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31.
Bioremediation of petroleum hydrocarbons in anoxic marine sediments: Consequences on the speciation of heavy metals 总被引:3,自引:0,他引:3
Antonio Dell’Anno Francesca Beolchini Massimo Gabellini Laura Rocchetti Antonio Pusceddu Roberto Danovaro 《Marine pollution bulletin》2009,58(12):1808-1814
We investigated the effects of biostimulation and bioagumentation strategies applied to harbor sediments displaying reducing conditions and high concentrations of petroleum hydrocarbons and heavy metals. We compared the microbial efficiency of hydrocarbon removal from sediments maintained for 60 days in anoxic conditions and inoculated with acetate, sulfate-reducing bacterial strains and acetate and sulfate-reducing bacteria. All treatments determined a significant increase in the microbial growth and significant decreases of hydrocarbon contents and of redox potential values. The addition of sulfate-reducing bacterial strains to the sediment was the most efficient treatment for the hydrocarbon removal. In all experiments, significant changes of the heavy metals’ phase repartition were observed. The results reported here suggest that the biodegradation of petroleum hydrocarbons in anoxic marine sediments may be enhanced by stimulating microbial anaerobic metabolism, but care should be applied to monitor the potential changes in the mobility and bioavailability of heavy metals induced by bio-treatments. 相似文献
32.
33.
Fabio Speranza Patrizia Landi Francesca D’Ajello Caracciolo Alessandro Pignatelli 《Bulletin of Volcanology》2010,72(7):847-858
We report on the paleomagnetism of ten sites in the products of the most recent silicic eruptive cycle of Pantelleria, Strait
of Sicily. Previously radiometrically dated at 5–10 ka, our comparison with proxies for geomagnetic field directions allows
us to narrow considerably the time window during which these eruptions occurred. The strongly peralkaline composition causes
the magmas to have low viscosities, locally resulting in strong agglutination of proximal fall deposits. This allows successful
extraction of paleomagnetic directions from the explosive phases of eruptions. One of our sites was located in the Serra della
Fastuca fall deposit, produced by the first explosive event of the eruptive cycle. The other nine sites were located in the
most recent explosive (pumice fall and agglutinate from Cuddia del Gallo and Cuddia Randazzo) and effusive (Khaggiar lava)
products. The (very similar) paleomagnetic directions gathered from eight internally consistent sites were compared to reference
geomagnetic field directions of the last 5–10 ka. Directions from Cuddia del Gallo agglutinate and Khaggiar flows translate
into 5.9- to 6.2-ka ages, whereas the Fastuca pumices yield a slightly older age of 6.2–6.8 ka. Hence, the most recent silicic
eruptive cycle lasted at most a millennium and as little as a few centuries around 6.0 ka. Paleomagnetically inferred ages
are in good agreement with published (and calibrated by us) 14C dates from paleosols/charcoals sampled below the studied volcanic units, whereas K/Ar data are more scattered and yield
∼30% older ages. Our data show that the time elapsed since the most recent silicic eruptions at Pantelleria is comparable
to the quiescence period separating the two latest volcanic cycles. 相似文献
34.
Francesca Garfagnoli Gianluca Martelloni Andrea Ciampalini Luca Innocenti Sandro Moretti 《Earth Science Informatics》2013,6(4):227-240
A new graphical user interface (GUI) for pre-processing reflectance spectra, built using MATLAB and expressly designed for the ASD FieldSpec® spectroradiometer, was developed to solve problems that generally affect experimental ASD data. The GUI is characterised by an easily readable, graphic visualisation of spectra, from which the absorption band depth (ABD) can be obtained for a selected wavelength. The output format of the ASD data is a binary file with an .asd extension. The binary file, that provides a single spectrum, can be processed using a software functionality, by means of a GUI, that allows to select one or more binary files to produce a spectral library in a unique .txt file. The spectral reflectance is re-calibrated with the “convex-hull” methodology to eliminate the convex shape, which is typical of reflectance spectra. Different examples of the use of the new GUI are provided. 相似文献
35.
Acta Geochimica - To quantify water erosion rates and annual soil loss in mountainous areas, two different empirical models were used to estimate the effects of soil erosion in a small mountain... 相似文献
36.
Iunio Iervolino Carmine Galasso Roberto Paolucci Francesca Pacor 《Bulletin of Earthquake Engineering》2011,9(6):1761-1778
This paper introduces REXELite, an internet version of REXEL, a software for automatic selection of ground motion suites for
nonlinear dynamic analysis of structures. REXELite was developed with the aim of integrating an advanced earthquake records’
repository, such as the ITalian ACcelerometric Archive (ITACA), with a tool to define seismic input for engineering seismic
analysis according to international standards (with priority to Europe). In fact, REXELite allows to define target design
spectra according either to Eurocode 8 or to the Italian building code, and to search ITACA for suitable sets of seven records
(comprised of one or two horizontal ground motion components) matching such target spectra: on average, in a user-specified
period range, and with the desired tolerance. The records in the set also have, individually and according to some criteria,
the most similar spectral shape with respect to that of the code. Selection options include magnitude, source-to-site distance,
soil conditions and, if desired, linear scaling of records to reduce further record-to-record variability of the selected
suite. 相似文献
37.
