Direct terrestrial-marine correlation demonstrates surprisingly late onset of the last interglacial in central Europe     

Mark J. Sier  Wil Roebroeks  Corrie C. Bakels  Enrico Brühl  Dimitri De Loecker  Norbert Hesse  Lutz Kindler  Thomas Laurat  Herman J. Mücher  Kirsty E.H. Penkman  Douwe J.J. van Hinsbergen 《Quaternary Research》2011,75(1):213-218

An interdisciplinary study of a small sedimentary basin at Neumark Nord 2 (NN2), Germany, has yielded a high-resolution record of the palaeomagnetic Blake Event, which we are able to place at the early part of the last interglacial pollen sequence documented from the same section. We use this data to calculate the duration of this stratigraphically important event at 3400 ± 350 yr. More importantly, the Neumark Nord 2 data enables precise terrestrial-marine correlation for the Eemian stage in central Europe. This shows a remarkably large time lag of ca. 5000 yr between the MIS 5e ‘peak’ in the marine record and the start of the last interglacial in this region.  相似文献   

Trophic interactions of the pelagic ciliate Stentor spp. in North Patagonian lakes     

Norbert Kamjunke  Bernhard Vogt 《Limnologica》2009,39(2):107-114

The zooplankton of oligotrophic lakes in North Patagonia is often dominated by mixotrophic ciliates, particularly Stentor amethystinus and Stentor araucanus. Therefore, we tested whether Stentor spp. (i) is an important food for juvenile endemic (Cheirodon australe, Galaxias maculatus, Odontesthes mauleanum, Percichthys trucha) and introduced (Oncorhynchus mykiss) fish species, and (ii) represents a remarkable grazer of bacteria. Ingestion rates of fish estimated by disappearance of Stentor in feeding experiments ranged between 8 (G. maculatus) and 53 (C. australe) ciliates per fish and day, and assimilation rates measured by using radioactively labelled Stentor ranged between 3 (P. trucha) and 52 (C. australe) ciliates per fish and day. However, although we detected the consumption of Stentor by fish, the daily consumption amounted to at most 0.2% of the fish biomass which can not cover the energy requirement of the fish. Furthermore, the daily consumption was equivalent to a maximum of 1.6% of the Stentor standing stock so that fish predation does not seem to be an important mortality factor for the ciliates. The clearance rate of Stentor sp. on natural bacteria was on average 3.8 μl cil⁻¹ h⁻¹. The daily ingestion (mean 3.9 ng C cil⁻¹ d⁻¹) was about 3.5% of the individual biomass of Stentor sp. Therefore, bacteria ingestion might explain a ciliate growth rate of appr. 1% d⁻¹, which was about 17% of the photosynthesis of endosymbiotic algae. The maximum density of Stentor sp. in the lake could ingest about 1 μg C L⁻¹ d⁻¹ bacteria which is only 3% of average bacterial production. Thus, grazing by Stentor sp. does not seem to be a main loss factor for the bacteria.  相似文献   

Estuaries of the northeastern United States: Habitat and land use signatures     

Charles T. Roman  Norbert Jaworski  Frederick T. Short  Stuart Findlay  R. Scott Warren 《Estuaries and Coasts》2000,23(6):743-764

Geographic signatures are physical, chemical, biotic, and human-induced characteristics or processes that help define similar or unique features of estuaries along latitudinal or geographic gradients. Geomorphologically, estuaries of the northeastern U.S., from the Hudson River estuary and northward along the Gulf of Maine shoreline, are highly diverse because of a complex bedrock geology and glacial history. Back-barrier estuaries and lagoons occur within the northeast region, but the domiant type is the drowned-river valley, often with rocky shores. Tidal range and mean depth of northeast estuaries are generally greater when compared to estuaries of the more southern U.S. Atlantic coast and Gulf of Mexico. Because of small estuarine drainage basins, low riverine flows, a bedrock substrate, and dense forest cover, sediment loads in northeast estuaries are generally quite low and water clarity is high. Tidal marshes, seagrass meadows, intertidal mudflats, and rocky shores represent major habitat types that fringe northeast estuaries, supporting commercially-important fauna, forage nekton and benthos, and coastal bird communities, while also serving as links between deeper estuarine waters and habitats through detritus-based pathways. Regarding land use and water quality trends, portions of the northeast have a history of over a century of intense urbanization as reflected in increased total nitrogen and total phosphorus loadings to estuaries, with wastewater treatment facilities and atmospheric deposition being major sources. Agricultural inputs are relatively minor throughout the northeast, with relative importance increasing for coastal plain estuaries. Identifying geographic signatures provides an objective means for comparing the structure, function, and processes of estuaries along latitudinal gradients.  相似文献   

