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96 Nutrient Cycling

Part 8. Water Quality and Biogeochemistry

  1. Anthony C Edwards1,2,
  2. Robert G Wetzel3,†,†

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa098

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Edwards, A. C. and Wetzel, R. G. 2006. Nutrient Cycling. Encyclopedia of Hydrological Sciences. 8:96.

Author Information

  1. 1

    Macaulay Institute, Catchment Management Group, Aberdeen, UK

  2. 2

    Nether Backhill, Aberdeen, UK

  3. 3

    The University of North Carolina, Department of Environmental Sciences and Engineering, Chapel Hill, NC, US

  1. Deceased April 18, 2005

Publication History

  1. Published Online: 15 APR 2006


Nutrient concentrations within aquatic ecosystems have increased markedly during the last fifty years due to a variety of causes. Significant changes to the rates of nutrient cycling, particularly of nitrogen and phosphorus, have influenced their biological availability on a global scale. Three broad groupings of processes that directly influence nutrient cycling within freshwaters are described. Retention modifies the availability of nutrients for transport, while selectivity between individual chemical species results in preferential uptake and/or transport, and finally transformation processes alter the physical state or reactivity of particular nutrients. Differences in spatial and temporal dynamics of delivery and transport mechanisms among individual nutrients have caused variable relative changes in nitrogen and phosphorus concentrations and fluxes. These composite dynamic factors make it difficult to couple causal relationships between nutrient sources and their impacts.


  • nitrogen;
  • phosphorus;
  • nutrient cycling;
  • lakes;
  • rivers;
  • retention;
  • selectivity;
  • transformation;
  • source apportionment