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By HEATHER D. GRAVEN † BRITTON B. STEPHENS THOMAS P. GUILDERSON TERESA L. CAMPOS DAVID S. SCHIMEL J. ELLIOTT CAMPBELL RALPH F. KEELING 《Tellus. Series B, Chemical and physical meteorology》2009,61(3):536-546
Measurements of Δ14 C in atmospheric CO2 are an effective method of separating CO2 additions from fossil fuel and biospheric sources or sinks of CO2 . We illustrate this technique with vertical profiles of CO2 and Δ14 C analysed in whole air flask samples collected above Colorado, USA in May and July 2004. Comparison of lower tropospheric composition to cleaner air at higher altitudes (>5 km) revealed considerable additions from respiration in the morning in both urban and rural locations. Afternoon concentrations were mainly governed by fossil fuel emissions and boundary layer depth, also showing net biospheric CO2 uptake in some cases. We estimate local industrial CO2 :CO emission ratios using in situ measurements of CO concentration. Ratios are found to vary by 100% and average 57 mole CO2 :1 mole CO, higher than expected from emissions inventories. Uncertainty in CO2 from different sources was ±1.1 to ±4.1 ppm for addition or uptake of −4.6 to 55.8 ppm, limited by Δ14 C measurement precision and uncertainty in background Δ14 C and CO2 levels. 相似文献
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Behaviour and dynamics of a hydrothermal plume in Lake Banyoles, Catalonia, NE Spain 总被引：1，自引：0，他引：1
TERESA SERRA† MARIANNA SOLER RAMON JULIÀ‡ XAVIER CASAMITJANA JORDI COLOMER† 《Sedimentology》2005,52(4):795-808
A hydrothermal plume forms in Lake Banyoles, NE Spain, as a result of convection above a springwater-fed suspension cloud ponded on the lake floor. The plume propagates upwards reaching a level of neutral buoyancy from where a turbidity current spreads out laterally. Two-dimensional temperature and particle concentration measurements show the fate of the hydrothermal plume and its associated turbidity current and reveal its seasonal development. Silt particles transported by the plume have been used as tracers to determine the maximum and equilibrium heights of the plume. When the lake is stratified, the vertical transport of sediment is confined to the lake hypolimnion, as the thermocline limits the vertical propagation of the plume. In contrast, when the lake water column is mixed, the plume reaches the surface of the lake. The field measurements have been compared with models for thermal convection from finite isolated sources. Measurements of the flow velocity at the source of the hydrothermal plume (i.e. the rim current velocity) indicate that cold hypolimnetic water is entrained by the plume. Sedimentation rates measured from sediment traps at the zone where the turbidity current develops vary between 10 and 25 g m−2 day−1, and result from continuous silt particle sedimentation from the turbidity current. Sedimentation rates in traps are higher for stations situated close to the source than those further away (<5 g m−2 day−1). Moreover, the results demonstrate that double diffusive sedimentation from the turbidity current was dominant over grain-by-grain settling, causing a mixed distribution of sediments in the region where the turbidity current spreads. The deposition of silt particles could explain the occurrence of silt layers interbedded with biocalcarenites in the littoral zones of the lake and the stratigraphy identified by seismic profiles and cores taken from the lake floor. 相似文献
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MICHELE CITTERIO GUGLIELMINA DIOLAIUTI CLAUDIO SMIRAGLIA CARLO D'AGATA TERESA CARNIELLI GIUSEPPE STELLA GIAN BARTOLOMEO SILETTO 《Geografiska Annaler: Series A, Physical Geography》2007,89(3):167-184
This paper describes the recent evolution of Italian glaciers through an analysis of all available terminus fluctuation data that the authors have entered in a glaciers database (named GLAD) containing 883 records collected on glaciers from 1908 to 2002. Furthermore, a representative subset of data (249 glaciers located in Lombardy) was analysed regarding surface area changes. For the analysis of terminus fluctuations, the glaciers were sorted by size classes according to length. The data showed that during the 20th century Italian Alpine glaciers underwent a generalized retreat, with one distinct and well documented readvance episode that occurred between the 1970s and mid‐1980s, and a poorly documented one around the early 1920s. The rates of terminus advance and retreat have changed without significant delays for the larger glaciers with respect to the smaller ones. However, the smaller the glacier, the more limited the advance (if any) during the 1970s and early 1980s. The behaviour of glaciers shorter than 1 km appears to have changed in the last decade, and between 1993 and 2002 they retreated at a very high rate. The analysis of the subset of data led to a quanti‐fication of surface reduction of c. 10% from 1992 to 1999 for glaciers in Lombardy. Small glaciers proved to contribute strongly to total area loss: in 1999, 232 glaciers (c. 90% of the total) were smaller than 1 km2, covering 27.2 km2 (less than 30% of the total area), but accounted for 58% of the total loss in area (they had lost 7.4 km2). 相似文献
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Last glacial hydrological variations at the southern margin of sub‐tropical North America and a regional comparison 
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Chronological and palaeoenvironmental context of human occupations at the Buendía rockshelter (Central Spain) during the late Upper Pleistocene in inland Iberia 下载免费PDF全文
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DARILJSZ KRZYSZKOWSKI TATJANA BÖTTGER FRANK W. JUNGE TERESA KUSZELL JERZY NAWROCKI 《Boreas: An International Journal of Quaternary Research》1996,25(4):283-296
The Ferdynandovian Interglacial is one of the most controversial Quaternary stratigraphic horizons in Europe. This study concentrates on palaeoclimatic reconstruction of this interglacial based on pollen succession, isotope composition and magnetic susceptibility. The section investigated is located in the open cast mine at Belchatow, central Poland. The lacustrine sequence contains laminated diatomite at the base, which was deposited in deep, meromictic lake, and massive diatomite to calcareous gyttja in its upper part. The latter were deposited in a holomictic lake, which became progressively more shallow. The gradual increase of δ18 O values and simultaneous decrease of susceptibility in the lower part of the Ferdynandovian sequence at Belchatow correspond well with climatic amelioration documented by pollen analysis. Simultaneous increase of precipitation of carbonates and its δ13 C values correspond well with the increase in biological activity in the lake. Results obtained by isotope investigations showed an increase in the mean annual temperature to a maximum of 7.5°C from the beginning of the interglacial to the first appearance of thermophilous, deciduous trees. The oxygen-isotope curve does not show any short-term climatic oscillations. Susceptibility oscillations are somewhat more distinct, but because the main magnetic carrier is greigite deposited on spores of unicellular organisms, they are linked to the concentration of these spores rather than with the climatic oscillations. Twelve secular cycles or their fragments have been recorded in the interglacial sequence by palaeomagnetic investigations, suggesting c . 9600 years of deposition. This corresponds well with the 10 000 years of deposition calculated for the same sequence based on annually laminated diatomites. 相似文献
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