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161.
Implications of land use change on the national terrestrial carbon budget of Georgia 总被引:1,自引:0,他引:1
Pontus Olofsson Paata Torchinava Curtis E Woodcock Alessandro Baccini Richard A Houghton Mutlu Ozdogan Feng Zhao Xiaoyuan Yang 《Carbon balance and management》2010,5(1):4
Background
Globally, the loss of forests now contributes almost 20% of carbon dioxide emissions to the atmosphere. There is an immediate need to reduce the current rates of forest loss, and the associated release of carbon dioxide, but for many areas of the world these rates are largely unknown. The Soviet Union contained a substantial part of the world's forests and the fate of those forests and their effect on carbon dynamics remain unknown for many areas of the former Eastern Bloc. For Georgia, the political and economic transitions following independence in 1991 have been dramatic. In this paper we quantify rates of land use changes and their effect on the terrestrial carbon budget for Georgia. A carbon book-keeping model traces changes in carbon stocks using historical and current rates of land use change. Landsat satellite images acquired circa 1990 and 2000 were analyzed to detect changes in forest cover since 1990. 相似文献162.
163.
Marco G. Malus Riccardo Polino Andrea Cerrina Feroni Alessandro Ellero Giuseppe Ottria Lahssen Baidder Giovanni Musumeci 《地学学报》2007,19(6):481-489
New field data integrated by fission‐track (FT) analysis unravel an innovative scenario for the post‐Variscan evolution of the eastern Anti‐Atlas. This area, unaffected by Meso‐Cenozoic tectonics according to most workers, is crosscut by crustal faults bearing evidence of a polyphase deformation history. Apatite FT ages, ranging between 284 and 88 Ma, point to fast Neogene exhumation and unravel contrasting cooling paths across major faults. Results show that the study area was buried beneath 2 km of allochthonous Variscan units, now eroded. The eastern Anti‐Atlas acted as the southern shoulder of the Atlasic rift in the Mesozoic, and underwent a dextral transpressional structuring of Neogene age followed by sub‐meridian shortening. The southern front of Atlasic deformation is therefore located inside the Anti‐Atlas region, and it is still active. 相似文献
164.
Alessandro Morbidelli Antonio Giorgilli 《Celestial Mechanics and Dynamical Astronomy》1989,47(2):173-204
The general theory exposed in the first part of this paper is applied to the following resonances with Jupiter's motion : 3/2, 2/1, 5/2, 3/1, 7/2, 4/1; these are the most relevant resonances for the asteroids. The whole analysis is performed in the framework of the spatial problem of three bodies, both in the circular and in the elliptic case. The results are also compared with the observed distribution of the asteroids. 相似文献
165.
Margherita Polacci Michael R. Burton Alessandro La Spina Filippo Murè Stefano Favretto Franco Zanini 《Journal of Volcanology and Geothermal Research》2009,179(3-4):265-269
We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 15 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation. 相似文献
166.
A. Aiuppa W. D’Alessandro S. Gurrieri P. Madonia F. Parello 《Environmental Geology》2007,53(4):903-913
Hydrological and geochemical studies performed on Lake Specchio di Venere on Pantelleria island (Italy) indicate that this
endorheic basin has been formed through upwelling of the water table, and that it is continuously fed by the thermal springs
situated on its shores. The lake is periodically stratified both thermally and in salinity, albeit this stratification is
rather unstable over time, since meteorological events such as strong rain or wind can determine the mixing of its waters.
Periodical analyses of the lake water chemistry show large variations of the salt content due to the yearly evaporation-rain
dilution cycle. These processes are also responsible for the saline stratification during steady meteorological conditions.
The mineralogical characterisation of the bottom sediments shows the almost exclusive presence of neoformation minerals, mainly
carbonates, formed in response to the pH gradient between spring- (pH ≈ 6) and lake-waters (pH ≈ 9). Finally, the CO2 partial pressures in the lake water slightly exceeding the atmospheric one, are due to the large amounts of CO2 brought to the lake through the bubbling free gas phase of the thermal springs. Nevertheless the high pH value of the lake
water, its small volume and its periodical mixing prevent dangerous built up of this gas. 相似文献
167.
