Effects of urbanization on streamflow in the Atlanta area (Georgia,USA): a comparative hydrological approach   总被引：1，自引：0，他引：1  

Seth Rose  Norman E. Peters 《水文研究》2001,15(8):1441-1457

For the period from 1958 to 1996, streamflow characteristics of a highly urbanized watershed were compared with less‐urbanized and non‐urbanized watersheds within a 20 000 km² region in the vicinity of Atlanta, Georgia: in the Piedmont and Blue Ridge physiographic provinces of the southeastern USA. Water levels in several wells completed in surficial and crystalline‐rock aquifers were also evaluated. Data were analysed for seven US Geological Survey (USGS) stream gauges, 17 National Weather Service rain gauges, and five USGS monitoring wells. Annual runoff coefficients (RCs; runoff as a fractional percentage of precipitation) for the urban stream (Peachtree Creek) were not significantly greater than for the less‐urbanized watersheds. The RCs for some streams were similar to others and the similar streams were grouped according to location. The RCs decreased from the higher elevation and higher relief watersheds to the lower elevation and lower relief watersheds: values were 0·54 for the two Blue Ridge streams, 0·37 for the four middle Piedmont streams (near Atlanta), and 0·28 for a southern Piedmont stream. For the 25 largest stormflows, the peak flows for Peachtree Creek were 30% to 100% greater than peak flows for the other streams. The storm recession period for the urban stream was 1–2 days less than that for the other streams and the recession was characterized by a 2‐day storm recession constant that was, on average, 40 to 100% greater, i.e. streamflow decreased more rapidly than for the other streams. Baseflow recession constants ranged from 35 to 40% lower for Peachtree Creek than for the other streams; this is attributed to lower evapotranspiration losses, which result in a smaller change in groundwater storage than in the less‐urbanized watersheds. Low flow of Peachtree Creek ranged from 25 to 35% less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of stormwater and the paving of groundwater recharge areas. The timing of daily or monthly groundwater‐level fluctuations was similar annually in each well, reflecting the seasonal recharge. Although water‐level monitoring only began in the 1980s for the two urban wells, water levels displayed a notable decline compared with non‐urban wells since then; this is attributed to decreased groundwater recharge in the urban watersheds due to increased imperviousness and related rapid storm runoff. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Dynamical aspects of ozone mini-hole formation     

D. Peters  J. Egger  G. Entzian 《Meteorology and Atmospheric Physics》1995,55(3-4):205-214

Summary A case study and statistical evaluations provide evidence that so-called ozone mini-hole events over Europe, where a rapid drop of total ozone is followed by complete recovery after a few days, are due to the northeascward motion of patches of air with low total ozone content. These patches appear to originate in subtropical latitudes. They correlate well with minima of potential vorticity near the tropopause. Contour dynamics is invoked to explain some basic features of the deformation and northward motion of the mini-holes as well as the related large-scale flow structures.  相似文献   

Oolithische Strukturen in Pyriten des Ventersdorp-Contact-Reefs,Südafrika     

Dr. Hartmut Schweigart  Herbert von Rahden 《International Journal of Earth Sciences》1965,54(2):1143-1148

Zusammenfassung Oolithische Strukturen in Pyriten des Ventersdorp-Contact-Reefs im Witwatersrand Gebiet, die bisher als radial pyrites beschrieben wurden, zeigen eine starke Ähnlichkeit zu Eisenoolithen der Pretoria Serie des Transvaal Systems. Letztere wurden bereits als primäre Strukturen gedeutet, an deren Bildung Algen wahrscheinlich wesentlich beteiligt waren. Die Verfasser sind der Ansicht, daß sowohl der authigene Kohlenstoff im Ventersdorp- und Witwatersrand System als auch die oolithischen Strukturen in Pyriten des Ventersdorp-Contact-Reefs wahrscheinlich Überbleibsel von primitiven Organismen darstellen, die vor rund 2750×10⁶ Jahren im Sedimentationsbecken des Witwatersrand Systems existierten.

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Oölitic textures present in pyrites of the Ventersdorp Contact Reef at Venterspost Gold Mine, South Africa, which have previously been described as radial pyrites strongly resemble iron oöliths of the Pretoria Series of the Transvaal System. The latter have been considered to be primary textures; a causative connection was believed to have existed between primitive organic life and the formation of these oöliths and related textures. It is suggested that both the authigenic carbonaceous material present in the Ventersdorp- and Witwatersrand Systems and the oölitic textures shown by the pyrite in the Ventersdorp Contact Reef probably represent relicts of an early form of life which existed in the sedimentary basin of the Witwatersrand System some 2,750 × 10⁶ years ago.

