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991.
992.
Torres MA Testa CP Gáspari C Masutti MB Panitz CM Curi-Pedrosa R de Almeida EA Di Mascio P Filho DW 《Marine pollution bulletin》2002,44(9):923-932
Digestive glands of the mangrove mussel Mytella guyanensis, collected at one non-polluted site (site 1) and two polluted sites (sites 2 and 3), were analysed for different antioxidant defenses, lipid peroxidation and DNA damage. Thiobarbituric acid-reactive substance (TBARS) and 8-oxo-7,8-dihydro-2'-deoxyguanosine levels were enhanced at the polluted sites. With the exception of superoxide dismutase, the activities of catalase and glutathione peroxidase were also higher at the polluted sites. Greater increases were observed in glutathione reductase, glutathione S-transferase and etoxyresorufine-O-deethylase activities at the polluted sites. Conversely, reduced glutathione content was higher at the control site. Trace metal contents in mussels collected at polluted sites were increased compared to the control site, and there were strong positive correlations between TBARS and Cu and Pb contents. M. guyanensis is routinely exposed to an oxidative stress condition at both polluted sites, and considering xenobiotic bioaccumulation in bivalve molluscs, the mangrove mussel represents an excellent bioindicator for environmental monitoring studies. 相似文献
993.
994.
Maria Mastalerz Philip R. Ames Penny L. Padgett 《International Journal of Coal Geology》2003,54(3-4):209
The coals of the upper part of the Mansfield, Brazil, and the lower part of the Staunton Formations (Atokan and Desmoinesian, Pennsylvanian) in Indiana (Illinois Basin) are characteristically thin and discontinuous. As a result, problems with correlation and identification of the seams have persisted for both researchers and industry. These discrepancies affect coal exploration, mine planning, and subsequently coal-fired utilities. This study presents exploration and operational examples demonstrating some of the correlation problems associated with the coals of the Brazil Formation, and the Upper Block and Lower Block, in particular, and the surrounding upper part of the Mansfield Formation and lower part of the Staunton Formations. Based on exploration boreholes, mine scale observations, and coal quality and petrographic data, this study suggests that (1) the coal mapped as the Upper Block Coal Member of Clay County may, in fact, be the same seam as the Lower Block Coal Member of Daviess County; and (2) the Lower Block coal of Clay County is not present south of the Switz City area of central Greene County, IN. 相似文献
995.
Michael H. Ort Giovanni Orsi Lucia Pappalardo Richard V. Fisher 《Bulletin of Volcanology》2003,65(1):55-72
The late Pleistocene trachytic Campanian Ignimbrite underlies much of the Campanian Plain near Naples, Italy, and occurs in valleys in the mountainous area surrounding the plain out to about 80 km from its source, the Campi Flegrei caldera. At sites within 15 km of the Campi Flegrei, anisotropy of magnetic susceptibility (AMS) principal directions indicate that, in the absence of significant topography, deposition came from a flow moving in a roughly radial direction. AMS studies of the more distal ignimbrite reveal downhill and/or downvalley flow directions prior to deposition, even where these directions are at high angles to a generally radial transport direction from the vent. On the flanks of Roccamonfina Volcano, flow was directly downhill, as if the source of the ignimbrite was the summit of the volcano. In most localities, the ignimbrite consists of a single massive deposit. In a few localities in the Apennine Mountains, however, the confluence of multiple drainage systems off mountains resulted in multiple local flow units that cannot be correlated between valleys. A detailed study of the ignimbrite in the flat Titerno River valley near Massa shows that the AMS fabrics are not due to late-stage creeping during deposition or compaction. Well-defined, but non-parallel AMS fabrics from vertical and lateral sections in the Massa area are best explained by the merging of gravity currents flowing down the valley and steep valley sides to form a single aggradational deposit. Clast compositions and AMS axes at Mondragone indicate that the pyroclastic flow encountered the Monte Massico massif and was partially blocked, so that flow during deposition was toward the Campi Flegrei. Similar AMS data from sites along the edge of the Campanian Plain indicate back-flow off the first ridge of the Apennine Mountains reached at least 5 km from their base. The Campanian Ignimbrite was deposited from a density-stratified pyroclastic flow. The depositional system consisted of the lower, denser portion of the current, and was controlled by topography. The grouping of the AMS axes is interpreted to indicate that deposition occurred under laminar flow conditions. 相似文献
996.
Transition countries are expected to become important players in the emerging market for greenhouse gas emission reductions, as they can cut emissions at a relatively low cost. However, the attractiveness of the region as a supplier of emission reductions will not only depend on its cost advantage. It will also depend on the business climate offered to carbon investors—factors like a well-functioning legal and regulatory system, economic and political stability and the capacity to process emission reduction projects efficiently. This paper looks at the carbon investment climate in the transition countries eligible for Joint Implementation (JI)—Russia, Ukraine, Croatia and the EU accession countries. It concludes that JI investors will face a clear trade-off between the scope for cheap JI on the one hand, and the quality of the business environment and JI institutions on the other. The countries with the highest potential for cheap emission reductions also tend to be the countries with the most difficult business climate and the least institutional capacity for JI. The most attractive JI locations may be median countries with a reasonable JI potential and an acceptable business climate, such as Bulgaria, Romania and the Slovak Republic. 相似文献
997.
Mireille Laigle Alfred Hirn Maria Sachpazi Christophe Clment 《Earth and Planetary Science Letters》2002,200(3-4):243-253
The western Hellenic arc has been commonly considered as a largely aseismic subduction zone, from the comparison of a small rate of shortening derived from the seismic moment release, with a large rate of convergence inferred from geology. Complete seismic coupling would instead be expected from models that consider a control by plate tectonic forces, because of the trenchward velocity of the Hellenic–Aegean upper plate now confirmed with GPS measurements. In the region of the Ionian Islands, a subduction interplate boundary has been recently imaged and its seismogenic downdip width suggested to be moderate, from reflection seismic profiling and local earthquake tomography. In the appropriate model for such an earthquake source region, which considers a single interplate fault and takes into account these features, the moderate seismic moment release is found consistent with complete seismic coupling of this subduction. The shallow downdip limit of the seismogenic zone can be interpreted as due to the interplate boundary being overlain there by the ductile deeper crust of the orogenically thickened Hellenides. 相似文献
998.
999.
Palaeomagnetic study of the El Quemado complex and Marifil formation, Patagonian Jurassic igneous province, Argentina 总被引:1,自引:0,他引:1
1000.
A. Maria del Rosario Prieto B. Ricardo García-Herrera Emiliano Hernández Martin 《Climatic change》2004,66(1-2):29-48
The use of documentary sources has proven useful to identify extremeclimatic events and their variability during the pre-instrumental period. Theaim of this paper is to describe iceberg sightings in the Western SouthAtlantic during the second half of the 18th century, as recorded from Spanishlogbooks. A total of five sightings have been found, two corresponding toisolated bergs and three to outbreaks. The relevance of these results istwofold: they are the first documented iceberg sightings to date and, aboveall, they correspond to very unusual episodes, characterized by a high numberof high-sized bergs and by the relatively low latitude of their location. Itis suggested that they could be associated to cold episodes in Antarctica. 相似文献