Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Removal of hexavalent chromium from aqueous solutions by use of chemically modified sour cherry stones

<p>A new adsorbent for Cr(VI) removal was prepared from sour cherry stones, by treatment with H₂SO₄ (12–96%). Adsorbent properties were characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, specific surface area, point of zero charge, iodine number, and analysis of surface functional groups. Surface area increased from 225.5 to 484.7 m² g⁻¹, point of zero charge decreased from 6.0 to 3.2, iodine number increased from 4 to 80, total amount of surface acidic groups increased from 1.12 to 2.3 mmol g⁻¹ and adsorption capacity increased from 0.53 to 5.27 mg g⁻¹, with increasing H₂SO₄ concentration from 0 to 96%. The pseudo-first- and pseudo-second-order kinetic models have been used to analyze the kinetics of the adsorption; it was found that kinetic experimental data were successfully fitted by the pseudo-first-order model. Equilibrium data were mathematically interpreted by applying the Langmuir, Freundlich, and Dubinin–Radushkevich models; the results indicate that Freundlich model provides the best correlation. Negative values of Gibbs free energy suggest an endothermic and spontaneous adsorption process. The mechanism of Cr(VI) removal involves adsorption of Cr(VI) followed by its partial reduction to Cr(III). Analysis of thermodynamic parameters, coupled with modeling of experimental data with two different intraparticle diffusion models, revealed that binding of Cr(VI) occurred via physisorption, while the rate-limiting step was film diffusion. On the basis of present study, it can be concluded that sour cherry could be suitable adsorbents for the removal of Cr(VI) from polluted waters.</p

Modification of Langmuir model for simulating initial pH and temperature effects on sorption process

The present study modifies the sorption isothermfor simulating the influences of initial pH and temperature variations on thecadmium sorption from contaminated water using waste foundry sand based on Langmuir,Freundlich and Temkin models. Results proved that the Langmuir expression is ableto adopt these effects by relating sorption capacity and affinity constantswith pH and temperature of aqueous solution through exponential relationships (determinationcoefficient = 0.9375). The present model is assumed that the sorption process occursthrough acidic functional groups and this is consistent with FTIR outputs. Interactionof cadmium/WFS is found to be exothermic by thermodynamic analysis.Validerad;2020;Nivå 2;2020-08-18 (johcin)</p

The Impact Of Introducing Virtual Slides As A Replacement For Powerpoint Presentations In The Students’ Microscopy Labs

INTRODUCTION / BACKGROUND: The medical school students in Timisoara, Romania have been studying pathology slides in microscopy labs according to a protocol which uses classical PowerrPoint presentations as guides for understanding the microscopic features of diseases, followed by individual examination of the glass slides under the microscope. AIMS: We aimed to assess the impact of replacing those presentations with virtual slides (VS). METHODS: In the middle of the semester, for the benign tumors microscopy lab, which is presented over the course of 2 weeks, we used 3 VS, while the other 3 slides were presented in the classical PowerPoint manner. All attending students from the 3rd year of the Medical School of the University of Medicine and Pharmacy “Victor Babes” Timisoara were asked to fill out an anonymous questionnaire at the end of the lab, in which they graded the difficulty in identifying lesions, chose the best/least understood lesion and pointed out the best manner of presentation. RESULTS: 431 valid questionnaires were collected. 52.9% of the students indicated one of the 3 VS as the best understood lesion, while 59.62% chose a different VS as a least understood one. One VS was also the top best (113/332 votes) while another the least understood (34/126 votes) lesion. 74.01% students agreed that VS helped them understand the microscopic criteria better, while 74.71% would like VS to be used in the labs to come. CONCLUSION: VS were appreciated by the students as a novelty and a more impressing way of studying pathology slides, but did not dramatically improve the easiness with which they identify and understand the lesions