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51.
Edward F. Tedesco 《Icarus》1979,40(3):375-382
Evidence is presented indicating that the Flora family is of common origin. The distribution of proper elements and physical properties of Flora-family asteroids are compared with those of families believed to have formed from the catastrophic disruption of parent bodies. Differences in these orbital and physical properties suggest that the creation of the Flora family was more complex. Available evidence concerning the Flora family, together with recent models for the collisional evolution of the asteroids, suggests that this family may have originated from a binary or multiple asteroid. A mechanism in which the Flora family may have been produced by the disruption of a former major satellite of 8 Flora is presented and compared with other possible modes of formation. 相似文献
52.
Mark Woodworth Miguel Goi Eric Tappa Kathy Tedesco Robert Thunell Yrene Astor Ramon Varela Jose Rafael Diaz-Ramos Frank Müller-Karger 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):2249
This study examined the relationship between carbon isotopic composition of sinking organic matter (OM) and the biological, physical and chemical properties of the surface ocean in the Cariaco Basin. The 13C/12C ratio of OM (δ13Corg) in sinking particles was determined on sediment trap samples from four depths collected from 1996 to 1999 as part of the CArbon Retention In A Colored Ocean time series. Water column properties, including temperature, productivity, chlorophyll and concentration of dissolved CO2, were concurrently measured on monthly cruises. The δ13Corg varied from a high of –17.7‰ to a low of –22.6‰ during the study period. The variation of the δ13Corg throughout seasonal cycles was directly proportional to the strength of upwelling and was negatively correlated with temperature (r2=0.64). During the 1996–1997 upwelling event, the strongest during the study period, the δ13Corg increased by 4.4‰ whereas during the 1998–1999 upwelling event, the weakest during the study period, the δ13Corg only increased by 3.3‰. Contrary to most previous studies, we observed a negative relationship (r2=0.53) between [CO2 aq] and the estimated isotopic fractionation factor (εp). However, there was no correlation between εp and the calculated growth rates indicating that there was non-diffusive uptake of carbon into phytoplankton cells. It thus appears that [CO2 aq] does not control the δ13Corg in the water column of the study site. The best explanation for the isotopic enrichment observed is a carbon concentrating mechanism (CCM) in phytoplankton. The existence of a CCM in phytoplankton has major implications for the interpretation of the δ13Corg in the Cariaco Basin. 相似文献
53.
Marvin Lanphere Duane Champion Leone Melluso Vincenzo Morra Annamaria Perrotta Claudio Scarpati Dario Tedesco Andrew Calvert 《Bulletin of Volcanology》2007,69(3):259-263
The Italian volcano, Vesuvius, erupted explosively in AD 79. Sanidine from pumice collected at Casti Amanti in Pompeii and Villa Poppea in Oplontis yielded a weighted-mean 40Ar/39Ar age of 1925±66 years in 2004 (1σ uncertainty) from incremental-heating experiments of eight aliquants of sanidine. This is the calendar age of the eruption. Our results together with the work of Renne et al. (1997) and Renne and Min (1998) demonstrate the validity of the 40Ar/39Ar method to reconstruct the recent eruptive history of young, active volcanoes. 相似文献
54.
Jean-Paul Toutain Jean-Claude Baubron Joseph Le Bronec Patrick Allard Pierre Briole Bernard Marty Gerarda Miele Dario Tedesco Giuseppe Luongo 《Bulletin of Volcanology》1992,54(2):147-155
The increasing activity of Vulcano Island (Italy) since 1985 led to the initiation of continuous geochemical monitoring of the lateral soil gas emissions. On the basis both of their relative geochemical characteristics and of local considerations, three gaseous components were selected for monitoring, namely CO2, He and 222Rn. Monitoring has been performed by means of specific analysers. Gases extracted from a water well located at the foot of the active cone were selected for monitoring, on the basis of their geochemical and isotopic characters that indicate their genetic link with central high temperature fumarolic gases emitted at the crater. Very strong variations of gas composition can be observed within one day (from 1 to about 94% for CO2). Some variations display a daily character and can be correlated with that of atmospheric pressure. The three monitored gases are highly correlated, suggesting very high kinetics of gas transfer in the system. Because of these considerable variations of chemical composition, bulk concentrations obviously are not suitable for monitoring at Vulcano. However, the evolution with time of ratios such as 222Rn/CO2 and He/CO2 (the latter being corrected for atmospheric contamination) supplies numerical parameters that the expected to characterize the intensity of the degassing process. A new input of magmatic gases, that would lead to an increase in the 222Rn/CO2 and He/CO2 ratios, should therefore be detected by such a monitoring station. 相似文献
55.
