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Valerio Lombardo Maria Fabrizia Buongiorno Stefania Amici 《Bulletin of Volcanology》2006,68(7-8):641-651
The simultaneous solution of the Planck equation (involving the widely used “dual-band” technique) using two shortwave infrared (SWIR) bands allows for an estimate of the fractional area of the hottest part of an active lava flow (f
h) and the background temperature of the cooler crust (T
c). The use of a high spectral and spatial resolution imaging spectrometer with a wide dynamic range of 15 bits (DAIS 7915) in the wavelength range from 0.501 to 12.67 μm resulted in the identification of crustal temperature and fractional areas for an intra-crater hot spot at Mount Etna, Italy. This study indicates the existence of a relationship between these T
c and f
h extracted from DAIS and Landsat TM data. When the dual band equation system is performed on a lava flow, a logarithmic distribution is obtained from a plot of the fractional area of the hottest temperature vs. the temperature of the cooler crust. An entirely different distribution is obtained over active degassing vents, where increases in T
c occur without any increase in f
h. This result indicates that we can use scatter plots of T
c vs. fh to discriminate between different types of volcanic activity, in this case between degassing vents and lava flows, using satellite thermal data. 相似文献
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Claudia Spinetti Francesco Mazzarini Ruggero Casacchia Laura Colini Marco Neri Boris Behncke Rosamaria Salvatori Maria Fabrizia Buongiorno Maria Teresa Pareschi 《International Journal of Applied Earth Observation and Geoinformation》2009
Spectral properties of volcanic materials in the optical region (350–2500 nm) of the electromagnetic spectrum are analyzed. The goal is to characterize air-fall deposits, recent lava flows, and old lava flows based on their spectral reflectance properties and on the textural characteristics (grain size) of pyroclastic deposits at an active basaltic volcano. Data were acquired during a spectroradiometric field survey at Mt. Etna (Italy) in summer 2003 and combined with hyperspectral satellite (Hyperion) and airborne LiDAR (Light Detection and Ranging) data. In addition, air-fall deposits produced by the highly explosive 2002–2003 eruption have been sampled and spectrally characterized at different distances from the new vents. The spectral analysis shows that air-fall deposits are characterized by low reflectance values besides variations in grain size. This distinguishes them from other surface materials. Old lava flows show highest reflectance values due to weathering and vegetation cover. The spectral data set derived from the field survey has been compared to corrected satellite hyperspectral data in order to investigate the Hyperion capabilities to differentiate the surface cover using the reflectance properties. This has allowed us to identify the 2002–2003 air-fall deposits in a thematic image just few months after their emplacement. Moreover, the observed differences in the field spectra of volcanic surfaces have been compared with differences in the signal intensity detected by airborne LiDAR survey showing the possibility to include information on the texture of volcanic surfaces at Mt. Etna. The approach presented here may be particularly useful for remote and inaccessible volcanic areas and also represents a potentially powerful tool for the exploration of extraterrestrial volcanic surfaces. 相似文献
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A study was performed in the Tyrrhenian Sea in front of S. Rossore Park (Pisa) to ascertain the degree of Cu, Pb, Cd and Cr pollution and to investigate whether the rivers flowing into the sea may be considered potential sources of seawater contamination. Owing to the variability of such a system, the research, covering a one-year period, involved five surveys on 13 selected sampling stations and two surveys following the floats along the river Arno and its plume. The results refer to the total concentration of the above metals in the water phase after filtration. The content of Cu, Pb and Cd was always found to be higher than in the reference station (about 8 km offshore), generally reaching maximum values around the mouths of the rivers. Concentrations exceeding the minimal risk concentration were observed in the case of Cd. As for Cr, its concentration was always below the detection limit of the analytical method used. Rivers thus appear to be the main sources of coastal metal pollution.By the samplings carried out along the river Arno and its plume (involving 3–5 km from the mouth), it was found that the dilution model represents the concentration pattern for Cu and Pb fairly well over a large range of salinity. 相似文献
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Alessandra Gallo Francesco Silvestre Annunziata Cuomo Fabrizia Papoff Elisabetta Tosti 《Marine Ecology》2011,32(2):222-231
Environmental pollution due to anthropogenic activities may exert an adverse impact on the reproductive mechanisms of animals. In particular, environmental chemicals introduced into seawater are able to disrupt the normal development and function of the reproductive system of marine animals. In this study, we have used the whole‐cell voltage clamp technique to examine the effects of four metals – lead, cadmium, mercury, and zinc – on reproductive mechanisms of the marine ascidian Ciona intestinalis (tunicates). In particular, we measured the effect of metals on plasma membrane electrical properties, the steady‐state conductance, the fertilization current in the mature oocyte, and larval development. Results show that oocyte voltage‐gated sodium currents are significantly reduced by all four metals, steady‐state conductance is affected only by zinc, and post‐fertilization contraction is inhibited only by lead. The fertilization current is suppressed in the presence of zinc and mercury. Embryo development up to larval stage is inhibited by zinc and mercury exposure with a reversible effect; however, a long‐term effect on larval morphology was observed. After exposure to cadmium, fertilization occurs but gives rise to abnormal larval development. These findings highlight the point that exposure to metals represents a significant risk factor for the physiology of reproduction of marine species and suggest a possible role of the C. intestinalis as a bioindicator for marine pollution monitoring. 相似文献
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