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Heavy metals in the Antarctic marine environment and correlated systems
Get PDFAll’interno del Progetto Italiano in Antartide questo lavoro riguarda lo studio della distribuzione di metalli pesanti in acqua di mare con un’attenzione particolare rivolta al fitoplancton e considerando anche l’influenza dell’aerosol atmosferico. Durante l’estate australe 2013-2014 a Baia Terranova sono stati raccolti campioni di acqua di mare da metà Dicembre a metà Febbraio. Questi campioni sono stati separati in aliquote soggette a diversi trattamenti per la determinazione della concentrazione totale dei metalli e per la determinazione dei metalli nella frazione disciolta, nel particellato totale e nella frazione associata al fitoplancton. Quest’ultima frazione è stata ottenuta attraverso una separazione fisica delle cellule fitoplantoniche dal campione d’acqua utilizzando una tecnica precedentemente ottimizzata. Campioni di particellato atmosferico (PM10) sono stati raccolti ogni 10 giorni dall’inizio di Dicembre 2013 all’inizio di Febbraio 2014 a Campo Faraglione. 1/8 del filtro originale è stato successivamente sottoposto ad una estrazione sequenziale per determinare due differenti frazioni di metalli (solubile e insolubile) associate a diverse sorgenti. Dai risultati ottenuti si ha evidenza che il Cd in acqua di mare è dominato dalla sua componente disciolta e che la sua distribuzione verticale è quella tipica di un profilo tipo-nutriente, con una deplezione superficiale di Cd disciolto da parte del fitoplancton e un riciclo lungo la colonna d’acqua. Anche la distribuzione del Cu è fortemente condizionata dall’ attività fitoplantonica: a Novembre il Cu mostra un andamento omogeneo, con la dominanza della frazione disciolta, quando la clorofilla-a inizia ad aumentare, il profilo diventa tipo-nutriente.
Il comportamento del Pb è quello tipico di un elemento scavenger con la frazione particellata che aumenta con la profondità. E’ stato dimostrato che la distribuzione dei metalli pesanti in acqua di mare è influenzata in parte anche dall’aerosol atmosferico
Pb, Cu and Cd distribution in five estuary systems of Marche, central Italy
Get PDFHeavy metals are subjected to monitoring in estuarine and marine water by the European Union Water Framework Directive, which requires water body health to be achieved by 2021. This is the first survey of heavy metals content in five estuaries of Marche, a region in central Italy. Results showed that total Pb and Cu concentrations decreased by 70-80%, from 1000-2000 to 100-200ngL(-1) (Pb) and from 2000-3000 to 500-1000ngL(-1) (Cu) from river to sea. Cd was consistently 20-40ngL(-1). Dissolved Pb and Cu concentrations declined by 50% and 70% respectively passing from oligohaline to euhaline water, from 150 to 70ngL(-1) and from 2000-1000 to 600-400ngL(-1). Cd decreased slightly from ∼20 to ∼10ngL(-1). Although such concentrations are in the range allowed by the Water Framework Directive, they far exceed (up to 10×) the ground content ceiling set for 2021
Frazionamento solubile/insolubile di Cd, Pb e Cu nella neve dell’Antartide e relazione con l’aerosol.
No full textDetermination of water-soluble, acid-extractable and inert fractions of Cd, Pb and Cu in Antarctic aerosol by square wave anodic stripping voltammetry after sequential extraction and microwave digestion
Get PDFA two-step microwave (MW) digestion (ramps to 135 °C and to 185 °C) was set up for the subsequent
voltammetric determination of the inert fraction of Cd, Pb and Cu in Antarctic aerosol (PM10), after a sequential
extraction with water (soluble fraction) and dilute HCl (acid extractable fraction) of the filter samples. A
digestion mixture of 5.0 mL HNO3, 1.0 mL H2O2, and 1.0 mL HF was used. The amount of H2O2 was adjusted at
a compromise value to avoid interferences from organic substances or fromthe reagent itself. Hydrogen fluoride
was used at the maximum quantity suggested in the literature, since there were no interferences due to excess
HF with the voltammetric measurement. Our procedure did not provide for a third digestion step with H3BO3,
as generally required in order to eliminate excess HFwhen subsequent spectrochemical analyses are to be carried
out. Thus the total digestion time was reduced from ~5 h to ~1.5 h. The ultrasensitive technique of square
wave anodic stripping voltammetry (SWASV) was used and optimized by maximizing the signal-to-noise
ratio (frequency 150 Hz, amplitude 20 mV). The limits of detection (e.g. for atmospheric concentration
0.1–0.3 pg m−3 for Cd and 1–5 pg m−3 for Pb and Cu) and the repeatabilities (Cd 21–26%, Pb 16–20%,
Cu 11–14% as atmospheric concentration) compared favourably with literature reports. Significant aliquots of
metals were present in all the three fractions determined and the inert fraction represented 20–74% for Cd,
10–63% for Pb, and 7–33% for Cu, against total contents of Cd 1–19 pg m−3, Pb 17–36 pg m−3, and
Cu 177–429 pg m−3. Possibly significant metal fractions could be associated to the crustal origin
Separation of micro-phytoplankton from inorganic particulate in Antarctic seawater (Ross Sea) for the determination of Cd, Pb and Cu: optimization of the analytical methodology
No full textDetermination of heavy metals in spring waters of the Sibylline Mountains National Park (Central Italy) by square wave anodic stripping voltammetry
No full textEvolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land
No full textWithin the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct
gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ~3-
km far from the Italian station “M. Zucchelli” (Terra Nova Bay, Ross Sea), during the 2014e2015 austral
summer. A six-stage high-volume cascade impactor with size classes between 10 mm and 0.49 mm, and,
in parallel, for comparison purposes, a PM10 high-volume sampler (50% cut-off aerodynamic diameter of
10 mm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried
out before and after exposure by using a microbalance specifically designed for the filter weight and
placed inside a glove bag in order to maintain stable temperature and humidity conditions during
weighing sessions. Measured atmospheric concentrations (referred to the “actual air conditions” of mean
temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the
following values, given as size range, means (interquartile range): Dp < 0.49 mm, 0.33 (0.26e0.34)
mgm3; 0.49e0.95 mm, 0.20 (0.19e0.24) mgm3; 0.95e1.5 mm, 0.16 (0.13e0.21) mgm3; 1.5e3.0 mm 0.075
(0.05e0.11) mg m3; 3.0e7.2 mm 0.12 (0.02e0.19) mg m3; 7.2e10 mm 0.06 (0.01e0.03) mg m3. The
average mass concentration of the total PM10 at Faraglione Camp for the entire sampling period was 0.92
(0.67e1.1) mg m3. Although a great variability, the aerosol mass concentration showed a tri-modal
distribution, with an accumulation mode (in the range 0.1e1.0 mm) and two coarse modes (CM1 in
the range 1.0e3.0 mm, and CM2 in the range 3.0e10 mm). From 50% to 90% of the PM10 mass comes from
particles of a size smaller than 1.0 mm. The two coarse modes represented from ~5% to ~35% of the PM10,
showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM10 mass
concentration increased to a maximum of ~1.6 mg m3 at mid-December, while in January it decreased to
values that are typical of November. Both accumulation and upper super-micron fractions showed a
maximum in the same period contributing to the PM10 peak of mid-summer
Determinazione di metalli in tracce nel fitoplancton marino antartico: messa a punto della metodica analitica
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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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