Water balance,nutrient and carbon export from a heath forest catchment in central Amazonia,Brazil          下载免费PDF全文

Fabrício B. Zanchi  Maarten J. Waterloo  Andrés Peralta Tapia  Maria S. Alvarado Barrientos  Marcos A. Bolson  Flávio J. Luizão  Antônio O. Manzi  Albertus J. Dolman 《水文研究》2015,29(17):3633-3648

Carbon storage values in the Amazon basin have been studied through different approaches in the last decades in order to clarify whether the rainforest ecosystem is likely to act as a sink or source for carbon in the near future. This water balance, dissolved organic carbon (DOC) and nutrient export study were carried out in a micro‐scale heath forest (Campina) catchment in central Amazonia, Brazil. For a 1‐year study period (18 March 2007 until 19 March 2008), rainfall amounted to 3054 mm; of which, 1532 mm was evaporated by the forest (4.1 mm day^?1). Rainfall interception loss amounted to 15.6% of gross rainfall. Surface runoff amounted to 485 mm, whereas another 1071 mm was discharged as regional groundwater outflow. Accumulated DOC exports in surface runoff amounted to 15.3 g m^?2 year^?1, whereas the total carbon exported was 55.9 g m^?2. This is much higher than that observed for a nearby tall rainforest catchment in central Amazonia (DOC export < 20 g m^?2). As Campina heath forest areas cover a significant proportion of the Amazon Basin, these differences in ecosystem hydrological carbon exports should be taken into account in future studies assessing the carbon budget for the Amazon Basin. Macro‐nutrient exports were low, but those of calcium and potassium were higher than those observed for tall rainforest in the Amazon, which may be caused by a lower retention capacity of the heath forest ecosystem. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Structural geometry of a thick‐skinned fold‐thrust belt termination: The Olary Block in the Adelaide Fold Belt,South Australia     

E. Paul  M. Sandiford  T. Flöttmann 《Australian Journal of Earth Sciences》2013,60(2):281-289

The Olary Block comprises a set of Palaeoproterozoic to Mesoproterozoic basement inliers that were deformed together with the Neoproterozoic sedimentary cover of the Adelaide Geosyncline during the ca 500 Ma Cambro‐Ordovician Delamerian Orogeny. Balanced and restored structural sections across this region show shortening of less than 20%. These basement inliers represent the interface between a region of thick‐skinned deformation bordering the Curnamona Craton to the north and a region of thin‐skinned deformation to the south and west in the Nackara Arc. The basement inliers represent upthrust segments of the subsided basin margin with the sedimentary package thickening to the south and to the west. Earlier formed extensional faults provided the major strain guides during Delamerian shortening. An early phase of east‐west shortening is interpreted to be synchronous with dextral strike‐slip deformation along basement‐relay structures (e.g. Darling River lineament). During progressive shortening the tectonic transport direction rotated into a northwest to north direction, coeval with the onset of the main phase of thin‐skinned fold deformation in the adjacent Nackara Arc.  相似文献   

In the footprints of evolutionary economic geography     

Arnt Fløysand  Stig-Erik Jakobsen 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(3):137-139

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Aggradation and carbonate accumulation of Holocene Norwegian cold‐water coral reefs          下载免费PDF全文

Jürgen Titschack  Daniel Baum  Ricardo De Pol‐Holz  Matthias López Correa  Nina Forster  Sascha Flögel  Dierk Hebbeln  André Freiwald 《Sedimentology》2015,62(7):1873-1898

