404 resultados para AROCLOR-1254


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In low and middle latitudes, the Cretaceous/Tertiary boundary is marked by a sudden and pronounced decrease in d13C values of near-surface-water carbonates and a reduction in the surface-to-bottom d13C gradient. These isotopic data have been interpreted as evidence of a decline in surface-water productivity that was responsible for the extinction of many planktic foraminiferal species and other marine organisms at or near the K/T boundary. We present planktic and benthic foraminiferal isotopic data from two almost biostratigraphically complete sections at Ocean Drilling Program Site 738 in the antarctic Indian Ocean and at Nye Kløv in Denmark. These data suggest that planktic carbonate d13C values in high latitudes may not have decreased dramatically at the K/T boundary; thus, surface-water productivity may not have been reduced as much as in low and middle latitudes. Comparison of the records of Site 738 with those of ODP Sites 690 and 750 indicates a pronounced decline in d13C values of planktic and benthic foraminifera and fine-fraction/bulk carbonate ~200 000 yr after the K/T boundary. This reflects a regional shift in the carbon isotopic composition of oceanic total dissolved carbon (TDC) and correlates with a similar change in benthic foraminiferal d13C values at mid- and low-latitude Deep Sea Drilling Project Sites 527 and 577. This oceanographic event was followed by the ecosystem's global recovery ~500 000 yr after the K/T boundary. These data suggest that the environmental effects of the K/T boundary may have been less severe in the high-latitude oceans than in tropical and subtropical regions.

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The Global River Discharge (RivDIS) data set contains monthly discharge measurements for 1018 stations located throughout the world. The period of record varies widely from station to station, with a mean of 21.5 years. These data were digitized from published UNESCO archives by Charles Voromarty, Balaze Fekete, and B.A. Tucker of the Complex Systems Research Center (CSRC) at the University of New Hampshire. River discharge is typically measured through the use of a rating curve that relates local water level height to discharge. This rating curve is used to estimate discharge from the observed water level. The rating curves are periodically rechecked and recalibrated through on-site measurement of discharge and river stage.

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In this study, we apply the inter-regional input–output model to explain the relationship between China’s inter-regional spillover of CO2 emissions and domestic supply chains for 2002 and 2007. Based on this model, we propose alternative indicators such as the trade in CO2 emissions, CO2 emissions in trade, regional trade balances, and comparative advantage of CO2 emissions. The empirical results not only reveal the nature and significance of inter-regional environmental spillover within China’s domestic regions but also demonstrate how CO2 emissions are created and distributed across regions via domestic production networks. The main finding shows that a region’s CO2 emissions depend on not only its intra-regional production technique, energy use efficiency but also its position and participation degree in domestic and global supply chains.

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Contiene : serie de Papas, Abades y Reyes de Aragón y los Progresos que tuvo el Monasterio desde el año 1254 hasta 1458