Behavioural and Physiological Responses of Gammarus pulex Exposed to Cadmium and Arsenate at Three Temperatures: Individual and Combined Effects

This study aimed at investigating both the individual and combined effects of cadmium (Cd) and arsenate (AsV) on the physiology and behaviour of the Crustacean Gammarus pulex at three temperatures (5, 10 and15°C). G. pulex was exposed during 96 h to (i) two [Cd] alone, (ii) two [AsV] alone, and (iii) four combinations of [Cd] and [AsV] to obtain a complete factorial plane. After exposure, survival, [AsV] or [Cd] in body tissues, behavioural (ventilatory and locomotor activities) and physiological responses (iono-regulation of [Na+] and [Cl−] in haemolymph) were examined. The interactive effects (antagonistic, additive or synergistic) of binary mixtures were evaluated for each tested temperature using a predictive model for the theoretically expected interactive effect of chemicals. In single metal exposure, both the internal metal concentration in body tissues and the mortality rate increased along metallic gradient concentration. Cd alone significantly impaired both [Na+] and [Cl−] while AsV alone had a weak impact only on [Cl−]. The behavioural responses of G. pulex declined with increasing metal concentration suggesting a reallocation of energy from behavioural responses to maintenance functions. The interaction between AsV and Cd was considered as ‘additive’ for all the tested binary mixtures and temperatures (except for the lowest combination at 10°C considered as “antagonistic”). In binary mixtures, the decrease in both ventilatory and locomotor activities and the decline in haemolymphatic [Cl−] were amplified when respectively compared to those observed with the same concentrations of AsV or Cd alone. However, the presence of AsV decreased the haemolymphatic [Na+] loss when G. pulex was exposed to the lowest Cd concentration. Finally, the observed physiological and behavioural effects (except ventilation) in G. pulex exposed to AsV and/or Cd were exacerbated under the highest temperature. The discussion encompasses both the toxicity mechanisms of these metals and their interaction with rising temperature

Laboratory study of an epoxy resin grouted sand

It is generally accepted that only chemical grouts or solutions are available to penetrate and fill narrow joints or soils with very small pore size. Over the last 30 years a few hundred different compounds have been used for this purpose. Such materials show a wide spectrum of properties. Epoxy resins are among the compounds that are commonly used in chemical grouting because of their high strength and durability against mechanical or physical erosion. In this paper the improvement of the physical and mechanical properties of fine sand injected with a watersoluble two-component epoxy resin is investigated. The experiments were carried out using either epoxy resin only («one-shot process’), or in combination with sodium silicate (‘two-shot process’). For this reason, two epoxy resin solutions were employed. One was thick, with a water/ resin (W/R) ratio of 1; the other was more dilute, with W/R of 2. The grouting was performed through 10 cm diameter columns, filled with siliceous sand with a particle size distribution of 0·149–2·38 mm and 0·076–2·38 mm. For the two-shot grouting, two solutions of sodium silicate were used, with sodium silicate/water ratios of 3 and 2 respectively. The results of a comparison between the above two processes show that the compressive strength of injected sand specimens of the one-shot process is lower than that of the two-shot process. The permeability and porosity of the sand were lowered much more in the first case. Il est généralement admis que seuls des ciments ou des solutions chimiques peuvent pénétrer et remplir des joints étroits ou des sols à trés petits pores. Depuis 30 ans, quelques centaines de compounds différents ont été utilisés dans ce but. Ces matériaux montrent un vaste spectre de propriétés. Les résines époxydes sont parmi les compounds qui sont les plus couramment utilisés pour la cimentation chimique en raison de leur grande résistance et durabilité contre l'érosion mécanique ou physique. Dans cet exposé, nous étudions l'amélioration des propriétés physiques et mécaniques d'un sable fin injecté de résine époxyde bicomposant soluble dans l'eau. Les expériences ont été effectués en utilisant soit une résineé poxyde seule (‘injection simple’). Pour cette raison, deux solutions de résines époxydes ont été employées. L'une était épaisse, avec un rapport eau-résine de l, l'autre était plus dilueé avec un rapport eaux-résine de 2. La cimentation a été faite par des colonnes de 10 cm de diamétre, remplies de sable siliceux avec une distribution de dimensions de particules de 0,149-2,38 mm et 0,076-2,38 mm. Pour la cimentation à injection double, deux solutions de silicate de sodium ont été utilisées, avec des rapports silicate-eau de 3 et de 2 respectivement. Les résultats d'une comparaison entre les deux processus susmentionnés montrent que la résistance à la compression des spécimens de sable injectés par injection simple est plus basse que celle de l'injection double. La perméabilité et la porosité du sable étaient bien plus basses dans le premier cas. </jats:p