38.
Size‐frequency distributions can support reliable inferences concerning population dynamics of brachiopods, but only a few data are available so far. In this study, length and width frequency distributions of dead specimens of the Recent brachiopods Joania cordata and Argyrotheca cuneata from the Marine Protected Area ‘Secche di Tor Paterno’, Central Tyrrhenian Sea, Italy (41°35′ N, 12°20′ E), are reported in order to add new data about size‐frequency distributions of brachiopods. The studied specimens came from death assemblages in the coralligenous substrate, in the Posidonia oceanica meadows, and in the sand channels. The observed patterns vary from left‐skewed (J. cordata) to right‐skewed (A. cuneata), indicating respectively a low and high mortality of smaller individuals. Significant differences between the coralligenous substrate and the P. oceanica meadow were observed for both species, revealing a variation among different habitats. All length and width distributions are clearly polymodal, but the biological meaning of the peaks is difficult to interpret, as the two species seem to have a 2‐year life span. A biometric analysis of shell sizes revealed that length and width are the most variable parameters during the growth of the animal. 相似文献
39.
We measured hydrogen isotope compositions (δD) of high-molecular-weight n-alkanes (C27-C33) from grasses grown in greenhouses and collected from the US Great Plains. In both cases, n-alkanes from C4 grasses are enriched in D by more than 20‰ relative to those from C3 grasses. The apparent enrichment factor (εC29-GW) between C29n-alkane and greenhouse water is −165 ± 12‰ for C3 grasses and −140 ± 15‰ for C4 grasses. For samples from the Great Plains, δD values of C29n-alkanes range from −280 to −136‰, with values for C4 grasses ca. 21‰ more positive than those for C3 grasses from the same site. Differences in C3 and C4 grass n-alkane δD values are consistent with the shorter interveinal distance in C4 grass leaves, and greater back-diffusion of enriched water from stomata to veins, than in C3 grass leaves. Great Plains’ grass n-alkane isotopic ratios largely reflect precipitation δD values. However, the offset or apparent fractionation between n-alkanes and precipitation is not uniform and varies with annual precipitation and relative humidity, suggesting climatic controls on lipid δD values. The dryer sites exhibit smaller absolute apparent fractionation indicative of D-enrichment of source waters through transpiration and/or soil evaporation. To explore the relationship between climate and n-alkane δD values, we develop three models. (1) The ‘direct analog’ model estimates δDC29 values simply by applying the apparent enrichment factors, εC29-GW, observed in greenhouse grasses to precipitation δD values from the Great Plains. (2) The ‘leaf-water’ model uses a Craig-Gordon model to estimate transpirational D-enrichment for both greenhouse and field sites. The transpiration-corrected enrichment factors between C29 and bulk leaf-water, εC29-GW, calculated from the greenhouse samples (−181‰ for C3 and −157‰ for C4) are applied to estimate δDC29 values relative to modeled bulk leaf-water δD values. (3) The ‘soil- and leaf-water’ model estimates the combined effects of soil evaporation, modeled by analogy with a flow-through lake, and transpiration on δDC29 values. Predictions improve with the addition of the explicit consideration of transpiration and soil evaporation, indicating that they are both important processes in determining plant lipid δD values. D-enrichment caused by these evaporative processes is controlled by relative humidity, suggesting that important climatic information is recorded in leaf wax n-alkane δD values. Calibration studies such as this one provide a baseline for future studies of plant-water-deuterium systematics and form the foundation for interpretation of plant wax hydrogen isotope ratios as a paleo-aridity proxy. 相似文献
40.
Polycyclic aromatic hydrocarbons in water, seston and copepods in a harbour area in the Western Mediterranean (Ligurian Sea) 总被引:2,自引:0,他引:2
Luigi Pane Simona Boccardo Fabio Bonfiglioli Gian Luigi Mariottini Francesca Priano & Osvaldo Conio 《Marine Ecology》2005,26(2):89-99
Polycyclic aromatic hydrocarbons (PAHs) are widespread carcinogenic, mutagenic and teratogenic pollutants that can significantly affect ecosystems and exert an influence on marine planktonic and benthic communities as well as on higher organisms such as fish and mammals, including humans. In this paper the concentrations of six PAHs in water, seston and copepods were examined in a harbour zone of the Genova Gulf (Ligurian Sea) from November 1997 to June 1998. The importance of freshwater inputs coming from a polluted stream and the influence of seasonal and atmospheric factors were also considered. Highest PAH values were recorded during spring. Fluoranthene, Benzo[b]fluoranthene and Benzo[k]fluoranthene were the most abundant PAHs either in water, seston or copepods. The concentration of total PAHs in seawater was often lower than the detection limit: recorded values ranged between 0.001 and 0.06 ppb. In seston, total PAHs ranged between 0.033 and 6.26 ng·g?1 and in copepods between 0.01 and 2.34 ng·g?1. With this study, PAH contamination in the harbour zone of Genova Sestri‐Ponente and the importance of inputs of organic pollutants coming from land and freshwaters have been emphasized. 相似文献