1,720,989 research outputs found
Direct quantification of chemical species by multivariate standard addition and net analyte signal method
No full textBotanical traceability of unifloral honeys by head-space gas-chromatography and chemometrics
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Toxic Metal Bio-Monitoring: An Innovative Procedure to Get Complete Information on the Long-Term Trend of the Metal Pollution Load in Environmental Ecosystems
No full textIn recent years, rapid spread of toxic metals has occurred in all environmental matrices. The phenomenon started since many decades. Due to their bioaccumulation and toxicity, these contaminants are very dangerous pollutants for human health. The hazardousness of toxic metals is not lower than pesticides. Indeed, toxic metals are perhaps the most important reason of the pollution load in environmental ecosystems; certainly they are among the greatest. They come from almost all human activities: industries, agriculture, vehicular traffic, urban heating and so on.
Pollution of an ecosystem can be caused in many ways, such as direct input through watercourses; for example, the case of aquatic ecosystems. But in general all ecosystems are subjected to pollution caused by atmospheric transport such as particulate or fumes.
In order to evaluate the pollution load of ecosystems, two paths can be followed:
1) determination of pollutant concentrations by timely and repeated sampling in well-defined ecosystem sites;
2) determination of the same pollutants in species that live and are continually present in the same ecosystem (bio-monitoring).
Evidently, punctual determinations cannot provide information to evaluate the long-term trend of the pollution load. This information can only be provided through bio-monitoring campaigns. Several Authors have given this suggestion, but the scientific community did not firmly support it.
For each toxic-metal determination, the present work reports various species employed in bio-monitoring campaigns: mussels, oysters and clams, algae, vegetables, lichens, mosses. For each bio-monitor and for all metals or group of metals, the various analytical techniques and procedures employed are critically discussed. Particular attention is paid to the analytical performance, in terms of accuracy and detectability.
A separate section is dedicated to the analytical procedure for the determination in bio-monitors of new emerging anthropic polluting traffic-related pollutants, i.e., the platinum group metals (platinum, palladium, rhodium, osmium, ruthenium and iridium
Analisi di campioni di aerosol atmosferico in due siti spagnoli (Sierra Nevada e Granada) e loro comparazione nell’ambito del progetto FRESA
No full textIn questo contributo presenteremo i principali risultati ottenuti nell’ambito del progetto nazionale spagnolo FRESA (Impact of dust-laden AFRican air massEs and of Stratospheric air masses in the
Iberian Peninsula. Role of the Atlas mountains, riferimento: CGL2015-70741-R) coordinato dal Prof. Josè Antonio Garcìa Orza dell’Università Miguel Hernández di Elche (Spagna).
Tale progetto ha previsto il campionamento giornaliero di filtri di particolato atmosferico (PM10), per una durata di tre anni (2017 - 2019) in due siti della Spagna meridionale: Granada (37.178 N,
3.610 W, 738m s.l.m.) e Sierra Nevada (37.096 N, 3.387 W, 2550m s.l.m.). Queste due località sono relativamente vicine fra loro (circa 25 Km di distanza in linea d’aria) ma, a causa della elevata differenza di altitudine, definiscono rispettivamente un ambiente urbano (Granada) ed uno remoto (Sierra Nevada).
La caratterizzazione chimica ha previsto l’utilizzo sinergico sia di metodi tradizionali per l’analisi dell’aerosol atmosferico (cromatografia ionica, Particle Induced X-ray Emission – PIXE) che più innovativi (Fourier Transform Infrared Spectroscopy – FTIR, Ultraviolet-Visible diffuse reflectance spectroscopy – UV-Vis DRS). Ciò ha consentito l’apporzionamento delle sorgenti di emissione dell’aerosol atmosferico mediante modelli a recettore Positive Matrix Factorization (PMF), le cui
conclusioni sono state avvalorate dai risultati di parametrizzazione e digitalizzazione dei colori dei filtri e dall’utilizzo untargeted di fingerprint dei gruppi funzionali IR-attivi. L’integrazione di queste informazioni con la caratterizzazione meteorologica e dinamica ha permesso di ben evidenziare le analogie e le differenze fra le due stazioni esaminate
Cleaner, sustainable, and safer: Green potential of alkali-activated materials in current building industry, radiological good practice, and a few tips
Full text linkAlkali-activated materials were prepared from four typical precursors (coal fly ash, granulated blast furnace slag, metakaolin, and brick waste powder) characterized for granulometry, elemental composition, and microstructure. High-resolution gamma-ray spectrometry was used to determine the activity concentration of Naturally Occurring Radioactive Materials (NORM) in all the materials to assess their radiological impact. All the investigated materials have been found to comply with the European dosimetric index (I) according to Directive 2013/59/Euratom. The results suggest the need for an accurate check of radioactivity throughout the mixing phases to prevent I exceedances. The productive chains were also evaluated by principal component analysis
ATR-FTIR Spectroscopy, a New Non-Destructive Approach for the Quantitative Determination of Biogenic Silica in Marine Sediments
No full textBiogenic silica is the major component of the external skeleton of marine micro-organisms, such as diatoms, which, after the organisms death, settle down onto the seabed. These micro-organisms are involved in the CO2 cycle because they remove it from the atmosphere through photosynthesis. The biogenic silica content in marine sediments, therefore, is an indicator of primary productivity in present and past epochs, which is useful to study the CO2 trends. Quantification of biosilica in sediments is traditionally carried out by wet chemistry followed by spectrophotometry, a time-consuming analytical method that, besides being destructive, is affected by a strong risk of analytical biases owing to the dissolution of other silicatic components in the mineral matrix. In the present work, the biosilica content was directly evaluated in sediment samples, without chemically altering them, by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Quantification was performed by combining the multivariate standard addition method (MSAM) with the net analyte signal (NAS) procedure to solve the strong matrix effect of sediment samples. Twenty-one sediment samples from a sediment core and one reference standard sample were analyzed, and the results (extrapolated concentrations) were found to be comparable to those obtained by the traditional wet method, thus demonstrating the feasibility of the ATR-FTIR-MSAM-NAS approach as an alternative method for the quantification of biosilica. Future developments will cover in depth investigation on biosilica from other biogenic sources, the extension of the method to sediments of other provenance, and the use higher resolution IR spectrometers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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