Immune responses,DNA damage and ultrastructural alterations of gills in the marine mussel Lithophaga lithophaga exposed to CuO nanoparticles

Environmental Science and Pollution Research - Nanoparticle (NP) pollution is a worldwide problem. Copper oxide nanoparticles (CuO NPs) are one of the most used NPs in a variety of applications,...     

Beyond ‘trees are good’: Disservices,management costs,and tradeoffs in urban forestry

The provision of ecosystem services is a prominent rationale for urban greening, and there is a prevailing mantra that ‘trees are good’. However, understanding how urban trees contribute to sustainability must also consider disservices. In this perspective article, we discuss recent research on ecosystem disservices of urban trees, including infrastructure conflicts, health and safety impacts, aesthetic issues, and environmentally detrimental consequences, as well as management costs related to ecological disturbances and risk management. We also discuss tradeoffs regarding species selection and local conservation concerns, as well as the central role of human perception in the interpretation of ecosystem services and disservices, particularly the uncritical assertion that ‘everybody loves trees’. Urban forestry decision-making that fails to account for disservices can have unintended negative consequences for communities. Further research is needed regarding life cycle assessments, stakeholder decision-making, return-on-investment, and framings of services and disservices in urban forestry.     

Study on the cytotoxicity of microcystin-LR on cultured cells

The toxicity of purified blue-green algal toxin, microcystin-LR, on permanent cell lines KB, NIH/3T3, H-4-II-E, HeLa, Vero, Hep G2, Caco-2 and HL-60 was studied. Assessment of cell viability using colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays indicated that purified microcystin-LR induced toxic effect on KB and H-4-II-E cell lines after 96 h incubation at toxin concentrations greater than 18.75 microg/ml. KB cell line was selected for further study when reproducibility, consistency and sensitivity were considered. Significant amounts of lactate dehydrogenase (LDH) were released from KB cells when incubation durations were 72 and 96 h with toxin concentrations of 18.75 microg/ml and higher. Although previous studies suggested that microcystin-LR had no cytotoxic effect on permanent cell lines, LDH release assay performed on KB cells indicated that exposure to microcystin-LR could result in damage to the cell membrane.     

Photooxidation mechanism of nitrogen-containing compounds at TiO2/H2O interfaces: an experimental and theoretical examination of hydrazine derivatives

The photocatalytic oxidation of oxalyldihydrazide, N,N'-bis(hydrazocarbonyl)hydrazide, N,N'-bis(ethoxycarbonyl)hydrazide, malonyldihydrazide, N-malonyl-bis[(N'-ethoxycarbonyl)hydrazide] was examined in aqueous TiO2 dispersions under UV illumination. The photomineralization of nitrogen and carbon atoms in the substrates into N2 gas, NH4+ (and/or NO3-) ions, and CO2 gas was determined by HPLC and GC analysis. The formation of carboxylic acid intermediates also occurred in the photooxidation process. The photocatalytic mechanism is discussed on the basis of the experimental results, and with molecular orbital (MO) simulation of frontier electron density and point charge. Substrate carbonyl groups readily adsorb on the TiO2 surface, and the bonds between carbonyl group carbon atoms and adjacent hydrazo group nitrogen atoms are cleaved predominantly in the initial photooxidation process. The hydrazo groups were photoconverted mainly into N2 gas (in mineralization yields above 70%) and partially to NH4 ions (below 10%). The formation of NO3- ions was scarcely recognized.     

