dissolved organic matter in leachates of compost

14C-labelled simazine was composted together with biowaste on a pilot (m3) scale. The herbicide was quickly bound to the compost matrix. By aqueous extraction of 29 and 200 days old compost (equivalent to thermophilic and mesophilic phase of composting) only 4.2% and 3.1% respectively of the radioactivity in the compost samples could be extracted with water. Analysis of the extracts using high-performance size exclusion chromatography (HPSEC) revealed that the dissolved organic matter (DOM) had molecular weights ranging between 2 and 28 kDa. The amount of DOM-associated radioactivity increased from 53% (day 29) to 65% (day 200) of total extractable radioactivity. The type of binding of the 14C-labelled residues and the DOM was elucidated by silylation of humic matter and subsequent HPSEC. The data demonstrated that besides polar metabolites also intact simazine was bound to the DOM. A distinct shift from rather weak interactions to strong covalent linkages of simazine and its metabolites with increasing age of the compost was observed. The results showed that only low amounts of free simazine and its degradates can be extracted with water. We concluded that the shift towards stable covalent linkages is equivalent to a detoxification of the contaminant in aged compost. Consequently, the use of the analysed compost in its mature stage should not pose an environmental risk to the groundwater or the subsoil.     

Institutional barriers to environmental information

Several barriers impede the free flow of environmental information in the government's hands to the public. The most important of these are the compartmentalization of environmental information among several departments, the manipulation of information to protect vested bureaucratic or political interests and, lastly, the withholding of information. The media's ineffective coverage of environmental issues and the small number of well-funded environmental groups constitute two additional institutional barriers to the broader dissemination of environmental information. Solutions proposed to reduce these barriers include the creation of an independent Commissioner on the environment reporting publicly to Parliament about the government's performance and the development of a widely-available system of indicators to inform the public about changes in environmental quality.