Search results for "15N"
showing 10 items of 67 documents
Trace elements and stable isotopes in penguin chicks and eggs: A baseline for monitoring the Ross Sea MPA and trophic transfer studies.
2021
Multi-tissue trace elements (TEs), C, N concentrations and stable isotopes (δ13C, δ15N) of chick carcasses and eggs of Adelie and Emperor penguins were studied to i) provide reference data before the recent institution of the Ross Sea Marine Protected Area (Antarctica), and ii) provide conversion factors that allow estimating C, N, δ13C and δ15N in edible tissues from non-edible ones, thus improving the use of stable isotopes in contamination and trophic transfer studies. Higher concentrations of As, Cd, Cr, Cu, Hg, Mn and Pb were found in chick carcasses than in eggs, suggesting increasing contamination in recent decades and high toxicity risks for penguin consumers. Isotopic conversion fa…
Carbon and nitrogen isotopic values in Lithops aucampiae during leaf development.
2021
Abstract Lithops (Aizoaceae) are succulent plants consisting of a pair of opposite succulent leaves inserted on an extremely short stem. The apical meristem produces a new leaf pair that develops between the older pair, recycling water and metabolites. This peculiar anatomy and growth form make ecophysiological studies quite challenging. Lithops are considered to have CAM metabolism, though experimental evidence is scarce. We followed the changes in carbon and nitrogen isotopic values in mature leaves, young leaves and roots, with the aim of investigating how the use of resources is optimized to achieve survival in extremely arid environments. Two-year-old plants of Lithops aucampiae were g…
Cross-validation of δ15N and FishBase estimates of fish trophic position in a Mediterranean lagoon: The importance of the isotopic baseline
2013
Abstract FishBase, a relational database freely available on the Internet, is to date widely used as a source of quantitative information on the trophic position of marine fish species. Here, we compared FishBase estimates for an assemblage of 30 fish species sampled in a Mediterranean lagoon (Acquatina lagoon, SE Italy) with their trophic positions calculated using nitrogen stable isotopes. To assess the influence of the trophic level used to compute the baseline indicator on the robustness of isotopic estimations, we compared the trophic position of fish calculated using the average δ 15 N signature of either basal resource or primary consumer taxa measured at three stations located in th…
Sedimentary record of anthropogenic contaminants (trace metals and PAHs) and organic matter in a Mediterranean coastal area (Gulf of Palermo, Italy)
2009
Abstract The Gulf of Palermo (Italy, Mediterranean Sea) is a contaminated coastal environment with a relatively high influx of unregulated industrial and domestic effluents. Two sediment box-cores were collected at water depths of 100 and 712 m. Samples were analysed for trace metals (As, Cu, Hg, Mn, Ni, Pb), total polycyclic aromatic hydrocarbons (ΣPAHs), organic carbon to total nitrogen (Corg/Ntot) ratios and organic carbon and nitrogen isotopic composition (δ13Corg and δ15Ntot). At the coastal site, trace metal and ΣPAH depth profiles show a clear upcore increase, indicating increasing contamination over the recent past. Concentrations of ΣPAHs, Hg, Pb, Cu, and As appear to be potentiall…
Effects of fish farming waste to sedimentary and particulate organic matter in a southern Mediterranean area (Gulf of Castellammare, Sicily): a multi…
2004
Abstract Carbon and nitrogen stable isotope analysis was used to investigate the dispersion area of waste material coming from fish farming activities in the western Mediterranean. Tests were conducted to see if uneaten feed and faecal material isotopic signals, originating from fish farms, could be detected in particulate organic matter (POM) and sedimentary organic matter (SOM). The detectable dispersion distance (from under cages as far as 1000 m) of cage-derived organic material was also examined. To do this, carbon (δ13C) and nitrogen (δ15N) composition in POM and SOM collected around the cages, in some control areas and in the waste material, was measured. Mean POM δ13C was −22.9±0.2‰…
Stable isotopes and trophic positions of littoral fishes from a Mediterranean Marine Protected Area
2008
Stable isotope analyses were employed to explore feeding and foraging habitats and trophic levels of littoral fishes in a western Mediterranean Marine Protected Area (Egadi Islands, Sicily, Italy). Carbon and nitrogen stable isotope ratios were measured in primary producers, invertebrates and fishes collected in December 2001 and January 2002. Fishes of the littoral region of the Egadi Islands had isotopic signatures that fell into a wider range for δ13C (about 6‰) than for δ15N (about 3‰). Carbon isotope ratios were consistent with a food web based on mixed sources and two trophic pathways leading to different fish species. Differences in the isotopic composition between islands were highe…
Community structure and physiological characterization of microbial mats in Byers Peninsula, Livingston Island (South Shetland Islands, Antarctica)
2007
The community structure and physiological characteristics of three microbial mat communities in Byers Peninsula (Livingston Island, South Shetland Islands, Antarctica) were compared. One of the mats was located at the edge of a stream and was dominated by diatoms (with a thin basal layer of oscillatorian cyanobacteria), whereas the other two mats, located over moist soil and the bottom of a pond, respectively, were dominated by cyanobacteria throughout their vertical profiles. The predominant xanthophyll was fucoxanthin in the stream mat and myxoxanthophyll in the cyanobacteria-dominated mats. The sheath pigment scytonemin was absent in the stream mat but present in the soil and pond mats. …
13C-NMR Based Evaluation of the Electronic and Steric Interactions in Aromatic Amines
2005
Abstract: Chemical shifts of the para carbon atoms, δ(13C-4), in a series of aromatic amines were used to calculate the Ãp, ÃR and ÃOR substituent constants for different amino groups. 1-Pyrrolidino, N,N-di-n-butylamino and N,N-diethylamino groups were found to be the most strong electron-donors. ortho-Substitution decreases the donor properties of the amino group. The amino groups in 2,6-di-i-propylaniline and N,N-2,6-tetramethylaniline have very weak electron-donor properties. The nitrogen atom in benzoquinuclidine and N,N-dimethyl-2,6-di-i-propylaniline have an electron-acceptor character. The calculated substituent constants of the amino groups studied are consistent with the s…
Sedimentary record of anthropogenic chemical and organic pollution in a Mediterranean coastal area (Gulf of Palermo, Italy).
2009
The relatively high influx of unregulated industrial and domestic effluents has progressively degraded the Palermo coastal environment in NW Sicily. To evaluate the poorly known effects of these inputs on the Palermo Gulf, three sediment box-cores were collected along a transect perpendicular to the coast, in front of the Oreto river mouth, in water depths of 20—750 m. The samples, dated by 210Pb and 137Cs, were analysed for concentration of major/trace elements, total polycyclic aromatic hydrocarbon (PAH), total organic carbon (TOC) and for organic carbon and nitrogen isotopic compositions. Total organic carbon concentrations show relatively high values (0.4—2.9%), with a decreasing seawar…
Efficacia delle Fasce Tampone e della Gestione del Suolo per il Controllo dei Nitrati in Vigneto
2010
Buffer strip use in vineyard could represent an environmental strategy for nitrate control of surface and deep water due to agricolture managment. Buffer strip determines a reduction of soil erosion and consequently can reduce nutritive and pollulant elements losses. With the aim to evaluate buffer strips and soil managment effectiveness on nitrate control in vineyard, a trial was carried out in a South-West part of Sicily characterized by an high nitrate losses sensitivity, an annual rainfall of about 516mm and an average temperature of 18°C. In a vineyard on about 7% slope and 90m lenght a 10 meter buffer strip was seeded using a Lolium perenne permanent meadow. Vineyard was managed both …