The occurrence of trihalomethanes in the drinking water in Greece

This paper summarizes and completes an investigation into the occurrence of trihalomethanes (THMs) in public water supplies in Greece. The investigation was conducted in three cities of Greece, Athens, Mytilene and Chalkida, from 1993 to 1998. Samples were collected from three treatment plants of Athens (Galatsi Treatment Plant--GTP, Menidi Treatment Plant--MTP, Kiourka Treatment Plant--KTP) and from the distribution systems of Athens, Mytilene and Chalkida. The sources for these systems are lakes, boreholes and wells. The concentrations of THMs ranged from 5 to 106 microg/l, from 4 to 27 microg/l and from 5 to 96 microg/l, in the distribution systems of Athens, Mytilene, Chalkida, respectively. The wide ranges of concentrations in three cities should be attributed to the organics concentration of raw water. In all the cases the THMs concentrations were higher during the summer and fall than in spring and winter. In GTP and in the distribution system receives water by GTP, from April 1993 to January 1995, Mytilene and Chalkida, brominated THMs dominated and existed at the highest concentration levels, whereas chloroform was the least prevalent compound, while in all the other cases the opposite was observed. In all samples the concentrations were lower than the maximum level of 100 microg/l for total trihalomethanes (TTHMs) set by European Community (EC).     

Monitoring, modelling and environmental exposure assessment of industrial chemicals in the aquatic environment

Monitoring and laboratory data play integral roles alongside fate and exposure models in comprehensive risk assessments. The principle in the European Union Technical Guidance Documents for risk assessment is that measured data may take precedence over model results but only after they are judged to be of adequate reliability and to be representative of the particular environmental compartments to which they are applied. In practice, laboratory and field data are used to provide parameters for the models, while monitoring data are used to validate the models' predictions. Thus, comprehensive risk assessments require the integration of laboratory and monitoring data with the model predictions. However, this interplay is often overlooked. Discrepancies between the results of models and monitoring should be investigated in terms of the representativeness of both. Certainly, in the context of the EU risk assessment of existing chemicals, the specific requirements for monitoring data have not been adequately addressed. The resources required for environmental monitoring, both in terms of manpower and equipment, can be very significant. The design of monitoring programmes to optimise the use of resources and the use of models as a cost-effective alternative are increasing in importance. Generic considerations and criteria for the design of new monitoring programmes to generate representative quality data for the aquatic compartment are outlined and the criteria for the use of existing data are discussed. In particular, there is a need to improve the accessibility to data sets, to standardise the data sets, to promote communication and harmonisation of programmes and to incorporate the flexibility to change monitoring protocols to amend the chemicals under investigation in line with changing needs and priorities.     

Mutagenic nitrated benzo[a]pyrene derivatives in the reaction product of benzo[a]pyrene in NO2-air in the presence of O3 or under photoirradiation

In order to clarify the contribution of nitrated products to the direct-mutagenic activity of products of the reactions of benzo[a]pyrene in NO2-air under various conditions, heterogeneous reactions of BaP deposited on filter in the air containing 10 ppm of NO2 have been conducted in dark or under photoirradiation. The reaction products have been analyzed by gas chromatography and mutagenicity of the products fractionated by preparative HPLC was assayed for Salmonella typhimurium strains TA98 and YG1024 in the absence of S9 mix. 3,6-dinitrobenzo[a]pyrene and 1,3-dinitrobenzo[a]pyrene, which are strong direct-acting mutagens, largely contributed to the total direct-acting mutagenicity of the dark reaction products in NO2-air. On the other hand, both the dark reaction in the presence of O3 and the photoreaction in NO2-air resulted in the formation of much smaller amounts of nitrobenzo[a]pyrenes than that observed in the dark reaction in the absence of O3. These results show that the contribution of other direct-acting mutagens to the total direct-acting mutagenicity of the products in these reactions should be considered. Benzo[a]pyrene lactones were identified in a highly mutagenic fraction of the products of the dark reaction in the presence of O3 and photoreaction and a nitrobenzo[a]pyrene lactone was also identified in a highly mutagenic fraction of the dark reaction products in the presence of O3. Nitrated oxygenated benzo[a]pyrene derivatives such as nitrobenzo[a]pyrene lactone were considered to largely contribute to direct-acting mutagenicity of the products of the dark reaction in the presence of O3 and photoreaction.     