Cold‐water coral ecosystems present common carbonate factories along the Atlantic continental margins, where they can form large reef structures. There is increasing knowledge on their ecology, molecular genetics, environmental controls and threats available. However, information on their carbo‐nate production and accumulation is still very limited, even though this information is essential for their evaluation as carbonate sinks. The aim of this study is to provide high‐resolution reef aggradation and carbonate accumulation rates for Norwegian cold‐water coral reefs from various settings (sunds, inner shelf and shelf margin). Furthermore, it introduces a new approach for the evaluation of the cold‐water coral preservation within cold‐water coral deposits by computed tomography analysis. This approach allows the differentiation of various kinds of cold‐water coral deposits by their macrofossil clast size and orientation signature. The obtained results suggest that preservation of cold‐water coral frameworks in living position is favoured by high reef aggradation rates, while preservation of coral rubble prevails by moderate aggradation rates. A high degree of macrofossil fragmentation indicates condensed intervals or unconformities. The observed aggradation rates with up to 1500 cm kyr^?1 exhibit the highest rates from cold‐water coral reefs so far. Reef aggradation within the studied cores was restricted to the Early and Late Holocene. Available datings of Norwegian cold‐water corals support this age pattern for other fjords while, on the shelf, cold‐water coral ages are reported additionally from the early Middle Holocene. The obtained mean carbonate accumulation rates of up to 103 g cm^?2 kyr^?1 exceed previous estimates of cold‐water coral reefs by a factor of two to three and by almost one order of magnitude to adjacent sedimentary environments (shelf, slope and deep sea). Only fjord basins locally exhibit carbonate accumulation rates in the range of the cold‐water coral reefs. Furthermore, cold‐water coral reef carbonate accumulation rates are in the range of tropical reef carbonate accumulation rates. These results clearly suggest the importance of cold‐water coral reefs as local, maybe regional to global, carbonate sinks.  相似文献   

Quantification by numerical simulation of the impact of gullies on the water budget of a basement area,southeastern Brazil     

Péterson Gonçalves de Lima  Flávio Nasser Drumond 《水文科学杂志》2013,58(12):1804-1816

ABSTRACT

Many regions of the world are affected by high density of large gullies that can impact on water resources. As these impacts have not been properly evaluated, this study presents a quantification model by numerical simulation of the effect of gullying on the water budget. An active gully of a very eroded region (Bação Complex) was selected and systematically monitored during a hydrological year. The simulation of the gully area by finite element method enabled the quantification of impacts, such as baseflow reduction and groundwater drawdown in the vicinity of this erosional feature. The baseflow reduction, when extrapolated to the whole complex, showed a significant baseflow loss during the dry seasons and an increase of stream flows during the rainy seasons, favouring floods. The numerical simulation results indicate that these modifications are relevant and must be considered when managing aquifers in intensely gullied areas with problems related to water availability.  相似文献   

Hydrological and hydrochemical studies in the permafrost drainage basin of Oobloyah Valley,N-Ellesmere Island,NWT, Canada     

Dr. W. -A. Flügel 《GeoJournal》1983,7(4):341-351

During the “Heidelberg-Ellesmere-Island-Expedition” to Oobloyah Valley, N-Ellesmere Island, NWT, Canada in 1978 the summerly water balance of this high arctic catchment area with continuous permafrost was investigated. The following results will be presented:

1. Three hydrogeological areas with different physical parameters, thawing depths and drainage are distinguished and studied on slope I, II and slope III.
2. The climatic situation of summer 1978 was mainly influenced by the change of radiating and cloudy periods. Due to air temperatures (2 m above ground), which never went below 0°C, these periods regulated the thawing of the glaciers and the respective run-off.
3. Most of the winterly snow cover melted before July, thereafter soil thawing and its drainage began. In none of the sediments the latter reached field capacity.
4. Considering the course of daily discharge and soil water balance the three studied streams were characterized by the “Dry-Weather-Discharge-Line”, DWL, of Peri-Creek the “Radiation-Weather-Discharge-Line”, RWL, and the “Cloudy-Weather-Discharge-Line”, CWL, of Nukapingwa River and Heidelberg River.
5. The periglacial streams never had a measurable sediment load not even during snow melt, whereas the glacial and mixed glacial-periglacial streams as Nukapingwa River and Heidelberg River showed a sediment drift depending on their run-off. Only in Peri-Creek the ion concentrations were correlated to discharge.
6. Precipitation (snow plus rain) add up to 51% of the summerly water balance. The glaciers contributed up to 48%, and the actual evapotranspiration is only 1%.

