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  • 1
    Digitale Medien
    Digitale Medien
    Diatoms as indicators of water quality in some English urban lakes (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. The paper describes diatom communities from a series of linked urban lakes in relation to water chemistry and uses multivariate statistical techniques to show how indicator groups can he defined.2. Diatoms are classified into ecological groups using two-way species indicator analysis (TWINSPAN). Each ecological group is associated with a specific range of water-quality conditions. The headwater stream environments are differentiated from the lake habitats at level 1. At level 2 of TWINSPAN. the sampling sites are grouped into five ecological groups, according to their water chemistry and irrespective of the time of year.3. Detrended correspondence analysis (DCA) and principal components analysis (PCA) provide two statistically independent methods of assessing the environmental gradients along which the ecological groups are distributed. The most important physico-chemical parameters are total hardness, specific conductance and pH, followed by phosphates and nitrates.4. Ecological groups I-V correspond to an environmental gradient ranging from the forested headwaters, which are acidic, of low specific conductance, total hardness and nutrient content, through the urban lakes, which are alkaline and of relatively high total hardness, specific conductance and nutrient content.5. Twelve site groups are identified at level 3 of TWINSPAN, each of which corresponds to a narrower range of water-quality conditions within the ecological groupings. A specific diatom assemblage is associated with each site group.6. Benthic diatoms form an integral part of the diatom assemblages found in the water column and this is identified as a topic for further study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00268.x
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  • 2
    Digitale Medien
    Digitale Medien
    The seasonal response of diatom communities to variable water quality in some English urban lakes (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. Five diatom assemblages and their corresponding site groups were associated with the urban lakes. When treated as a single dataset, DC A and PCA grouped these diatom assemblages along an environmental gradient from circum natural. dilute waters to strongly alkaline, concentrated, nutrient-rich waters.2. When treated as individual datasets, 75% of the known variance was explained by the first axis of DCA in all five diatom assemblages; this indicated the existence of a strong primary environmental gradient. The PCA results showed that the identity of this primary environmental gradient can be different for each assemblage.3. The statistical analyses showed that the physicochemical gradients were continuous and not discrete. Nevertheless, fine-scale analysis can identify smaller, more precise species and site groups.4. Two types of species response could be identified within most sub-assemblages in the urban lakes: the first was a quasi-seasonal response and was characterized by a gradual rise to a peak relative abundance of one dominant or several co-dominant species which could be sustained for a period of weeks before a gradual decline. A quasi-seasonal response was sometimes interrupted by a storm response. The storm response was characterized by a sudden increase in the relative abundance of one or more diatom species following a storm, after which the species declined to pre-storm abundances within 7 days.5. The effects of urban runoff on the water quality of urban lakes can override the effects of true seasonal factors such as water temperature and day length on the relative abundance of species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00269.x
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  • 3
    Digitale Medien
    Digitale Medien
    Late Quaternary history of the Nile (1980)
    [s.l.] : Nature Publishing Group
    Nature 288 (1980), S. 50-55 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] During the intertropical cold dry phase from ∼20,000 to 12,500 yr BP, the aggrading Nile was a braided, highly seasonal river. With a headwaters change to warmer, wetter conditions, it became an incised, sinuous, suspended load river. Overflow from Lake Victoria and severe floods in Egypt ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/288050a0
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  • 4
    Digitale Medien
    Digitale Medien
    Evolution of Lake Abhé (Ethiopia and TFAI), from 70,000 b.p. (1977)
    [s.l.] : Nature Publishing Group
    Nature 265 (1977), S. 42-45 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The results come from a multidisciplinary 5-yr project, and supporting detail is available elsewhere1. Analyses of diatom associations, which are sensitive indicators of ecological conditions, were carried out on 492 samples, and supplemented toy convergent evidence from sedimentary facies and ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/265042a0
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  • 5
    Digitale Medien
    Digitale Medien
    Plio–Pleistocene environments at Gadeb prehistoric site, Ethiopia (1979)
    [s.l.] : Nature Publishing Group
    Nature 282 (1979), S. 29-33 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Widespread artefact-bearing gravels overlie Pliocene diatomites in the plain of Gadeb (7°02′–7°13′N, 39° 15′–39°28′E) at 2,300 m in east-central Ethiopia. The diatomites are from 2.7 to 2.35 Myr old, and the bulk of the Developed Oldowan and ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/282029a0
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  • 6
    Digitale Medien
    Digitale Medien
    Abrupt post-glacial climate events in West Asia and North Africa monsoon domains
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 126 (1994), S. 435-456 
    Details
    ISSN: 0012-821X
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/0012-821X(94)90123-6
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  • 7
    Digitale Medien
    Digitale Medien
    The CASPIA project: diatoms, salt lakes, and environmental change (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 191-196 
    Details
    ISSN: 1573-0417
    Schlagwort(e): diatoms ; saline lakes ; palaeolimnology ; palaeoclimate ; transfer functions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract The Climate and Salinity (CASPIA) Project is concerned with diatoms as environmental indicators in inland waters and their use in reconstructing salinity and major ion composition from fossil diatom assemblages in lake sediments. By comparing saline lake diatom floras from around the world the project aims to establish a common, harmonised approach to sample collection, diatom identification and nomenclature, and to develop techniques for numerical analysis and data storage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00678020
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  • 8
    Digitale Medien
    Digitale Medien
    A 13,000-year climate record from western Tibet (1991)
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 742-745 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The 1989 Sino-French expedition (Kunlun-Karakorum Programme, CNRS-Academia Sinica) investigated lakes in western Tibet (mean elevation 〉 5,000m above sea level), the coldest and driest part of the Tibetan-Qinghai plateau11. Located in the rain shadow of two high mountain ranges, the Kunlun and ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/353742a0
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  • 9
    Digitale Medien
    Digitale Medien
    Freshwater to marine-like environments from Holocene lakes in northern Sahara (1985)
    [s.l.] : Nature Publishing Group
    Nature 317 (1985), S. 608-610 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Stratified carbonaceous, sediments lie in closed depressions of the hamada plateau. Some of them formed when dry valleys were blocked by the displacement of sand dunes in th Great Western Erg. At the present time,, the water table of the aquifer is at about -50 m. The topography of the basins and ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/317608a0
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  • 10
    Digitale Medien
    Digitale Medien
    Relation between century-scale Holocene arid intervals in tropical and temperate zones (1995)
    [s.l.] : Nature Publishing Group
    Nature 373 (1995), S. 134-137 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Tigalmamine (32° 54' N, 5° 21' W, area 6 ha, maximum depth 16m) is the largest of a group of solution lakes in Lower Lias dolomite bedrock, at 1,628 m above sea level in the Middle Atlas of Morocco. The lake (Table 1) is fed by ground water, surface springs, and winter runoff ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/373134a0
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