Magnetostratigraphic results from the eastern Arctic Ocean: AMS ¹⁴C ages and relative palaeointensity data of the Mono Lake and Laschamp geomagnetic reversal excursions     

Norbert R. Nowaczyk  & Jochen Knies 《Geophysical Journal International》2000,140(1):185-197

A new high-resolution magnetostratigraphic record from the eastern Arctic Ocean has yielded further evidence for the existence of the Laschamp excursion (37–35  ka), the Mono Lake excursion (27–25.5  ka) and possibly another very short excursion (22  ka) inferred from steep negative inclinations. Ages are based on nine AMS (accelerator mass spectrometry) ¹⁴C dates, oxygen isotope stratigraphy and correlation with ODP site 983. Estimates of relative palaeointensity variations for the time interval from 80 to 10  ka have revealed that the documented geomagnetic excursions are linked to large fluctuations of the relative palaeointensity. The lowest values were obtained for the two excursions and the normal–reversed (N–R) and reversed–normal (R–N) transitions of the Laschamp polarity excursion, which itself is characterized by a slight increase of relative palaeointensity during its reversed state. The results are in general agreement with palaeointensity studies from other regions, indicating that these fluctuations could be global phenomena and that the geomagnetic field of the Brunhes Chron was very variable in amplitude as well as in geometry. The new result is one of the rare records comprising large directional as well as large relative palaeointensity variations.  相似文献   

Photoelectric photometry of comets in the system of standard IHW filters and the special case of comet P/Halley     

B. Stecklum  W. Pfau  M. Hesse 《Astronomische Nachrichten》1987,308(4):239-246

Magnitudes of comets P/Giacobini-Zinner (1984e), P/Halley (1982i), P/Hartley-Good (1985 1), and Thiele (1985 m) in the bandpasses of the standard IHW comet filters are presented. For comet P/Halley production rates for CN, C₃, C₂, and solids were derived. For the gaseous components these show a strong dependence on heliocentric distance. The dependence is less steep for the solids which may be due to relatively pronounced backscattering properties in case of comet P/Halley. During one night (1985 Dec. 22/23) intensity profiles along three sections through the coma of comet P/Halley were measured. Compared with theoretical profiles they show a global anisotropy of the coma and possibly local structure.  相似文献   

A watershed nitrogen and phosphorus balance: The upper Potomac River basin   总被引：1，自引：0，他引：1  

Norbert A. Jaworski  Peter M. Groffman  Aimee A. Keller  Jan C. Prager 《Estuaries and Coasts》1992,15(1):83-95

Nitrogen and phosphorus mass balances were estimated for the portion of the Potomac River basin watershed located above Washington, D.C. The total nitrogen (N) balance included seven input tource terms, six sinks, and one “change-in-storage” term, but was simplified to five input terms and three output terms. The phosphorus (P) balance had four input and three output terms. The estimated balances are based on watershed data from seven information sources. Major sources of nitrogen are amimal waste and atmospheric deposition. The major sources of phosphorus are animal waste and fertilizer. The major sink, for nitrogen is combined denitrification, volatilization, and change-in-storage. The major sink for phosphorus is change-in-storage. River exports of N and P were 17% and 8%, respectively, of the total N and P inputs. Over 60% of the N and P were volatilized or stored. The major input and output terms on the budget are estimated from direct measurements, but the change-in-storage term is calculated by difference. The factors regulating retention and storage processes are discussed and research needs are identified.  相似文献   

Basiswerte fossiler Kohlenwasserstoffe im Nordost-Atlantik     

Dr. Norbert Theobald  Wilfried Lange  Kirsten Jerzycki-Brandes 《Ocean Dynamics》1991,44(1):17-33

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Correlation between rainfall and dust occurrence at mildura,Australia: The difference between local and source area rainfalls     

B. Yu  D. T. Neil  P. P. Hesse 《地球表面变化过程与地形》1992,17(7):723-727

In studies of temporal variation in dust activity, rainfall recorded at the same location as the dust events (local rainfall) has commonly been used as a climatic control variable. The main objectives of this note are to test the validity of using local rainfall and to determine the improvement in the relationship between rainfall and dust activity that could be achieved by using regional rainfall in the dust source area. For the period 1960-1989 at Mildura, Australia, the likely dust source area was identified by analysing wind direction during dust events. It was found that a marked improvement in the correlation between dust activity and antecedent rainfall can be achieved by using the regional source area rainfall rather than local rainfall. The improved correlation suggests that widespread drought is more important than local below-average rainfall in intensifying dust activity.  相似文献