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Darstellung und Kristallographie von K2 TiSi6O15 —isotyp mit Dalyit K2 ZrSi6O15     

Dr. W. Gebert  Dr. O. Medenbach  Dr. O. W. Flörke 《Mineralogy and Petrology》1983,31(1-2):69-79

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Hydrothermal recrystallization and transformation of tridymite     

O. W. Flörke  K. Langer 《Contributions to Mineralogy and Petrology》1972,36(3):221-230

Well ordered tridymites containing atmost 0.016% Na (0.004% Na) were prepared at 1400° C from Na₂WO₄-(K₂WO₄-) fluxes using high purity amorphous silica as starting material. No further reduction of these Na-contents was attainable by soxhlet extraction. These tridymites were treated hydrothermally at temperatures between 815 and 950° C and 200 bars H₂O. The products obtained were investigated optically as well as by powder X-ray methods and were analyzed for Na-contents: the hydrothermal treatment resulted either in recrystallization of tridymite or transformation into quartz mostly depending on Na-contents. Na-contents below about 0.015% tend to favour recrystallization of tridymite within the quartz field (<870° C), Na-contents above about 0.03% tend to favour formation of quartz within the tridymite field (>870° C). This may be due to influences of Na-traces either on the kinetics or on the equilibrium temperature of tridymite-quartz transformation.  相似文献   

Precipitazioni intense al margine meridionale delle Alpi     

Fl. Ambrosettl 《Pure and Applied Geophysics》1955,30(1):222-236

Riassunto In questo lavoro sono studiate specialmente le precipitazioni intense (quantità giornaliere 50 mm) del periodo 1901–1950, mediante 6 stazioni del margine meridionale delle Alpi, confrontate con una stazione del nord delle Alpi (Zurigo) e una della Lombardia (Milano). Si trova che le precipitazioni intense sul versante sud delle Alpi sono molto più frequenti che nelle stazioni di confronto e che al margine meridionale delle Alpi è considerevole l'apporto delle precipitazioni intense alla somma totale.

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Summary In the present paper is being examined particularly the frequency of large precipitations (daily amounts 50 mm) on the southern side of the Swiss Alps (period 1901–1950). For this purpose the conditions of precipitation of six stations in Southern Switzerland are compared with those of one station on the northern side of the Alps (Zürich) and of one in Lombardy (Milan). It is shown that the frequency of large precipitations is much higher on the southern slope of the Alps than on the stations mentioned in comparison. Also that the share of the amount of large precipitations on the total amount is rather considerable.

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Zusammenfassung In der vorliegenden Arbeit werden vor allem die grossen Niederschläge (Tagesmengen 50 mm) der Periode 1901–1950 anhand von 6 Stationen auf der Alpensüdseite untersucht und mit je einer Station auf der Alpennordseite (Zürich) und in der Lombardei (Mailand) verglichen. Dabei zeigt sich, dass grosse Niederschläge an der Südabdachung der Alpen viel häufiger sind als an den Vergleichstationen und dass der Anteil der grossen Niederschläge an der Gesamtmenge am Alpensüdfuss beträchtlich ist.

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Heat flow and quantity of methane deduced from a gas hydrate field in the vicinity of the Dnieper Canyon,northwestern Black Sea   总被引：1，自引：1，他引：1  

Thomas?LüdmannEmail author  How?Kin?Wong  Philipp?Konerding  Matthias?Zillmer  J?rg?Petersen  Ernst?Flüh 《Geo-Marine Letters》2004,24(3):182-193

Seismic reflection data document for the first time the existence of a BSR in a limited area west of the Dnieper Canyon in the northwestern Black Sea. Seismic wide-angle data suggest that gas hydrates occupy in average 15±2% of the pore space in a zone of 100 m in thickness. A conservative quantification of the amount of methane associated with this gas hydrate occurrence is about 12±3×10¹¹ m³ (0.6±0.2 Gt of methane carbon). Conductive heat flow deduced from the BSR depth is in the range of 21±6 to 55±15 mW m^–2.  相似文献