1,721,525 research outputs found
Ecotoxicological risks related to perfluorinated organic compounds dispersion in aquatic environments
No full textPolycyclic Aromatic Hydrocarbons in marine environments: sources, fate, and biological effects
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Litter & microplastics features in table salts from marine origin: Italian versus Croatian brands
Full text linkThis study estimates litter content, including microplastics, mesoplastic, and macroplastic in marine table salts coming from Italy and Croatia. Both high (HC) and low (LC) costs commercial brands easily found at the supermarket were analysed. Any macroplastic or mesoplastic were recovered while microplastics and other litter impurities significantly affect table salts of all tested brands. Average microplastic values ranged within 1.57 (HC) – 8.23 (LC) (Italy) and 27.13 (HC) – 31.68 (LC) items/g (Croatia). Microplastics sizes (min-max) ranged within 4–2100 μm (Italy) and 15–4628 μm (Croatia). In samples from both Nations, a significant general positive correlation between the average number of items/g recorded and the total amount of general impurities was recorded. Concerning microplastic shapes, in Italy, fragments dominated even if fibres, granules, films, and foams are frequently recorded. On the contrary, clear PP fibres dominated in Croatian brands even if also other shape classes were recorded
Sperimentando le scienze. Percorsi di didattica laboratoriale per la scuola secondaria superiore
No full textEffects of an alluvial event on the quality of the fish caught in a highly anthropized area of the Region of Calabria
No full textSediment quality in Italian harbours: relationships among pollutants levels and human impacts
No full textEcotoxicity of nano-metal oxides: A case study on daphnia magna
Full text linkIn Europe REACH framework directive imposes data acquisition concerning toxicity on acquatic species before the commercialization of chemicals to assess environmental risks. According to official methods, exposure tests are performed under in vitro and standardized conditions: OECD’s guideline rules external variables such as water type, feeding conditions, and exposure time. As consequence, such obtained results could be different from effects observed in natural environments. This study collects effects within 24–96 h of exposure to nano metal-oxides (ZnO, TiO2) on D. magna obtained by the exposure under standard OECD conditions comparing them with results obtained by the exposure under more similar conditions to natural environment (i.e. mixture, feeding). High doses exposure determines gas-bubble disease. Animals exposed to LC10 actively ingest nanoparticles under both fasting and feeding conditions. Furthermore, body burial by a coat of nanoparticles thicker in mixtures than in single dispersions was recorded. Furthermore, results show that: (i) effects increase over time; (ii) n-ZnO results less effective than n-TiO2 in both single dispersion, and mixture; (iii) the presence of surfactant increases toxicity of nanoparticles; (iv) immobilization is a more sensitive endpoint than mortality; (v) feeding increases test sensitiveness improving differences among treated and controls till 96 h and allowing longer exposure times than standard OECD test. As general remark, this study provides evidence that in vitro ecotoxicological results obtained under standardized OECD conditions could be significant different to animals’ responses under natural (feeding and mixtures) exposure conditions
A generalized theoretical methodology to forecast flow coefficient, head coefficient and efficiency of Pumps-as-Turbines (PaTs)
Full text linkAmong the most used hydraulic machines in the small-scale hydropower sector, Pump-as-Turbine (PaT) technology is suitable for both practical and economical aspects. These machines are already profitably applied in remote and rural zones for electricity production and in energy recovery applications in both civil and industrial plants, like Water Distribution Networks (WDNs) and chemical plants. Several studies aimed to provide theoretical formulas able to forecast flow rate and head at the Best Efficiency Point (BEP) in turbine mode obtaining, however, contrasting results and a lack of generalization. In this work, a generalized theoretical methodology for forecasting the flow rate, the head and the efficiency of PaTs at their BEP is studied. Specific correlations between the non-dimensional parameters of PaTs in pump and in turbine mode are presented and discussed. The accuracy of the presented methodology is compared to the ones available in literature showing a good generalization capability and a significant improvement in forecasting the behaviour of the PaT, starting from the available performance characteristics in pump mode
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