Alessandro Bonforte Salvatore Gambino Francesco Guglielmino Francesco Obrizzo Mimmo Palano Giuseppe Puglisi 《Bulletin of Volcanology》2007,69(7):757-768
On 22 September 2002, 1 month before the beginning of the flank eruption on the NE Rift, an M-3.7 earthquake struck the northeastern
part of Mt. Etna, on the westernmost part of the Pernicana fault. In order to investigate the ground deformation pattern associated
with this event, a multi-disciplinary approach is presented here. Just after the earthquake, specific GPS surveys were carried
out on two small sub-networks, aimed at monitoring the eastern part of the Pernicana fault, and some baselines belonging to
the northeastern EDM monitoring network of Mt. Etna were measured. The leveling route on the northeastern flank of the volcano
was also surveyed. Furthermore, an investigation using SAR interferometry was performed and also the continuous tilt data
recorded at a high precision sensor close to the epicenter were analyzed to constrain the coseismic deformation. The results
of the geodetic surveys show a ground deformation pattern that affects the entire northeastern flank of the volcano, clearly
shaped by the Pernicana fault, but too strong and wide to be related only to an M-3.7 earthquake. Leveling and DInSAR data
highlight a local strong subsidence, up to 7 cm, close to the Pernicana fault. Significant displacements, up to 2 cm, were
also detected on the upper part of the NE Rift and in the summit craters area, while the displacements decrease at lower altitude,
suggesting that the dislocation did not continue further eastward. Three-dimensional GPS data inversions have been attempted
in order to model the ground deformation source and its relationship with the volcano plumbing system. The model has also
been constrained by vertical displacements measured by the leveling survey and by the deformation map obtained by SAR interferometry. 相似文献
168.
F. D’Alessandro A. A. Deshpande P. M. McCulloch 《Journal of Astrophysics and Astronomy》1997,18(1):5-14
Power spectra of the timing noise observed in 18 southern pulsars have been derived using a novel technique, based on the
CLEAN algorithm. Most of the spectra are well described by a single- or double-component power-law model. Some of these spectra
can be interpreted in the context of one or more of the current timing noise models. The results combined with those obtained
from the time-domain analyses of the timing activity in these pulsars are used to assess the viability of the various theoretical
models of pulsar timing noise. 相似文献
169.
Linda Schmidtobreick Claus Tappert Alessandro Ederoclite Ivo Saviane Elena Mason 《Astrophysics and Space Science》2006,304(1-4):303-305
We report preliminary results of an observing run at the 1--m telescope at CTIO during which we followed RR Pic over several nights in February 2005. The resulting light curves show no sign of an eclipse. Apart from the 3.48 h period, which is usually interpreted as the orbital one, we find an additional period at P=3.78 h, which we interpret as the superhump period of the system.We furthermore present high–resolution Doppler maps in Hα, Hβ and He II, which we derived from observations at the NTT, La Silla in February 2004. They show strong variations in the emission distribution from one day to the next. While Hα and Hβ emission clearly show the accretion disc with some additional isolated sources, the He II emission is confined to an elongated region at low velocities. 相似文献
170.
Luigi Folco Massimo D'Orazio Alessandro Burroni 《Meteoritics & planetary science》2006,41(8):1183-1198
Abstract— The Frontier Mountain (FRO) 93001 meteorite is a 4.86 g fragment of an unshocked, medium‐ to coarse‐grained rock from the acapulcoite‐lodranite (AL) parent body. It consists of anhedral orthoenstatite (Fs13.3 ± 0.4Wo3.1 ± 0.2), augite (Fs6.1 ± 0.7Wo42.3 ± 0.9; Cr2O3 = 1.54 ± 0.03), and oligoclase (Ab80.5 ± 3.3Or3.1 ± 0.6) up to >1 cm in size enclosing polycrystalline aggregates of fine‐grained olivine (average grain size: 460 ± 210 μm) showing granoblastic textures, often associated with Fe,Ni metal, troilite, chromite (cr# = 0.91 ± 0.03; fe# = 0.62 ± 0.04), schreibersite, and phosphates. Such aggregates appear to have been corroded by a melt. They are interpreted as lodranitic xenoliths. After the igneous (the term “igneous” is used here strictly to describe rocks or minerals that solidified from molten material) lithology intruding an acapulcoite host in Lewis Cliff (LEW) 86220, FRO 93001 is the second‐known silicate‐rich melt from the AL parent asteroid. Despite some similarities, the silicate igneous component of FRO 93001 (i.e., the pyroxene‐plagioclase mineral assemblage) differs in being coarser‐grained and containing abundant enstatite. Melting‐crystallization modeling suggests that FRO 93001 formed through high‐degree partial melting (≥35 wt%; namely, ≥15 wt% silicate melting and ?20 wt% metal melting) of an acapulcoitic source rock, or its chondritic precursor, at temperatures ≥1200 °C, under reducing conditions. The resulting magnesium‐rich silicate melt then underwent equilibrium crystallization; prior to complete crystallization at ?1040 °C, it incorporated lodranitic xenoliths. FRO 93001 is the highest‐temperature melt from the AL parent‐body so far available in laboratory. The fact that FRO 93001 could form by partial melting and crystallization under equilibrium conditions, coupled with the lack of quench‐textures and evidence for shock deformation in the xenoliths, suggests that FRO 93001 is a magmatic rock produced by endogenic heating rather than impact melting. 相似文献