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  • 1985-1989  (3)
  • 1880-1889
  • Aquatic ecosystems  (2)
  • 14C uptake  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Summer total phosphorus in lakes: A map of Minnesota, Wisconsin, and Michigan, USA (1988)
    Springer
    Environmental management 12 (1988), S. 815-825 
    Details
    ISSN: 1432-1009
    Keywords: Lake restoration ; Lake management ; Eutrophication ; Water quality ; Trophic state ; Regionalization ; Total phosphorus map ; Aquatic ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A map of summer total phosphorus in lakes has been compiled for Minnesota, Wisconsin, and Michigan to clarify regional patterns in attainable lake trophic state. Total phosphorus was used as a measure of lake trophic state because: (1) phosphorus plays a central role in controlling the overall fertility of most lakes, (2) total phosphorus values are available for a great number of lakes, and (3) phosphorus is measured in a consistent manner. The maps were compiled using patterns of total phosphorus data and observed associations between these data and geographic characteristics including physiography, land use, geology, and soils. Regions depicted on the map represent areas of similarity in phosphorus concentrations in lakes, or similarity in the mosaic of values, as compared to adjacent areas. Within each region, differences in total phosphorus can be compared to natural and anthropogenic factors to determine the types of lakes representative of each region, the factors associated with differences in quality, and the realistically attainable phosphorus levels for each type of lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01867609
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Regional reference sites: a method for assessing stream potentials (1986)
    Springer
    Environmental management 10 (1986), S. 629-635 
    Details
    ISSN: 1432-1009
    Keywords: Aquatic ecosystems ; Aquatic ecoregions ; Control sites ; Stream classification ; Land classification ; Water body standards
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Field assessments of impacted streams require a control or at least an unbiased estimate of attainable conditions. Control sites, such as upstream/downstream or wilderness sites, have proven inadequate for assessing attainable ecological conditions where the control streams differ naturally from the impacted streams to a considerable degree or where different disturbances exist than those being studied. Relatively undisturbed reference sites with watersheds in areas having the same land-surface form, soil, potential natural vegetation, and land use as are predominant in large, relatively homogeneous regions are suggested as alternative control sites. These areas are considered typical of the region and therefore the sites also are considered typical of the region because their watersheds exhibit all the terrestrial variables that make that region a region. The logical basis for developing regional reference sites lies in the ability to group watersheds and common stream types into regions by integrating available maps of terrestrial variables that influence streams. Relatively undisturbed reference sites can be selected from typical areas of the regions and from transition zones where one or two of the terrestrial variables are not the predominant one(s) of the region. These reference sites are useful for estimating attainable conditions, for evaluating temporal and spatial changes in ecological integrity, for classifying attainable uses of streams, and for setting biological and environmental criteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01866767
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Light and dark uptake and loss of 14C: methodological problems with productivity measurements in oceanic waters (1989)
    Springer
    Hydrobiologia 173 (1989), S. 95-105 
    Details
    ISSN: 1573-5117
    Keywords: 14C uptake ; 14C loss ; productivity ; assimilation number ; oligotrophic water ; phytoplankton ; bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurements of the uptake and loss of 4C in the light and in the dark in the Tasman and Coral Seas have revealed methodological problems with the estimation of productivity in these waters. Rates of productivity estimated without replication, time series incubations and dark controls frequently overestimated the true rates of autotrophic production. The data showed unexpectedly high rates of both uptake and loss in the dark in oligotrophic waters. In oligotrophic oceanic waters, dark incorporation of 14C sometimes equalled the uptake of 14C in the light bottle. Rapid uptake of isotope in the dark controls appeared to be the result of rapid bacterial growth and metabolism. This problem was exacerbated by agitation of the sample before or during the incubation. Tropical samples were particularly susceptible to problems arising from the agitation of the samples. Latitudinal gradients of dark uptake and loss were revealed in these incubations. The loss of label during 8–12 hours in the dark (after 12 hr in the light) was as high as 50% in subtropical waters. The loss was frequently unmeasurable (〈 10%) in temperate waters. The time course of 14C uptake indicated active grazing in the bottles and suggested that most of the nighttime losses of label were due to grazing by microheterotrophs. Respiratory losses appeared to be small. Calculated values of the assimilation number (or photosynthetic capacity) which did not correct for dark 14C uptake were too high to be biochemically realistic. The errors were due to the heterotrophic uptake of label and the lack of dark controls. Rapid release of 14C in the dark after incubation in the light meant that the estimate of ‘productivity’ was dependant on the trophic state of the sample and on the period of incubation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015519
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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