Interactive effects of elevated ozone and carbon dioxide on growth and yield of leaf rust-infected versus non-infected wheat

Spring wheat (Triticum aestivum L. cv. Turbo) was grown from seedling emergence to maturity (129 days) in chambers simulating the physical climate and ozone pollution of a field site in Northern Germany from 1 April to 31 July with a mean 1-h daily maximum of 61.5-62.4 nl l(-1) ozone compared to a constant low level of 21.5-22.8 nl l(-1) ozone. The two ozone levels were combined with either a current (374.1-380.2 microl l(-1)) or enriched (610.6-615.0 microl l(-1)) CO(2) atmosphere. Additionally, a leaf rust epidemic (Puccinia recondita f. sp. tritici) was induced at tillering stage by repeated re-inoculations with the inoculum formed on the plants. Leaf rust disease was strongly inhibited by ozone, but largely unaffected by elevated CO(2). Ozone damage on leaves was strongly affected by CO(2) and infection. On infected plants, ozone lesions appeared 2-4 weeks earlier and were up to fourfold more severe compared to non-infected plants. Elevated CO(2) did not delay the onset of ozone lesions but it significantly reduced the severity of leaf damage. It also enhanced the photosynthetic rate of flag leaves and increased the water use efficiency, biomass formation and grain yield. The relative increases in growth and yield induced by CO(2) were much larger on ozone-stressed than on non-stressed plants. Both ozone and fungal infection reduced biomass formation, number of grains per plant, thousand grain weight and grain yield; however, adverse effects of leaf rust infection were more severe. Elevated CO(2) largely equalized the negative effects of ozone on the photosynthetic rate, growth and yield parameters, but was not capable of compensating for the detrimental effects of fungal infection. The data imply that the impact of ozone in the field cannot be estimated without considering the predisposing effects deriving from fungal infections and the compensating effects deriving from elevated CO(2).     

Trace elements, organochlorines, polycyclic aromatic hydrocarbons, dioxins, and furans in lesser scaup wintering on the Indiana Harbor Canal

During the winter of 1993-94, male lesser scaup (Aythya affinis) were collected on the heavily polluted Indiana Harbor Canal (IHC), East Chicago, IN, USA, and examined for tissue contaminant levels. Lesser scaup collected on the IHC had higher concentrations of cadmium (Cd), mercury (Hg), selenium (Se), polychlorinated biphenyls (PCBs), selected organchlorine pesticides, polychlorinated dibenzodioxins, polychlorinated dibenzofurans, polycyclic aromatic hydrocarbons, and aliphatic hydrocarbons than reference birds. Of the scaup collected on the IHC, 44% had Cd concentrations in the liver considered above background for freshwater waterfowl (>3 microg/g dry wt.), 50% had Se concentrations in the liver above a level possibly harmful to the health of young and adult birds (>33 microg/g dry wt.), and 88% of the scaup carcasses exceeded the PCB human consumption guidelines for edible poultry in the USA (>3.0 microg/g lipid wt.). The ratio of pristane:n-heptadecane concentrations in 47% of lesser scaup collected on IHC was elevated above 1.0, which is indicative of chronic exposure to petroleum hydrocarbons.     

Flotation of metal-loaded clay anion exchangers. Part I: the case of chromates

Synthetic hydrotalcite-like layered materials are known for their ability to remove anions, like the chromates. These sorbents usually exist in powder form, thereby exhibiting high surface area and rapid kinetics for adsorption, but presenting appreciable problems in the subsequent solid/liquid separation process. Almost complete removals were obtained in this paper, from batchwork dispersed-air flotation in presence of a flocculant. Due to the experienced difficulty of flotation of thermally activated (at 500 degrees C) hydrotalcite metal-loaded particles, the application of various surfactants was studied. Continuous-flow laboratory runs certified also the effectiveness of this combined process of sorptive flotation, a promising innovative treatment technology.