Cu(III)-polypeptide complexes exhibiting SOD-like activity

The SOD-like activity of Cu(III)-complexes with polypeptides poly-L-lysine and poly-L-glutamic acid respectively was investigated. The Cu(II)-polypeptide complexes were first oxidized by K2IrCl6 to give the corresponding Cu(III)-compounds. The oxidation of Cu(II) and the corresponding Cu(II)/Cu(III) potential was evaluated by cyclic voltammetry (c.v.), UV-Vis and EPR spectroscopic (r.t.) experiments. Spin trapping EPR spectra were also conducted to confirm the formation of the superoxide radical. The SOD-like activity of each Cu(III)-complex was proved using the nitro blue tetrazolium (NBT) method slightly modified.Amino Acid

Interactive toxic effects of heavy metals and humic acids on Vibrio fischeri

The effect of humic acids (HAs) on the toxicity of copper, zinc, and lead was investigated using the photobacterium Vibrio fischeri (Microtox test) as a test organism. The effects of HAs on metal toxicity were evaluated as functions of time and concentration in pure compound solutions. The toxicities of copper and lead were generally comparable, while the toxicity of zinc was lower than those of the other two metals. The toxicity of copper decreased with the addition of HAs, while the toxicity of zinc remained almost constant. On the other hand, the toxicity of lead increased, depending on the concentration of HAs. The interactive effects between copper and zinc and between lead and zinc were synergistic, while the interactive effect between copper and lead on the bioluminescence of V. fischeri was additive. The presence of HAs caused relatively high toxicity reduction in the binary mixtures of zinc and copper or zinc and lead, while the toxicity reduction in the case of the binary mixture of copper and lead was negligible. (c) 2005 Elsevier Inc. All rights reserved

Underground space and urban sustainability: an integrated approach to the city of the future

The use of underground space is not a recent novelty. Its use was primarily defined in regards to survival reasons; protection from natural hazards. Currently, there is a notable increase of underground space applications especially in urban environments. The field of underground space uses is vast in response to various reasons: for commuting and transporting goods to shopping centers, housing and even farming facilities and storage facilities, mining and geothermal energy to nuclear waste disposals. This paper focuses on examining underground space use in today’s urban environments, specifically in urban centers adopting an interdisciplinary and comprehensive approach. This research work introduces the eight global goals for sustainable development based on the United Nations sustainability goals. The methodology used takes into consideration the existing social and economic setting in the cases under investigation, which include both hypothetical models and practices, as well as applied examples of underground spaces in use internationally. Based on two different models of economy, the circular economy and the doughnut economy this paper highlights the principles that should be embedded to achieve resilience and sustainability during the construction and operation of urban infrastructures emphasizing on the spatial contribution of underground developments, on an economic, environmental and furthermost social perspective. By looking into the infrastructural construction of underground spaces, we wish to articulate on their spatial production through the relationships that emerge with the urban environment, and thus examine the balanced evolution of the underground space and its uses. Focusing on determining the underground space’s eco-system will allow for further understanding of its social dimensions and active processes of production, as a spatial node on an intertwined web of spatial networks formulating our urban environments

Toxic properties of metals and organotin compounds and their interactions on Daphnia magna and Vibrio fischeri

In the present study toxicity tests were performed in order to determine the toxic properties of four organotin compounds and three heavy metals and to examine the interactive effects of binary metal mixtures on two different test species: the freshwater crustacean Daphnia magna and the marine bacterium Vibrio fischeri. D. magna proved to be more sensitive to metals than V. fischeri. Tributyltin chloride and copper were found to be the most toxic substances on both test organisms. The interactive effects between trimethyltin chloride/copper and trimethyltin/chromium on both test species were investigated and synergistic, additive and antagonistic actions were observed. © 2004 Kluwer Academic Publishers