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Résumé Les textures oolitiques dans les pyrites du Ventersdorp-Contact-Reef dans la région du Witwatersrand, étant dénommées jusqu'ici «radial pyrites», nous montre une affinité très forte avec oolites ferriques de la série Prétoria du système Transvaal. On a déjà interprété les derniers comme textures primaires; probablement alginite. Suivant l'opinion des auteurs, non seulement le carbone authigène dans le système Ventersdorp et Witwatersrand mais encore les textures oolitiques dans les pyrites du Ventersdorp-Contact-Reef sont probablement des restes des organismes primitifs, ayant existés dans le bassin sédimentaire du système Witwatersrand il y a 2750×10⁶ années.

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Pyroxmangite: Stability in H2O-CO2 mixtures at a total pressure of 2000 bars     

Tj. Peters 《Contributions to Mineralogy and Petrology》1971,32(4):267-273

The curve of the reaction: 1 Rhodochrosite + 1 Quartz Pyroxmangite was determined experimentally using gas mixtures with different CO₂H₂O ratios at a total pressure of 2 kb. In pure CO₂, the equilibrium temperature is 508±2° C. By plotting the equilibrium data in terms of InX_CO2 versus reciprocal temperature, a H of reaction of 51.7 kcal was obtained. This plot shows a straight-line relationship, indicating internal consistency of the data, and is in good agreement with previous findings that CO₂ and H₂O mix ideally within the investigated temperature range (400–600° C). When applied to pyroxmangites formed during moderate greenschist facies metamorphism, these data indicate a high acitivity of H₂O.  相似文献   

K-Ar ages of the metamorphic sole of the Semail Ophiolite: implications for ophiolite cooling history     

Edwin Gnos  Tjerk Peters 《Contributions to Mineralogy and Petrology》1993,113(3):325-332

K–Ar ages have been determined on micas and hornblendes in the basal metamorphic sequence and in metamorphic rocks squeezed into the mantle sequence of the Semail Ophiolite. The hornblende ages of 99±0.5 and 102±0.8 Ma and the 90 Ma ages of coexisting micas from the high-grade metamorphic portion of the sequence are interpreted as cooling stages following the peak of metamorphism (T 800–850° C, P 6.5–9 kbar). The new pressure estimates are based on findings of kyanite in garnet-amphibolite and cordierite in quartzitic rocks. These data indicate a cooling rate of 10–30° C/Ma. The oldest mica ages of 95±1 Ma are observed in the lowest-grade greenschists. These also largely represent cooling ages, but might in part also include formation ages. The pattern of the muscovite ages across the metamorphic sole indicates that the cooling front moved from the low-grade metamorphic zone, through the high-grade rocks and into the base of the overlying ophiolite. Radiometric ages of hornblendes (92.3±0.5 and 94.8±0.6 Ma) indicate that the crustal gabbro sequence cooled below 500° C later than the base of the ophiolite sequence. Metamorphism of the sole rocks occurred during subduction of oceanic sediments and volcanic or gabbroic rocks as they progressively came into contact with hotter zones at the base of the overriding plate. The peak of metamorphism must have been contemporaneous with the main magmatism in the Semail Ophiolite. One of the dated muscovites yields an age of 81.3±0.8 Ma, but this is related to discrete deformation zones that were active during late-stage emplacement of the ophiolite.  相似文献   

Nucleation and growth rates of homogeneously condensing water vapor in argon from shock tube experiments     

F. Peters  B. Paikert 《Mineralium Deposita》1993,28(4):521-530

A special shock tube process combining a reflected expansion wave with a weak shock wave is analyzed and calibrated. The process is employed to transfer water vapor carried in argon into a known supersaturated state for a short period of time (0.5 ms). During that period steady state homogeneous nucleation takes place followed by condensational growth. Nucleation and growth rates are measured by a 90° Mie-light scattering technique in the temperature range 200–260 K. The results are compared with existing theoretical models.  相似文献   

Bioaccumulation and histopathological effects of oil on a stony coral     

Esther C. Peters  Philip A. Meyers  Paul P. Yevich  Norman J. Blake 《Marine pollution bulletin》1981,12(10):333-339

Colonies of the shallow-water Caribbean coral Manicina areolata incorporated petroleum hydrocarbons into their tissues during exposure to water accommodated fractions of No. 2 fuel oil for three months. This contamination was not removed after depuration periods of up to two weeks. Although these corals remained alive, evidence of pathological responses was found which included impaired development of reproductive tissues, degeneration and loss of symbiotic zooxanthellae, and atrophy of mucous secretory cells and muscle bundles.  相似文献   