56.
Eliot?A.?AtekwanaEmail author Lenore?P.?Tedesco Leda?R.?Jackson 《Estuaries and Coasts》2003,26(6):1391-1400
Physical and chemical parameters were measured in a subtropical estuary with a blind river source in southwest Florida, United States, to assess seasonal discharge of overland flow and groundwater in hydrologic mixing. Water temperature, pH, salinity, alkalinity, dissolved inorganic carbon (DIC), δ18O, and δ13CDIC varied significantly due to seasonal rainfall and climate. Axial distribution of the physical and chemical parameters constrained by tidal conditions during sampling showed that river water at low tide was a mixture of freshwater from overland flow and saline ground-water in the wet season and mostly saline groundwater in the dry season. Relationships between salinity and temperature, δ18O, and DIC for both the dry and wet seasons showed that DIC was most sensitive to seawater mixing in the estuary as DIC changed in concentration between values measured in river water at the tidal front to the most seaward station. A salinity-δ13CDIC model was able to describe seawater mixing in the estuary for the wet season but not for the dry season because river water salinity was higher than that of seawater and the salinity gradient between seawater and river water was small. A DIC-δ13CDIC mixing model was able to describe mixing of carbon from sheet flow and river water at low tide, and river water and seawater at high tide for both wet and dry seasons. The DIC-δ13CDIC model was able to predict the seawater end member DIC for the wet season. The model was not able to predict the seawater end member DIC for the dry season data due to secondary physical and biogeochemical processes that altered estuarine DIC prior to mixing with seawater. The results of this study suggest that DIC and δ13CDIC can provide additional insights into mixing of river water and seawater in estuaries during periods where small salinity gradients between river water and seawater and higher river water salinities preclude the use of salinity-carbon models. 相似文献
57.
S. Borsi G. Marinelli F. Mazzoncini M. Mittempergher C. Tedesco 《Bulletin of Volcanology》1963,25(1):359-363
Ignimbrite deposits are present at Pantelleria and Eolian Islands. Purpose of this note is just to signal them. 相似文献
58.
E.F. Tedesco R.C. Taylor J. Drummond D. Harwood I. Nickoloff F. Scaltriti V. Zappalà 《Icarus》1983,54(1):30-37
We present 26 lightcurves of 16 Psyche from 1975 and 1976. The synodic period during this apparition was 4h.1958. Combining photometric data from this opposition with those from previous apparitions allowed us to derive a mean phase coefficient in V of 0.026 ± 0.002 mag/deg and to establish that Psyche's absolute V0 magnitude and rotational amplitude vary with aspect; at 90° aspect, V0(1, 0) = 6.27 ± 0.05 and the lightcurve amplitude is 0.30 mag, while at 0° or 180° aspect, V0(1, 0) = 6.02 ± 0.02 and the amplitude is ?0.03 mag. This behavior is accounted for if, to first order, Psyche's shape is that of a triaxial ellipsoid with axial ratios near 5:4:3. Colors at zero phase are U-B = 0.26 ± 0.01 and B-V = 0.71 ± 0.01. Color phase coefficients are <0.001 mag/deg in U-B and 0.0010 ± 0.0004 mag/deg in B-V. 相似文献