@article{Weyhenmeyer2007Nitra-7200,
  year={2007},
  doi={10.4319/lo.2007.52.4.1346},
  title={Nitrate-depleted conditions on the increase in shallow northern European lakes},
  number={4},
  volume={52},
  journal={Limnology and Oceanography},
  pages={1346--1353},
  author={Weyhenmeyer, Gesa A. and Jeppesen, Erik and Adrian, Rita and Arvola, Lauri and Blenckner, Thorsten and Jankowski, Thomas and Jennings, Eleanor and Nỡges, Peeter and Nỡges, Tiina and Straile, Dietmar}
}

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    <dc:contributor>Nỡges, Peeter</dc:contributor>
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    <dc:contributor>Nỡges, Tiina</dc:contributor>
    <dc:contributor>Jennings, Eleanor</dc:contributor>
    <dc:creator>Straile, Dietmar</dc:creator>
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    <dc:contributor>Jankowski, Thomas</dc:contributor>
    <dc:creator>Adrian, Rita</dc:creator>
    <dcterms:title>Nitrate-depleted conditions on the increase in shallow northern European lakes</dcterms:title>
    <dc:contributor>Blenckner, Thorsten</dc:contributor>
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    <dcterms:abstract xml:lang="eng">We determined relative nitrate nitrogen (NO3-N) loss rates in 100 north mid-European lakes from late spring to summer by using the exponential function N2 = N1e -k(t2 - t2), where N1 and N2 are NO3-N concentrations at&lt;br /&gt;the beginning (t1) and the end (t2) of the time interval, respectively, and k is the specific NO3-N loss rate. We found that k decreased with increasing lake depth. Adjusting k to the lake depth (k adj), we observed that k adj was&lt;br /&gt;positively related to spring NO3-N concentrations, but this relationship became insignificant at mean lake depths exceeding 12.5 m. A relationship between k adj and spring NO3-N concentrations in lakes shallower than 12.5 m implies that changes in spring NO3-N concentrations influence the NO3-N loss rate and thereby summer NO3-N concentrations. Time series from one Estonian, one German, and 14 Swedish lakes shallower than 12.5 m since 1988 revealed that May to August NO3-N concentrations have decreased over time everywhere, and the number of time periods exhibiting a NO3-N depleted condition, i.e., NO3-N levels below 10 mg L21, in these lakes has tripled since 1988. We explained the decreasing NO3-N concentrations by a reduction in external nitrogen loading including atmospheric deposition, and by changes in climate. The observed prolongation of NO3-N depleted conditions might be one possible explanation for the increasing occurrence of nitrogen-fixing cyanobacteria in a variety of lake ecosystems.</dcterms:abstract>
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    <dc:contributor>Adrian, Rita</dc:contributor>
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    <dc:contributor>Arvola, Lauri</dc:contributor>
    <dc:creator>Jankowski, Thomas</dc:creator>
    <dc:creator>Nỡges, Tiina</dc:creator>
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    <dc:contributor>Weyhenmeyer, Gesa A.</dc:contributor>
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    <dc:creator>Jeppesen, Erik</dc:creator>
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    <dc:rights>Attribution-NonCommercial-NoDerivs 2.0 Generic</dc:rights>
    <dc:creator>Jennings, Eleanor</dc:creator>
    <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:32:36Z</dc:date>
    <dc:language>eng</dc:language>
    <dc:creator>Arvola, Lauri</dc:creator>
    <dc:creator>Weyhenmeyer, Gesa A.</dc:creator>
    <dc:creator>Blenckner, Thorsten</dc:creator>
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    <dc:contributor>Jeppesen, Erik</dc:contributor>
    <dc:creator>Nỡges, Peeter</dc:creator>
    <dcterms:bibliographicCitation>First publ. in: Limnology and Oceanography, 52 (2007), 4, pp. 1346 1353</dcterms:bibliographicCitation>
    <dc:contributor>Straile, Dietmar</dc:contributor>
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    <dcterms:issued>2007</dcterms:issued>
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