Geology,petrography, and petrology of Pinzon Island,galapagos archipelago     

Hartmut W. Baitis  Marilyn M. Lindstrom 《Contributions to Mineralogy and Petrology》1980,72(4):367-386

Three stratigraphic units based on geologic relationships and paleomagnetic observations may be distinguished on Pinzon Island. The oldest unit is a broad shield which forms the main body of the island and was erupted during a period of reversed magnetic polarity from an area now occupied by a caldera. Subsequent activity was centered about 1.5 km to the north-northwest from vents later engulfed by the collapse of a younger caldera. The lower portion of this sequence was erupted during a period of transitional pole positions and is overlain by flows of normal polarity. Pinzon has the most diverse suite of differentiated tholeiitic rocks found in the Galapagos Archipelago. Products of eruptive cycles are preserved as sequences of tuffs and flows that have decreasing degrees of differentiation and increasing phenocryst abundance upsection. The sequences may be a consequence of tapping successively deeper levels of compositionally zoned magma chambers. Such a model is consistent with computer calculations utilizing major and trace element data for Pinzon rocks, which suggest that lavas of the island may be related by shallow-level crystal fractionation of observed phenocryst minerals.  相似文献   

Über die Bildungsbereiche mediterraner Jurasedimente am Beispiel der Betischen Kordillere (Südost-Spanien)     

Dr. Hartmut Seyfried 《International Journal of Earth Sciences》1980,69(1):149-178

Zusammenfassung In der Betischen Kordillere sind die Lagerungsbeziehungen der Faziestypen des mediterranen Juras sehr gut erschlossen. Aus Geländebeobachtungen und sedimentologischen Untersuchungen ergab sich die Hypothese, daß das Entstehen derartiger Faziestypen in erster Linie von den morphologischen Verhältnissen am Meeresboden abhängt; die Wassertiefe wirkt sich nur mittelbar aus. Veränderungen der submarinen Land schaft und damit auch Fazieswechsel wurden hauptsächlich durch bruchtektonische Vorgänge hervorgerufen. Eine verhältnismäßig klare paläogeographische Gliederung erhält man im Bereich der pelagischen Schwellen, deren Ablagerungen normalerweise sehr starke diagenetische Veränderungen erfahren haben. Hierbei fällt den roten Knollenkalken (Ammonitico rosso-Fazies) eine Schlüsselrolle zu.

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Due to large scale exposures in the Betic Cordilleras, it is possible there to study the interrelations of mediterranean Jurassic facies types. Field work and sedimentological investigations resulted in the hypothesis, that the origin of a facies type depends in the first place on submarine morphological settings; water depth bears only secondary influence. Changes in submarine morphology were controled by faulting. A detailed paleography can be obtained on the seamont areas, where sediments were normally affected by important diagenetic alterations. A key role, in this connection, must be attributed to red nodular limestones.

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Résumé Dans les Cordillères Bétiques, les relations entre les différents types de facies du Jurassique méditerranéen sont bien exposées. Des investigations sédimentologiques, complétées d'observations de terrain, conduisent à cette hypothèse que ces types de facies dépendent en premier lieu des relations morphologiques au sein du fond marin; la profondeur de l'eau n'a qu'une influence indirecte. Pendant le Jurassique, les changements morphologiques du fond marin, et avec eux les modifications de faciès ont été induits par une tectonique de failles radiales. Généralement, les sédiments des seuils pélagiques sont affectés par des altérations diagénétiques bien marquées, il est donc possible d'en déduire une paléogéographie bien détaillée. Dans ce contexte, on doit attribuer un rôle-clef aux calcaires noduleux rouges (faciès »Ammonitico rosso«).

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Manganese pyroxenoids and carbonates: Critical phase relations in metamorphic assemblages from the Alps     

Tj. Peters  V. Trommsdorff  J. Sommerauer 《Contributions to Mineralogy and Petrology》1978,66(4):383-388

The compositions of coexisting pyroxmangites, rhodonites, rhodochrosites and manganese calcites in regional metamorphosed manganese cale-silicate marbles from Val Scerscen and Alagna were analysed by microprobe and permit definition of critical tie lines at metamorphic grades appropriate to temperatures between 400 and 450 °C.Variations in composition of coexisting mineral pairs in one and the same locality are attributed to variations in and not to metamorphic temperatures. From the analysed assemblages isothermal plots (with SiO₂ as excess component) were constructed for the system CaO-MnO-SiO₂-CO₂.  相似文献